posix: mqueue: pop mode as int with va_arg() #67071
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keith-packard
previously approved these changes
Dec 29, 2023
That's a good point - better to be safe than sorry! |
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@keith-packard - fixed! |
There was some discussion about whether it was suitable to have
an architecture-specific workaround in mqueue.c after that
workaround was copied to a different source file in a PR.
The original issue was that newlib and picolibc declare mode_t
to be unsigned short instead of unsigned long when __svr4__
is not defined along with __sparc__. This is specifically
impactful, because va_arg() deals (mainly) with 32-bit and
64-bit values that are all naturally aligned to 4 bytes.
#if defined(__sparc__) && !defined(__sparc_v9__)
#ifdef __svr4__
typedef unsigned long __mode_t;
#else
typedef unsigned short __mode_t;
#endif
A uint16_t is naturally aligned to 2 bytes, so not only would
a 16-bit mode_t be corrupted, it would also generate a warning
with recent gcc versions which is promoted to error (rightfully
so) when run through CI.
mqueue.c:61:35: error: 'mode_t' {aka 'short unsigned int'} is
promoted to 'int' when passed through '...' [-Werror]
61 | mode = va_arg(va, mode_t);
Instead of using an architecture-specific workaround, simply
add a build assert that the size of mode_t is less than or
equal to the size of an int, and use an int to retrieve it
via va_arg().
Signed-off-by: Christopher Friedt <[email protected]>
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# Date: Fri Dec 29 10:06:44 2023 -0500
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# On branch posix-mqueue-always-use-int-for-mode-t-va-arg
# Changes to be committed:
# modified: lib/posix/mqueue.c
# modified: tests/posix/common/testcase.yaml
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keith-packard
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jukkar
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There was some discussion about whether it was suitable to have an architecture-specific workaround in mqueue.c after that workaround was copied to a different source file in #67007.
The original issue was that newlib and picolibc declare mode_t to be unsigned short (16-bits) instead of unsigned long when
__svr4__is not defined along with__sparc__. This is specifically impactful, becauseva_arg()deals (mainly) with 32-bit and 64-bit values that are all naturally aligned to 4 bytes (or 8 bytes)A uint16_t is naturally aligned to 2 bytes, so not only would a 16-bit mode_t be corrupted, it would also generate a warning with recent gcc versions which is promoted to error (rightfully so) when run through CI.
Instead of using an architecture-specific workaround, simply add a build assert that the size of
mode_tis less than or equal to the size of an int, and use an int to retrieve it viava_arg().Also ensure that we allow testing via
qemu_leon3which was not part of the fix in 6d126e7.