#include <mntent.h>
#include <paths.h>
#include <pthread.h>
+#include <search.h>
#include <semaphore.h>
#include <stdarg.h>
#include <stdio.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. */
+lll_lock_t __sem_mappings_lock = 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);
+
+ /* 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 if (existing != SEM_FAILED)
+ {
+ /* We haven't found a mapping but the caller has a mapping.
+ Install it. */
+ struct inuse_sem *newp;
+
+ newp = (struct inuse_sem *) malloc (sizeof (*newp) + namelen);
+ if (newp != NULL)
+ {
+ 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 (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);
+ }
+
+ if (result != existing && existing != SEM_FAILED)
+ {
+ /* Do not disturb errno. */
+ INTERNAL_SYSCALL_DECL (err);
+ INTERNAL_SYSCALL (munmap, err, 2, existing, sizeof (sem_t));
+ }
+
+ return result;
+}
+
+
sem_t *
sem_open (const char *name, int oflag, ...)
{
char *finalname;
- size_t namelen;
sem_t *result = SEM_FAILED;
int fd;
__set_errno (EINVAL);
return SEM_FAILED;
}
- namelen = strlen (name);
+ size_t namelen = strlen (name) + 1;
/* Create the name of the final file. */
- finalname = (char *) alloca (mountpoint.dirlen + namelen + 1);
+ finalname = (char *) alloca (mountpoint.dirlen + namelen);
__mempcpy (__mempcpy (finalname, mountpoint.dir, mountpoint.dirlen),
- name, namelen + 1);
+ name, namelen);
/* If the semaphore object has to exist simply open it. */
if ((oflag & O_CREAT) == 0 || (oflag & O_EXCL) == 0)
if (fd == -1)
{
/* If we are supposed to create the file try this next. */
- if ((oflag & O_CREAT) != 0)
+ if ((oflag & O_CREAT) != 0 && errno == ENOENT)
goto try_create;
/* Return. errno is already set. */
}
else
- /* Map the sem_t structure from the file. */
- result = (sem_t *) mmap (NULL, sizeof (sem_t), PROT_READ | PROT_WRITE,
- MAP_SHARED, fd, 0);
+ {
+ /* Check whether we already have this semaphore mapped. */
+ result = check_add_mapping (name, namelen, fd, SEM_FAILED);
+
+ /* Map the sem_t structure from the file. */
+ if (result == SEM_FAILED)
+ result = (sem_t *) mmap (NULL, sizeof (sem_t),
+ PROT_READ | PROT_WRITE, MAP_SHARED,
+ fd, 0);
+ }
}
else
{
return SEM_FAILED;
}
- tmpfname = (char *) alloca (mountpoint.dirlen + 6 + 1);
- strcpy (__mempcpy (tmpfname, mountpoint.dir, mountpoint.dirlen),
- "XXXXXX");
-
- fd = mkstemp (tmpfname);
- if (fd == -1)
- return SEM_FAILED;
-
/* Create the initial file content. */
sem_t initsem;
memset ((char *) &initsem + sizeof (struct sem), '\0',
sizeof (sem_t) - sizeof (struct sem));
+ tmpfname = (char *) alloca (mountpoint.dirlen + 6 + 1);
+ char *xxxxxx = __mempcpy (tmpfname, mountpoint.dir, mountpoint.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, &initsem, sizeof (sem_t)))
== sizeof (sem_t)
- /* Adjust the permission. */
- && fchmod (fd, mode) == 0
/* Map the sem_t structure from the file. */
&& (result = (sem_t *) mmap (NULL, sizeof (sem_t),
PROT_READ | PROT_WRITE, MAP_SHARED,
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
/* We don't need the file descriptor anymore. */
if (fd != -1)
- (void) __libc_close (fd);
+ {
+ /* Do not disturb errno. */
+ INTERNAL_SYSCALL_DECL (err);
+ INTERNAL_SYSCALL (close, err, 1, fd);
+ }
return result;
}
-/* Copyright (C) 2002 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
+#include <semaphore.h>
#include "pthreadP.h"
+
/* Mount point of the shared memory filesystem. */
struct mountpoint_info
{
size_t dirlen;
};
+/* Keeping track of currently used mappings. */
+struct inuse_sem
+{
+ dev_t dev;
+ ino_t ino;
+ int refcnt;
+ sem_t *sem;
+ char name[0];
+};
+
/* Variables used in multiple interfaces. */
extern struct mountpoint_info mountpoint attribute_hidden;
extern pthread_once_t __namedsem_once attribute_hidden;
+/* The search tree for existing mappings. */
+extern void *__sem_mappings attribute_hidden;
+
+/* Lock to protect the search tree. */
+extern lll_lock_t __sem_mappings_lock;
+
/* Initializer for mountpoint. */
extern void __where_is_shmfs (void) attribute_hidden;
+/* Comparison function for search in tree with existing mappings. */
+extern int __sem_search (const void *a, const void *b) attribute_hidden;
+
/* Prototypes of functions with multiple interfaces. */
extern int __new_sem_init (sem_t *sem, int pshared, unsigned int value);
--- /dev/null
+/* Copyright (C) 2003 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
+
+ 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <semaphore.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+
+static void
+remove_sem (int status, void *arg)
+{
+ sem_unlink (arg);
+}
+
+
+int
+main (void)
+{
+ sem_t *s;
+ sem_t *s2;
+ sem_t *s3;
+
+ s = sem_open ("/glibc-tst-sem7", O_CREAT, 0600, 1);
+ if (s == SEM_FAILED)
+ {
+ if (errno == ENOSYS)
+ {
+ puts ("sem_open not supported. Oh well.");
+ return 0;
+ }
+
+ /* Maybe the shm filesystem has strict permissions. */
+ if (errno == EACCES)
+ {
+ puts ("sem_open not allowed. Oh well.");
+ return 0;
+ }
+
+ printf ("sem_open: %m\n");
+ return 1;
+ }
+
+ on_exit (remove_sem, (void *) "/glibc-tst-sem7");
+
+ /* We have the semaphore object. Now try again. We should get the
+ same address. */
+ s2 = sem_open ("/glibc-tst-sem7", O_CREAT, 0600, 1);
+ if (s2 == SEM_FAILED)
+ {
+ puts ("2nd sem_open failed");
+ return 1;
+ }
+ if (s != s2)
+ {
+ puts ("2nd sem_open didn't return the same address");
+ return 1;
+ }
+
+ /* And again, this time without O_CREAT. */
+ s3 = sem_open ("/glibc-tst-sem7", 0);
+ if (s3 == SEM_FAILED)
+ {
+ puts ("3rd sem_open failed");
+ return 1;
+ }
+ if (s != s3)
+ {
+ puts ("3rd sem_open didn't return the same address");
+ return 1;
+ }
+
+ /* Now close the handle. Three times. */
+ if (sem_close (s2) != 0)
+ {
+ puts ("1st sem_close failed");
+ return 1;
+ }
+ if (sem_close (s) != 0)
+ {
+ puts ("2nd sem_close failed");
+ return 1;
+ }
+ if (sem_close (s3) != 0)
+ {
+ puts ("3rd sem_close failed");
+ return 1;
+ }
+
+ return 0;
+}
projects / platform / upstream / glibc.git / commitdiff