1 #define _GNU_SOURCE
2 #include <string.h>
3 #include "pthread_impl.h"
4 #include "syscall.h"
5
6 hidden long __cancel(), __syscall_cp_asm(), __syscall_cp_c();
7
__cancel()8 long __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
17 long __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
__syscall_cp_c(syscall_arg_t nr,syscall_arg_t u,syscall_arg_t v,syscall_arg_t w,syscall_arg_t x,syscall_arg_t y,syscall_arg_t z)21 long __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
_sigaddset(sigset_t * set,int sig)40 static 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
46 extern hidden const char __cp_begin[1], __cp_end[1], __cp_cancel[1];
47
cancel_handler(int sig,siginfo_t * si,void * ctx)48 static 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 || pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) {
60 uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel;
61 #ifdef CANCEL_GOT
62 uc->uc_mcontext.MC_GOT = CANCEL_GOT;
63 #endif
64 return;
65 }
66
67 __syscall(SYS_tkill, self->tid, SIGCANCEL);
68 }
69
__testcancel()70 void __testcancel()
71 {
72 pthread_t self = __pthread_self();
73 if (self->cancel && !self->canceldisable)
74 __cancel();
75 }
76
init_cancellation()77 static void init_cancellation()
78 {
79 struct sigaction sa = {
80 .sa_flags = SA_SIGINFO | SA_RESTART,
81 .sa_sigaction = cancel_handler
82 };
83 memset(&sa.sa_mask, -1, _NSIG/8);
84 __libc_sigaction(SIGCANCEL, &sa, 0);
85 }
86
pthread_cancel(pthread_t t)87 int pthread_cancel(pthread_t t)
88 {
89 static int init;
90 if (!init) {
91 init_cancellation();
92 init = 1;
93 }
94 a_store(&t->cancel, 1);
95 if (t == pthread_self()) {
96 if (t->canceldisable == PTHREAD_CANCEL_ENABLE && t->cancelasync)
97 pthread_exit(PTHREAD_CANCELED);
98 return 0;
99 }
100 return pthread_kill(t, SIGCANCEL);
101 }
102