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