musl/src/signal/raise.c

#include <signal.h>
#include <errno.h>
#include <stdint.h>
#include "syscall.h"
#include "pthread_impl.h"

int raise(int sig)
{
	int pid, tid, ret;
	sigset_t set;
	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, &set, _NSIG/8);
	tid = syscall(SYS_gettid);
	pid = syscall(SYS_getpid);
	ret = syscall(SYS_tgkill, pid, tid, sig);
	__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, 0, _NSIG/8);
	return ret;
}
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00			`#include <signal.h>`
fix raise semantics with threads. 2011-03-09 19:42:06 -05:00			`#include <errno.h>`
overhaul implementation-internal signal protections the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sigset() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used. 2011-05-07 23:23:58 -04:00			`#include <stdint.h>`
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00			`#include "syscall.h"`
fix (hopefully) all hard-coded 8's for kernel sigset_t size some minor changes to how hard-coded sets for thread-related purposes are handled were also needed, since the old object sizes were not necessarily sufficient. things have gotten a bit ugly in this area, and i think a cleanup is in order at some point, but for now the goal is just to get the code working on all supported archs including mips, which was badly broken by linux rejecting syscalls with the wrong sigset_t size. 2012-08-09 22:52:13 -04:00			`#include "pthread_impl.h"`
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00
			`int raise(int sig)`
			`{`
fix raise semantics with threads. 2011-03-09 19:42:06 -05:00			`int pid, tid, ret;`
fix race condition in raise - just mask signals a signal handler could fork after the pid/tid were read, causing the wrong process to be signalled. i'm not sure if this is supposed to have UB or not, but raise is async-signal-safe, so it probably is allowed. the current solution is slightly expensive so this implementation is likely to be changed in the future. 2011-03-09 20:07:24 -05:00			`sigset_t set;`
remove __SYSCALL_SSLEN arch macro in favor of using public _NSIG the issue at hand is that many syscalls require as an argument the kernel-ABI size of sigset_t, intended to allow the kernel to switch to a larger sigset_t in the future. previously, each arch was defining this size in syscall_arch.h, which was redundant with the definition of _NSIG in bits/signal.h. as it's used in some not-quite-portable application code as well, _NSIG is much more likely to be recognized and understood immediately by someone reading the code, and it's also shorter and less cluttered. note that _NSIG is actually 65/129, not 64/128, but the division takes care of throwing away the off-by-one part. 2013-03-26 23:07:31 -04:00			`__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, &set, _NSIG/8);`
global cleanup to use the new syscall interface 2011-03-20 00:16:43 -04:00			`tid = syscall(SYS_gettid);`
			`pid = syscall(SYS_getpid);`
			`ret = syscall(SYS_tgkill, pid, tid, sig);`
remove __SYSCALL_SSLEN arch macro in favor of using public _NSIG the issue at hand is that many syscalls require as an argument the kernel-ABI size of sigset_t, intended to allow the kernel to switch to a larger sigset_t in the future. previously, each arch was defining this size in syscall_arch.h, which was redundant with the definition of _NSIG in bits/signal.h. as it's used in some not-quite-portable application code as well, _NSIG is much more likely to be recognized and understood immediately by someone reading the code, and it's also shorter and less cluttered. note that _NSIG is actually 65/129, not 64/128, but the division takes care of throwing away the off-by-one part. 2013-03-26 23:07:31 -04:00			`__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, 0, _NSIG/8);`
fix raise semantics with threads. 2011-03-09 19:42:06 -05:00			`return ret;`
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00			`}`