Bug#610824: libc6-dev: POSIX/SUS defines and functions require GNU specific defines
tag 610824 + fixed-upstream
severity 610824 normal
thanks
On Sat, Jan 22, 2011 at 10:26:51PM +0200, Nach wrote:
> Package: libc6-dev
> Version: 2.11.2-9
> Severity: important
> Tags: upstream
>
>
> Several standardized defines and functions which are part of POSIX.1-2008/SUSv4 require nonstandard GNU defines in order to function properly.
> I don't know the full range of standardized functions and defines which are affected, but I have found several.
>
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html
> Specifies that O_DIRECTORY, O_NOFOLLOW, and O_CLOEXEC are part of the standard for open()/openat().
>
> The manpages incorrectly states regarding some, that they are Linux-specific, when they aren't.
> O_DIRECTORY
> If pathname is not a directory, cause the open to fail. This flag is Linux-specific, and was added in kernel version 2.1.126, to avoid
> denial-of-service problems if opendir(3) is called on a FIFO or tape device, but should not be used outside of the implementation of
> opendir(3).
>
> <fcntl.h> ends up wrapping them as follows:
> #ifdef __USE_GNU
> # define O_DIRECT 040000 /* Direct disk access. */
> # define O_DIRECTORY 0200000 /* Must be a directory. */
> # define O_NOFOLLOW 0400000 /* Do not follow links. */
> # define O_NOATIME 01000000 /* Do not set atime. */
> # define O_CLOEXEC 02000000 /* Set close_on_exec. */
> #endif
>
> 3 out of those 5 should not be wrapped like that.
>
> I found similar issues with pread() and pwrite().
> The standard http://pubs.opengroup.org/onlinepubs/9699919799/functions/pread.html states they should be included with <unistd.h>, but they aren't.
> The manpages state that _POSIX_C_SOURCE >= 200809L would include them, but it doesn't seem to help.
>
> <unistd.h> contains the following:
> #ifdef __USE_UNIX98
> # ifndef __USE_FILE_OFFSET64
> /* Read NBYTES into BUF from FD at the given position OFFSET without
> changing the file pointer. Return the number read, -1 for errors
> or 0 for EOF.
>
> This function is a cancellation point and therefore not marked with
> __THROW. */
> extern ssize_t pread (int __fd, void *__buf, size_t __nbytes,
> __off_t __offset) __wur;
>
> /* Write N bytes of BUF to FD at the given position OFFSET without
> changing the file pointer. Return the number written, or -1.
>
> This function is a cancellation point and therefore not marked with
> __THROW. */
> extern ssize_t pwrite (int __fd, __const void *__buf, size_t __n,
> __off_t __offset) __wur;
>
>
>
> Adding -D__USE_UNIX98 when compiling fixes the problem, but that shouldn't be needed.
>
> This problem seems to be quite widespread. Adding -D_POSIX_C_SOURCE=200809L for example seems to no longer include many functions which should
> be included as part of POSIX.1-2008, such as the *at() functions.
>
Both issues are fixed in the new upstream version. This new upstream
version will be uploaded shortly after the Squeeze release.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurelien@aurel32.net http://www.aurel32.net
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