1#define _GNU_SOURCE
2#include <string.h>
3#include "pthread_impl.h"
4#include "syscall.h"
5
6hidden long __cancel(), __syscall_cp_asm(), __syscall_cp_c();
7
8long __cancel()
9{
10 pthread_t self = __pthread_self();
11 if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync)
12 pthread_exit(PTHREAD_CANCELED);
13 self->canceldisable = PTHREAD_CANCEL_DISABLE;
14 return -ECANCELED;
15}
16
17long __syscall_cp_asm(volatile void *, syscall_arg_t,
18 syscall_arg_t, syscall_arg_t, syscall_arg_t,
19 syscall_arg_t, syscall_arg_t, syscall_arg_t);
20
21long __syscall_cp_c(syscall_arg_t nr,
22 syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
23 syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
24{
25 pthread_t self;
26 long r;
27 int st;
28
29 if ((st=(self=__pthread_self())->canceldisable)
30 && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close))
31 return __syscall(nr, u, v, w, x, y, z);
32
33 r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
34 if (r==-EINTR && nr!=SYS_close && self->cancel &&
35 self->canceldisable != PTHREAD_CANCEL_DISABLE)
36 r = __cancel();
37 return r;
38}
39
40static void _sigaddset(sigset_t *set, int sig)
41{
42 unsigned s = sig-1;
43 set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
44}
45
46extern hidden const char __cp_begin[1], __cp_end[1], __cp_cancel[1];
47
48static void cancel_handler(int sig, siginfo_t *si, void *ctx)
49{
50 pthread_t self = __pthread_self();
51 ucontext_t *uc = ctx;
52 uintptr_t pc = uc->uc_mcontext.MC_PC;
53
54 a_barrier();
55 if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
56
57 _sigaddset(&uc->uc_sigmask, SIGCANCEL);
58
59 if (self->cancelasync) {
60 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
61 __cancel();
62 }
63
64 if (pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) {
65 uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel;
66#ifdef CANCEL_GOT
67 uc->uc_mcontext.MC_GOT = CANCEL_GOT;
68#endif
69 return;
70 }
71
72 __syscall(SYS_tkill, self->tid, SIGCANCEL);
73}
74
75void __testcancel()
76{
77 pthread_t self = __pthread_self();
78 if (self->cancel && !self->canceldisable)
79 __cancel();
80}
81
82static void init_cancellation()
83{
84 struct sigaction sa = {
85 .sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK,
86 .sa_sigaction = cancel_handler
87 };
88 memset(&sa.sa_mask, -1, _NSIG/8);
89 __libc_sigaction(SIGCANCEL, &sa, 0);
90}
91
92int pthread_cancel(pthread_t t)
93{
94 static int init;
95 if (!init) {
96 init_cancellation();
97 init = 1;
98 }
99 a_store(&t->cancel, 1);
100 if (t == pthread_self()) {
101 if (t->canceldisable == PTHREAD_CANCEL_ENABLE && t->cancelasync)
102 pthread_exit(PTHREAD_CANCELED);
103 return 0;
104 }
105 return pthread_kill(t, SIGCANCEL);
106}