+++ /dev/null
-/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
-
- The GNU C Library 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.
-
- The GNU C Library 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 the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-#include <errno.h>
-#include <fcntl.h>
-#include <pthread.h>
-#include <search.h>
-#include <semaphore.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include "semaphoreP.h"
-#include <futex-internal.h>
-#include <shm-directory.h>
-
-
-/* Comparison function for search of existing mapping. */
-int
-attribute_hidden
-__sem_search (const void *a, const void *b)
-{
- const struct inuse_sem *as = (const struct inuse_sem *) a;
- const struct inuse_sem *bs = (const struct inuse_sem *) b;
-
- if (as->ino != bs->ino)
- /* Cannot return the difference the type is larger than int. */
- return as->ino < bs->ino ? -1 : (as->ino == bs->ino ? 0 : 1);
-
- if (as->dev != bs->dev)
- /* Cannot return the difference the type is larger than int. */
- return as->dev < bs->dev ? -1 : (as->dev == bs->dev ? 0 : 1);
-
- return strcmp (as->name, bs->name);
-}
-
-
-/* The search tree for existing mappings. */
-void *__sem_mappings attribute_hidden;
-
-/* Lock to protect the search tree. */
-int __sem_mappings_lock attribute_hidden = LLL_LOCK_INITIALIZER;
-
-
-/* Search for existing mapping and if possible add the one provided. */
-static sem_t *
-check_add_mapping (const char *name, size_t namelen, int fd, sem_t *existing)
-{
- sem_t *result = SEM_FAILED;
-
- /* Get the information about the file. */
- struct stat64 st;
- if (__fxstat64 (_STAT_VER, fd, &st) == 0)
- {
- /* Get the lock. */
- lll_lock (__sem_mappings_lock, LLL_PRIVATE);
-
- /* Search for an existing mapping given the information we have. */
- struct inuse_sem *fake;
- fake = (struct inuse_sem *) alloca (sizeof (*fake) + namelen);
- memcpy (fake->name, name, namelen);
- fake->dev = st.st_dev;
- fake->ino = st.st_ino;
-
- struct inuse_sem **foundp = __tfind (fake, &__sem_mappings,
- __sem_search);
- if (foundp != NULL)
- {
- /* There is already a mapping. Use it. */
- result = (*foundp)->sem;
- ++(*foundp)->refcnt;
- }
- else
- {
- /* We haven't found a mapping. Install ione. */
- struct inuse_sem *newp;
-
- newp = (struct inuse_sem *) malloc (sizeof (*newp) + namelen);
- if (newp != NULL)
- {
- /* If the caller hasn't provided any map it now. */
- if (existing == SEM_FAILED)
- existing = (sem_t *) mmap (NULL, sizeof (sem_t),
- PROT_READ | PROT_WRITE, MAP_SHARED,
- fd, 0);
-
- newp->dev = st.st_dev;
- newp->ino = st.st_ino;
- newp->refcnt = 1;
- newp->sem = existing;
- memcpy (newp->name, name, namelen);
-
- /* Insert the new value. */
- if (existing != MAP_FAILED
- && __tsearch (newp, &__sem_mappings, __sem_search) != NULL)
- /* Successful. */
- result = existing;
- else
- /* Something went wrong while inserting the new
- value. We fail completely. */
- free (newp);
- }
- }
-
- /* Release the lock. */
- lll_unlock (__sem_mappings_lock, LLL_PRIVATE);
- }
-
- if (result != existing && existing != SEM_FAILED && existing != MAP_FAILED)
- {
- /* Do not disturb errno. */
- int save = errno;
- munmap (existing, sizeof (sem_t));
- errno = save;
- }
-
- return result;
-}
-
-
-sem_t *
-sem_open (const char *name, int oflag, ...)
-{
- int fd;
- sem_t *result;
-
- /* Create the name of the final file in local variable SHM_NAME. */
- SHM_GET_NAME (EINVAL, SEM_FAILED, SEM_SHM_PREFIX);
-
- /* If the semaphore object has to exist simply open it. */
- if ((oflag & O_CREAT) == 0 || (oflag & O_EXCL) == 0)
- {
- try_again:
- fd = __libc_open (shm_name,
- (oflag & ~(O_CREAT|O_ACCMODE)) | O_NOFOLLOW | O_RDWR);
-
- if (fd == -1)
- {
- /* If we are supposed to create the file try this next. */
- if ((oflag & O_CREAT) != 0 && errno == ENOENT)
- goto try_create;
-
- /* Return. errno is already set. */
- }
- else
- /* Check whether we already have this semaphore mapped and
- create one if necessary. */
- result = check_add_mapping (name, namelen, fd, SEM_FAILED);
- }
- else
- {
- /* We have to open a temporary file first since it must have the
- correct form before we can start using it. */
- char *tmpfname;
- mode_t mode;
- unsigned int value;
- va_list ap;
-
- try_create:
- va_start (ap, oflag);
-
- mode = va_arg (ap, mode_t);
- value = va_arg (ap, unsigned int);
-
- va_end (ap);
-
- if (value > SEM_VALUE_MAX)
- {
- __set_errno (EINVAL);
- return SEM_FAILED;
- }
-
- /* Create the initial file content. */
- union
- {
- sem_t initsem;
- struct new_sem newsem;
- } sem;
-
- sem.newsem.value = value << SEM_VALUE_SHIFT;
- sem.newsem.pad = 0;
- sem.newsem.nwaiters = 0;
-
- /* This always is a shared semaphore. */
- sem.newsem.private = FUTEX_SHARED;
-
- /* Initialize the remaining bytes as well. */
- memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',
- sizeof (sem_t) - sizeof (struct new_sem));
-
- tmpfname = __alloca (shm_dirlen + sizeof SEM_SHM_PREFIX + 6);
- char *xxxxxx = __mempcpy (tmpfname, shm_dir, shm_dirlen);
-
- int retries = 0;
-#define NRETRIES 50
- while (1)
- {
- /* Add the suffix for mktemp. */
- strcpy (xxxxxx, "XXXXXX");
-
- /* We really want to use mktemp here. We cannot use mkstemp
- since the file must be opened with a specific mode. The
- mode cannot later be set since then we cannot apply the
- file create mask. */
- if (__mktemp (tmpfname) == NULL)
- return SEM_FAILED;
-
- /* Open the file. Make sure we do not overwrite anything. */
- fd = __libc_open (tmpfname, O_RDWR | O_CREAT | O_EXCL, mode);
- if (fd == -1)
- {
- if (errno == EEXIST)
- {
- if (++retries < NRETRIES)
- continue;
-
- __set_errno (EAGAIN);
- }
-
- return SEM_FAILED;
- }
-
- /* We got a file. */
- break;
- }
-
- if (TEMP_FAILURE_RETRY (__libc_write (fd, &sem.initsem, sizeof (sem_t)))
- == sizeof (sem_t)
- /* Map the sem_t structure from the file. */
- && (result = (sem_t *) mmap (NULL, sizeof (sem_t),
- PROT_READ | PROT_WRITE, MAP_SHARED,
- fd, 0)) != MAP_FAILED)
- {
- /* Create the file. Don't overwrite an existing file. */
- if (link (tmpfname, shm_name) != 0)
- {
- /* Undo the mapping. */
- (void) munmap (result, sizeof (sem_t));
-
- /* Reinitialize 'result'. */
- result = SEM_FAILED;
-
- /* This failed. If O_EXCL is not set and the problem was
- that the file exists, try again. */
- if ((oflag & O_EXCL) == 0 && errno == EEXIST)
- {
- /* Remove the file. */
- (void) unlink (tmpfname);
-
- /* Close the file. */
- (void) __libc_close (fd);
-
- goto try_again;
- }
- }
- else
- /* Insert the mapping into the search tree. This also
- determines whether another thread sneaked by and already
- added such a mapping despite the fact that we created it. */
- result = check_add_mapping (name, namelen, fd, result);
- }
-
- /* Now remove the temporary name. This should never fail. If
- it fails we leak a file name. Better fix the kernel. */
- (void) unlink (tmpfname);
- }
-
- /* Map the mmap error to the error we need. */
- if (MAP_FAILED != (void *) SEM_FAILED && result == MAP_FAILED)
- result = SEM_FAILED;
-
- /* We don't need the file descriptor anymore. */
- if (fd != -1)
- {
- /* Do not disturb errno. */
- int save = errno;
- __libc_close (fd);
- errno = save;
- }
-
- return result;
-}
git://sourceware.org / glibc.git / commitdiff