73db33b949
the bug was that cancellation requests which arrived while a cancellation point was interrupted by a signal handler would not be acted upon when the signal handler returns. this was because cp_sp was never set; it's no longer needed or used. instead, just always re-raise the signal when cancellation was not acted upon. this wastes a tiny amount of time in the rare case where it even matters, but it ensures correctness and simplifies the code.
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
#include "pthread_impl.h"
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void __cancel()
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{
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pthread_t self = __pthread_self();
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self->canceldisable = 1;
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self->cancelasync = 0;
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pthread_exit(PTHREAD_CANCELED);
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}
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long __syscall_cp_asm(volatile void *, long, long, long, long, long, long, long);
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long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
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{
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pthread_t self;
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long r;
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if (!libc.main_thread || (self = __pthread_self())->canceldisable)
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return __syscall(nr, u, v, w, x, y, z);
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r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
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if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
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__cancel();
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return r;
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}
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static void _sigaddset(sigset_t *set, int sig)
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{
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unsigned s = sig-1;
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set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
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}
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static void cancel_handler(int sig, siginfo_t *si, void *ctx)
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{
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pthread_t self = __pthread_self();
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ucontext_t *uc = ctx;
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const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
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extern const char __cp_begin[1], __cp_end[1];
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if (!self->cancel || self->canceldisable) return;
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_sigaddset(&uc->uc_sigmask, SIGCANCEL);
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if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
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self->canceldisable = 1;
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pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
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__cancel();
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}
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__syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
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}
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void __testcancel()
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{
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pthread_t self = pthread_self();
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if (self->cancel && !self->canceldisable)
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__cancel();
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}
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static void init_cancellation()
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{
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struct sigaction sa = {
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.sa_flags = SA_SIGINFO | SA_RESTART,
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.sa_sigaction = cancel_handler
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};
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sigfillset(&sa.sa_mask);
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__libc_sigaction(SIGCANCEL, &sa, 0);
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}
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int pthread_cancel(pthread_t t)
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{
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static int init;
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if (!init) {
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init_cancellation();
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init = 1;
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}
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a_store(&t->cancel, 1);
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return pthread_kill(t, SIGCANCEL);
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}
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