0cdd6d71bb
RPM-Changelog: - Fix memory leak in freopen, mode flag and wide-oriented stream handling (RHEL-115823) - Add comprehensive tests and document limitations (RHEL-115823) Resolves: RHEL-115823
34 lines
1.5 KiB
Diff
34 lines
1.5 KiB
Diff
commit a2509a8bc955988f01f389a1cf74db3a9da42409
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Author: Joseph Myers <josmyers@redhat.com>
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Date: Fri Sep 6 20:38:23 2024 +0000
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Document limitations on streams passed to freopen
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As recently discussed, document that freopen does not work with
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streams opened with functions such as popen, fmemopen, open_memstream
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or fopencookie. I've filed
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<https://austingroupbugs.net/view.php?id=1855> to clarify this issue
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in POSIX.
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Tested with "make info" and "make html".
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diff --git a/manual/stdio.texi b/manual/stdio.texi
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index de174eafcd5fde0c..7d787735079ea964 100644
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--- a/manual/stdio.texi
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+++ b/manual/stdio.texi
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@@ -330,6 +330,14 @@ this ability, so using @code{freopen} is more portable.
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When the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
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32 bit machine this function is in fact @code{freopen64} since the LFS
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interface replaces transparently the old interface.
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+
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+@Theglibc{} only supports use of @code{freopen} on streams opened with
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+@code{fopen} or @code{fopen64} and on the original values of the
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+standard streams @code{stdin}, @code{stdout}, and @code{stderr}; such
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+a stream may be reopened multiple times with @code{freopen}. If it is
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+called on another kind of stream (opened with functions such as
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+@code{popen}, @code{fmemopen}, @code{open_memstream}, and
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+@code{fopencookie}), @code{freopen} fails and returns a null pointer.
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@end deftypefun
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@deftypefun {FILE *} freopen64 (const char *@var{filename}, const char *@var{opentype}, FILE *@var{stream})
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