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Diffstat (limited to 'src/posix-lock.c')
| -rw-r--r-- | src/posix-lock.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/src/posix-lock.c b/src/posix-lock.c new file mode 100644 index 0000000..5b0cab5 --- /dev/null +++ b/src/posix-lock.c @@ -0,0 +1,225 @@ +/* posix-lock.c - GPGRT lock functions for POSIX systems + Copyright (C) 2005-2009 Free Software Foundation, Inc. + Copyright (C) 2014 g10 Code GmbH + + This file is part of libgpg-error. + + libgpg-error 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. + + libgpg-error 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 <http://www.gnu.org/licenses/>. + + Parts of the code, in particular use_pthreads_p, are based on code + from gettext, written by Bruno Haible <bruno@clisp.org>, 2005. + */ + +#if HAVE_CONFIG_H +#include <config.h> +#endif + +#ifdef HAVE_W32_SYSTEM +# error This module may not be build for Windows. +#endif + +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <errno.h> + +#if USE_POSIX_THREADS +# include <pthread.h> +#endif + +#include "gpg-error.h" +#include "lock.h" +#include "posix-lock-obj.h" + + +#if USE_POSIX_THREADS +# if USE_POSIX_THREADS_WEAK + /* On ELF systems it is easy to use pthreads using weak + references. Take care not to test the address of a weak + referenced function we actually use; some GCC versions have a + bug were &foo != NULL is always evaluated to true in PIC mode. */ +# pragma weak pthread_cancel +# pragma weak pthread_mutex_init +# pragma weak pthread_mutex_lock +# pragma weak pthread_mutex_unlock +# pragma weak pthread_mutex_destroy +# if ! PTHREAD_IN_USE_DETECTION_HARD +# define use_pthread_p() (!!pthread_cancel) +# endif +# else /*!USE_POSIX_THREADS_WEAK*/ +# if ! PTHREAD_IN_USE_DETECTION_HARD +# define use_pthread_p() (1) +# endif +# endif /*!USE_POSIX_THREADS_WEAK*/ +# if PTHREAD_IN_USE_DETECTION_HARD +/* The function to be executed by a dummy thread. */ +static void * +dummy_thread_func (void *arg) +{ + return arg; +} + +static int +use_pthread_p (void) +{ + static int tested; + static int result; /* 1: linked with -lpthread, 0: only with libc */ + + if (!tested) + { + pthread_t thread; + + if (pthread_create (&thread, NULL, dummy_thread_func, NULL)) + result = 0; /* Thread creation failed. */ + else + { + /* Thread creation works. */ + void *retval; + if (pthread_join (thread, &retval) != 0) + abort (); + result = 1; + } + tested = 1; + } + return result; +} +#endif /*PTHREAD_IN_USE_DETECTION_HARD*/ +#endif /*USE_POSIX_THREADS*/ + + + +static _gpgrt_lock_t * +get_lock_object (gpgrt_lock_t *lockhd) +{ + _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd; + + if (lock->vers != LOCK_ABI_VERSION) + abort (); + if (sizeof (gpgrt_lock_t) < sizeof (_gpgrt_lock_t)) + abort (); + + return lock; +} + + +gpg_err_code_t +gpgrt_lock_init (gpgrt_lock_t *lockhd) +{ + _gpgrt_lock_t *lock = (_gpgrt_lock_t*)lockhd; + int rc; + + /* If VERS is zero we assume that no static initialization has been + done, so we setup our ABI version right here. The caller might + have called us to test whether lock support is at all available. */ + if (!lock->vers) + { + if (sizeof (gpgrt_lock_t) < sizeof (_gpgrt_lock_t)) + abort (); + lock->vers = LOCK_ABI_VERSION; + } + else /* Run the usual check. */ + lock = get_lock_object (lockhd); + +#if USE_POSIX_THREADS + if (use_pthread_p()) + { + rc = pthread_mutex_init (&lock->u.mtx, NULL); + if (rc) + rc = gpg_err_code_from_errno (rc); + } + else + rc = 0; /* Threads are not used. */ +#else /* Unknown thread system. */ + rc = GPG_ERR_NOT_IMPLEMENTED; +#endif /* Unknown thread system. */ + + return rc; +} + + +gpg_err_code_t +gpgrt_lock_lock (gpgrt_lock_t *lockhd) +{ + _gpgrt_lock_t *lock = get_lock_object (lockhd); + int rc; + +#if USE_POSIX_THREADS + if (use_pthread_p()) + { + rc = pthread_mutex_lock (&lock->u.mtx); + if (rc) + rc = gpg_err_code_from_errno (rc); + } + else + rc = 0; /* Threads are not used. */ +#else /* Unknown thread system. */ + rc = GPG_ERR_NOT_IMPLEMENTED; +#endif /* Unknown thread system. */ + + return rc; +} + + +gpg_err_code_t +gpgrt_lock_unlock (gpgrt_lock_t *lockhd) +{ + _gpgrt_lock_t *lock = get_lock_object (lockhd); + int rc; + +#if USE_POSIX_THREADS + if (use_pthread_p()) + { + rc = pthread_mutex_unlock (&lock->u.mtx); + if (rc) + rc = gpg_err_code_from_errno (rc); + } + else + rc = 0; /* Threads are not used. */ +#else /* Unknown thread system. */ + rc = GPG_ERR_NOT_IMPLEMENTED; +#endif /* Unknown thread system. */ + + return rc; +} + + +/* Note: Use this function only if no other thread holds or waits for + this lock. */ +gpg_err_code_t +gpgrt_lock_destroy (gpgrt_lock_t *lockhd) +{ + _gpgrt_lock_t *lock = get_lock_object (lockhd); + int rc; + +#if USE_POSIX_THREADS + if (use_pthread_p()) + { + rc = pthread_mutex_destroy (&lock->u.mtx); + if (rc) + rc = gpg_err_code_from_errno (rc); + else + { + /* Re-init the mutex so that it can be re-used. */ + gpgrt_lock_t tmp = GPGRT_LOCK_INITIALIZER; + memcpy (lockhd, &tmp, sizeof tmp); + } + } + else + rc = 0; /* Threads are not used. */ +#else /* Unknown thread system. */ + rc = GPG_ERR_NOT_IMPLEMENTED; +#endif /* Unknown thread system. */ + + return rc; +} |