summary refs log tree commit diff
path: root/linuxthreads/signals.c
blob: 714e346fab9a9f4cc3ada304081c38340d52f61f (plain) (blame)
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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
/* Linuxthreads - a simple clone()-based implementation of Posix        */
/* threads for Linux.                                                   */
/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
/*                                                                      */
/* This program is free software; you can redistribute it and/or        */
/* modify it under the terms of the GNU Library General Public License  */
/* as published by the Free Software Foundation; either version 2       */
/* of the License, or (at your option) any later version.               */
/*                                                                      */
/* This program is distributed in the hope that it will be useful,      */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of       */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
/* GNU Library General Public License for more details.                 */

/* Handling of signals */

#include <errno.h>
#include <signal.h>
#include "pthread.h"
#include "internals.h"
#include "spinlock.h"
#include <ucontext.h>
#include <sigcontextinfo.h>

int pthread_sigmask(int how, const sigset_t * newmask, sigset_t * oldmask)
{
  sigset_t mask;

  if (newmask != NULL) {
    mask = *newmask;
    /* Don't allow __pthread_sig_restart to be unmasked.
       Don't allow __pthread_sig_cancel to be masked. */
    switch(how) {
    case SIG_SETMASK:
      sigaddset(&mask, __pthread_sig_restart);
      sigdelset(&mask, __pthread_sig_cancel);
      break;
    case SIG_BLOCK:
      sigdelset(&mask, __pthread_sig_cancel);
      break;
    case SIG_UNBLOCK:
      sigdelset(&mask, __pthread_sig_restart);
      break;
    }
    newmask = &mask;
  }
  if (sigprocmask(how, newmask, oldmask) == -1)
    return errno;
  else
    return 0;
}

int pthread_kill(pthread_t thread, int signo)
{
  pthread_handle handle = thread_handle(thread);
  int pid;

  __pthread_lock(&handle->h_lock, NULL);
  if (invalid_handle(handle, thread)) {
    __pthread_unlock(&handle->h_lock);
    return ESRCH;
  }
  pid = handle->h_descr->p_pid;
  __pthread_unlock(&handle->h_lock);
  if (kill(pid, signo) == -1)
    return errno;
  else
    return 0;
}

/* User-provided signal handlers */
typedef void (*arch_sighandler_t) (int, SIGCONTEXT);
static union
{
  arch_sighandler_t old;
  void (*rt) (int, struct siginfo *, struct ucontext *);
} sighandler[NSIG];

/* The wrapper around user-provided signal handlers */
static void pthread_sighandler(int signo, SIGCONTEXT ctx)
{
  pthread_descr self;
  char * in_sighandler;
  self = thread_self();
  /* If we're in a sigwait operation, just record the signal received
     and return without calling the user's handler */
  if (THREAD_GETMEM(self, p_sigwaiting)) {
    THREAD_SETMEM(self, p_sigwaiting, 0);
    THREAD_SETMEM(self, p_signal, signo);
    return;
  }
  /* Record that we're in a signal handler and call the user's
     handler function */
  in_sighandler = THREAD_GETMEM(self, p_in_sighandler);
  if (in_sighandler == NULL)
    THREAD_SETMEM(self, p_in_sighandler, CURRENT_STACK_FRAME);
  CALL_SIGHANDLER(sighandler[signo].old, signo, ctx);
  if (in_sighandler == NULL)
    THREAD_SETMEM(self, p_in_sighandler, NULL);
}

/* The same, this time for real-time signals.  */
static void pthread_sighandler_rt(int signo, struct siginfo *si,
				  struct ucontext *uc)
{
  pthread_descr self;
  char * in_sighandler;
  self =  thread_self();
  /* If we're in a sigwait operation, just record the signal received
     and return without calling the user's handler */
  if (THREAD_GETMEM(self, p_sigwaiting)) {
    THREAD_SETMEM(self, p_sigwaiting, 0);
    THREAD_SETMEM(self, p_signal, signo);
    return;
  }
  /* Record that we're in a signal handler and call the user's
     handler function */
  in_sighandler = THREAD_GETMEM(self, p_in_sighandler);
  if (in_sighandler == NULL)
    THREAD_SETMEM(self, p_in_sighandler, CURRENT_STACK_FRAME);
  sighandler[signo].rt(signo, si, uc);
  if (in_sighandler == NULL)
    THREAD_SETMEM(self, p_in_sighandler, NULL);
}

/* The wrapper around sigaction.  Install our own signal handler
   around the signal. */
int __sigaction(int sig, const struct sigaction * act,
              struct sigaction * oact)
{
  struct sigaction newact;
  struct sigaction *newactp;

  if (sig == __pthread_sig_restart ||
      sig == __pthread_sig_cancel ||
      (sig == __pthread_sig_debug && __pthread_sig_debug > 0))
    {
      __set_errno (EINVAL);
      return -1;
    }
  if (act)
    {
      newact = *act;
      if (act->sa_handler != SIG_IGN && act->sa_handler != SIG_DFL
	  && sig > 0 && sig < NSIG)
	{
	  if (act->sa_flags & SA_SIGINFO)
	    newact.sa_handler = (__sighandler_t) pthread_sighandler_rt;
	  else
	    newact.sa_handler = (__sighandler_t) pthread_sighandler;
	}
      newactp = &newact;
    }
  else
    newactp = NULL;
  if (__libc_sigaction(sig, newactp, oact) == -1)
    return -1;
  if (sig > 0 && sig < NSIG)
    {
      if (oact != NULL)
	oact->sa_handler = (__sighandler_t) sighandler[sig].old;
      if (act)
	/* For the assignment is does not matter whether it's a normal
	   or real-time signal.  */
	sighandler[sig].old = (arch_sighandler_t) act->sa_handler;
    }
  return 0;
}
strong_alias(__sigaction, sigaction)

/* A signal handler that does nothing */
static void pthread_null_sighandler(int sig) { }

/* sigwait -- synchronously wait for a signal */
int sigwait(const sigset_t * set, int * sig)
{
  volatile pthread_descr self = thread_self();
  sigset_t mask;
  int s;
  sigjmp_buf jmpbuf;
  struct sigaction sa;

  /* Get ready to block all signals except those in set
     and the cancellation signal.
     Also check that handlers are installed on all signals in set,
     and if not, install our dummy handler.  This is conformant to
     POSIX: "The effect of sigwait() on the signal actions for the
     signals in set is unspecified." */
  sigfillset(&mask);
  sigdelset(&mask, __pthread_sig_cancel);
  for (s = 1; s <= NSIG; s++) {
    if (sigismember(set, s) &&
        s != __pthread_sig_restart &&
        s != __pthread_sig_cancel &&
        s != __pthread_sig_debug) {
      sigdelset(&mask, s);
      if (sighandler[s].old == NULL ||
          sighandler[s].old == (arch_sighandler_t) SIG_DFL ||
          sighandler[s].old == (arch_sighandler_t) SIG_IGN) {
        sa.sa_handler = pthread_null_sighandler;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        sigaction(s, &sa, NULL);
      }
    }
  }
  /* Test for cancellation */
  if (sigsetjmp(jmpbuf, 1) == 0) {
    THREAD_SETMEM(self, p_cancel_jmp, &jmpbuf);
    if (! (THREAD_GETMEM(self, p_canceled)
	   && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)) {
      /* Reset the signal count */
      THREAD_SETMEM(self, p_signal, 0);
      /* Say we're in sigwait */
      THREAD_SETMEM(self, p_sigwaiting, 1);
      /* Unblock the signals and wait for them */
      sigsuspend(&mask);
    }
  }
  THREAD_SETMEM(self, p_cancel_jmp, NULL);
  /* The signals are now reblocked.  Check for cancellation */
  pthread_testcancel();
  /* We should have self->p_signal != 0 and equal to the signal received */
  *sig = THREAD_GETMEM(self, p_signal);
  return 0;
}

/* Redefine raise() to send signal to calling thread only,
   as per POSIX 1003.1c */
int raise (int sig)
{
  int retcode = pthread_kill(pthread_self(), sig);
  if (retcode == 0)
    return 0;
  else {
    errno = retcode;
    return -1;
  }
}