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exfile.c
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exfile.c
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/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
/*
* $Id$
*
* @file exfile.c
* @brief Allow multiple threads to write to the same set of files.
*
* @author Alan DeKok <aland@freeradius.org>
* @copyright 2014 The FreeRADIUS server project
*/
#include <freeradius-devel/radiusd.h>
#include <freeradius-devel/exfile.h>
#include <sys/stat.h>
#include <fcntl.h>
typedef struct exfile_entry_t {
int fd; //!< File descriptor associated with an entry.
int dup;
uint32_t hash; //!< Hash for cheap comparison.
time_t last_used; //!< Last time the entry was used.
char *filename; //!< Filename.
} exfile_entry_t;
struct exfile_t {
uint32_t max_entries; //!< How many file descriptors we keep track of.
uint32_t max_idle; //!< Maximum idle time for a descriptor.
time_t last_cleaned;
#ifdef HAVE_PTHREAD_H
pthread_mutex_t mutex;
#endif
exfile_entry_t *entries;
bool locking;
};
#ifdef HAVE_PTHREAD_H
#define PTHREAD_MUTEX_LOCK pthread_mutex_lock
#define PTHREAD_MUTEX_UNLOCK pthread_mutex_unlock
#else
/*
* This is easier than ifdef's throughout the code.
*/
#define PTHREAD_MUTEX_LOCK(_x)
#define PTHREAD_MUTEX_UNLOCK(_x)
#endif
#define MAX_TRY_LOCK 4 //!< How many times we attempt to acquire a lock
//!< before giving up.
static int _exfile_free(exfile_t *ef)
{
uint32_t i;
PTHREAD_MUTEX_LOCK(&ef->mutex);
for (i = 0; i < ef->max_entries; i++) {
if (!ef->entries[i].filename) continue;
close(ef->entries[i].fd);
}
PTHREAD_MUTEX_UNLOCK(&ef->mutex);
#ifdef HAVE_PTHREAD_H
pthread_mutex_destroy(&ef->mutex);
#endif
return 0;
}
/** Initialize a way for multiple threads to log to one or more files.
*
* @param ctx The talloc context
* @param max_entries Max file descriptors to cache, and manage locks for.
* @param max_idle Maximum time a file descriptor can be idle before it's closed.
* @param locking whether or not to lock the files.
* @return the new context, or NULL on error.
*/
exfile_t *exfile_init(TALLOC_CTX *ctx, uint32_t max_entries, uint32_t max_idle, bool locking)
{
exfile_t *ef;
ef = talloc_zero(ctx, exfile_t);
if (!ef) return NULL;
ef->entries = talloc_zero_array(ef, exfile_entry_t, max_entries);
if (!ef->entries) {
talloc_free(ef);
return NULL;
}
#ifdef HAVE_PTHREAD_H
if (pthread_mutex_init(&ef->mutex, NULL) != 0) {
talloc_free(ef);
return NULL;
}
#endif
ef->max_entries = max_entries;
ef->max_idle = max_idle;
ef->locking = locking;
talloc_set_destructor(ef, _exfile_free);
return ef;
}
static void exfile_cleanup_entry(exfile_entry_t *entry)
{
TALLOC_FREE(entry->filename);
close(entry->fd);
entry->hash = 0;
entry->fd = -1;
entry->dup = -1;
}
/** Open a new log file, or maybe an existing one.
*
* When multithreaded, the FD is locked via a mutex. This way we're
* sure that no other thread is writing to the file.
*
* @param ef The logfile context returned from exfile_init().
* @param filename the file to open.
* @param permissions to use.
* @param append If true seek to the end of the file.
* @return an FD used to write to the file, or -1 on error.
*/
int exfile_open(exfile_t *ef, char const *filename, mode_t permissions, bool append)
{
int i, tries, unused, oldest;
uint32_t hash;
time_t now = time(NULL);
struct stat st;
if (!ef || !filename) return -1;
hash = fr_hash_string(filename);
unused = -1;
PTHREAD_MUTEX_LOCK(&ef->mutex);
/*
* Clean up idle entries.
*/
if (now > (ef->last_cleaned + 1)) {
ef->last_cleaned = now;
for (i = 0; i < (int) ef->max_entries; i++) {
if (!ef->entries[i].filename) continue;
if ((ef->entries[i].last_used + ef->max_idle) >= now) continue;
/*
* This will block forever if a thread is
* doing something stupid.
*/
exfile_cleanup_entry(&ef->entries[i]);
}
}
/*
* Find the matching entry, or an unused one.
*
* Also track which entry is the oldest, in case there
* are no unused entries.
*/
oldest = -1;
for (i = 0; i < (int) ef->max_entries; i++) {
if (!ef->entries[i].filename) {
if (unused < 0) unused = i;
continue;
}
if ((oldest < 0) ||
(ef->entries[i].last_used < ef->entries[oldest].last_used)) {
oldest = i;
}
if (ef->entries[i].hash != hash) continue;
/*
* Same hash but different filename. Give up.
*/
if (strcmp(ef->entries[i].filename, filename) != 0) {
PTHREAD_MUTEX_UNLOCK(&ef->mutex);
return -1;
}
goto do_return;
}
/*
* There are no unused entries, free the oldest one.
*/
if (unused < 0) {
exfile_cleanup_entry(&ef->entries[oldest]);
unused = oldest;
}
/*
* Create a new entry.
*/
i = unused;
ef->entries[i].hash = hash;
ef->entries[i].filename = talloc_strdup(ef->entries, filename);
ef->entries[i].fd = -1;
ef->entries[i].dup = -1;
ef->entries[i].fd = open(filename, O_RDWR | O_APPEND | O_CREAT, permissions);
if (ef->entries[i].fd < 0) {
mode_t dirperm;
char *p, *dir;
/*
* Maybe the directory doesn't exist. Try to
* create it.
*/
dir = talloc_strdup(ef, filename);
if (!dir) goto error;
p = strrchr(dir, FR_DIR_SEP);
if (!p) {
fr_strerror_printf("No '/' in '%s'", filename);
goto error;
}
*p = '\0';
/*
* Ensure that the 'x' bit is set, so that we can
* read the directory.
*/
dirperm = permissions;
if ((dirperm & 0600) != 0) dirperm |= 0100;
if ((dirperm & 0060) != 0) dirperm |= 0010;
if ((dirperm & 0006) != 0) dirperm |= 0001;
if (rad_mkdir(dir, dirperm, -1, -1) < 0) {
fr_strerror_printf("Failed to create directory %s: %s",
dir, strerror(errno));
talloc_free(dir);
goto error;
}
talloc_free(dir);
ef->entries[i].fd = open(filename, O_WRONLY | O_CREAT, permissions);
if (ef->entries[i].fd < 0) {
fr_strerror_printf("Failed to open file %s: %s",
filename, strerror(errno));
goto error;
} /* else fall through to creating the rest of the entry */
} /* else the file was already opened */
do_return:
/*
* Lock from the start of the file.
*/
if (lseek(ef->entries[i].fd, 0, SEEK_SET) < 0) {
fr_strerror_printf("Failed to seek in file %s: %s", filename, strerror(errno));
error:
exfile_cleanup_entry(&ef->entries[i]);
PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
return -1;
}
/*
* Try to lock it. If we can't lock it, it's because
* some reader has re-named the file to "foo.work" and
* locked it. So, we close the current file, re-open it,
* and try again/
*/
if (ef->locking) {
for (tries = 0; tries < MAX_TRY_LOCK; tries++) {
if (rad_lockfd_nonblock(ef->entries[i].fd, 0) >= 0) break;
if (errno != EAGAIN) {
fr_strerror_printf("Failed to lock file %s: %s", filename, strerror(errno));
goto error;
}
close(ef->entries[i].fd);
ef->entries[i].fd = open(filename, O_WRONLY | O_CREAT, permissions);
if (ef->entries[i].fd < 0) {
fr_strerror_printf("Failed to open file %s: %s",
filename, strerror(errno));
goto error;
}
}
if (tries >= MAX_TRY_LOCK) {
fr_strerror_printf("Failed to lock file %s: too many tries", filename);
goto error;
}
}
/*
* Maybe someone deleted the file while we were waiting
* for the lock. If so, re-open it.
*/
if (fstat(ef->entries[i].fd, &st) < 0) {
fr_strerror_printf("Failed to stat file %s: %s", filename, strerror(errno));
goto error;
}
if (st.st_nlink == 0) {
close(ef->entries[i].fd);
ef->entries[i].fd = open(filename, O_WRONLY | O_CREAT, permissions);
if (ef->entries[i].fd < 0) {
fr_strerror_printf("Failed to open file %s: %s",
filename, strerror(errno));
goto error;
}
}
/*
* Seek to the end of the file before returning the FD to
* the caller.
*/
if (append) lseek(ef->entries[i].fd, 0, SEEK_END);
/*
* Return holding the mutex for the entry.
*/
ef->entries[i].last_used = now;
ef->entries[i].dup = dup(ef->entries[i].fd);
if (ef->entries[i].dup < 0) {
fr_strerror_printf("Failed calling dup(): %s", strerror(errno));
goto error;
}
return ef->entries[i].dup;
}
/** Close the log file. Really just return it to the pool.
*
* When multithreaded, the FD is locked via a mutex. This way we're
* sure that no other thread is writing to the file. This function
* will unlock the mutex, so that other threads can write to the file.
*
* @param ef The logfile context returned from exfile_init()
* @param fd the FD to close (i.e. return to the pool)
* @return 0 on success, or -1 on error
*/
int exfile_close(exfile_t *ef, int fd)
{
uint32_t i;
for (i = 0; i < ef->max_entries; i++) {
if (!ef->entries[i].filename) continue;
/*
* Unlock the bytes that we had previously locked.
*/
if (ef->entries[i].dup == fd) {
if (ef->locking) (void) rad_unlockfd(ef->entries[i].dup, 0);
close(ef->entries[i].dup); /* releases the fcntl lock */
ef->entries[i].dup = -1;
PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
return 0;
}
}
PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
fr_strerror_printf("Attempt to unlock file which is not tracked");
return -1;
}
int exfile_unlock(exfile_t *ef, int fd)
{
uint32_t i;
for (i = 0; i < ef->max_entries; i++) {
if (!ef->entries[i].filename) continue;
if (ef->entries[i].dup == fd) {
ef->entries[i].dup = -1;
PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
return 0;
}
}
PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
fr_strerror_printf("Attempt to unlock file which does not exist");
return -1;
}