2018-06-28 17:33:50 +02:00
|
|
|
/* Copyright (c) 2003-2004, Roger Dingledine
|
|
|
|
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
|
|
|
|
* Copyright (c) 2007-2018, The Tor Project, Inc. */
|
|
|
|
/* See LICENSE for licensing information */
|
|
|
|
|
2018-07-02 02:22:55 +02:00
|
|
|
/**
|
|
|
|
* \file lockfile.c
|
|
|
|
*
|
|
|
|
* \brief Implements lock files to prevent two Tor processes from using the
|
|
|
|
* same data directory at the same time.
|
|
|
|
**/
|
|
|
|
|
2018-06-28 17:33:50 +02:00
|
|
|
#include "orconfig.h"
|
|
|
|
#include "lib/fs/files.h"
|
|
|
|
#include "lib/fs/lockfile.h"
|
|
|
|
#include "lib/log/torlog.h"
|
|
|
|
#include "lib/log/util_bug.h"
|
|
|
|
#include "lib/malloc/util_malloc.h"
|
|
|
|
|
|
|
|
#ifdef HAVE_SYS_FILE_H
|
|
|
|
#include <sys/file.h>
|
|
|
|
#endif
|
|
|
|
#ifdef HAVE_FCNTL_H
|
|
|
|
#include <fcntl.h>
|
|
|
|
#endif
|
|
|
|
#ifdef HAVE_UNISTD_H
|
|
|
|
#include <unistd.h>
|
|
|
|
#endif
|
|
|
|
#ifdef _WIN32
|
|
|
|
#include <windows.h>
|
|
|
|
#include <sys/locking.h>
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#include <errno.h>
|
|
|
|
#include <string.h>
|
|
|
|
|
|
|
|
/** Represents a lockfile on which we hold the lock. */
|
|
|
|
struct tor_lockfile_t {
|
|
|
|
/** Name of the file */
|
|
|
|
char *filename;
|
|
|
|
/** File descriptor used to hold the file open */
|
|
|
|
int fd;
|
|
|
|
};
|
|
|
|
|
|
|
|
/** Try to get a lock on the lockfile <b>filename</b>, creating it as
|
|
|
|
* necessary. If someone else has the lock and <b>blocking</b> is true,
|
|
|
|
* wait until the lock is available. Otherwise return immediately whether
|
|
|
|
* we succeeded or not.
|
|
|
|
*
|
|
|
|
* Set *<b>locked_out</b> to true if somebody else had the lock, and to false
|
|
|
|
* otherwise.
|
|
|
|
*
|
|
|
|
* Return a <b>tor_lockfile_t</b> on success, NULL on failure.
|
|
|
|
*
|
|
|
|
* (Implementation note: because we need to fall back to fcntl on some
|
|
|
|
* platforms, these locks are per-process, not per-thread. If you want
|
|
|
|
* to do in-process locking, use tor_mutex_t like a normal person.
|
|
|
|
* On Windows, when <b>blocking</b> is true, the maximum time that
|
|
|
|
* is actually waited is 10 seconds, after which NULL is returned
|
|
|
|
* and <b>locked_out</b> is set to 1.)
|
|
|
|
*/
|
|
|
|
tor_lockfile_t *
|
|
|
|
tor_lockfile_lock(const char *filename, int blocking, int *locked_out)
|
|
|
|
{
|
|
|
|
tor_lockfile_t *result;
|
|
|
|
int fd;
|
|
|
|
*locked_out = 0;
|
|
|
|
|
|
|
|
log_info(LD_FS, "Locking \"%s\"", filename);
|
|
|
|
fd = tor_open_cloexec(filename, O_RDWR|O_CREAT|O_TRUNC, 0600);
|
|
|
|
if (fd < 0) {
|
|
|
|
log_warn(LD_FS,"Couldn't open \"%s\" for locking: %s", filename,
|
|
|
|
strerror(errno));
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
#ifdef _WIN32
|
|
|
|
_lseek(fd, 0, SEEK_SET);
|
|
|
|
if (_locking(fd, blocking ? _LK_LOCK : _LK_NBLCK, 1) < 0) {
|
|
|
|
if (errno != EACCES && errno != EDEADLOCK)
|
|
|
|
log_warn(LD_FS,"Couldn't lock \"%s\": %s", filename, strerror(errno));
|
|
|
|
else
|
|
|
|
*locked_out = 1;
|
|
|
|
close(fd);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
#elif defined(HAVE_FLOCK)
|
|
|
|
if (flock(fd, LOCK_EX|(blocking ? 0 : LOCK_NB)) < 0) {
|
|
|
|
if (errno != EWOULDBLOCK)
|
|
|
|
log_warn(LD_FS,"Couldn't lock \"%s\": %s", filename, strerror(errno));
|
|
|
|
else
|
|
|
|
*locked_out = 1;
|
|
|
|
close(fd);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
#else
|
|
|
|
{
|
|
|
|
struct flock lock;
|
|
|
|
memset(&lock, 0, sizeof(lock));
|
|
|
|
lock.l_type = F_WRLCK;
|
|
|
|
lock.l_whence = SEEK_SET;
|
|
|
|
if (fcntl(fd, blocking ? F_SETLKW : F_SETLK, &lock) < 0) {
|
|
|
|
if (errno != EACCES && errno != EAGAIN)
|
|
|
|
log_warn(LD_FS, "Couldn't lock \"%s\": %s", filename, strerror(errno));
|
|
|
|
else
|
|
|
|
*locked_out = 1;
|
|
|
|
close(fd);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
#endif /* defined(_WIN32) || ... */
|
|
|
|
|
|
|
|
result = tor_malloc(sizeof(tor_lockfile_t));
|
|
|
|
result->filename = tor_strdup(filename);
|
|
|
|
result->fd = fd;
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
|
|
|
/** Release the lock held as <b>lockfile</b>. */
|
|
|
|
void
|
|
|
|
tor_lockfile_unlock(tor_lockfile_t *lockfile)
|
|
|
|
{
|
|
|
|
tor_assert(lockfile);
|
|
|
|
|
|
|
|
log_info(LD_FS, "Unlocking \"%s\"", lockfile->filename);
|
|
|
|
#ifdef _WIN32
|
|
|
|
_lseek(lockfile->fd, 0, SEEK_SET);
|
|
|
|
if (_locking(lockfile->fd, _LK_UNLCK, 1) < 0) {
|
|
|
|
log_warn(LD_FS,"Error unlocking \"%s\": %s", lockfile->filename,
|
|
|
|
strerror(errno));
|
|
|
|
}
|
|
|
|
#elif defined(HAVE_FLOCK)
|
|
|
|
if (flock(lockfile->fd, LOCK_UN) < 0) {
|
|
|
|
log_warn(LD_FS, "Error unlocking \"%s\": %s", lockfile->filename,
|
|
|
|
strerror(errno));
|
|
|
|
}
|
|
|
|
#else
|
|
|
|
/* Closing the lockfile is sufficient. */
|
|
|
|
#endif /* defined(_WIN32) || ... */
|
|
|
|
|
|
|
|
close(lockfile->fd);
|
|
|
|
lockfile->fd = -1;
|
|
|
|
tor_free(lockfile->filename);
|
|
|
|
tor_free(lockfile);
|
|
|
|
}
|