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Hash :
49a35c02
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Date :
2025-07-23T09:12:55
thrd: Avoid conversion between different function pointer types. Reported by Collin Funk in <https://lists.gnu.org/archive/html/bug-gnulib/2025-07/msg00170.html>. * m4/thrd.m4 (gl_FUNC_THRD_JOIN): Define BROKEN_THRD_START_T or BROKEN_THRD_JOIN. Don't define BROKEN_THRD_START_T_OR_JOIN. * lib/thrd.c (thrd_main_func): Define with the right return type, depending on BROKEN_THRD_START_T.
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/* Creating and controlling ISO C 11 threads.
Copyright (C) 2005-2025 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005, 2019.
Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h. */
#include <config.h>
#include <threads.h>
#include <stdlib.h>
#if HAVE_THREADS_H
/* Provide workarounds. */
# if BROKEN_THRD_START_T || BROKEN_THRD_JOIN
# undef thrd_t
/* AIX 7.1..7.2 defines thrd_start_t incorrectly, namely as
'void * (*) (void *)' instead of 'int (*) (void *)'.
As a consequence, its thrd_join function never stores an exit code.
AIX 7.3.1 has a corrected thrd_start_t. But the thrd_join function still
never stores an exit code. */
/* The Thread-Specific Storage (TSS) key that allows accessing each thread's
'struct thrd_with_exitcode *' pointer. */
static tss_t thrd_with_exitcode_key;
/* Initializes thrd_with_exitcode_key.
This function must only be called once. */
static void
do_init_thrd_with_exitcode_key (void)
{
if (tss_create (&thrd_with_exitcode_key, NULL) != thrd_success)
abort ();
}
/* Initializes thrd_with_exitcode_key. */
static void
init_thrd_with_exitcode_key (void)
{
static once_flag once = ONCE_FLAG_INIT;
call_once (&once, do_init_thrd_with_exitcode_key);
}
typedef union
{
struct thrd_with_exitcode t;
struct
{
thrd_t tid; /* reserve memory for t.tid */
int detached; /* reserve memory for t.detached */
thrd_start_t mainfunc;
void *arg;
} a;
}
main_arg_t;
static
# if BROKEN_THRD_START_T
void *
# else /* BROKEN_THRD_JOIN */
int
# endif
thrd_main_func (void *pmarg)
{
/* Unpack the object that combines mainfunc and arg. */
main_arg_t *main_arg = (main_arg_t *) pmarg;
thrd_start_t mainfunc = main_arg->a.mainfunc;
void *arg = main_arg->a.arg;
if (tss_set (thrd_with_exitcode_key, &main_arg->t) != thrd_success)
abort ();
/* Execute mainfunc, with arg as argument. */
{
int exitcode = mainfunc (arg);
/* Store the exitcode, for use by thrd_join(). */
main_arg->t.exitcode = exitcode;
if (main_arg->t.detached)
{
/* Clean up the thread, like thrd_join would do. */
free (&main_arg->t);
}
# if BROKEN_THRD_START_T
return NULL;
# else /* BROKEN_THRD_JOIN */
return 0;
# endif
}
}
int
rpl_thrd_create (rpl_thrd_t *threadp, thrd_start_t mainfunc, void *arg)
# undef thrd_create
{
init_thrd_with_exitcode_key ();
{
/* Combine mainfunc and arg in a single object.
A stack-allocated object does not work, because it would be out of
existence when thrd_create returns before pthread_main_func is
entered. So, allocate it in the heap. */
main_arg_t *main_arg = (main_arg_t *) malloc (sizeof (main_arg_t));
if (main_arg == NULL)
return thrd_nomem;
main_arg->a.mainfunc = mainfunc;
main_arg->a.arg = arg;
main_arg->t.detached = 0;
{
int err =
thrd_create ((thrd_t *) &main_arg->t.tid, thrd_main_func, main_arg);
if (err == thrd_success)
*threadp = &main_arg->t;
else
free (main_arg);
return err;
}
}
}
rpl_thrd_t
rpl_thrd_current (void)
# undef thrd_current
{
init_thrd_with_exitcode_key ();
{
rpl_thrd_t thread =
(struct thrd_with_exitcode *) tss_get (thrd_with_exitcode_key);
if (thread == NULL)
{
/* This happens only in threads that have not been created through
thrd_create(), such as the main thread. */
for (;;)
{
thread =
(struct thrd_with_exitcode *)
malloc (sizeof (struct thrd_with_exitcode));
if (thread != NULL)
break;
/* Memory allocation failed. There is not much we can do. Have to
busy-loop, waiting for the availability of memory. */
{
struct timespec ts =
{
.tv_sec = 1,
.tv_nsec = 0
};
thrd_sleep (&ts, NULL);
}
}
thread->tid = thrd_current ();
thread->detached = 0; /* This can lead to a memory leak. */
thread->exitcode = 0; /* just to be deterministic */
if (tss_set (thrd_with_exitcode_key, thread) != thrd_success)
abort ();
}
return thread;
}
}
int
rpl_thrd_equal (rpl_thrd_t thread1, rpl_thrd_t thread2)
{
return thread1 == thread2;
}
int
rpl_thrd_detach (rpl_thrd_t thread)
# undef thrd_detach
{
if (thread->detached)
return thrd_error;
{
int err =
thrd_detach (thread == rpl_thrd_current ()
? /* thread->tid may not be initialized at this point. */
thrd_current ()
: thread->tid);
if (err == thrd_success)
thread->detached = 1;
return err;
}
}
int
rpl_thrd_join (rpl_thrd_t thread, int *exitcodep)
# undef thrd_join
{
if (thread == rpl_thrd_current () || thread->detached)
return thrd_error;
{
int err = thrd_join (thread->tid, NULL);
if (err == thrd_success)
{
if (exitcodep != NULL)
*exitcodep = thread->exitcode;
free (thread);
}
return err;
}
}
_Noreturn void
rpl_thrd_exit (int exitcode)
{
rpl_thrd_t t = rpl_thrd_current ();
/* Store the exitcode, for use by thrd_join(). */
t->exitcode = exitcode;
if (t->detached)
{
/* Clean up the thread, like thrd_join would do. */
free (t);
}
pthread_exit (NULL);
}
# endif
# if BROKEN_THRD_JOIN_NULL
/* On Solaris 11.4, thrd_join crashes when the second argument is NULL. */
int
rpl_thrd_join (thrd_t thread, int *exitcodep)
# undef thrd_join
{
int exitcode;
int err = thrd_join (thread, &exitcode);
if (err == 0 && exitcodep != NULL)
*exitcodep = exitcode;
return err;
}
# endif
#else
# include <errno.h>
# include <stdint.h>
# if defined _WIN32 && ! defined __CYGWIN__
/* Use Windows threads. */
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
# else
/* Use POSIX threads. */
# include <pthread.h>
# include <sched.h>
# endif
/* The main functions passed to thrd_create and
pthread_create/glwthread_thread_create have different return types:
'int' vs. 'void *'. */
struct pthread_main_arg_t
{
thrd_start_t mainfunc;
void *arg;
};
static void *
pthread_main_func (void *pmarg)
{
/* Unpack the object that combines mainfunc and arg. */
struct pthread_main_arg_t *pthread_main_arg =
(struct pthread_main_arg_t *) pmarg;
thrd_start_t mainfunc = pthread_main_arg->mainfunc;
void *arg = pthread_main_arg->arg;
/* Free it. */
free (pmarg);
/* Execute mainfunc, with arg as argument. */
{
int exitcode = mainfunc (arg);
/* Note: When using Windows threads, this exit code is different from the
argument passed to ExitThread(), because the latter should never be 259,
see <https://docs.microsoft.com/de-de/windows/desktop/api/processthreadsapi/nf-processthreadsapi-getexitcodethread>,
whereas the exit code passed to thrd_exit() is not constrained. */
return (void *) (intptr_t) exitcode;
}
}
# if defined _WIN32 && ! defined __CYGWIN__
/* Use Windows threads. */
int
thrd_create (thrd_t *threadp, thrd_start_t mainfunc, void *arg)
{
/* Combine mainfunc and arg in a single object.
A stack-allocated object does not work, because it would be out of
existence when thrd_create returns before pthread_main_func is
entered. So, allocate it in the heap. */
struct pthread_main_arg_t *pthread_main_arg =
(struct pthread_main_arg_t *) malloc (sizeof (struct pthread_main_arg_t));
if (pthread_main_arg == NULL)
return thrd_nomem;
pthread_main_arg->mainfunc = mainfunc;
pthread_main_arg->arg = arg;
{
int err = glwthread_thread_create (threadp, 0,
pthread_main_func, pthread_main_arg);
if (err != 0)
free (pthread_main_arg);
return (err == 0 ? thrd_success :
err == ENOMEM /* || err == EAGAIN */ ? thrd_nomem :
thrd_error);
}
}
thrd_t
thrd_current (void)
{
return glwthread_thread_self ();
}
int
thrd_equal (thrd_t thread1, thrd_t thread2)
{
return thread1 == thread2;
}
void
thrd_yield (void)
{
Sleep (0);
}
int
thrd_detach (thrd_t thread)
{
int err = glwthread_thread_detach (thread);
return (err == 0 ? thrd_success : thrd_error);
}
int
thrd_join (thrd_t thread, int *exitcodep)
{
void *exitptr;
int err = glwthread_thread_join (thread, &exitptr);
if (err == 0)
{
if (exitcodep != NULL)
*exitcodep = (int) (intptr_t) exitptr;
return thrd_success;
}
else
return thrd_error;
}
_Noreturn void
thrd_exit (int exitcode)
{
glwthread_thread_exit ((void *) (intptr_t) exitcode);
}
# else
/* Use POSIX threads. */
int
thrd_create (thrd_t *threadp, thrd_start_t mainfunc, void *arg)
{
/* Combine mainfunc and arg in a single object.
A stack-allocated object does not work, because it would be out of
existence when thrd_create returns before pthread_main_func is
entered. So, allocate it in the heap. */
struct pthread_main_arg_t *pthread_main_arg =
(struct pthread_main_arg_t *) malloc (sizeof (struct pthread_main_arg_t));
if (pthread_main_arg == NULL)
return thrd_nomem;
pthread_main_arg->mainfunc = mainfunc;
pthread_main_arg->arg = arg;
{
int err = pthread_create (threadp, NULL,
pthread_main_func, pthread_main_arg);
if (err != 0)
free (pthread_main_arg);
return (err == 0 ? thrd_success :
err == ENOMEM /* || err == EAGAIN */ ? thrd_nomem :
thrd_error);
}
}
thrd_t
thrd_current (void)
{
return pthread_self ();
}
int
thrd_equal (thrd_t thread1, thrd_t thread2)
{
return pthread_equal (thread1, thread2);
}
void
thrd_yield (void)
{
sched_yield ();
}
int
thrd_detach (thrd_t thread)
{
int err = pthread_detach (thread);
return (err == 0 ? thrd_success : thrd_error);
}
int
thrd_join (thrd_t thread, int *exitcodep)
{
void *exitptr;
int err = pthread_join (thread, &exitptr);
if (err == 0)
{
if (exitcodep != NULL)
*exitcodep = (int) (intptr_t) exitptr;
return thrd_success;
}
else
return thrd_error;
}
_Noreturn void
thrd_exit (int exitcode)
{
pthread_exit ((void *) (intptr_t) exitcode);
}
# endif
int
thrd_sleep (const struct timespec *duration, struct timespec *remaining)
{
int ret = nanosleep (duration, remaining);
return (ret == 0 ? 0 : errno == EINTR ? -1 : -2);
}
#endif