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NPTL: Refactor named semaphore code to use shm-directory.h

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This commit is contained in:
Roland McGrath 2014-12-12 13:17:21 -08:00
parent c76d1ff514
commit e4f639e4a1
14 changed files with 113 additions and 183 deletions
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31
ChangeLog
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@ -1,3 +1,34 @@
2014-12-12 Roland McGrath <roland@hack.frob.com>
* sysdeps/posix/shm-directory.h (SHM_GET_NAME): Take new argument
PREFIX, string constant to insert between directory and name.
* sysdeps/posix/shm_open.c: Update caller.
* sysdeps/posix/shm_unlink.c: Likewise.
* nptl/semaphoreP.h (struct mountpoint_info): Type removed.
(__where_is_shmfs, mountpoint, __namedsem_once): Declarations removed.
(SEM_SHM_PREFIX): New macro.
* sysdeps/posix/Makefile (librt-routines): Add shm-directory only if
[$(have-thread-library) = no].
* nptl/Makefile (libpthread-routines): Add shm-directory.
* nptl/Versions (GLIBC_PRIVATE): Add __shm_directory.
* sysdeps/nptl/shm-directory.h: New file.
* sysdeps/posix/shm-directory.c
[IS_IN (libpthread)] (__shm_directory): Add hidden_def.
* sysdeps/unix/sysv/linux/shm-directory.c: Likewise.
* nptl/sem_open.c (check_add_mapping): Use munmap function rather than
INTERNAL_SYSCALL.
(__where_is_shmfs): Function removed.
(mountpoint, defaultmount, defaultdir, __namedsem_once):
Variables removed.
(sem_open): Use __libc_close function rather than INTERNAL_SYSCALL.
Use SHM_GET_NAME.
* nptl/sem_unlink.c: Prototypify. Use SHM_GET_NAME.
* sysdeps/nptl/bits/libc-lockP.h [IS_IN (libpthread)]
(PTFAVAIL, __libc_ptf_call, __libc_ptf_call_always): Define as
unconditional for use inside libpthread.
[IS_IN (libpthread)]: Include <nptl/pthreadP.h>.
2014-12-12 Roland McGrath <roland@hack.frob.com>
* nptl/pthread_getaffinity.c: New file.

1
nptl/Makefile
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@ -96,6 +96,7 @@ libpthread-routines = nptl-init vars events version \
old_pthread_atfork pthread_atfork \
pthread_getcpuclockid \
pthread_clock_gettime pthread_clock_settime \
shm-directory \
sem_init sem_destroy \
sem_open sem_close sem_unlink \
sem_getvalue \

1
nptl/Versions
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@ -270,5 +270,6 @@ libpthread {
__pthread_initialize_minimal;
__pthread_clock_gettime; __pthread_clock_settime;
__pthread_unwind; __pthread_get_minstack;
__shm_directory;
}
}

143
nptl/sem_open.c
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@ -18,8 +18,6 @@
#include <errno.h>
#include <fcntl.h>
#include <mntent.h>
#include <paths.h>
#include <pthread.h>
#include <search.h>
#include <semaphore.h>
@ -30,98 +28,8 @@
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <linux_fsinfo.h>
#include "semaphoreP.h"
/* Information about the mount point. */
struct mountpoint_info mountpoint attribute_hidden;
/* This is the default mount point. */
static const char defaultmount[] = "/dev/shm";
/* This is the default directory. */
static const char defaultdir[] = "/dev/shm/sem.";
/* Protect the `mountpoint' variable above. */
pthread_once_t __namedsem_once attribute_hidden = PTHREAD_ONCE_INIT;
/* Determine where the shmfs is mounted (if at all). */
void
attribute_hidden
__where_is_shmfs (void)
{
char buf[512];
struct statfs f;
struct mntent resmem;
struct mntent *mp;
FILE *fp;
/* The canonical place is /dev/shm. This is at least what the
documentation tells everybody to do. */
if (__statfs (defaultmount, &f) == 0 && (f.f_type == SHMFS_SUPER_MAGIC
|| f.f_type == RAMFS_MAGIC))
{
/* It is in the normal place. */
mountpoint.dir = (char *) defaultdir;
mountpoint.dirlen = sizeof (defaultdir) - 1;
return;
}
/* OK, do it the hard way. Look through the /proc/mounts file and if
this does not exist through /etc/fstab to find the mount point. */
fp = __setmntent ("/proc/mounts", "r");
if (__glibc_unlikely (fp == NULL))
{
fp = __setmntent (_PATH_MNTTAB, "r");
if (__glibc_unlikely (fp == NULL))
/* There is nothing we can do. Blind guesses are not helpful. */
return;
}
/* Now read the entries. */
while ((mp = __getmntent_r (fp, &resmem, buf, sizeof buf)) != NULL)
/* The original name is "shm" but this got changed in early Linux
2.4.x to "tmpfs". */
if (strcmp (mp->mnt_type, "tmpfs") == 0
|| strcmp (mp->mnt_type, "shm") == 0)
{
/* Found it. There might be more than one place where the
filesystem is mounted but one is enough for us. */
size_t namelen;
/* First make sure this really is the correct entry. At least
some versions of the kernel give wrong information because
of the implicit mount of the shmfs for SysV IPC. */
if (__statfs (mp->mnt_dir, &f) != 0 || (f.f_type != SHMFS_SUPER_MAGIC
&& f.f_type != RAMFS_MAGIC))
continue;
namelen = strlen (mp->mnt_dir);
if (namelen == 0)
/* Hum, maybe some crippled entry. Keep on searching. */
continue;
mountpoint.dir = (char *) malloc (namelen + 4 + 2);
if (mountpoint.dir != NULL)
{
char *cp = __mempcpy (mountpoint.dir, mp->mnt_dir, namelen);
if (cp[-1] != '/')
*cp++ = '/';
cp = stpcpy (cp, "sem.");
mountpoint.dirlen = cp - mountpoint.dir;
}
break;
}
/* Close the stream. */
__endmntent (fp);
}
#include <shm-directory.h>
/* Comparison function for search of existing mapping. */
@ -217,8 +125,9 @@ check_add_mapping (const char *name, size_t namelen, int fd, sem_t *existing)
if (result != existing && existing != SEM_FAILED && existing != MAP_FAILED)
{
/* Do not disturb errno. */
INTERNAL_SYSCALL_DECL (err);
INTERNAL_SYSCALL (munmap, err, 2, existing, sizeof (sem_t));
int save = errno;
munmap (existing, sizeof (sem_t));
errno = save;
}
return result;
@ -228,42 +137,17 @@ check_add_mapping (const char *name, size_t namelen, int fd, sem_t *existing)
sem_t *
sem_open (const char *name, int oflag, ...)
{
char *finalname;
sem_t *result = SEM_FAILED;
int fd;
sem_t *result;
/* Determine where the shmfs is mounted. */
__pthread_once (&__namedsem_once, __where_is_shmfs);
/* If we don't know the mount points there is nothing we can do. Ever. */
if (mountpoint.dir == NULL)
{
__set_errno (ENOSYS);
return SEM_FAILED;
}
/* Construct the filename. */
while (name[0] == '/')
++name;
if (name[0] == '\0')
{
/* The name "/" is not supported. */
__set_errno (EINVAL);
return SEM_FAILED;
}
size_t namelen = strlen (name) + 1;
/* Create the name of the final file. */
finalname = (char *) alloca (mountpoint.dirlen + namelen);
__mempcpy (__mempcpy (finalname, mountpoint.dir, mountpoint.dirlen),
name, namelen);
/* 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 (finalname,
fd = __libc_open (shm_name,
(oflag & ~(O_CREAT|O_ACCMODE)) | O_NOFOLLOW | O_RDWR);
if (fd == -1)
@ -317,8 +201,8 @@ sem_open (const char *name, int oflag, ...)
memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',
sizeof (sem_t) - sizeof (struct new_sem));
tmpfname = (char *) alloca (mountpoint.dirlen + 6 + 1);
char *xxxxxx = __mempcpy (tmpfname, mountpoint.dir, mountpoint.dirlen);
tmpfname = __alloca (shm_dirlen + sizeof SEM_SHM_PREFIX + 6);
char *xxxxxx = __mempcpy (tmpfname, shm_dir, shm_dirlen);
int retries = 0;
#define NRETRIES 50
@ -361,7 +245,7 @@ sem_open (const char *name, int oflag, ...)
fd, 0)) != MAP_FAILED)
{
/* Create the file. Don't overwrite an existing file. */
if (link (tmpfname, finalname) != 0)
if (link (tmpfname, shm_name) != 0)
{
/* Undo the mapping. */
(void) munmap (result, sizeof (sem_t));
@ -402,8 +286,9 @@ sem_open (const char *name, int oflag, ...)
if (fd != -1)
{
/* Do not disturb errno. */
INTERNAL_SYSCALL_DECL (err);
INTERNAL_SYSCALL (close, err, 1, fd);
int save = errno;
__libc_close (fd);
errno = save;
}
return result;

36
nptl/sem_unlink.c
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@ -22,44 +22,16 @@
#include <string.h>
#include <unistd.h>
#include "semaphoreP.h"
#include <shm-directory.h>
int
sem_unlink (name)
const char *name;
sem_unlink (const char *name)
{
char *fname;
size_t namelen;
/* Determine where the shmfs is mounted. */
__pthread_once (&__namedsem_once, __where_is_shmfs);
/* If we don't know the mount points there is nothing we can do. Ever. */
if (mountpoint.dir == NULL)
{
__set_errno (ENOSYS);
return -1;
}
/* Construct the filename. */
while (name[0] == '/')
++name;
if (name[0] == '\0')
{
/* The name "/" is not supported. */
__set_errno (ENOENT);
return -1;
}
namelen = strlen (name);
/* Create the name of the file. */
fname = (char *) alloca (mountpoint.dirlen + namelen + 1);
__mempcpy (__mempcpy (fname, mountpoint.dir, mountpoint.dirlen),
name, namelen + 1);
SHM_GET_NAME (ENOENT, -1, SEM_SHM_PREFIX);
/* Now try removing it. */
int ret = unlink (fname);
int ret = unlink (shm_name);
if (ret < 0 && errno == EPERM)
__set_errno (EACCES);
return ret;

16
nptl/semaphoreP.h
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@ -19,13 +19,7 @@
#include <semaphore.h>
#include "pthreadP.h"
/* Mount point of the shared memory filesystem. */
struct mountpoint_info
{
char *dir;
size_t dirlen;
};
#define SEM_SHM_PREFIX "sem."
/* Keeping track of currently used mappings. */
struct inuse_sem
@ -38,11 +32,6 @@ struct inuse_sem
};
/* 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;
@ -50,9 +39,6 @@ extern void *__sem_mappings attribute_hidden;
extern int __sem_mappings_lock attribute_hidden;
/* 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;

12
sysdeps/nptl/bits/libc-lockP.h
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@ -34,6 +34,12 @@
#include <tls.h>
#include <pthread-functions.h>
#if IS_IN (libpthread)
/* This gets us the declarations of the __pthread_* internal names,
and hidden_proto for them. */
# include <nptl/pthreadP.h>
#endif
/* Mutex type. */
#if !IS_IN (libc) && !IS_IN (libpthread)
typedef pthread_mutex_t __libc_lock_t;
@ -114,6 +120,12 @@ typedef pthread_key_t __libc_key_t;
(__libc_pthread_functions_init ? PTHFCT_CALL (ptr_##FUNC, ARGS) : ELSE)
# define __libc_ptf_call_always(FUNC, ARGS) \
PTHFCT_CALL (ptr_##FUNC, ARGS)
#elif IS_IN (libpthread)
# define PTFAVAIL(NAME) 1
# define __libc_ptf_call(FUNC, ARGS, ELSE) \
FUNC ARGS
# define __libc_ptf_call_always(FUNC, ARGS) \
FUNC ARGS
#else
# define PTFAVAIL(NAME) (NAME != NULL)
# define __libc_ptf_call(FUNC, ARGS, ELSE) \

31
sysdeps/nptl/shm-directory.h Normal file
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@ -0,0 +1,31 @@
/* Header for directory for shm/sem files. NPTL version.
Copyright (C) 2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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/>. */
#ifndef _SHM_DIRECTORY_H
#include <sysdeps/posix/shm-directory.h>
/* For NPTL the __shm_directory function lives in libpthread.
We don't want PLT calls from there. But it's also used from
librt, so it cannot just be declared hidden. */
#if IS_IN (libpthread)
hidden_proto (__shm_directory)
#endif
#endif /* shm-directory.h */

4
sysdeps/posix/Makefile
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@ -4,6 +4,8 @@ TMP_MAX = 238328
L_ctermid = 9
L_cuserid = 9
ifeq ($(subdir),rt)
ifeq ($(subdir)|$(have-thread-library),rt|no)
# With NPTL, this lives in libpthread so it can be used for sem_open too.
# Without NPTL, it's just private in librt.
librt-routines += shm-directory
endif

3
sysdeps/posix/shm-directory.c
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@ -31,5 +31,8 @@ __shm_directory (size_t *len)
*len = sizeof SHMDIR - 1;
return SHMDIR;
}
# if IS_IN (libpthread)
hidden_def (__shm_directory)
# endif
#endif

11
sysdeps/posix/shm-directory.h
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@ -36,9 +36,10 @@ extern const char *__shm_directory (size_t *len);
strlen (NAME) + 1. If NAME is invalid, it sets errno to
ERRNO_FOR_INVALID and returns RETVAL_FOR_INVALID. Finally, it defines
the local variable SHM_NAME, giving the absolute file name of the shm
file corresponding to NAME. */
file corresponding to NAME. PREFIX is a string constant used as a
prefix on NAME. */
#define SHM_GET_NAME(errno_for_invalid, retval_for_invalid) \
#define SHM_GET_NAME(errno_for_invalid, retval_for_invalid, prefix) \
size_t shm_dirlen; \
const char *shm_dir = __shm_directory (&shm_dirlen); \
/* If we don't know what directory to use, there is nothing we can do. */ \
@ -57,7 +58,9 @@ extern const char *__shm_directory (size_t *len);
__set_errno (errno_for_invalid); \
return retval_for_invalid; \
} \
char *shm_name = __alloca (shm_dirlen + namelen); \
__mempcpy (__mempcpy (shm_name, shm_dir, shm_dirlen), name, namelen)
char *shm_name = __alloca (shm_dirlen + sizeof prefix - 1 + namelen); \
__mempcpy (__mempcpy (__mempcpy (shm_name, shm_dir, shm_dirlen), \
prefix, sizeof prefix - 1), \
name, namelen)
#endif /* shm-directory.h */

2
sysdeps/posix/shm_open.c
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@ -32,7 +32,7 @@
int
shm_open (const char *name, int oflag, mode_t mode)
{
SHM_GET_NAME (EINVAL, -1);
SHM_GET_NAME (EINVAL, -1, "");
# ifdef O_NOFOLLOW
oflag |= O_NOFOLLOW;

2
sysdeps/posix/shm_unlink.c
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@ -32,7 +32,7 @@
int
shm_unlink (const char *name)
{
SHM_GET_NAME (ENOENT, -1);
SHM_GET_NAME (ENOENT, -1, "");
int result = unlink (shm_name);
if (result < 0 && errno == EPERM)

3
sysdeps/unix/sysv/linux/shm-directory.c
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@ -133,6 +133,9 @@ __shm_directory (size_t *len)
*len = mountpoint.dirlen;
return mountpoint.dir;
}
#if IS_IN (libpthread)
hidden_def (__shm_directory)
#endif
/* Make sure the table is freed if we want to free everything before