1 #define _GNU_SOURCE
2 #include <string.h>
3 #include "pthread_impl.h"
4 #include "syscall.h"
5
6 #ifdef FEATURE_PTHREAD_CANCEL
7 hidden long __cancel(), __syscall_cp_asm(), __syscall_cp_c();
8
__cancel()9 long __cancel()
10 {
11 pthread_t self = __pthread_self();
12 if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync)
13 pthread_exit(PTHREAD_CANCELED);
14 self->canceldisable = PTHREAD_CANCEL_DISABLE;
15 return -ECANCELED;
16 }
17
18 long __syscall_cp_asm(volatile void *, syscall_arg_t,
19 syscall_arg_t, syscall_arg_t, syscall_arg_t,
20 syscall_arg_t, syscall_arg_t, syscall_arg_t);
21
__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)22 long __syscall_cp_c(syscall_arg_t nr,
23 syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
24 syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
25 {
26 pthread_t self;
27 long r;
28 int st;
29
30 if ((st=(self=__pthread_self())->canceldisable)
31 && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close))
32 return __syscall(nr, u, v, w, x, y, z);
33
34 r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
35 if (r==-EINTR && nr!=SYS_close && self->cancel &&
36 self->canceldisable != PTHREAD_CANCEL_DISABLE)
37 r = __cancel();
38 return r;
39 }
40
_sigaddset(sigset_t * set,int sig)41 static void _sigaddset(sigset_t *set, int sig)
42 {
43 unsigned s = sig-1;
44 set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
45 }
46
47 extern hidden const char __cp_begin[1], __cp_end[1], __cp_cancel[1];
48
cancel_handler(int sig,siginfo_t * si,void * ctx)49 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
50 {
51 pthread_t self = __pthread_self();
52 ucontext_t *uc = ctx;
53 uintptr_t pc = uc->uc_mcontext.MC_PC;
54
55 a_barrier();
56 if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
57
58 _sigaddset(&uc->uc_sigmask, SIGCANCEL);
59
60 if (self->cancelasync || pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) {
61 uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel;
62 #ifdef CANCEL_GOT
63 uc->uc_mcontext.MC_GOT = CANCEL_GOT;
64 #endif
65 return;
66 }
67
68 __syscall(SYS_tkill, self->tid, SIGCANCEL);
69 }
70
__testcancel()71 void __testcancel()
72 {
73 pthread_t self = __pthread_self();
74 if (self->cancel && !self->canceldisable)
75 __cancel();
76 }
77
init_cancellation()78 static void init_cancellation()
79 {
80 struct sigaction sa = {
81 .sa_flags = SA_SIGINFO | SA_RESTART,
82 .sa_sigaction = cancel_handler
83 };
84 memset(&sa.sa_mask, -1, _NSIG/8);
85 __libc_sigaction(SIGCANCEL, &sa, 0);
86 }
87
pthread_cancel(pthread_t t)88 int pthread_cancel(pthread_t t)
89 {
90 static int init;
91 if (!init) {
92 init_cancellation();
93 init = 1;
94 }
95 a_store(&t->cancel, 1);
96 if (t == pthread_self()) {
97 if (t->canceldisable == PTHREAD_CANCEL_ENABLE && t->cancelasync)
98 pthread_exit(PTHREAD_CANCELED);
99 return 0;
100 }
101 return pthread_kill(t, SIGCANCEL);
102 }
103 #else
__cancel()104 hidden long __cancel()
105 {
106 }
107
pthread_cancel(pthread_t t)108 int pthread_cancel(pthread_t t)
109 {
110 }
111 #endif
112