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libc: fix the pthread_sigmask implementation 

The old code didn't work because the kernel expects a 64-bit sigset_t
while the one provided by our ABI is only 32-bit. This is originally
due to the fact that the kernel headers themselves define sigset_t
as a 32-bit type when __KERNEL__ is not defined (apparently to cater
to libc5 or some similarly old C library).

We can't modify the size of sigset_t without breaking the NDK ABI,
so instead perform runtime translation during the call.

Change-Id: Ibfdc3cbceaff864af7a05ca193aa050047b4773f
This commit is contained in:
David 'Digit' Turner 2011-11-14 12:57:47 +01:00
parent 7939908c83
commit 9bf330b567
1 changed files with 36 additions and 7 deletions
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43
libc/bionic/pthread.c
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@ -1856,7 +1856,21 @@ int pthread_kill(pthread_t tid, int sig)
return ret;
}
extern int __rt_sigprocmask(int, const sigset_t *, sigset_t *, size_t);
/* Despite the fact that our kernel headers define sigset_t explicitly
* as a 32-bit integer, the kernel system call really expects a 64-bit
* bitmap for the signal set, or more exactly an array of two-32-bit
* values (see $KERNEL/arch/$ARCH/include/asm/signal.h for details).
*
* Unfortunately, we cannot fix the sigset_t definition without breaking
* the C library ABI, so perform a little runtime translation here.
*/
typedef union {
sigset_t bionic;
uint32_t kernel[2];
} kernel_sigset_t;
/* this is a private syscall stub */
extern int __rt_sigprocmask(int, const kernel_sigset_t *, kernel_sigset_t *, size_t);
int pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
{
@ -1865,16 +1879,31 @@ int pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
*/
int ret, old_errno = errno;
/* Use NSIG which corresponds to the number of signals in
* our 32-bit sigset_t implementation. As such, this function, or
* anything that deals with sigset_t cannot manage real-time signals
* (signo >= 32). We might want to introduce sigset_rt_t as an
* extension to do so in the future.
/* We must convert *set into a kernel_sigset_t */
kernel_sigset_t in_set, *in_set_ptr;
kernel_sigset_t out_set;
in_set.kernel[0] = in_set.kernel[1] = 0;
out_set.kernel[0] = out_set.kernel[1] = 0;
/* 'in_set_ptr' is the second parameter to __rt_sigprocmask. It must be NULL
* if 'set' is NULL to ensure correct semantics (which in this case would
* be to ignore 'how' and return the current signal set into 'oset'.
*/
ret = __rt_sigprocmask(how, set, oset, NSIG / 8);
if (set == NULL) {
in_set_ptr = NULL;
} else {
in_set.bionic = *set;
in_set_ptr = &in_set;
}
ret = __rt_sigprocmask(how, in_set_ptr, &out_set, sizeof(kernel_sigset_t));
if (ret < 0)
ret = errno;
if (oset)
*oset = out_set.bionic;
errno = old_errno;
return ret;
}