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stdio: don't require ignore_value around fwrite
From: |
Paul Eggert |
Subject: |
stdio: don't require ignore_value around fwrite |
Date: |
Sun, 20 Mar 2011 12:18:27 -0700 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.14) Gecko/20110223 Thunderbird/3.1.8 |
I've tried out the following proposed patch with Emacs.
However, I'm no expert with C++ and the C++ parts of it
need another pair of eyes to look at.
A similar fix is needed for fwrite_unlocked but I figured
one function at a time.
----
diff --git a/ChangeLog b/ChangeLog
index 1b42d3c..a1ff2b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,32 @@
+2011-03-19 Paul Eggert <address@hidden>
+
+ stdio: don't require ignore_value around fwrite
+
+ This patch works around libc bug 11959
+ <http://sources.redhat.com/bugzilla/show_bug.cgi?id=11959>.
+ Without this patch, applications must often write
+ ignore_value (fwrite (...)) even though the ignore_value is
+ not helpful here. It's common to write many objects, using
+ fwrite/printf/etc., and then use ferror to detect output error.
+
+ I considered making this patch optional, but decided against it,
+ because libc is obviously being inconsistent here: there is no
+ reason libc should insist that user code must inspect fwrite
+ return's value without also insisting that it inspect printf's,
+ putchar's, etc. If user code wants to have a strict style where
+ all these functions' values are checked (so that ferror need not
+ be checked), we could add support for that style in a new gnulib
+ module, but in the meantime it's better to be consistent and to
+ support common usage.
+
+ * lib/stdio.in.h (rpl_fwrite): Define this wrapper around fwrite,
+ to work around libc bug 11959, if __USE_FORTIFY_LEVEL indicates
+ that we are compiling in checking mode, and if not already
+ wrapping fwrite for some other reason.
+ (GNULIB_inline_rpl_fwrite): New macro, defined to 1 if this new
+ wrapper is in use.
+ (fwrite): Adjust to the possibility that this new wrapper is in use.
+
2011-03-19 Jim Meyering <address@hidden>
maint.mk: fix po-file syntax-check rule
diff --git a/lib/stdio.in.h b/lib/stdio.in.h
index b5083d1..3ceb98a 100644
--- a/lib/stdio.in.h
+++ b/lib/stdio.in.h
@@ -481,22 +481,39 @@ _GL_WARN_ON_USE (ftell, "ftell cannot handle files larger
than 4 GB "
"use ftello function for handling of large files");
#endif
+#if (0 < __USE_FORTIFY_LEVEL \
+ && ! (@GNULIB_FWRITE@ \
+ && @REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@))
+# define GNULIB_inline_rpl_fwrite 1
+static inline size_t _GL_ARG_NONNULL ((1, 4))
+rpl_fwrite (const void *ptr, size_t s, size_t n, FILE *stream)
+{
+ size_t r = fwrite (ptr, s, n, stream);
+ (void) r;
+ return r;
+}
+#endif
-#if @GNULIB_FWRITE@
-# if @REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@
+#if @GNULIB_FWRITE@ || GNULIB_inline_rpl_fwrite
+# if ((@REPLACE_STDIO_WRITE_FUNCS@ && @GNULIB_STDIO_H_SIGPIPE@) \
+ || GNULIB_inline_rpl_fwrite)
# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
# undef fwrite
# define fwrite rpl_fwrite
# endif
+# if !GNULIB_inline_rpl_fwrite
_GL_FUNCDECL_RPL (fwrite, size_t,
(const void *ptr, size_t s, size_t n, FILE *stream)
_GL_ARG_NONNULL ((1, 4)));
+# endif
_GL_CXXALIAS_RPL (fwrite, size_t,
(const void *ptr, size_t s, size_t n, FILE *stream));
# else
_GL_CXXALIAS_SYS (fwrite, size_t,
(const void *ptr, size_t s, size_t n, FILE *stream));
# endif
+#endif
+#if @GNULIB_FWRITE@
_GL_CXXALIASWARN (fwrite);
#endif
- stdio: don't require ignore_value around fwrite,
Paul Eggert <=