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004f708a5e
* modules/freopen-safer: New module. * m4/stdio-safer.m4 (gl_FREOPEN_SAFER): New macro. * lib/freopen-safer.c (freopen_safer): New file. * lib/stdio-safer.h (freopen_safer): New declaration. * lib/stdio--.h (freopen): New override. * MODULES.html.sh (File stream based Input/Output): Mention it. * doc/posix-functions/freopen.texi (freopen): Mention pitfalls and freopen-safer module. * doc/posix-functions/stderr.texi (stderr): Likewise. * doc/posix-functions/stdin.texi (stdin): Likewise. * doc/posix-functions/stdout.texi (stdout): Likewise. * modules/freopen-safer-tests: New test. * tests/test-reopen-safer.c: New file. Signed-off-by: Eric Blake <ebb9@byu.net>
28 lines
891 B
Plaintext
28 lines
891 B
Plaintext
@node stdout
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@section @code{stdout}
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@findex stdout
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POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/stdout.html}
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Gnulib module: ---
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Portability problems fixed by Gnulib:
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@itemize
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@end itemize
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Portability problems not fixed by Gnulib:
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@itemize
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@item
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stdout is created in 32-bit mode instead of 64-bit mode: Cygwin 1.5.x.
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One workaround is to use freopen(NULL, ``w'', stdout) on Cygwin 1.5.21
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or newer. Another is to use the gnulib ftello module and do
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ftello(stdout).
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@item
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POSIX states that a setuid application can guarantee that fd 1 is
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open, but some systems guarantee this even for non-setuid programs.
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If an application is executed with fd 1 closed, use of @code{stdout}
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can affect an unrelated file that happened to be assigned to fd 1.
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The gnulib *-safer modules may be used to guarantee that fd 1 stays
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reserved for @code{stdout}.
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@end itemize
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