From ae6440eecc4d6c018a3634c2c06052757bde962f Mon Sep 17 00:00:00 2001
From: Nat Goodspeed <nat@lindenlab.com>
Date: Wed, 28 Jan 2015 15:55:18 -0500
Subject: MAINT-4744: Eliminate viewer dependency on (old) GNU libstdc++. To be
more accurate, this changeset doesn't actually eliminate the dependency: it
eliminates the use cases for the llifstream / llofstream feature that
requires it. Currently you can construct an llifstream or llofstream from an
open LLFILE* file handle (or, except on Windows, an int file descriptor). But
rather than containing a streambuf implementation based on FILE*, llfile.h
relies on the fact that the Windows std::filebuf happens to support that as a
nonstandard extension; also on a nonstandard GNU extension
__gnu_cxx::stdio_filebuf<char>. To move from GNU libstdc++ to clang's libc++
(the direction on Mac), we could code a streambuf that supports FILE*. But
before doing that, it's worth asking whether anyone actually uses this
questionable feature. In fact there were only two methods:
LLWearable::exportFile() and importFile() -- and only one call to either, in
LLViewerWearable::saveNewAsset(). The code in saveNewAsset() opened the
LLFILE* immediately before calling exportFile(), meaning we could reasonably
push the open operation down into exportFile(). That logic was complex anyway
due to the need for the caller to close the LLFILE* regardless of the success
of the exportFile(). Change LLWearable::exportFile() and importFile() to
accept a std::string filename rather than an open LLFILE*. Change
LLViewerWearable::saveNewAsset() to simply call exportFile(filename) rather
than horsing around with an LLFILE* handle. (This improves the code in
another way too: it encapsulates the need to open the relevant file in binary
mode. Previously, each caller had to remember to do that.) To prevent
inadvertent reintroduction of ll[io]fstream(LLFILE*) code, add
llstream_LLFILE preprocessor macro (default 0) to control access to the
relevant constructors. Also suppress rdbuf() override, the only method whose
signature references llstdio_filebuf.
---
indra/llcommon/llfile.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
(limited to 'indra/llcommon/llfile.h')
diff --git a/indra/llcommon/llfile.h b/indra/llcommon/llfile.h
index 0612071d67..44a1e42fa5 100755
--- a/indra/llcommon/llfile.h
+++ b/indra/llcommon/llfile.h
@@ -86,6 +86,12 @@ public:
static const char * tmpdir();
};
+// Remove ll[io]fstream support for [LL]FILE*, preparing to remove dependency
+// on GNU's standard library.
+#if ! defined(llstream_LLFILE)
+#define llstream_LLFILE 0
+#endif
+
/**
* @brief Provides a layer of compatibility for C/POSIX.
*
@@ -228,6 +234,7 @@ public:
explicit llifstream(const char* _Filename,
ios_base::openmode _Mode = ios_base::in);
+#if llstream_LLFILE
/**
* @brief Create a stream using an open c file stream.
* @param File An open @c FILE*.
@@ -253,6 +260,7 @@ public:
//size_t _Size = static_cast<size_t>(BUFSIZ));
size_t _Size = static_cast<size_t>(1));
#endif
+#endif // llstream_LLFILE
/**
* @brief The destructor does nothing.
@@ -263,6 +271,7 @@ public:
virtual ~llifstream() {}
// Members:
+#if llstream_LLFILE
/**
* @brief Accessing the underlying buffer.
* @return The current basic_filebuf buffer.
@@ -271,6 +280,7 @@ public:
*/
llstdio_filebuf* rdbuf() const
{ return const_cast<llstdio_filebuf*>(&_M_filebuf); }
+#endif // llstream_LLFILE
/**
* @brief Wrapper to test for an open file.
@@ -340,6 +350,7 @@ public:
explicit llofstream(const char* _Filename,
ios_base::openmode _Mode = ios_base::out|ios_base::trunc);
+#if llstream_LLFILE
/**
* @brief Create a stream using an open c file stream.
* @param File An open @c FILE*.
@@ -365,6 +376,7 @@ public:
//size_t _Size = static_cast<size_t>(BUFSIZ));
size_t _Size = static_cast<size_t>(1));
#endif
+#endif // llstream_LLFILE
/**
* @brief The destructor does nothing.
@@ -375,6 +387,7 @@ public:
virtual ~llofstream() {}
// Members:
+#if llstream_LLFILE
/**
* @brief Accessing the underlying buffer.
* @return The current basic_filebuf buffer.
@@ -383,6 +396,7 @@ public:
*/
llstdio_filebuf* rdbuf() const
{ return const_cast<llstdio_filebuf*>(&_M_filebuf); }
+#endif // llstream_LLFILE
/**
* @brief Wrapper to test for an open file.
--
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