Merge branch main (DRTVWR-582) into DRTVWR-567

# Conflicts:
#	indra/newview/app_settings/settings.xml
#	indra/newview/llinventoryfunctions.cpp
#	indra/newview/llinventoryfunctions.h
#	indra/newview/llinventorymodel.cpp
#	indra/newview/llinventoryobserver.cpp
#	indra/newview/llinventoryobserver.h
#	indra/newview/skins/default/xui/ja/floater_inventory_item_properties.xml

17 files changed, 890 insertions, 502 deletions

diff --git a/indra/llcommon/hbxxh.h b/indra/llcommon/hbxxh.h
index 236716722a..9c0e9cf172 100644
--- a/indra/llcommon/hbxxh.h
+++ b/indra/llcommon/hbxxh.h
@@ -96,6 +96,15 @@ public:
         }
     }
 
+    // Make this class no-copy (it would be possible, with custom copy
+    // operators, but it is not trivially copyable, because of the mState
+    // pointer): it does not really make sense to allow copying it anyway,
+    // since all we care about is the resulting digest (so you should only
+    // need and care about storing/copying the digest and not a class
+    // instance).
+    HBXXH64(const HBXXH64&) noexcept = delete;
+    HBXXH64& operator=(const HBXXH64&) noexcept = delete;
+
     ~HBXXH64();
 
     void update(const void* buffer, size_t len);
@@ -199,6 +208,15 @@ public:
         }
     }
 
+    // Make this class no-copy (it would be possible, with custom copy
+    // operators, but it is not trivially copyable, because of the mState
+    // pointer): it does not really make sense to allow copying it anyway,
+    // since all we care about is the resulting digest (so you should only
+    // need and care about storing/copying the digest and not a class
+    // instance).
+    HBXXH128(const HBXXH128&) noexcept = delete;
+    HBXXH128& operator=(const HBXXH128&) noexcept = delete;
+
     ~HBXXH128();
 
     void update(const void* buffer, size_t len);
diff --git a/indra/llcommon/indra_constants.h b/indra/llcommon/indra_constants.h
index 10b98f49aa..679f79039b 100644
--- a/indra/llcommon/indra_constants.h
+++ b/indra/llcommon/indra_constants.h
@@ -345,6 +345,7 @@ const U8 CLICK_ACTION_PLAY = 5;
 const U8 CLICK_ACTION_OPEN_MEDIA = 6;
 const U8 CLICK_ACTION_ZOOM = 7;
 const U8 CLICK_ACTION_DISABLED = 8;
+const U8 CLICK_ACTION_IGNORE = 9;
 // DO NOT CHANGE THE SEQUENCE OF THIS LIST!!
 
 
diff --git a/indra/llcommon/lldefs.h b/indra/llcommon/lldefs.h
index 5c46f6a796..4e25001fff 100644
--- a/indra/llcommon/lldefs.h
+++ b/indra/llcommon/lldefs.h
@@ -167,48 +167,34 @@ const U32	MAXADDRSTR		= 17;		// 123.567.901.345 = 15 chars + \0 + 1 for good luc
 //
 // defined for U16, U32, U64, S16, S32, S64, :
 //   llclampb(a)     // clamps a to [0 .. 255]
-//   				   
-
-template <typename T1, typename T2> 
-inline auto llmax(T1 d1, T2 d2)
-{
-	return (d1 > d2) ? d1 : d2;
-}
-
-template <typename T1, typename T2, typename T3> 
-inline auto llmax(T1 d1, T2 d2, T3 d3)
-{
-	auto r = llmax(d1,d2);
-	return llmax(r, d3);
-}
+//
 
-template <typename T1, typename T2, typename T3, typename T4> 
-inline auto llmax(T1 d1, T2 d2, T3 d3, T4 d4)
+// recursion tail
+template <typename T>
+inline auto llmax(T data)
 {
-	auto r1 = llmax(d1,d2);
-	auto r2 = llmax(d3,d4);
-	return llmax(r1, r2);
+    return data;
 }
 
-template <typename T1, typename T2> 
-inline auto llmin(T1 d1, T2 d2)
+template <typename T0, typename T1, typename... Ts> 
+inline auto llmax(T0 d0, T1 d1, Ts... rest)
 {
-	return (d1 < d2) ? d1 : d2;
+    auto maxrest = llmax(d1, rest...);
+    return (d0 > maxrest)? d0 : maxrest;
 }
 
-template <typename T1, typename T2, typename T3> 
-inline auto llmin(T1 d1, T2 d2, T3 d3)
+// recursion tail
+template <typename T>
+inline auto llmin(T data)
 {
-	auto r = llmin(d1,d2);
-	return (r < d3 ? r : d3);
+    return data;
 }
 
-template <typename T1, typename T2, typename T3, typename T4> 
-inline auto llmin(T1 d1, T2 d2, T3 d3, T4 d4)
+template <typename T0, typename T1, typename... Ts> 
+inline auto llmin(T0 d0, T1 d1, Ts... rest)
 {
-	auto r1 = llmin(d1,d2);
-	auto r2 = llmin(d3,d4);
-	return llmin(r1, r2);
+    auto minrest = llmin(d1, rest...);
+    return (d0 < minrest) ? d0 : minrest;
 }
 
 template <typename A, typename MIN, typename MAX> 
diff --git a/indra/llcommon/llleap.cpp b/indra/llcommon/llleap.cpp
index c87c0758fe..259f5bc505 100644
--- a/indra/llcommon/llleap.cpp
+++ b/indra/llcommon/llleap.cpp
@@ -204,30 +204,35 @@ public:
         LLSD packet(LLSDMap("pump", pump)("data", data));
 
         std::ostringstream buffer;
-        buffer << LLSDNotationStreamer(packet);
+        // SL-18330: for large data blocks, it's much faster to parse binary
+        // LLSD than notation LLSD. Use serialize(LLSD_BINARY) rather than
+        // directly calling LLSDBinaryFormatter because, unlike the latter,
+        // serialize() prepends the relevant header, needed by a general-
+        // purpose LLSD parser to distinguish binary from notation.
+        LLSDSerialize::serialize(packet, buffer, LLSDSerialize::LLSD_BINARY,
+                                 LLSDFormatter::OPTIONS_NONE);
 
 /*==========================================================================*|
         // DEBUGGING ONLY: don't copy str() if we can avoid it.
         std::string strdata(buffer.str());
         if (std::size_t(buffer.tellp()) != strdata.length())
         {
-            LL_ERRS("LLLeap") << "tellp() -> " << buffer.tellp() << " != "
+            LL_ERRS("LLLeap") << "tellp() -> " << static_cast<U64>(buffer.tellp()) << " != "
                               << "str().length() -> " << strdata.length() << LL_ENDL;
         }
         // DEBUGGING ONLY: reading back is terribly inefficient.
         std::istringstream readback(strdata);
         LLSD echo;
-        LLPointer<LLSDParser> parser(new LLSDNotationParser());
-        S32 parse_status(parser->parse(readback, echo, strdata.length()));
-        if (parse_status == LLSDParser::PARSE_FAILURE)
+        bool parse_status(LLSDSerialize::deserialize(echo, readback, strdata.length()));
+        if (! parse_status)
         {
-            LL_ERRS("LLLeap") << "LLSDNotationParser() cannot parse output of "
-                              << "LLSDNotationStreamer()" << LL_ENDL;
+            LL_ERRS("LLLeap") << "LLSDSerialize::deserialize() cannot parse output of "
+                              << "LLSDSerialize::serialize(LLSD_BINARY)" << LL_ENDL;
         }
         if (! llsd_equals(echo, packet))
         {
-            LL_ERRS("LLLeap") << "LLSDNotationParser() produced different LLSD "
-                              << "than passed to LLSDNotationStreamer()" << LL_ENDL;
+            LL_ERRS("LLLeap") << "LLSDSerialize::deserialize() returned different LLSD "
+                              << "than passed to LLSDSerialize::serialize()" << LL_ENDL;
         }
 |*==========================================================================*/
 
@@ -314,9 +319,17 @@ public:
             LL_DEBUGS("LLLeap") << "needed " << mExpect << " bytes, got "
                                 << childout.size() << ", parsing LLSD" << LL_ENDL;
             LLSD data;
+#if 1
+            // specifically require notation LLSD from child
             LLPointer<LLSDParser> parser(new LLSDNotationParser());
             S32 parse_status(parser->parse(childout.get_istream(), data, mExpect));
             if (parse_status == LLSDParser::PARSE_FAILURE)
+#else
+            // SL-18330: accept any valid LLSD serialization format from child
+            // Unfortunately this runs into trouble we have not yet debugged.
+            bool parse_status(LLSDSerialize::deserialize(data, childout.get_istream(), mExpect));
+            if (! parse_status)
+#endif
             {
                 bad_protocol("unparseable LLSD data");
             }
diff --git a/indra/llcommon/llmd5.cpp b/indra/llcommon/llmd5.cpp
index 9b2a2bab60..0abe817f1d 100644
--- a/indra/llcommon/llmd5.cpp
+++ b/indra/llcommon/llmd5.cpp
@@ -96,7 +96,7 @@ LLMD5::LLMD5()
 // operation, processing another message block, and updating the
 // context.
 
-void LLMD5::update (const uint1 *input, const size_t input_length) {
+void LLMD5::update (const uint8_t *input, const size_t input_length) {
 
   size_t input_index, buffer_index;
   size_t buffer_space;                // how much space is left in buffer
@@ -189,7 +189,7 @@ void LLMD5::finalize (){
 
   unsigned char bits[8];		/* Flawfinder: ignore */
   size_t index, padLen;
-  static uint1 PADDING[64]={
+  static uint8_t PADDING[64]={
     0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
@@ -201,8 +201,8 @@ void LLMD5::finalize (){
   }
 
   // Save number of bits.
-  // Treat count, a uint64_t, as uint4[2].
-  encode (bits, reinterpret_cast<uint4*>(&count), 8);
+  // Treat count, a uint64_t, as uint32_t[2].
+  encode (bits, reinterpret_cast<uint32_t*>(&count), 8);
 
   // Pad out to 56 mod 64.
   index = size_t((count >> 3) & 0x3f);
@@ -412,7 +412,7 @@ Rotation is separate from addition to prevent recomputation.
 // LLMD5 basic transformation. Transforms state based on block.
 void LLMD5::transform (const U8 block[64]){
 
-  uint4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
+  uint32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];
 
   decode (x, block, 64);
 
@@ -496,38 +496,38 @@ void LLMD5::transform (const U8 block[64]){
   state[3] += d;
 
   // Zeroize sensitive information.
-  memset ( (uint1 *) x, 0, sizeof(x));
+  memset ( (uint8_t *) x, 0, sizeof(x));
 
 }
 
 
 
-// Encodes input (UINT4) into output (unsigned char). Assumes len is
+// Encodes input (uint32_t) into output (unsigned char). Assumes len is
 // a multiple of 4.
-void LLMD5::encode (uint1 *output, const uint4 *input, const size_t len) {
+void LLMD5::encode (uint8_t *output, const uint32_t *input, const size_t len) {
 
   size_t i, j;
 
   for (i = 0, j = 0; j < len; i++, j += 4) {
-    output[j]   = (uint1)  (input[i] & 0xff);
-    output[j+1] = (uint1) ((input[i] >> 8) & 0xff);
-    output[j+2] = (uint1) ((input[i] >> 16) & 0xff);
-    output[j+3] = (uint1) ((input[i] >> 24) & 0xff);
+    output[j]   = (uint8_t)  (input[i] & 0xff);
+    output[j+1] = (uint8_t) ((input[i] >> 8) & 0xff);
+    output[j+2] = (uint8_t) ((input[i] >> 16) & 0xff);
+    output[j+3] = (uint8_t) ((input[i] >> 24) & 0xff);
   }
 }
 
 
 
 
-// Decodes input (unsigned char) into output (UINT4). Assumes len is
+// Decodes input (unsigned char) into output (uint32_t). Assumes len is
 // a multiple of 4.
-void LLMD5::decode (uint4 *output, const uint1 *input, const size_t len){
+void LLMD5::decode (uint32_t *output, const uint8_t *input, const size_t len){
 
   size_t i, j;
 
   for (i = 0, j = 0; j < len; i++, j += 4)
-    output[i] = ((uint4)input[j]) | (((uint4)input[j+1]) << 8) |
-      (((uint4)input[j+2]) << 16) | (((uint4)input[j+3]) << 24);
+    output[i] = ((uint32_t)input[j]) | (((uint32_t)input[j+1]) << 8) |
+      (((uint32_t)input[j+2]) << 16) | (((uint32_t)input[j+3]) << 24);
 }
 
 
diff --git a/indra/llcommon/llmd5.h b/indra/llcommon/llmd5.h
index 8530dc0389..7d6373c20c 100644
--- a/indra/llcommon/llmd5.h
+++ b/indra/llcommon/llmd5.h
@@ -67,6 +67,8 @@ documentation and/or software.
 
 */
 
+#include <cstdint>                  // uint32_t et al.
+
 // use for the raw digest output
 const int MD5RAW_BYTES = 16;
 
@@ -75,18 +77,13 @@ const int MD5HEX_STR_SIZE = 33;  // char hex[MD5HEX_STR_SIZE]; with null
 const int MD5HEX_STR_BYTES = 32; // message system fixed size
 
 class LL_COMMON_API LLMD5 {
-// first, some types:
-  typedef unsigned       int uint4; // assumes integer is 4 words long
-  typedef unsigned short int uint2; // assumes short integer is 2 words long
-  typedef unsigned      char uint1; // assumes char is 1 word long
-
 // how many bytes to grab at a time when checking files
   static const int BLOCK_LEN;
 
 public:
 // methods for controlled operation:
   LLMD5              ();  // simple initializer
-  void  update     (const uint1 *input, const size_t input_length);
+  void  update     (const uint8_t *input, const size_t input_length);
   void  update     (std::istream& stream);
   void  update     (FILE *file);
   void  update     (const std::string& str);
@@ -109,19 +106,19 @@ private:
 
 
 // next, the private data:
-  uint4 state[4];
+  uint32_t state[4];
   uint64_t count;     // number of *bits*, mod 2^64
-  uint1 buffer[64];   // input buffer
-  uint1 digest[16];
-  uint1 finalized;
+  uint8_t buffer[64];   // input buffer
+  uint8_t digest[16];
+  uint8_t finalized;
 
 // last, the private methods, mostly static:
   void init             ();               // called by all constructors
-  void transform        (const uint1 *buffer);  // does the real update work.  Note 
+  void transform        (const uint8_t *buffer);  // does the real update work.  Note 
                                           // that length is implied to be 64.
 
-  static void encode    (uint1 *dest, const uint4 *src, const size_t length);
-  static void decode    (uint4 *dest, const uint1 *src, const size_t length);
+  static void encode    (uint8_t *dest, const uint32_t *src, const size_t length);
+  static void decode    (uint32_t *dest, const uint8_t *src, const size_t length);
 
 };
 
diff --git a/indra/llcommon/llsdserialize.cpp b/indra/llcommon/llsdserialize.cpp
index b7e316da10..3db456ddb3 100644
--- a/indra/llcommon/llsdserialize.cpp
+++ b/indra/llcommon/llsdserialize.cpp
@@ -48,6 +48,7 @@
 #endif
 
 #include "lldate.h"
+#include "llmemorystream.h"
 #include "llsd.h"
 #include "llstring.h"
 #include "lluri.h"
@@ -64,6 +65,23 @@ const std::string LLSD_NOTATION_HEADER("llsd/notation");
 #define windowBits 15
 #define ENABLE_ZLIB_GZIP 32
 
+// If we published this in llsdserialize.h, we could use it in the
+// implementation of LLSDOStreamer's operator<<().
+template <class Formatter>
+void format_using(const LLSD& data, std::ostream& ostr,
+                  LLSDFormatter::EFormatterOptions options=LLSDFormatter::OPTIONS_PRETTY_BINARY)
+{
+    LLPointer<Formatter> f{ new Formatter };
+    f->format(data, ostr, options);
+}
+
+template <class Parser>
+S32 parse_using(std::istream& istr, LLSD& data, size_t max_bytes, S32 max_depth=-1)
+{
+    LLPointer<Parser> p{ new Parser };
+    return p->parse(istr, data, max_bytes, max_depth);
+}
+
 /**
  * LLSDSerialize
  */
@@ -86,10 +104,10 @@ void LLSDSerialize::serialize(const LLSD& sd, std::ostream& str, ELLSD_Serialize
 		f = new LLSDXMLFormatter;
 		break;
 
-    case LLSD_NOTATION:
-        str << "<? " << LLSD_NOTATION_HEADER << " ?>\n";
-        f = new LLSDNotationFormatter;
-        break;
+	case LLSD_NOTATION:
+		str << "<? " << LLSD_NOTATION_HEADER << " ?>\n";
+		f = new LLSDNotationFormatter;
+		break;
 
 	default:
 		LL_WARNS() << "serialize request for unknown ELLSD_Serialize" << LL_ENDL;
@@ -104,18 +122,37 @@ void LLSDSerialize::serialize(const LLSD& sd, std::ostream& str, ELLSD_Serialize
 // static
 bool LLSDSerialize::deserialize(LLSD& sd, std::istream& str, llssize max_bytes)
 {
-	LLPointer<LLSDParser> p = NULL;
 	char hdr_buf[MAX_HDR_LEN + 1] = ""; /* Flawfinder: ignore */
-	int i;
-	int inbuf = 0;
-	bool legacy_no_header = false;
 	bool fail_if_not_legacy = false;
-	std::string header;
 
-	/*
-	 * Get the first line before anything.
-	 */
-	str.get(hdr_buf, MAX_HDR_LEN, '\n');
+    /*
+     * Get the first line before anything. Don't read more than max_bytes:
+     * this get() overload reads no more than (count-1) bytes into the
+     * specified buffer. In the usual case when max_bytes exceeds
+     * sizeof(hdr_buf), get() will read no more than sizeof(hdr_buf)-2.
+     */
+    llssize max_hdr_read = MAX_HDR_LEN;
+	if (max_bytes != LLSDSerialize::SIZE_UNLIMITED)
+	{
+        max_hdr_read = llmin(max_bytes + 1, max_hdr_read);
+	}
+    str.get(hdr_buf, max_hdr_read, '\n');
+	auto inbuf = str.gcount();
+
+	// https://en.cppreference.com/w/cpp/io/basic_istream/get
+	// When the get() above sees the specified delimiter '\n', it stops there
+	// without pulling it from the stream. If it turns out that the stream
+	// does NOT contain a header, and the content includes meaningful '\n',
+	// it's important to pull that into hdr_buf too.
+	if (inbuf < max_bytes && str.get(hdr_buf[inbuf]))
+	{
+		// got the delimiting '\n'
+		++inbuf;
+		// None of the following requires that hdr_buf contain a final '\0'
+		// byte. We could store one if needed, since even the incremented
+		// inbuf won't exceed sizeof(hdr_buf)-1, but there's no need.
+	}
+	std::string header{ hdr_buf, static_cast<std::string::size_type>(inbuf) };
 	if (str.fail())
 	{
 		str.clear();
@@ -123,79 +160,97 @@ bool LLSDSerialize::deserialize(LLSD& sd, std::istream& str, llssize max_bytes)
 	}
 
 	if (!strncasecmp(LEGACY_NON_HEADER, hdr_buf, strlen(LEGACY_NON_HEADER))) /* Flawfinder: ignore */
+	{	// Create a LLSD XML parser, and parse the first chunk read above.
+		LLSDXMLParser x;
+		x.parsePart(hdr_buf, inbuf);	// Parse the first part that was already read
+		auto parsed = x.parse(str, sd, max_bytes - inbuf); // Parse the rest of it
+		// Formally we should probably check (parsed != PARSE_FAILURE &&
+		// parsed > 0), but since PARSE_FAILURE is -1, this suffices.
+		return (parsed > 0);
+	}
+
+	if (fail_if_not_legacy)
 	{
-		legacy_no_header = true;
-		inbuf = (int)str.gcount();
+		LL_WARNS() << "deserialize LLSD parse failure" << LL_ENDL;
+		return false;
 	}
-	else
+
+	/*
+	* Remove the newline chars
+	*/
+	std::string::size_type lastchar = header.find_last_not_of("\r\n");
+	if (lastchar != std::string::npos)
 	{
-		if (fail_if_not_legacy)
-			goto fail;
-		/*
-		* Remove the newline chars
-		*/
-		for (i = 0; i < MAX_HDR_LEN; i++)
-		{
-			if (hdr_buf[i] == 0 || hdr_buf[i] == '\r' ||
-				hdr_buf[i] == '\n')
-			{
-				hdr_buf[i] = 0;
-				break;
-			}
-		}
-		header = hdr_buf;
+		// It's important that find_last_not_of() returns size_type, which is
+		// why lastchar explicitly declares the type above. erase(size_type)
+		// erases from that offset to the end of the string, whereas
+		// erase(iterator) erases only a single character.
+		header.erase(lastchar+1);
+	}
 
-		std::string::size_type start = std::string::npos;
-		std::string::size_type end = std::string::npos;
-		start = header.find_first_not_of("<? ");
-		if (start != std::string::npos)
+	// trim off the <? ... ?> header syntax
+	auto start = header.find_first_not_of("<? ");
+	if (start != std::string::npos)
+	{
+		auto end = header.find_first_of(" ?", start);
+		if (end != std::string::npos)
 		{
-			end = header.find_first_of(" ?", start);
+			header = header.substr(start, end - start);
+			ws(str);
 		}
-		if ((start == std::string::npos) || (end == std::string::npos))
-			goto fail;
-
-		header = header.substr(start, end - start);
-		ws(str);
 	}
 	/*
 	 * Create the parser as appropriate
 	 */
-	if (legacy_no_header)
-	{	// Create a LLSD XML parser, and parse the first chunk read above
-		LLSDXMLParser* x = new LLSDXMLParser();
-		x->parsePart(hdr_buf, inbuf);	// Parse the first part that was already read
-		x->parseLines(str, sd);			// Parse the rest of it
-		delete x;
-		return true;
-	}
-
-	if (header == LLSD_BINARY_HEADER)
+	if (0 == LLStringUtil::compareInsensitive(header, LLSD_BINARY_HEADER))
 	{
-		p = new LLSDBinaryParser;
+		return (parse_using<LLSDBinaryParser>(str, sd, max_bytes-inbuf) > 0);
 	}
-	else if (header == LLSD_XML_HEADER)
+	else if (0 == LLStringUtil::compareInsensitive(header, LLSD_XML_HEADER))
 	{
-		p = new LLSDXMLParser;
+		return (parse_using<LLSDXMLParser>(str, sd, max_bytes-inbuf) > 0);
 	}
-	else if (header == LLSD_NOTATION_HEADER)
+	else if (0 == LLStringUtil::compareInsensitive(header, LLSD_NOTATION_HEADER))
 	{
-		p = new LLSDNotationParser;
+		return (parse_using<LLSDNotationParser>(str, sd, max_bytes-inbuf) > 0);
 	}
-	else
+	else // no header we recognize
 	{
-		LL_WARNS() << "deserialize request for unknown ELLSD_Serialize" << LL_ENDL;
-	}
-
-	if (p.notNull())
-	{
-		p->parse(str, sd, max_bytes);
-		return true;
+		LLPointer<LLSDParser> p;
+		if (inbuf && hdr_buf[0] == '<')
+		{
+			// looks like XML
+			LL_DEBUGS() << "deserialize request with no header, assuming XML" << LL_ENDL;
+			p = new LLSDXMLParser;
+		}
+		else
+		{
+			// assume notation
+			LL_DEBUGS() << "deserialize request with no header, assuming notation" << LL_ENDL;
+			p = new LLSDNotationParser;
+		}
+		// Since we've already read 'inbuf' bytes into 'hdr_buf', prepend that
+		// data to whatever remains in 'str'.
+		LLMemoryStreamBuf already(reinterpret_cast<const U8*>(hdr_buf), inbuf);
+		cat_streambuf prebuff(&already, str.rdbuf());
+		std::istream  prepend(&prebuff);
+#if 1
+		return (p->parse(prepend, sd, max_bytes) > 0);
+#else
+		// debugging the reconstituted 'prepend' stream
+		// allocate a buffer that we hope is big enough for the whole thing
+		std::vector<char> wholemsg((max_bytes == size_t(SIZE_UNLIMITED))? 1024 : max_bytes);
+		prepend.read(wholemsg.data(), std::min(max_bytes, wholemsg.size()));
+		LLMemoryStream replay(reinterpret_cast<const U8*>(wholemsg.data()), prepend.gcount());
+		auto success{ p->parse(replay, sd, prepend.gcount()) > 0 };
+		{
+			LL_DEBUGS() << (success? "parsed: $$" : "failed: '")
+						<< std::string(wholemsg.data(), llmin(prepend.gcount(), 100)) << "$$"
+						<< LL_ENDL;
+		}
+		return success;
+#endif
 	}
-
-fail:
-	LL_WARNS() << "deserialize LLSD parse failure" << LL_ENDL;
-	return false;
 }
 
 /**
@@ -2193,9 +2248,9 @@ LLUZipHelper::EZipRresult LLUZipHelper::unzip_llsd(LLSD& data, std::istream& is,
 LLUZipHelper::EZipRresult LLUZipHelper::unzip_llsd(LLSD& data, const U8* in, S32 size)
 {
 	U8* result = NULL;
-	U32 cur_size = 0;
+	llssize cur_size = 0;
 	z_stream strm;
-		
+
 	constexpr U32 CHUNK = 1024 * 512;
 
 	static thread_local std::unique_ptr<U8[]> out;
@@ -2388,7 +2443,7 @@ U8* unzip_llsdNavMesh( bool& valid, size_t& outsize, std::istream& is, S32 size
 	return result;
 }
 
-char* strip_deprecated_header(char* in, U32& cur_size, U32* header_size)
+char* strip_deprecated_header(char* in, llssize& cur_size, llssize* header_size)
 {
 	const char* deprecated_header = "<? LLSD/Binary ?>";
 	constexpr size_t deprecated_header_size = 17;
diff --git a/indra/llcommon/llsdserialize.h b/indra/llcommon/llsdserialize.h
index 2f12c6d1ff..676b7bfd6a 100644
--- a/indra/llcommon/llsdserialize.h
+++ b/indra/llcommon/llsdserialize.h
@@ -873,5 +873,5 @@ LL_COMMON_API std::string zip_llsd(LLSD& data);
 LL_COMMON_API U8* unzip_llsdNavMesh( bool& valid, size_t& outsize,std::istream& is, S32 size);
 
 // returns a pointer to the array or past the array if the deprecated header exists
-LL_COMMON_API char* strip_deprecated_header(char* in, U32& cur_size, U32* header_size = nullptr);
+LL_COMMON_API char* strip_deprecated_header(char* in, llssize& cur_size, llssize* header_size = nullptr);
 #endif // LL_LLSDSERIALIZE_H
diff --git a/indra/llcommon/llstreamtools.cpp b/indra/llcommon/llstreamtools.cpp
index 1ff15fcf89..bc32b6fd9e 100644
--- a/indra/llcommon/llstreamtools.cpp
+++ b/indra/llcommon/llstreamtools.cpp
@@ -513,3 +513,29 @@ std::istream& operator>>(std::istream& str, const char *tocheck)
 	}
 	return str;
 }
+
+int cat_streambuf::underflow()
+{
+    if (gptr() == egptr())
+    {
+        // here because our buffer is empty
+        std::streamsize size = 0;
+        // Until we've run out of mInputs, try reading the first of them
+        // into mBuffer. If that fetches some characters, break the loop.
+        while (! mInputs.empty()
+               && ! (size = mInputs.front()->sgetn(mBuffer.data(), mBuffer.size())))
+        {
+            // We tried to read mInputs.front() but got zero characters.
+            // Discard the first streambuf and try the next one.
+            mInputs.pop_front();
+        }
+        // Either we ran out of mInputs or we succeeded in reading some
+        // characters, that is, size != 0. Tell base class what we have.
+        setg(mBuffer.data(), mBuffer.data(), mBuffer.data() + size);
+    }
+    // If we fell out of the above loop with mBuffer still empty, return
+    // eof(), otherwise return the next character.
+    return (gptr() == egptr())
+        ? std::char_traits<char>::eof()
+        : std::char_traits<char>::to_int_type(*gptr());
+}
diff --git a/indra/llcommon/llstreamtools.h b/indra/llcommon/llstreamtools.h
index 1b04bf91d7..bb7bc20327 100644
--- a/indra/llcommon/llstreamtools.h
+++ b/indra/llcommon/llstreamtools.h
@@ -27,8 +27,10 @@
 #ifndef LL_STREAM_TOOLS_H
 #define LL_STREAM_TOOLS_H
 
+#include <deque>
 #include <iostream>
 #include <string>
+#include <vector>
 
 // unless specifed otherwise these all return input_stream.good()
 
@@ -113,6 +115,27 @@ LL_COMMON_API std::streamsize fullread(
 
 LL_COMMON_API std::istream& operator>>(std::istream& str, const char *tocheck);
 
-#endif
-
+/**
+ * cat_streambuf is a std::streambuf subclass that accepts a variadic number
+ * of std::streambuf* (e.g. some_istream.rdbuf()) and virtually concatenates
+ * their contents.
+ */
+// derived from https://stackoverflow.com/a/49441066/5533635
+class cat_streambuf: public std::streambuf
+{
+private:
+    std::deque<std::streambuf*> mInputs;
+    std::vector<char> mBuffer;
+
+public:
+    // only valid for std::streambuf* arguments
+    template <typename... Inputs>
+    cat_streambuf(Inputs... inputs):
+        mInputs{inputs...},
+        mBuffer(1024)
+    {}
+
+    int underflow() override;
+};
 
+#endif
diff --git a/indra/llcommon/lltracerecording.cpp b/indra/llcommon/lltracerecording.cpp
index a8dcc5226a..bb3d667a42 100644
--- a/indra/llcommon/lltracerecording.cpp
+++ b/indra/llcommon/lltracerecording.cpp
@@ -577,10 +577,12 @@ S32 Recording::getSampleCount( const StatType<EventAccumulator>& stat )
 // PeriodicRecording
 ///////////////////////////////////////////////////////////////////////
 
-PeriodicRecording::PeriodicRecording( S32 num_periods, EPlayState state) 
+PeriodicRecording::PeriodicRecording( size_t num_periods, EPlayState state) 
 :	mAutoResize(num_periods == 0),
 	mCurPeriod(0),
 	mNumRecordedPeriods(0),
+	// This guarantee that mRecordingPeriods cannot be empty is essential for
+	// code in several methods.
 	mRecordingPeriods(num_periods ? num_periods : 1)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
@@ -596,18 +598,19 @@ PeriodicRecording::~PeriodicRecording()
 
 void PeriodicRecording::nextPeriod()
 {
-    LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
+	LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	if (mAutoResize)
 	{
 		mRecordingPeriods.push_back(Recording());
 	}
 
 	Recording& old_recording = getCurRecording();
-	mCurPeriod = (mCurPeriod + 1) % mRecordingPeriods.size();
+	inci(mCurPeriod);
 	old_recording.splitTo(getCurRecording());
 
-	mNumRecordedPeriods = mRecordingPeriods.empty()? 0 :
-		llmin(mRecordingPeriods.size() - 1, mNumRecordedPeriods + 1);
+	// Since mRecordingPeriods always has at least one entry, we can always
+	// safely subtract 1 from its size().
+	mNumRecordedPeriods = llmin(mRecordingPeriods.size() - 1, mNumRecordedPeriods + 1);
 }
 
 void PeriodicRecording::appendRecording(Recording& recording)
@@ -620,31 +623,29 @@ void PeriodicRecording::appendRecording(Recording& recording)
 
 void PeriodicRecording::appendPeriodicRecording( PeriodicRecording& other )
 {
-    LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
+	LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	if (other.mRecordingPeriods.empty()) return;
 
 	getCurRecording().update();
 	other.getCurRecording().update();
-	
-	const auto other_recording_slots = other.mRecordingPeriods.size();
+
 	const auto other_num_recordings = other.getNumRecordedPeriods();
 	const auto other_current_recording_index = other.mCurPeriod;
-	const auto other_oldest_recording_index = (other_current_recording_index + other_recording_slots - other_num_recordings) % other_recording_slots;
+	const auto other_oldest_recording_index = other.previ(other_current_recording_index, other_num_recordings);
 
 	// append first recording into our current slot
 	getCurRecording().appendRecording(other.mRecordingPeriods[other_oldest_recording_index]);
 
 	// from now on, add new recordings for everything after the first
-	auto other_index = (other_oldest_recording_index + 1) % other_recording_slots;
+	auto other_index = other.nexti(other_oldest_recording_index);
 
 	if (mAutoResize)
 	{
 		// push back recordings for everything in the middle
-		auto other_index = (other_oldest_recording_index + 1) % other_recording_slots;
 		while (other_index != other_current_recording_index)
 		{
 			mRecordingPeriods.push_back(other.mRecordingPeriods[other_index]);
-			other_index = (other_index + 1) % other_recording_slots;
+			other.inci(other_index);
 		}
 
 		// add final recording, if it wasn't already added as the first
@@ -653,36 +654,25 @@ void PeriodicRecording::appendPeriodicRecording( PeriodicRecording& other )
 			mRecordingPeriods.push_back(other.mRecordingPeriods[other_current_recording_index]);
 		}
 
-		mCurPeriod = mRecordingPeriods.empty()? 0 : mRecordingPeriods.size() - 1;
+		// mRecordingPeriods is never empty()
+		mCurPeriod = mRecordingPeriods.size() - 1;
 		mNumRecordedPeriods = mCurPeriod;
 	}
 	else
 	{
-		S32 num_to_copy = llmin((S32)mRecordingPeriods.size(), (S32)other_num_recordings);
-
-		std::vector<Recording>::iterator src_it = other.mRecordingPeriods.begin() + other_index ;
-		std::vector<Recording>::iterator dest_it = mRecordingPeriods.begin() + mCurPeriod;
-
+		auto num_to_copy = llmin(mRecordingPeriods.size(), other_num_recordings);
 		// already consumed the first recording from other, so start counting at 1
-		for(S32 i = 1; i < num_to_copy; i++)
+		for (size_t n = 1, srci = other_index, dsti = mCurPeriod;
+			 n < num_to_copy;
+			 ++n, other.inci(srci), inci(dsti))
 		{
-			*dest_it = *src_it;
-
-			if (++src_it == other.mRecordingPeriods.end())
-			{
-				src_it = other.mRecordingPeriods.begin();
-			}
-
-			if (++dest_it == mRecordingPeriods.end())
-			{
-				dest_it = mRecordingPeriods.begin();
-			}
+			mRecordingPeriods[dsti] = other.mRecordingPeriods[srci];
 		}
-		
+
 		// want argument to % to be positive, otherwise result could be negative and thus out of bounds
 		llassert(num_to_copy >= 1);
 		// advance to last recording period copied, and make that our current period
-		mCurPeriod = (mCurPeriod + num_to_copy - 1) % mRecordingPeriods.size();
+		inci(mCurPeriod, num_to_copy - 1);
 		mNumRecordedPeriods = llmin(mRecordingPeriods.size() - 1, mNumRecordedPeriods + num_to_copy - 1);
 	}
 
@@ -694,13 +684,11 @@ void PeriodicRecording::appendPeriodicRecording( PeriodicRecording& other )
 
 F64Seconds PeriodicRecording::getDuration() const
 {
-    LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
+	LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	F64Seconds duration;
-	auto num_periods = mRecordingPeriods.size();
-	for (size_t i = 1; i <= num_periods; i++)
+	for (size_t n = 0; n < mRecordingPeriods.size(); ++n)
 	{
-		auto index = (mCurPeriod + num_periods - i) % num_periods;
-		duration += mRecordingPeriods[index].getDuration();
+		duration += mRecordingPeriods[nexti(mCurPeriod, n)].getDuration();
 	}
 	return duration;
 }
@@ -737,16 +725,14 @@ const Recording& PeriodicRecording::getCurRecording() const
 
 Recording& PeriodicRecording::getPrevRecording( size_t offset )
 {
-	auto num_periods = mRecordingPeriods.size();
-	offset = llclamp(offset, 0, num_periods - 1);
-	return mRecordingPeriods[(mCurPeriod + num_periods - offset) % num_periods];
+	// reuse const implementation, but return non-const reference
+	return const_cast<Recording&>(
+		const_cast<const PeriodicRecording*>(this)->getPrevRecording(offset));
 }
 
 const Recording& PeriodicRecording::getPrevRecording( size_t offset ) const
 {
-	auto num_periods = mRecordingPeriods.size();
-	offset = llclamp(offset, 0, num_periods - 1);
-	return mRecordingPeriods[(mCurPeriod + num_periods - offset) % num_periods];
+	return mRecordingPeriods[previ(mCurPeriod, offset)];
 }
 
 void PeriodicRecording::handleStart()
@@ -789,14 +775,14 @@ void PeriodicRecording::handleSplitTo(PeriodicRecording& other)
 	getCurRecording().splitTo(other.getCurRecording());
 }
 
-F64 PeriodicRecording::getPeriodMin( const StatType<EventAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMin( const StatType<EventAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	bool has_value = false;
 	F64 min_val = std::numeric_limits<F64>::max();
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -811,14 +797,14 @@ F64 PeriodicRecording::getPeriodMin( const StatType<EventAccumulator>& stat, siz
 			: NaN;
 }
 
-F64 PeriodicRecording::getPeriodMax( const StatType<EventAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMax( const StatType<EventAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	bool has_value = false;
 	F64 max_val = std::numeric_limits<F64>::min();
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -834,7 +820,7 @@ F64 PeriodicRecording::getPeriodMax( const StatType<EventAccumulator>& stat, siz
 }
 
 // calculates means using aggregates per period
-F64 PeriodicRecording::getPeriodMean( const StatType<EventAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMean( const StatType<EventAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -842,7 +828,7 @@ F64 PeriodicRecording::getPeriodMean( const StatType<EventAccumulator>& stat, si
 	F64 mean = 0;
 	S32 valid_period_count = 0;
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -857,7 +843,7 @@ F64 PeriodicRecording::getPeriodMean( const StatType<EventAccumulator>& stat, si
 			: NaN;
 }
 
-F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<EventAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<EventAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -866,7 +852,7 @@ F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<EventAccumulat
 	F64 sum_of_squares = 0;
 	S32 valid_period_count = 0;
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -882,14 +868,14 @@ F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<EventAccumulat
 			: NaN;
 }
 
-F64 PeriodicRecording::getPeriodMin( const StatType<SampleAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMin( const StatType<SampleAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	bool has_value = false;
 	F64 min_val = std::numeric_limits<F64>::max();
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -904,14 +890,14 @@ F64 PeriodicRecording::getPeriodMin( const StatType<SampleAccumulator>& stat, si
 			: NaN;
 }
 
-F64 PeriodicRecording::getPeriodMax(const StatType<SampleAccumulator>& stat, size_t num_periods /*= S32_MAX*/)
+F64 PeriodicRecording::getPeriodMax(const StatType<SampleAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	bool has_value = false;
 	F64 max_val = std::numeric_limits<F64>::min();
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -927,7 +913,7 @@ F64 PeriodicRecording::getPeriodMax(const StatType<SampleAccumulator>& stat, siz
 }
 
 
-F64 PeriodicRecording::getPeriodMean( const StatType<SampleAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMean( const StatType<SampleAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -935,7 +921,7 @@ F64 PeriodicRecording::getPeriodMean( const StatType<SampleAccumulator>& stat, s
 	S32 valid_period_count = 0;
 	F64 mean = 0;
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -950,13 +936,13 @@ F64 PeriodicRecording::getPeriodMean( const StatType<SampleAccumulator>& stat, s
 			: NaN;
 }
 
-F64 PeriodicRecording::getPeriodMedian( const StatType<SampleAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodMedian( const StatType<SampleAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	std::vector<F64> buf;
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.getDuration() > (F32Seconds)0.f)
@@ -976,7 +962,7 @@ F64 PeriodicRecording::getPeriodMedian( const StatType<SampleAccumulator>& stat,
 	return F64((buf.size() % 2 == 0) ? (buf[buf.size() / 2 - 1] + buf[buf.size() / 2]) / 2 : buf[buf.size() / 2]);
 }
 
-F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<SampleAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<SampleAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -985,7 +971,7 @@ F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<SampleAccumula
 	S32 valid_period_count = 0;
 	F64 sum_of_squares = 0;
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
@@ -1002,13 +988,13 @@ F64 PeriodicRecording::getPeriodStandardDeviation( const StatType<SampleAccumula
 }
 
 
-F64Kilobytes PeriodicRecording::getPeriodMin( const StatType<MemAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64Kilobytes PeriodicRecording::getPeriodMin( const StatType<MemAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	F64Kilobytes min_val(std::numeric_limits<F64>::max());
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		min_val = llmin(min_val, recording.getMin(stat));
@@ -1022,13 +1008,13 @@ F64Kilobytes PeriodicRecording::getPeriodMin(const MemStatHandle& stat, size_t n
 	return getPeriodMin(static_cast<const StatType<MemAccumulator>&>(stat), num_periods);
 }
 
-F64Kilobytes PeriodicRecording::getPeriodMax(const StatType<MemAccumulator>& stat, size_t num_periods /*= S32_MAX*/)
+F64Kilobytes PeriodicRecording::getPeriodMax(const StatType<MemAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/)
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	F64Kilobytes max_val(0.0);
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		max_val = llmax(max_val, recording.getMax(stat));
@@ -1042,14 +1028,14 @@ F64Kilobytes PeriodicRecording::getPeriodMax(const MemStatHandle& stat, size_t n
 	return getPeriodMax(static_cast<const StatType<MemAccumulator>&>(stat), num_periods);
 }
 
-F64Kilobytes PeriodicRecording::getPeriodMean( const StatType<MemAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64Kilobytes PeriodicRecording::getPeriodMean( const StatType<MemAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 	F64Kilobytes mean(0);
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		mean += recording.getMean(stat);
@@ -1063,7 +1049,7 @@ F64Kilobytes PeriodicRecording::getPeriodMean(const MemStatHandle& stat, size_t
 	return getPeriodMean(static_cast<const StatType<MemAccumulator>&>(stat), num_periods);
 }
 
-F64Kilobytes PeriodicRecording::getPeriodStandardDeviation( const StatType<MemAccumulator>& stat, size_t num_periods /*= S32_MAX*/ )
+F64Kilobytes PeriodicRecording::getPeriodStandardDeviation( const StatType<MemAccumulator>& stat, size_t num_periods /*= std::numeric_limits<size_t>::max()*/ )
 {
     LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 	num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -1072,7 +1058,7 @@ F64Kilobytes PeriodicRecording::getPeriodStandardDeviation( const StatType<MemAc
 	S32 valid_period_count = 0;
 	F64 sum_of_squares = 0;
 
-	for (S32 i = 1; i <= num_periods; i++)
+	for (size_t i = 1; i <= num_periods; i++)
 	{
 		Recording& recording = getPrevRecording(i);
 		if (recording.hasValue(stat))
diff --git a/indra/llcommon/lltracerecording.h b/indra/llcommon/lltracerecording.h
index 8b56721f42..a6b1a67d02 100644
--- a/indra/llcommon/lltracerecording.h
+++ b/indra/llcommon/lltracerecording.h
@@ -33,6 +33,7 @@
 #include "lltimer.h"
 #include "lltraceaccumulators.h"
 #include "llpointer.h"
+#include <limits>
 
 class LLStopWatchControlsMixinCommon
 {
@@ -330,7 +331,7 @@ namespace LLTrace
 	:	public LLStopWatchControlsMixin<PeriodicRecording>
 	{
 	public:
-		PeriodicRecording(S32 num_periods, EPlayState state = STOPPED);
+		PeriodicRecording(size_t num_periods, EPlayState state = STOPPED);
 		~PeriodicRecording();
 
 		void nextPeriod();
@@ -353,7 +354,7 @@ namespace LLTrace
 		Recording snapshotCurRecording() const;
 
 		template <typename T>
-		auto getSampleCount(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		auto getSampleCount(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
 			LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
@@ -373,14 +374,14 @@ namespace LLTrace
 
 		// catch all for stats that have a defined sum
 		template <typename T>
-		typename T::value_t getPeriodMin(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		typename T::value_t getPeriodMin(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			bool has_value = false;
 			typename T::value_t min_val(std::numeric_limits<typename T::value_t>::max());
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				if (recording.hasValue(stat))
@@ -396,39 +397,39 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		T getPeriodMin(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMin(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMin(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodMin(const StatType<SampleAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMin(const StatType<SampleAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		T getPeriodMin(const SampleStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMin(const SampleStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMin(static_cast<const StatType<SampleAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodMin(const StatType<EventAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMin(const StatType<EventAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		T getPeriodMin(const EventStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMin(const EventStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMin(static_cast<const StatType<EventAccumulator>&>(stat), num_periods));
 		}
 
-		F64Kilobytes getPeriodMin(const StatType<MemAccumulator>& stat, size_t num_periods = S32_MAX);
-		F64Kilobytes getPeriodMin(const MemStatHandle& stat, size_t num_periods = S32_MAX);
+		F64Kilobytes getPeriodMin(const StatType<MemAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
+		F64Kilobytes getPeriodMin(const MemStatHandle& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 
 		template <typename T>
-		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMinPerSec(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMinPerSec(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			typename RelatedTypes<typename T::value_t>::fractional_t min_val(std::numeric_limits<F64>::max());
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				min_val = llmin(min_val, recording.getPerSec(stat));
@@ -437,7 +438,7 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodMinPerSec(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMinPerSec(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMinPerSec(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
@@ -449,14 +450,14 @@ namespace LLTrace
 
 		// catch all for stats that have a defined sum
 		template <typename T>
-		typename T::value_t getPeriodMax(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		typename T::value_t getPeriodMax(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			bool has_value = false;
 			typename T::value_t max_val(std::numeric_limits<typename T::value_t>::min());
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				if (recording.hasValue(stat))
@@ -472,39 +473,39 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		T getPeriodMax(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMax(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMax(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodMax(const StatType<SampleAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMax(const StatType<SampleAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		T getPeriodMax(const SampleStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMax(const SampleStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMax(static_cast<const StatType<SampleAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodMax(const StatType<EventAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMax(const StatType<EventAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		T getPeriodMax(const EventStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		T getPeriodMax(const EventStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return T(getPeriodMax(static_cast<const StatType<EventAccumulator>&>(stat), num_periods));
 		}
 
-		F64Kilobytes getPeriodMax(const StatType<MemAccumulator>& stat, size_t num_periods = S32_MAX);
-		F64Kilobytes getPeriodMax(const MemStatHandle& stat, size_t num_periods = S32_MAX);
+		F64Kilobytes getPeriodMax(const StatType<MemAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
+		F64Kilobytes getPeriodMax(const MemStatHandle& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 
 		template <typename T>
-		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMaxPerSec(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMaxPerSec(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			F64 max_val = std::numeric_limits<F64>::min();
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				max_val = llmax(max_val, recording.getPerSec(stat));
@@ -513,7 +514,7 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodMaxPerSec(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMaxPerSec(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMaxPerSec(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
@@ -525,14 +526,14 @@ namespace LLTrace
 
 		// catch all for stats that have a defined sum
 		template <typename T>
-		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMean(const StatType<T >& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMean(const StatType<T >& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			typename RelatedTypes<typename T::value_t>::fractional_t mean(0);
 
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				if (recording.getDuration() > (F32Seconds)0.f)
@@ -546,39 +547,39 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodMean(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMean(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMean(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
 		}
-		F64 getPeriodMean(const StatType<SampleAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMean(const StatType<SampleAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T> 
-		typename RelatedTypes<T>::fractional_t getPeriodMean(const SampleStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMean(const SampleStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMean(static_cast<const StatType<SampleAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodMean(const StatType<EventAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMean(const StatType<EventAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodMean(const EventStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMean(const EventStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMean(static_cast<const StatType<EventAccumulator>&>(stat), num_periods));
 		}
 
-		F64Kilobytes getPeriodMean(const StatType<MemAccumulator>& stat, size_t num_periods = S32_MAX);
-		F64Kilobytes getPeriodMean(const MemStatHandle& stat, size_t num_periods = S32_MAX);
+		F64Kilobytes getPeriodMean(const StatType<MemAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
+		F64Kilobytes getPeriodMean(const MemStatHandle& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		
 		template <typename T>
-		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMeanPerSec(const StatType<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMeanPerSec(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			num_periods = llmin(num_periods, getNumRecordedPeriods());
 
 			typename RelatedTypes<typename T::value_t>::fractional_t mean = 0;
 
-			for (S32 i = 1; i <= num_periods; i++)
+			for (size_t i = 1; i <= num_periods; i++)
 			{
 				Recording& recording = getPrevRecording(i);
 				if (recording.getDuration() > (F32Seconds)0.f)
@@ -593,64 +594,64 @@ namespace LLTrace
 		}
 
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodMeanPerSec(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodMeanPerSec(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodMeanPerSec(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
 		}
 
-        F64 getPeriodMedian( const StatType<SampleAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodMedian( const StatType<SampleAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 
-        template <typename T>
-        typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMedianPerSec(const StatType<T>& stat, size_t num_periods = S32_MAX)
-        {
-            LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
-            num_periods = llmin(num_periods, getNumRecordedPeriods());
-
-            std::vector <typename RelatedTypes<typename T::value_t>::fractional_t> buf;
-            for (S32 i = 1; i <= num_periods; i++)
-            {
-                Recording& recording = getPrevRecording(i);
-                if (recording.getDuration() > (F32Seconds)0.f)
-                {
-                    buf.push_back(recording.getPerSec(stat));
-                }
-            }
-            std::sort(buf.begin(), buf.end());
-
-            return typename RelatedTypes<T>::fractional_t((buf.size() % 2 == 0) ? (buf[buf.size() / 2 - 1] + buf[buf.size() / 2]) / 2 : buf[buf.size() / 2]);
-        }
-
-        template<typename T>
-        typename RelatedTypes<T>::fractional_t getPeriodMedianPerSec(const CountStatHandle<T>& stat, size_t num_periods = S32_MAX)
-        {
-            LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
-            return typename RelatedTypes<T>::fractional_t(getPeriodMedianPerSec(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
-        }
+		template <typename T>
+		typename RelatedTypes<typename T::value_t>::fractional_t getPeriodMedianPerSec(const StatType<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
+		{
+			LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
+			num_periods = llmin(num_periods, getNumRecordedPeriods());
+
+			std::vector <typename RelatedTypes<typename T::value_t>::fractional_t> buf;
+			for (size_t i = 1; i <= num_periods; i++)
+			{
+				Recording& recording = getPrevRecording(i);
+				if (recording.getDuration() > (F32Seconds)0.f)
+				{
+					buf.push_back(recording.getPerSec(stat));
+				}
+			}
+			std::sort(buf.begin(), buf.end());
+
+			return typename RelatedTypes<T>::fractional_t((buf.size() % 2 == 0) ? (buf[buf.size() / 2 - 1] + buf[buf.size() / 2]) / 2 : buf[buf.size() / 2]);
+		}
+
+		template<typename T>
+		typename RelatedTypes<T>::fractional_t getPeriodMedianPerSec(const CountStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
+		{
+			LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
+			return typename RelatedTypes<T>::fractional_t(getPeriodMedianPerSec(static_cast<const StatType<CountAccumulator>&>(stat), num_periods));
+		}
 
 		//
 		// PERIODIC STANDARD DEVIATION
 		//
 
-		F64 getPeriodStandardDeviation(const StatType<SampleAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodStandardDeviation(const StatType<SampleAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 
 		template<typename T> 
-		typename RelatedTypes<T>::fractional_t getPeriodStandardDeviation(const SampleStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodStandardDeviation(const SampleStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodStandardDeviation(static_cast<const StatType<SampleAccumulator>&>(stat), num_periods));
 		}
 
-		F64 getPeriodStandardDeviation(const StatType<EventAccumulator>& stat, size_t num_periods = S32_MAX);
+		F64 getPeriodStandardDeviation(const StatType<EventAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 		template<typename T>
-		typename RelatedTypes<T>::fractional_t getPeriodStandardDeviation(const EventStatHandle<T>& stat, size_t num_periods = S32_MAX)
+		typename RelatedTypes<T>::fractional_t getPeriodStandardDeviation(const EventStatHandle<T>& stat, size_t num_periods = std::numeric_limits<size_t>::max())
 		{
             LL_PROFILE_ZONE_SCOPED_CATEGORY_STATS;
 			return typename RelatedTypes<T>::fractional_t(getPeriodStandardDeviation(static_cast<const StatType<EventAccumulator>&>(stat), num_periods));
 		}
 
-		F64Kilobytes getPeriodStandardDeviation(const StatType<MemAccumulator>& stat, size_t num_periods = S32_MAX);
-		F64Kilobytes getPeriodStandardDeviation(const MemStatHandle& stat, size_t num_periods = S32_MAX);
+		F64Kilobytes getPeriodStandardDeviation(const StatType<MemAccumulator>& stat, size_t num_periods = std::numeric_limits<size_t>::max());
+		F64Kilobytes getPeriodStandardDeviation(const MemStatHandle& stat, size_t num_periods = std::numeric_limits<size_t>::max());
 
 	private:
 		// implementation for LLStopWatchControlsMixin
@@ -659,6 +660,35 @@ namespace LLTrace
 		/*virtual*/ void handleReset();
 		/*virtual*/ void handleSplitTo(PeriodicRecording& other);
 
+		// helper methods for wraparound ring-buffer arithmetic
+		inline
+		size_t wrapi(size_t i) const
+		{
+			return i % mRecordingPeriods.size();
+		}
+
+		inline
+		size_t nexti(size_t i, size_t offset=1) const
+		{
+			return wrapi(i + offset);
+		}
+
+		inline
+		size_t previ(size_t i, size_t offset=1) const
+		{
+			auto num_periods = mRecordingPeriods.size();
+			// constrain offset
+			offset = llclamp(offset, 0, num_periods - 1);
+			// add size() so expression can't go (unsigned) "negative"
+			return wrapi(i + num_periods - offset);
+		}
+
+		inline
+		void inci(size_t& i, size_t offset=1) const
+		{
+			i = nexti(i, offset);
+		}
+
 	private:
 		std::vector<Recording>	mRecordingPeriods;
 		const bool				mAutoResize;
diff --git a/indra/llcommon/lluuid.cpp b/indra/llcommon/lluuid.cpp
index fc04dca08d..5655e8e2f2 100644
--- a/indra/llcommon/lluuid.cpp
+++ b/indra/llcommon/lluuid.cpp
@@ -884,7 +884,7 @@ U32 LLUUID::getRandomSeed()
    seed[7]=(unsigned char)(pid);
    getSystemTime((uuid_time_t *)(&seed[8]));
 
-   U64 seed64 = HBXXH64((const void*)seed, 16).digest();
+   U64 seed64 = HBXXH64::digest((const void*)seed, 16);
    return U32(seed64) ^ U32(seed64 >> 32);
 }
 
diff --git a/indra/llcommon/lluuid.h b/indra/llcommon/lluuid.h
index c139c4eb4e..80597fa186 100644
--- a/indra/llcommon/lluuid.h
+++ b/indra/llcommon/lluuid.h
@@ -116,6 +116,14 @@ public:
 	U16 getCRC16() const;
 	U32 getCRC32() const;
 
+	// Returns a 64 bits digest of the UUID, by XORing its two 64 bits long
+	// words. HB
+	inline U64 getDigest64() const
+	{
+		U64* tmp = (U64*)mData;
+		return tmp[0] ^ tmp[1];
+	}
+
 	static BOOL validate(const std::string& in_string); // Validate that the UUID string is legal.
 
 	static const LLUUID null;
@@ -165,36 +173,22 @@ public:
 	LLAssetID makeAssetID(const LLUUID& session) const;
 };
 
-// Generate a hash of an LLUUID object using the boost hash templates. 
-template <>
-struct boost::hash<LLUUID>
-{
-    typedef LLUUID argument_type;
-    typedef std::size_t result_type;
-    result_type operator()(argument_type const& s) const
-    {
-        result_type seed(0);
-
-        for (S32 i = 0; i < UUID_BYTES; ++i)
-        {
-            boost::hash_combine(seed, s.mData[i]);
-        }
-
-        return seed;
-    }
-};
-
-// Adapt boost hash to std hash
+// std::hash implementation for LLUUID
 namespace std
 {
-    template<> struct hash<LLUUID>
-    {
-        std::size_t operator()(LLUUID const& s) const noexcept
-        {
-            return boost::hash<LLUUID>()(s);
-        }
-    };
+	template<> struct hash<LLUUID>
+	{
+		inline size_t operator()(const LLUUID& id) const noexcept
+		{
+			return (size_t)id.getDigest64();
+		}
+	};
 }
-#endif
 
+// For use with boost containers.
+inline size_t hash_value(const LLUUID& id) noexcept
+{
+	return (size_t)id.getDigest64();
+}
 
+#endif // LL_LLUUID_H
diff --git a/indra/llcommon/stdtypes.h b/indra/llcommon/stdtypes.h
index da8512169c..0b43d7ad4b 100644
--- a/indra/llcommon/stdtypes.h
+++ b/indra/llcommon/stdtypes.h
@@ -41,7 +41,7 @@ typedef unsigned int			U32;
 
 // to express an index that might go negative
 // (ssize_t is provided by SOME compilers, don't collide)
-typedef typename std::make_signed<size_t>::type llssize;
+typedef typename std::make_signed<std::size_t>::type llssize;
 
 #if LL_WINDOWS
 // https://docs.microsoft.com/en-us/cpp/build/reference/zc-wchar-t-wchar-t-is-native-type
diff --git a/indra/llcommon/tests/llleap_test.cpp b/indra/llcommon/tests/llleap_test.cpp
index 7ee36a9ea6..3ae48a2532 100644
--- a/indra/llcommon/tests/llleap_test.cpp
+++ b/indra/llcommon/tests/llleap_test.cpp
@@ -109,7 +109,12 @@ namespace tut
                    "import os\n"
                    "import sys\n"
                    "\n"
-                   "from llbase import llsd\n"
+                   "try:\n"
+                   // new freestanding llsd package
+                   "    import llsd\n"
+                   "except ImportError:\n"
+                   // older llbase.llsd module
+                   "    from llbase import llsd\n"
                    "\n"
                    "class ProtocolError(Exception):\n"
                    "    def __init__(self, msg, data):\n"
@@ -120,26 +125,26 @@ namespace tut
                    "    pass\n"
                    "\n"
                    "def get():\n"
-                   "    hdr = ''\n"
-                   "    while ':' not in hdr and len(hdr) < 20:\n"
-                   "        hdr += sys.stdin.read(1)\n"
+                   "    hdr = []\n"
+                   "    while b':' not in hdr and len(hdr) < 20:\n"
+                   "        hdr.append(sys.stdin.buffer.read(1))\n"
                    "        if not hdr:\n"
                    "            sys.exit(0)\n"
-                   "    if not hdr.endswith(':'):\n"
+                   "    if not hdr[-1] == b':':\n"
                    "        raise ProtocolError('Expected len:data, got %r' % hdr, hdr)\n"
                    "    try:\n"
-                   "        length = int(hdr[:-1])\n"
+                   "        length = int(b''.join(hdr[:-1]))\n"
                    "    except ValueError:\n"
                    "        raise ProtocolError('Non-numeric len %r' % hdr[:-1], hdr[:-1])\n"
                    "    parts = []\n"
                    "    received = 0\n"
                    "    while received < length:\n"
-                   "        parts.append(sys.stdin.read(length - received))\n"
+                   "        parts.append(sys.stdin.buffer.read(length - received))\n"
                    "        received += len(parts[-1])\n"
-                   "    data = ''.join(parts)\n"
+                   "    data = b''.join(parts)\n"
                    "    assert len(data) == length\n"
                    "    try:\n"
-                   "        return llsd.parse(data.encode())\n"
+                   "        return llsd.parse(data)\n"
                    //   Seems the old indra.base.llsd module didn't properly
                    //   convert IndexError (from running off end of string) to
                    //   LLSDParseError.
@@ -179,11 +184,11 @@ namespace tut
                    "    return _reply\n"
                    "\n"
                    "def put(req):\n"
-                   "    sys.stdout.write(':'.join((str(len(req)), req)))\n"
+                   "    sys.stdout.buffer.write(b'%d:%b' % (len(req), req))\n"
                    "    sys.stdout.flush()\n"
                    "\n"
                    "def send(pump, data):\n"
-                   "    put(llsd.format_notation(dict(pump=pump, data=data)).decode())\n"
+                   "    put(llsd.format_notation(dict(pump=pump, data=data)))\n"
                    "\n"
                    "def request(pump, data):\n"
                    "    # we expect 'data' is a dict\n"
diff --git a/indra/llcommon/tests/llsdserialize_test.cpp b/indra/llcommon/tests/llsdserialize_test.cpp
index 5dbcf4c9b8..acb2953b5b 100644
--- a/indra/llcommon/tests/llsdserialize_test.cpp
+++ b/indra/llcommon/tests/llsdserialize_test.cpp
@@ -46,20 +46,24 @@ typedef U32 uint32_t;
 
 #include "boost/range.hpp"
 #include "boost/foreach.hpp"
-#include "boost/function.hpp"
 #include "boost/bind.hpp"
 #include "boost/phoenix/bind/bind_function.hpp"
 #include "boost/phoenix/core/argument.hpp"
 using namespace boost::phoenix;
 
-#include "../llsd.h"
-#include "../llsdserialize.h"
+#include "llsd.h"
+#include "llsdserialize.h"
 #include "llsdutil.h"
-#include "../llformat.h"
+#include "llformat.h"
+#include "llmemorystream.h"
 
 #include "../test/lltut.h"
 #include "../test/namedtempfile.h"
 #include "stringize.h"
+#include <functional>
+
+typedef std::function<void(const LLSD& data, std::ostream& str)> FormatterFunction;
+typedef std::function<bool(std::istream& istr, LLSD& data, llssize max_bytes)> ParserFunction;
 
 std::vector<U8> string_to_vector(const std::string& str)
 {
@@ -112,7 +116,7 @@ namespace tut
 		mSD = LLUUID::null;
 		expected = "<llsd><uuid /></llsd>\n";
 		xml_test("null uuid", expected);
-		
+
 		mSD = LLUUID("c96f9b1e-f589-4100-9774-d98643ce0bed");
 		expected = "<llsd><uuid>c96f9b1e-f589-4100-9774-d98643ce0bed</uuid></llsd>\n";
 		xml_test("uuid", expected);
@@ -136,7 +140,7 @@ namespace tut
 		expected = "<llsd><binary encoding=\"base64\">aGVsbG8=</binary></llsd>\n";
 		xml_test("binary", expected);
 	}
-	
+
 	template<> template<>
 	void sd_xml_object::test<2>()
 	{
@@ -225,7 +229,7 @@ namespace tut
 		expected = "<llsd><map><key>baz</key><undef /><key>foo</key><string>bar</string></map></llsd>\n";
 		xml_test("2 element map", expected);
 	}
-	
+
 	template<> template<>
 	void sd_xml_object::test<6>()
 	{
@@ -241,7 +245,7 @@ namespace tut
 		expected = "<llsd><binary encoding=\"base64\">Nnw2fGFzZGZoYXBweWJveHw2MGU0NGVjNS0zMDVjLTQzYzItOWExOS1iNGI4OWIxYWUyYTZ8NjBlNDRlYzUtMzA1Yy00M2MyLTlhMTktYjRiODliMWFlMmE2fDYwZTQ0ZWM1LTMwNWMtNDNjMi05YTE5LWI0Yjg5YjFhZTJhNnwwMDAwMDAwMC0wMDAwLTAwMDAtMDAwMC0wMDAwMDAwMDAwMDB8N2ZmZmZmZmZ8N2ZmZmZmZmZ8MHwwfDgyMDAwfDQ1MGZlMzk0LTI5MDQtYzlhZC0yMTRjLWEwN2ViN2ZlZWMyOXwoTm8gRGVzY3JpcHRpb24pfDB8MTB8MA==</binary></llsd>\n";
 		xml_test("binary", expected);
 	}
-	
+
 	class TestLLSDSerializeData
 	{
 	public:
@@ -250,9 +254,34 @@ namespace tut
 
 		void doRoundTripTests(const std::string&);
 		void checkRoundTrip(const std::string&, const LLSD& v);
-		
-		LLPointer<LLSDFormatter> mFormatter;
-		LLPointer<LLSDParser> mParser;
+
+		void setFormatterParser(LLPointer<LLSDFormatter> formatter, LLPointer<LLSDParser> parser)
+		{
+			mFormatter = [formatter](const LLSD& data, std::ostream& str)
+			{
+				formatter->format(data, str);
+			};
+			// this lambda must be mutable since otherwise the bound 'parser'
+			// is assumed to point to a const LLSDParser
+			mParser = [parser](std::istream& istr, LLSD& data, llssize max_bytes) mutable
+			{
+				// reset() call is needed since test code re-uses parser object
+				parser->reset();
+				return (parser->parse(istr, data, max_bytes) > 0);
+			};
+		}
+
+		void setParser(bool (*parser)(LLSD&, std::istream&, llssize))
+		{
+			// why does LLSDSerialize::deserialize() reverse the parse() params??
+			mParser = [parser](std::istream& istr, LLSD& data, llssize max_bytes)
+			{
+				return parser(data, istr, max_bytes);
+			};
+		}
+
+		FormatterFunction mFormatter;
+		ParserFunction mParser;
 	};
 
 	TestLLSDSerializeData::TestLLSDSerializeData()
@@ -265,12 +294,11 @@ namespace tut
 
 	void TestLLSDSerializeData::checkRoundTrip(const std::string& msg, const LLSD& v)
 	{
-		std::stringstream stream;	
-		mFormatter->format(v, stream);
+		std::stringstream stream;
+		mFormatter(v, stream);
 		//LL_INFOS() << "checkRoundTrip: length " << stream.str().length() << LL_ENDL;
 		LLSD w;
-		mParser->reset();	// reset() call is needed since test code re-uses mParser
-		mParser->parse(stream, w, stream.str().size());
+		mParser(stream, w, stream.str().size());
 
 		try
 		{
@@ -299,52 +327,52 @@ namespace tut
 			fillmap(root[key], width, depth - 1);
 		}
 	}
-	
+
 	void TestLLSDSerializeData::doRoundTripTests(const std::string& msg)
 	{
 		LLSD v;
 		checkRoundTrip(msg + " undefined", v);
-		
+
 		v = true;
 		checkRoundTrip(msg + " true bool", v);
-		
+
 		v = false;
 		checkRoundTrip(msg + " false bool", v);
-		
+
 		v = 1;
 		checkRoundTrip(msg + " positive int", v);
-		
+
 		v = 0;
 		checkRoundTrip(msg + " zero int", v);
-		
+
 		v = -1;
 		checkRoundTrip(msg + " negative int", v);
-		
+
 		v = 1234.5f;
 		checkRoundTrip(msg + " positive float", v);
-		
+
 		v = 0.0f;
 		checkRoundTrip(msg + " zero float", v);
-		
+
 		v = -1234.5f;
 		checkRoundTrip(msg + " negative float", v);
-		
+
 		// FIXME: need a NaN test
-		
+
 		v = LLUUID::null;
 		checkRoundTrip(msg + " null uuid", v);
-		
+
 		LLUUID newUUID;
 		newUUID.generate();
 		v = newUUID;
 		checkRoundTrip(msg + " new uuid", v);
-		
+
 		v = "";
 		checkRoundTrip(msg + " empty string", v);
-		
+
 		v = "some string";
 		checkRoundTrip(msg + " non-empty string", v);
-		
+
 		v =
 "Second Life is a 3-D virtual world entirely built and owned by its residents. "
 "Since opening to the public in 2003, it has grown explosively and today is "
@@ -372,7 +400,7 @@ namespace tut
 		for (U32 block = 0x000000; block <= 0x10ffff; block += block_size)
 		{
 			std::ostringstream out;
-			
+
 			for (U32 c = block; c < block + block_size; ++c)
 			{
 				if (c <= 0x000001f
@@ -386,7 +414,7 @@ namespace tut
 				if (0x00fdd0 <= c  &&  c <= 0x00fdef) { continue; }
 				if ((c & 0x00fffe) == 0x00fffe) { continue; }		
 					// see Unicode standard, section 15.8 
-				
+
 				if (c <= 0x00007f)
 				{
 					out << (char)(c & 0x7f);
@@ -410,55 +438,55 @@ namespace tut
 					out << (char)(0x80 | ((c >>  0) & 0x3f));
 				}
 			}
-			
+
 			v = out.str();
 
 			std::ostringstream blockmsg;
 			blockmsg << msg << " unicode string block 0x" << std::hex << block; 
 			checkRoundTrip(blockmsg.str(), v);
 		}
-		
+
 		LLDate epoch;
 		v = epoch;
 		checkRoundTrip(msg + " epoch date", v);
-		
+
 		LLDate aDay("2002-12-07T05:07:15.00Z");
 		v = aDay;
 		checkRoundTrip(msg + " date", v);
-		
+
 		LLURI path("http://slurl.com/secondlife/Ambleside/57/104/26/");
 		v = path;
 		checkRoundTrip(msg + " url", v);
-		
+
 		const char source[] = "it must be a blue moon again";
 		std::vector<U8> data;
 		// note, includes terminating '\0'
 		copy(&source[0], &source[sizeof(source)], back_inserter(data));
-		
+
 		v = data;
 		checkRoundTrip(msg + " binary", v);
-		
+
 		v = LLSD::emptyMap();
 		checkRoundTrip(msg + " empty map", v);
-		
+
 		v = LLSD::emptyMap();
 		v["name"] = "luke";		//v.insert("name", "luke");
 		v["age"] = 3;			//v.insert("age", 3);
 		checkRoundTrip(msg + " map", v);
-		
+
 		v.clear();
 		v["a"]["1"] = true;
 		v["b"]["0"] = false;
 		checkRoundTrip(msg + " nested maps", v);
-		
+
 		v = LLSD::emptyArray();
 		checkRoundTrip(msg + " empty array", v);
-		
+
 		v = LLSD::emptyArray();
 		v.append("ali");
 		v.append(28);
 		checkRoundTrip(msg + " array", v);
-		
+
 		v.clear();
 		v[0][0] = true;
 		v[1][0] = false;
@@ -468,7 +496,7 @@ namespace tut
 		fillmap(v, 10, 3); // 10^6 maps
 		checkRoundTrip(msg + " many nested maps", v);
 	}
-	
+
 	typedef tut::test_group<TestLLSDSerializeData> TestLLSDSerializeGroup;
 	typedef TestLLSDSerializeGroup::object TestLLSDSerializeObject;
 	TestLLSDSerializeGroup gTestLLSDSerializeGroup("llsd serialization");
@@ -476,35 +504,106 @@ namespace tut
 	template<> template<> 
 	void TestLLSDSerializeObject::test<1>()
 	{
-		mFormatter = new LLSDNotationFormatter(false, "", LLSDFormatter::OPTIONS_PRETTY_BINARY);
-		mParser = new LLSDNotationParser();
+		setFormatterParser(new LLSDNotationFormatter(false, "", LLSDFormatter::OPTIONS_PRETTY_BINARY),
+						   new LLSDNotationParser());
 		doRoundTripTests("pretty binary notation serialization");
 	}
 
 	template<> template<> 
 	void TestLLSDSerializeObject::test<2>()
 	{
-		mFormatter = new LLSDNotationFormatter(false, "", LLSDFormatter::OPTIONS_NONE);
-		mParser = new LLSDNotationParser();
+		setFormatterParser(new LLSDNotationFormatter(false, "", LLSDFormatter::OPTIONS_NONE),
+						   new LLSDNotationParser());
 		doRoundTripTests("raw binary notation serialization");
 	}
 
 	template<> template<> 
 	void TestLLSDSerializeObject::test<3>()
 	{
-		mFormatter = new LLSDXMLFormatter();
-		mParser = new LLSDXMLParser();
+		setFormatterParser(new LLSDXMLFormatter(), new LLSDXMLParser());
 		doRoundTripTests("xml serialization");
 	}
 
 	template<> template<> 
 	void TestLLSDSerializeObject::test<4>()
 	{
-		mFormatter = new LLSDBinaryFormatter();
-		mParser = new LLSDBinaryParser();
+		setFormatterParser(new LLSDBinaryFormatter(), new LLSDBinaryParser());
 		doRoundTripTests("binary serialization");
 	}
 
+	template<> template<>
+	void TestLLSDSerializeObject::test<5>()
+	{
+		mFormatter = [](const LLSD& sd, std::ostream& str)
+		{
+			LLSDSerialize::serialize(sd, str, LLSDSerialize::LLSD_BINARY);
+		};
+		setParser(LLSDSerialize::deserialize);
+		doRoundTripTests("serialize(LLSD_BINARY)");
+	};
+
+	template<> template<>
+	void TestLLSDSerializeObject::test<6>()
+	{
+		mFormatter = [](const LLSD& sd, std::ostream& str)
+		{
+			LLSDSerialize::serialize(sd, str, LLSDSerialize::LLSD_XML);
+		};
+		setParser(LLSDSerialize::deserialize);
+		doRoundTripTests("serialize(LLSD_XML)");
+	};
+
+	template<> template<>
+	void TestLLSDSerializeObject::test<7>()
+	{
+		mFormatter = [](const LLSD& sd, std::ostream& str)
+		{
+			LLSDSerialize::serialize(sd, str, LLSDSerialize::LLSD_NOTATION);
+		};
+		setParser(LLSDSerialize::deserialize);
+		// In this test, serialize(LLSD_NOTATION) emits a header recognized by
+		// deserialize().
+		doRoundTripTests("serialize(LLSD_NOTATION)");
+	};
+
+	template<> template<>
+	void TestLLSDSerializeObject::test<8>()
+	{
+		setFormatterParser(new LLSDNotationFormatter(false, "", LLSDFormatter::OPTIONS_NONE),
+						   new LLSDNotationParser());
+		setParser(LLSDSerialize::deserialize);
+		// This is an interesting test because LLSDNotationFormatter does not
+		// emit an llsd/notation header.
+		doRoundTripTests("LLSDNotationFormatter -> deserialize");
+	};
+
+	template<> template<>
+	void TestLLSDSerializeObject::test<9>()
+	{
+		setFormatterParser(new LLSDXMLFormatter(false, "", LLSDFormatter::OPTIONS_NONE),
+						   new LLSDXMLParser());
+		setParser(LLSDSerialize::deserialize);
+		// This is an interesting test because LLSDXMLFormatter does not
+		// emit an LLSD/XML header.
+		doRoundTripTests("LLSDXMLFormatter -> deserialize");
+	};
+
+/*==========================================================================*|
+	// We do not expect this test to succeed. Without a header, neither
+	// notation LLSD nor binary LLSD reliably start with a distinct character,
+	// the way XML LLSD starts with '<'. By convention, we default to notation
+	// rather than binary.
+	template<> template<>
+	void TestLLSDSerializeObject::test<10>()
+	{
+		setFormatterParser(new LLSDBinaryFormatter(false, "", LLSDFormatter::OPTIONS_NONE),
+						   new LLSDBinaryParser());
+		setParser(LLSDSerialize::deserialize);
+		// This is an interesting test because LLSDBinaryFormatter does not
+		// emit an LLSD/Binary header.
+		doRoundTripTests("LLSDBinaryFormatter -> deserialize");
+	};
+|*==========================================================================*/
 
 	/**
 	 * @class TestLLSDParsing
@@ -555,7 +654,7 @@ namespace tut
 	public:
 		TestLLSDXMLParsing() {}
 	};
-	
+
 	typedef tut::test_group<TestLLSDXMLParsing> TestLLSDXMLParsingGroup;
 	typedef TestLLSDXMLParsingGroup::object TestLLSDXMLParsingObject;
 	TestLLSDXMLParsingGroup gTestLLSDXMLParsingGroup("llsd XML parsing");
@@ -586,8 +685,8 @@ namespace tut
 			LLSD(),
 			LLSDParser::PARSE_FAILURE);
 	}
-	
-	
+
+
 	template<> template<> 
 	void TestLLSDXMLParsingObject::test<2>()
 	{
@@ -596,7 +695,7 @@ namespace tut
 		v["amy"] = 23;
 		v["bob"] = LLSD();
 		v["cam"] = 1.23;
-		
+
 		ensureParse(
 			"unknown data type",
 			"<llsd><map>"
@@ -607,16 +706,16 @@ namespace tut
 			v,
 			v.size() + 1);
 	}
-	
+
 	template<> template<> 
 	void TestLLSDXMLParsingObject::test<3>()
 	{
 		// test handling of nested bad data
-		
+
 		LLSD v;
 		v["amy"] = 23;
 		v["cam"] = 1.23;
-		
+
 		ensureParse(
 			"map with html",
 			"<llsd><map>"
@@ -626,7 +725,7 @@ namespace tut
 			"</map></llsd>",
 			v,
 			v.size() + 1);
-			
+
 		v.clear();
 		v["amy"] = 23;
 		v["cam"] = 1.23;
@@ -639,7 +738,7 @@ namespace tut
 			"</map></llsd>",
 			v,
 			v.size() + 1);
-			
+
 		v.clear();
 		v["amy"] = 23;
 		v["bob"] = LLSD::emptyMap();
@@ -661,7 +760,7 @@ namespace tut
 		v[0] = 23;
 		v[1] = LLSD();
 		v[2] = 1.23;
-		
+
 		ensureParse(
 			"array value of html",
 			"<llsd><array>"
@@ -671,7 +770,7 @@ namespace tut
 			"</array></llsd>",
 			v,
 			v.size() + 1);
-			
+
 		v.clear();
 		v[0] = 23;
 		v[1] = LLSD::emptyMap();
@@ -1225,7 +1324,7 @@ namespace tut
 		vec[0] = 'a'; vec[1] = 'b'; vec[2] = 'c';
 		vec[3] = '3'; vec[4] = '2'; vec[5] = '1';
 		LLSD value = vec;
-		
+
 		vec.resize(11);
 		vec[0] = 'b';  // for binary
 		vec[5] = 'a'; vec[6] = 'b'; vec[7] = 'c';
@@ -1694,85 +1793,83 @@ namespace tut
 		ensureBinaryAndXML("map", test);
 	}
 
-    struct TestPythonCompatible
+    // helper for TestPythonCompatible
+    static std::string import_llsd("import os.path\n"
+                                   "import sys\n"
+                                   "try:\n"
+                                   // new freestanding llsd package
+                                   "    import llsd\n"
+                                   "except ImportError:\n"
+                                   // older llbase.llsd module
+                                   "    from llbase import llsd\n");
+
+    // helper for TestPythonCompatible
+    template <typename CONTENT>
+    void python(const std::string& desc, const CONTENT& script, int expect=0)
     {
-        TestPythonCompatible():
-            // Note the peculiar insertion of __FILE__ into this string. Since
-            // this script is being written into a platform-dependent temp
-            // directory, we can't locate indra/lib/python relative to
-            // Python's __file__. Use __FILE__ instead, navigating relative
-            // to this C++ source file. Use Python raw-string syntax so
-            // Windows pathname backslashes won't mislead Python's string
-            // scanner.
-            import_llsd("import os.path\n"
-                        "import sys\n"
-                        "from llbase import llsd\n")
-        {}
-        ~TestPythonCompatible() {}
+        auto PYTHON(LLStringUtil::getenv("PYTHON"));
+        ensure("Set $PYTHON to the Python interpreter", !PYTHON.empty());
 
-        std::string import_llsd;
+        NamedTempFile scriptfile("py", script);
 
-        template <typename CONTENT>
-        void python(const std::string& desc, const CONTENT& script, int expect=0)
+#if LL_WINDOWS
+        std::string q("\"");
+        std::string qPYTHON(q + PYTHON + q);
+        std::string qscript(q + scriptfile.getName() + q);
+        int rc = _spawnl(_P_WAIT, PYTHON.c_str(), qPYTHON.c_str(), qscript.c_str(), NULL);
+        if (rc == -1)
         {
-            auto PYTHON(LLStringUtil::getenv("PYTHON"));
-            ensure("Set $PYTHON to the Python interpreter", !PYTHON.empty());
-
-            NamedTempFile scriptfile("py", script);
+            char buffer[256];
+            strerror_s(buffer, errno); // C++ can infer the buffer size!  :-O
+            ensure(STRINGIZE("Couldn't run Python " << desc << "script: " << buffer), false);
+        }
+        else
+        {
+            ensure_equals(STRINGIZE(desc << " script terminated with rc " << rc), rc, expect);
+        }
 
-#if LL_WINDOWS
-            std::string q("\"");
-            std::string qPYTHON(q + PYTHON + q);
-            std::string qscript(q + scriptfile.getName() + q);
-            int rc = _spawnl(_P_WAIT, PYTHON.c_str(), qPYTHON.c_str(), qscript.c_str(), NULL);
-            if (rc == -1)
-            {
-                char buffer[256];
-                strerror_s(buffer, errno); // C++ can infer the buffer size!  :-O
-                ensure(STRINGIZE("Couldn't run Python " << desc << "script: " << buffer), false);
-            }
-            else
+#else  // LL_DARWIN, LL_LINUX
+        LLProcess::Params params;
+        params.executable = PYTHON;
+        params.args.add(scriptfile.getName());
+        LLProcessPtr py(LLProcess::create(params));
+        ensure(STRINGIZE("Couldn't launch " << desc << " script"), bool(py));
+        // Implementing timeout would mean messing with alarm() and
+        // catching SIGALRM... later maybe...
+        int status(0);
+        if (waitpid(py->getProcessID(), &status, 0) == -1)
+        {
+            int waitpid_errno(errno);
+            ensure_equals(STRINGIZE("Couldn't retrieve rc from " << desc << " script: "
+                                    "waitpid() errno " << waitpid_errno),
+                          waitpid_errno, ECHILD);
+        }
+        else
+        {
+            if (WIFEXITED(status))
             {
-                ensure_equals(STRINGIZE(desc << " script terminated with rc " << rc), rc, expect);
+                int rc(WEXITSTATUS(status));
+                ensure_equals(STRINGIZE(desc << " script terminated with rc " << rc),
+                              rc, expect);
             }
-
-#else  // LL_DARWIN, LL_LINUX
-            LLProcess::Params params;
-            params.executable = PYTHON;
-            params.args.add(scriptfile.getName());
-            LLProcessPtr py(LLProcess::create(params));
-            ensure(STRINGIZE("Couldn't launch " << desc << " script"), bool(py));
-            // Implementing timeout would mean messing with alarm() and
-            // catching SIGALRM... later maybe...
-            int status(0);
-            if (waitpid(py->getProcessID(), &status, 0) == -1)
+            else if (WIFSIGNALED(status))
             {
-                int waitpid_errno(errno);
-                ensure_equals(STRINGIZE("Couldn't retrieve rc from " << desc << " script: "
-                                        "waitpid() errno " << waitpid_errno),
-                              waitpid_errno, ECHILD);
+                ensure(STRINGIZE(desc << " script terminated by signal " << WTERMSIG(status)),
+                       false);
             }
             else
             {
-                if (WIFEXITED(status))
-                {
-                    int rc(WEXITSTATUS(status));
-                    ensure_equals(STRINGIZE(desc << " script terminated with rc " << rc),
-                                  rc, expect);
-                }
-                else if (WIFSIGNALED(status))
-                {
-                    ensure(STRINGIZE(desc << " script terminated by signal " << WTERMSIG(status)),
-                           false);
-                }
-                else
-                {
-                    ensure(STRINGIZE(desc << " script produced impossible status " << status),
-                           false);
-                }
+                ensure(STRINGIZE(desc << " script produced impossible status " << status),
+                       false);
             }
-#endif
         }
+#endif
+    }
+
+    struct TestPythonCompatible
+    {
+        TestPythonCompatible() {}
+        ~TestPythonCompatible() {}
     };
 
     typedef tut::test_group<TestPythonCompatible> TestPythonCompatibleGroup;
@@ -1798,25 +1895,33 @@ namespace tut
                "print('Running on', sys.platform)\n");
     }
 
-    // helper for test<3>
-    static void writeLLSDArray(std::ostream& out, const LLSD& array)
+    // helper for test<3> - test<7>
+    static void writeLLSDArray(const FormatterFunction& serialize,
+                               std::ostream& out, const LLSD& array)
     {
-        BOOST_FOREACH(LLSD item, llsd::inArray(array))
+        for (const LLSD& item : llsd::inArray(array))
         {
-            LLSDSerialize::toNotation(item, out);
-            // It's important to separate with newlines because Python's llsd
-            // module doesn't support parsing from a file stream, only from a
-            // string, so we have to know how much of the file to read into a
-            // string.
-            out << '\n';
+            // It's important to delimit the entries in this file somehow
+            // because, although Python's llsd.parse() can accept a file
+            // stream, the XML parser expects EOF after a single outer element
+            // -- it doesn't just stop. So we must extract a sequence of bytes
+            // strings from the file. But since one of the serialization
+            // formats we want to test is binary, we can't pick any single
+            // byte value as a delimiter! Use a binary integer length prefix
+            // instead.
+            std::ostringstream buffer;
+            serialize(item, buffer);
+            auto buffstr{ buffer.str() };
+            int bufflen{ static_cast<int>(buffstr.length()) };
+            out.write(reinterpret_cast<const char*>(&bufflen), sizeof(bufflen));
+            out.write(buffstr.c_str(), buffstr.length());
         }
     }
 
-    template<> template<>
-    void TestPythonCompatibleObject::test<3>()
+    // helper for test<3> - test<7>
+    static void toPythonUsing(const std::string& desc,
+                              const FormatterFunction& serialize)
     {
-        set_test_name("verify sequence to Python");
-
         LLSD cdata(llsd::array(17, 3.14,
                                "This string\n"
                                "has several\n"
@@ -1836,7 +1941,7 @@ namespace tut
             "    except StopIteration:\n"
             "        pass\n"
             "    else:\n"
-            "        assert False, 'Too many data items'\n";
+            "        raise AssertionError('Too many data items')\n";
 
         // Create an llsdXXXXXX file containing 'data' serialized to
         // notation.
@@ -1845,32 +1950,128 @@ namespace tut
                            // takes a callable. To this callable it passes the
                            // std::ostream with which it's writing the
                            // NamedTempFile.
-                           boost::bind(writeLLSDArray, _1, cdata));
+                           [serialize, cdata]
+                           (std::ostream& out)
+                           { writeLLSDArray(serialize, out, cdata); });
 
-        python("read C++ notation",
+        python("read C++ " + desc,
                placeholders::arg1 <<
                import_llsd <<
-               "def parse_each(iterable):\n"
-               "    for item in iterable:\n"
-               "        yield llsd.parse(item)\n" <<
-               pydata <<
+               "from functools import partial\n"
+               "import io\n"
+               "import struct\n"
+               "lenformat = struct.Struct('i')\n"
+               "def parse_each(inf):\n"
+               "    for rawlen in iter(partial(inf.read, lenformat.size), b''):\n"
+               "        len = lenformat.unpack(rawlen)[0]\n"
+               // Since llsd.parse() has no max_bytes argument, instead of
+               // passing the input stream directly to parse(), read the item
+               // into a distinct bytes object and parse that.
+               "        data = inf.read(len)\n"
+               "        try:\n"
+               "            frombytes = llsd.parse(data)\n"
+               "        except llsd.LLSDParseError as err:\n"
+               "            print(f'*** {err}')\n"
+               "            print(f'Bad content:\\n{data!r}')\n"
+               "            raise\n"
+               // Also try parsing from a distinct stream.
+               "        stream = io.BytesIO(data)\n"
+               "        fromstream = llsd.parse(stream)\n"
+               "        assert frombytes == fromstream\n"
+               "        yield frombytes\n"
+               << pydata <<
                // Don't forget raw-string syntax for Windows pathnames.
                "verify(parse_each(open(r'" << file.getName() << "', 'rb')))\n");
     }
 
     template<> template<>
+    void TestPythonCompatibleObject::test<3>()
+    {
+        set_test_name("to Python using LLSDSerialize::serialize(LLSD_XML)");
+        toPythonUsing("LLSD_XML",
+                      [](const LLSD& sd, std::ostream& out)
+        { LLSDSerialize::serialize(sd, out, LLSDSerialize::LLSD_XML); });
+    }
+
+    template<> template<>
     void TestPythonCompatibleObject::test<4>()
     {
-        set_test_name("verify sequence from Python");
+        set_test_name("to Python using LLSDSerialize::serialize(LLSD_NOTATION)");
+        toPythonUsing("LLSD_NOTATION",
+                      [](const LLSD& sd, std::ostream& out)
+        { LLSDSerialize::serialize(sd, out, LLSDSerialize::LLSD_NOTATION); });
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<5>()
+    {
+        set_test_name("to Python using LLSDSerialize::serialize(LLSD_BINARY)");
+        toPythonUsing("LLSD_BINARY",
+                      [](const LLSD& sd, std::ostream& out)
+        { LLSDSerialize::serialize(sd, out, LLSDSerialize::LLSD_BINARY); });
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<6>()
+    {
+        set_test_name("to Python using LLSDSerialize::toXML()");
+        toPythonUsing("toXML()", LLSDSerialize::toXML);
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<7>()
+    {
+        set_test_name("to Python using LLSDSerialize::toNotation()");
+        toPythonUsing("toNotation()", LLSDSerialize::toNotation);
+    }
 
+/*==========================================================================*|
+    template<> template<>
+    void TestPythonCompatibleObject::test<8>()
+    {
+        set_test_name("to Python using LLSDSerialize::toBinary()");
+        // We don't expect this to work because, without a header,
+        // llsd.parse() will assume notation rather than binary.
+        toPythonUsing("toBinary()", LLSDSerialize::toBinary);
+    }
+|*==========================================================================*/
+
+    // helper for test<8> - test<12>
+    bool itemFromStream(std::istream& istr, LLSD& item, const ParserFunction& parse)
+    {
+        // reset the output value for debugging clarity
+        item.clear();
+        // We use an int length prefix as a foolproof delimiter even for
+        // binary serialized streams.
+        int length{ 0 };
+        istr.read(reinterpret_cast<char*>(&length), sizeof(length));
+//      return parse(istr, item, length);
+        // Sadly, as of 2022-12-01 it seems we can't really trust our LLSD
+        // parsers to honor max_bytes: this test works better when we read
+        // each item into its own distinct LLMemoryStream, instead of passing
+        // the original istr with a max_bytes constraint.
+        std::vector<U8> buffer(length);
+        istr.read(reinterpret_cast<char*>(buffer.data()), length);
+        LLMemoryStream stream(buffer.data(), length);
+        return parse(stream, item, length);
+    }
+
+    // helper for test<8> - test<12>
+    void fromPythonUsing(const std::string& pyformatter,
+                         const ParserFunction& parse=
+                         [](std::istream& istr, LLSD& data, llssize max_bytes)
+                         { return LLSDSerialize::deserialize(data, istr, max_bytes); })
+    {
         // Create an empty data file. This is just a placeholder for our
         // script to write into. Create it to establish a unique name that
         // we know.
         NamedTempFile file("llsd", "");
 
-        python("write Python notation",
+        python("Python " + pyformatter,
                placeholders::arg1 <<
                import_llsd <<
+               "import struct\n"
+               "lenformat = struct.Struct('i')\n"
                "DATA = [\n"
                "    17,\n"
                "    3.14,\n"
@@ -1881,34 +2082,87 @@ namespace tut
                "]\n"
                // Don't forget raw-string syntax for Windows pathnames.
                // N.B. Using 'print' implicitly adds newlines.
-               "with open(r'" << file.getName() << "', 'w') as f:\n"
+               "with open(r'" << file.getName() << "', 'wb') as f:\n"
                "    for item in DATA:\n"
-               "        print(llsd.format_notation(item).decode(), file=f)\n");
+               "        serialized = llsd." << pyformatter << "(item)\n"
+               "        f.write(lenformat.pack(len(serialized)))\n"
+               "        f.write(serialized)\n");
 
         std::ifstream inf(file.getName().c_str());
         LLSD item;
-        // Notice that we're not doing anything special to parse out the
-        // newlines: LLSDSerialize::fromNotation ignores them. While it would
-        // seem they're not strictly necessary, going in this direction, we
-        // want to ensure that notation-separated-by-newlines works in both
-        // directions -- since in practice, a given file might be read by
-        // either language.
-        ensure_equals("Failed to read LLSD::Integer from Python",
-                      LLSDSerialize::fromNotation(item, inf, LLSDSerialize::SIZE_UNLIMITED),
-                      1);
-        ensure_equals(item.asInteger(), 17);
-        ensure_equals("Failed to read LLSD::Real from Python",
-                      LLSDSerialize::fromNotation(item, inf, LLSDSerialize::SIZE_UNLIMITED),
-                      1);
-        ensure_approximately_equals("Bad LLSD::Real value from Python",
-                                    item.asReal(), 3.14, 7); // 7 bits ~= 0.01
-        ensure_equals("Failed to read LLSD::String from Python",
-                      LLSDSerialize::fromNotation(item, inf, LLSDSerialize::SIZE_UNLIMITED),
-                      1);
-        ensure_equals(item.asString(), 
-                      "This string\n"
-                      "has several\n"
-                      "lines.");
-        
+        try
+        {
+            ensure("Failed to read LLSD::Integer from Python",
+                   itemFromStream(inf, item, parse));
+            ensure_equals(item.asInteger(), 17);
+            ensure("Failed to read LLSD::Real from Python",
+                   itemFromStream(inf, item, parse));
+            ensure_approximately_equals("Bad LLSD::Real value from Python",
+                                        item.asReal(), 3.14, 7); // 7 bits ~= 0.01
+            ensure("Failed to read LLSD::String from Python",
+                   itemFromStream(inf, item, parse));
+            ensure_equals(item.asString(), 
+                          "This string\n"
+                          "has several\n"
+                          "lines.");
+        }
+        catch (const tut::failure& err)
+        {
+            std::cout << "for " << err.what() << ", item = " << item << std::endl;
+            throw;
+        }
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<8>()
+    {
+        set_test_name("from Python XML using LLSDSerialize::deserialize()");
+        fromPythonUsing("format_xml");
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<9>()
+    {
+        set_test_name("from Python notation using LLSDSerialize::deserialize()");
+        fromPythonUsing("format_notation");
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<10>()
+    {
+        set_test_name("from Python binary using LLSDSerialize::deserialize()");
+        fromPythonUsing("format_binary");
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<11>()
+    {
+        set_test_name("from Python XML using fromXML()");
+        // fromXML()'s optional 3rd param isn't max_bytes, it's emit_errors
+        fromPythonUsing("format_xml",
+                        [](std::istream& istr, LLSD& data, llssize)
+                        { return LLSDSerialize::fromXML(data, istr) > 0; });
+    }
+
+    template<> template<>
+    void TestPythonCompatibleObject::test<12>()
+    {
+        set_test_name("from Python notation using fromNotation()");
+        fromPythonUsing("format_notation",
+                        [](std::istream& istr, LLSD& data, llssize max_bytes)
+                        { return LLSDSerialize::fromNotation(data, istr, max_bytes) > 0; });
+    }
+
+/*==========================================================================*|
+    template<> template<>
+    void TestPythonCompatibleObject::test<13>()
+    {
+        set_test_name("from Python binary using fromBinary()");
+        // We don't expect this to work because format_binary() emits a
+        // header, but fromBinary() won't recognize a header.
+        fromPythonUsing("format_binary",
+                        [](std::istream& istr, LLSD& data, llssize max_bytes)
+                        { return LLSDSerialize::fromBinary(data, istr, max_bytes) > 0; });
     }
+|*==========================================================================*/
 }