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readlink("link-to-symlink/",buf,len) mistakenly read the contents of "symlink", rather than failing. * m4/readlink.m4 (gl_FUNC_READLINK): Also detect FreeBSD bug with slash on symlink. * doc/posix-functions/readlink.texi (readlink): Document the bug. * tests/test-readlink.h (test_readlink): Enhance test. Signed-off-by: Eric Blake <ebb9@byu.net>
43 lines
1.5 KiB
Plaintext
43 lines
1.5 KiB
Plaintext
@node readlink
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@section @code{readlink}
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@findex readlink
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POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/readlink.html}
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Gnulib module: readlink
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Portability problems fixed by Gnulib:
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@itemize
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@item
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Some platforms mistakenly succeed on @code{readlink("link/",buf,len)}:
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FreeBSD 7.2, Solaris 9.
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@item
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On some platforms, @code{readlink} returns @code{int} instead of
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@code{ssize_t}:
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FreeBSD 6.0, OpenBSD 3.8, Cygwin 1.5.x.
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@item
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This function is missing on some platforms:
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mingw.
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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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When @code{readlink} is called on a directory: In the case of NFS mounted
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directories, Cygwin sets @code{errno} to @code{ENOENT} or @code{EIO} instead of
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@code{EINVAL}. To avoid this problem, check for a directory before calling
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@code{readlink}.
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@item
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When @code{readlink} is called on a file that is not a symbolic link:
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Irix may set @code{errno} to @code{ENXIO} instead of @code{EINVAL}. Cygwin
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may set errno to @code{EACCES} instead of @code{EINVAL}.
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@item
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Symlink contents do not always have a trailing null byte, and there is
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no indication if symlink contents were truncated if the return value
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matches the length. Furthermore, AIX 5.1 and HP-UX 11 set
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@code{errno} to @code{ERANGE} rather than returning truncated
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contents, and Linux sets @code{errno} to @code{EINVAL} if the
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requested length is zero. Use the gnulib module areadlink for
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improved ability to read symlink contents.
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@end itemize
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