1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
#include "pthread_impl.h"
#include "syscall.h"
#include "libc.h"
void __cancel()
{
pthread_exit(PTHREAD_CANCELED);
}
/* If __syscall_cp_asm has adjusted the stack pointer, it must provide a
* definition of __cp_cancel to undo those adjustments and call __cancel.
* Otherwise, __cancel provides a definition for __cp_cancel. */
weak_alias(__cancel, __cp_cancel);
long __syscall_cp_asm(volatile void *, syscall_arg_t,
syscall_arg_t, syscall_arg_t, syscall_arg_t,
syscall_arg_t, syscall_arg_t, syscall_arg_t);
long __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)
{
pthread_t self;
long r;
if (!libc.has_thread_pointer || (self = __pthread_self())->canceldisable)
return __syscall(nr, u, v, w, x, y, z);
r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
__cancel();
return r;
}
static void _sigaddset(sigset_t *set, int sig)
{
unsigned s = sig-1;
set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
}
static void cancel_handler(int sig, siginfo_t *si, void *ctx)
{
pthread_t self = __pthread_self();
ucontext_t *uc = ctx;
const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
extern const char __cp_begin[1], __cp_end[1];
a_barrier();
if (!self->cancel || self->canceldisable) return;
_sigaddset(&uc->uc_sigmask, SIGCANCEL);
if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
self->canceldisable = 1;
pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
__cancel();
}
__syscall(SYS_tkill, self->tid, SIGCANCEL);
}
void __testcancel()
{
if (!libc.has_thread_pointer) return;
pthread_t self = __pthread_self();
if (self->cancel && !self->canceldisable)
__cancel();
}
static void init_cancellation()
{
struct sigaction sa = {
.sa_flags = SA_SIGINFO | SA_RESTART,
.sa_sigaction = cancel_handler
};
sigfillset(&sa.sa_mask);
__libc_sigaction(SIGCANCEL, &sa, 0);
}
int pthread_cancel(pthread_t t)
{
static int init;
if (!init) {
init_cancellation();
init = 1;
}
a_store(&t->cancel, 1);
return pthread_kill(t, SIGCANCEL);
}
|
