1/* Send a signal to a specific pthread. Stub version.
2 Copyright (C) 2014-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <libc-lock.h>
20#include <unistd.h>
21#include <pthreadP.h>
22#include <shlib-compat.h>
23
24/* Sends SIGNO to THREADID. If the thread is about to exit or has
25 already exited on the kernel side, return NO_TID. Otherwise return
26 0 or an error code. */
27static int
28__pthread_kill_implementation (pthread_t threadid, int signo, int no_tid)
29{
30 struct pthread *pd = (struct pthread *) threadid;
31 if (pd == THREAD_SELF)
32 {
33 /* Use the actual TID from the kernel, so that it refers to the
34 current thread even if called after vfork. There is no
35 signal blocking in this case, so that the signal is delivered
36 immediately, before __pthread_kill_internal returns: a signal
37 sent to the thread itself needs to be delivered
38 synchronously. (It is unclear if Linux guarantees the
39 delivery of all pending signals after unblocking in the code
40 below. POSIX only guarantees delivery of a single signal,
41 which may not be the right one.) */
42 pid_t tid = INTERNAL_SYSCALL_CALL (gettid);
43 int ret = INTERNAL_SYSCALL_CALL (tgkill, __getpid (), tid, signo);
44 return INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
45 }
46
47 /* Block all signals, as required by pd->exit_lock. */
48 internal_sigset_t old_mask;
49 internal_signal_block_all (&old_mask);
50 __libc_lock_lock (pd->exit_lock);
51
52 int ret;
53 if (pd->exiting)
54 /* The thread is about to exit (or has exited). Sending the
55 signal is either not observable (the target thread has already
56 blocked signals at this point), or it will fail, or it might be
57 delivered to a new, unrelated thread that has reused the TID.
58 So do not actually send the signal. */
59 ret = no_tid;
60 else
61 {
62 ret = INTERNAL_SYSCALL_CALL (tgkill, __getpid (), pd->tid, signo);
63 ret = INTERNAL_SYSCALL_ERROR_P (ret) ? INTERNAL_SYSCALL_ERRNO (ret) : 0;
64 }
65
66 __libc_lock_unlock (pd->exit_lock);
67 internal_signal_restore_set (&old_mask);
68
69 return ret;
70}
71
72int
73__pthread_kill_internal (pthread_t threadid, int signo)
74{
75 /* Do not report an error in the no-tid case because the threadid
76 argument is still valid (the thread ID lifetime has not ended),
77 and ESRCH (for example) would be misleading. */
78 return __pthread_kill_implementation (threadid, signo, 0);
79}
80
81int
82__pthread_kill (pthread_t threadid, int signo)
83{
84 /* Disallow sending the signal we use for cancellation, timers,
85 for the setxid implementation. */
86 if (is_internal_signal (signo))
87 return EINVAL;
88
89 return __pthread_kill_internal (threadid, signo);
90}
91
92/* Some architectures (for instance arm) might pull raise through libgcc, so
93 avoid the symbol version if it ends up being used on ld.so. */
94#if !IS_IN(rtld)
95libc_hidden_def (__pthread_kill)
96versioned_symbol (libc, __pthread_kill, pthread_kill, GLIBC_2_34);
97
98# if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
99/* Variant which returns ESRCH in the no-TID case, for backwards
100 compatibility. */
101int
102attribute_compat_text_section
103__pthread_kill_esrch (pthread_t threadid, int signo)
104{
105 if (is_internal_signal (signo))
106 return EINVAL;
107
108 return __pthread_kill_implementation (threadid, signo, ESRCH);
109}
110compat_symbol (libc, __pthread_kill_esrch, pthread_kill, GLIBC_2_0);
111# endif
112#endif
113