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370f78f)
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.
#include <errno.h>
#include "syscall.h"
#include <errno.h>
#include "syscall.h"
+int __sigprocmask(int, const sigset_t *, sigset_t *);
+
int raise(int sig)
{
int pid, tid, ret;
int raise(int sig)
{
int pid, tid, ret;
- /* Getting the pid/tid pair is not atomic, and could give wrong
- * result if a fork occurs in a signal handler between the two
- * syscalls. Use the tgkill syscall's ESRCH semantics to detect
- * this condition and retry. */
- do {
- tid = syscall0(__NR_gettid);
- pid = syscall0(__NR_getpid);
- ret = syscall3(__NR_tgkill, pid, tid, sig);
- } while (ret<0 && errno == ESRCH);
+ sigset_t set;
+ sigfillset(&set);
+ __sigprocmask(SIG_BLOCK, &set, &set);
+ tid = syscall0(__NR_gettid);
+ pid = syscall0(__NR_getpid);
+ ret = syscall3(__NR_tgkill, pid, tid, sig);
+ __sigprocmask(SIG_SETMASK, &set, 0);