summaryrefslogtreecommitdiffstats
path: root/src/main/exfile.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/main/exfile.c')
-rw-r--r--src/main/exfile.c544
1 files changed, 544 insertions, 0 deletions
diff --git a/src/main/exfile.c b/src/main/exfile.c
new file mode 100644
index 0000000..529524d
--- /dev/null
+++ b/src/main/exfile.c
@@ -0,0 +1,544 @@
+/*
+ * 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.
+ uint32_t hash; //!< Hash for cheap comparison.
+ time_t last_used; //!< Last time the entry was used.
+ dev_t st_dev; //!< device inode
+ ino_t st_ino; //!< inode number
+ 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->max_entries = max_entries;
+ ef->max_idle = max_idle;
+ ef->locking = locking;
+
+ /*
+ * If we're not locking the files, just return the
+ * handle. Each call to exfile_open() will just open a
+ * new file descriptor.
+ */
+ if (!locking) return ef;
+
+ 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
+
+ talloc_set_destructor(ef, _exfile_free);
+
+ return ef;
+}
+
+
+static void exfile_cleanup_entry(exfile_entry_t *entry)
+{
+ TALLOC_FREE(entry->filename);
+
+ if (entry->fd >= 0) close(entry->fd);
+ entry->hash = 0;
+ entry->fd = -1;
+}
+
+
+/*
+ * Try to open the file. If it doesn't exist, try to
+ * create it's parent directories.
+ */
+static int exfile_open_mkdir(exfile_t *ef, char const *filename, mode_t permissions)
+{
+ int fd;
+
+ /*
+ * Files in /dev/ are special. We don't try to create
+ * their parent directories, and we don't try to create
+ * the files.
+ */
+ if (strncmp(filename, "/dev/", 5) == 0) {
+ int oflag;
+
+ if (((permissions & 0222) == 0) && (permissions & 0444) != 0) { /* !W + R */
+ oflag = O_RDONLY;
+
+ } else if (((permissions & 0222) != 0) && (permissions & 0444) == 0) { /* W + !R */
+ oflag = O_WRONLY;
+
+ } else { /* unknown, make it R+W */
+ oflag = O_RDWR;
+ }
+
+ fd = open(filename, oflag, permissions);
+ if (fd < 0) {
+ fr_strerror_printf("Failed to open file %s: %s",
+ filename, strerror(errno));
+ return -1;
+ }
+
+ return fd;
+ }
+
+ fd = open(filename, O_RDWR | O_CREAT, permissions);
+ if (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) return -1;
+ p = strrchr(dir, FR_DIR_SEP);
+ if (!p) {
+ fr_strerror_printf("No '/' in '%s'", filename);
+ talloc_free(dir);
+ return -1;
+ }
+ *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);
+ return -1;
+ }
+ talloc_free(dir);
+
+ fd = open(filename, O_RDWR | O_CREAT, permissions);
+ if (fd < 0) {
+ fr_strerror_printf("Failed to open file %s: %s",
+ filename, strerror(errno));
+ return -1;
+ }
+ }
+
+ return fd;
+}
+
+
+/** 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.
+ * @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)
+{
+ int i, found, tries, unused, oldest;
+ uint32_t hash;
+ time_t now;
+ struct stat st;
+
+ if (!ef || !filename) return -1;
+
+ /*
+ * No locking: just return a new FD.
+ */
+ if (!ef->locking) {
+ found = exfile_open_mkdir(ef, filename, permissions);
+ if (found < 0) return -1;
+
+ (void) lseek(found, 0, SEEK_END);
+ return found;
+ }
+
+ /*
+ * It's faster to do hash comparisons of a string than
+ * full string comparisons.
+ */
+ hash = fr_hash_string(filename);
+ now = time(NULL);
+
+ 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.
+ */
+ found = oldest = unused = -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;
+ }
+
+ /*
+ * Hash comparisons are fast. String comparisons are slow.
+ */
+ if (ef->entries[i].hash != hash) continue;
+
+ /*
+ * But we still need to do string comparisons if
+ * the hash matches, because 1/2^16 filenames
+ * will result in a hash collision. And that's
+ * enough filenames in a long-running server to
+ * ensure that it happens.
+ */
+ if (strcmp(ef->entries[i].filename, filename) != 0) continue;
+
+ found = i;
+ break;
+ }
+
+ /*
+ * If it wasn't found, create a new entry.
+ */
+ if (found < 0) {
+ /*
+ * There are no unused entries. Clean up 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;
+
+ /*
+ * We've just created the entry. Open the file
+ * and cache the FD.
+ */
+ reopen:
+ ef->entries[i].fd = exfile_open_mkdir(ef, filename, permissions);
+ if (ef->entries[i].fd < 0) {
+ error:
+ exfile_cleanup_entry(&ef->entries[i]);
+ PTHREAD_MUTEX_UNLOCK(&(ef->mutex));
+ return -1;
+ }
+
+ if (fstat(ef->entries[i].fd, &st) < 0) goto error;
+
+ /*
+ * Remember which device and inode this file is
+ * for.
+ */
+ ef->entries[i].st_dev = st.st_dev;
+ ef->entries[i].st_ino = st.st_ino;
+
+ } else {
+ i = found;
+
+ /*
+ * Stat the *filename*, not the file we opened.
+ * If that's not the file we opened, then go back
+ * and re-open the file.
+ */
+ if (stat(ef->entries[i].filename, &st) == 0) {
+ if ((st.st_dev != ef->entries[i].st_dev) ||
+ (st.st_ino != ef->entries[i].st_ino)) {
+ /*
+ * No longer the same file; reopen.
+ */
+ close(ef->entries[i].fd);
+ goto reopen;
+ }
+ } else {
+ /*
+ * Error calling stat, likely the
+ * file has been moved. Reopen it.
+ */
+ close(ef->entries[i].fd);
+ goto reopen;
+ }
+ }
+
+ /*
+ * 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.
+ */
+
+ /*
+ * Lock from the start of the file. It's the
+ * only point in the file which is guaranteed to
+ * exist, and to be consistent across all threads
+ * and processes.
+ */
+ if (lseek(ef->entries[i].fd, 0, SEEK_SET) < 0) {
+ fr_strerror_printf("Failed to seek in file %s: %s", filename, strerror(errno));
+ goto error;
+ }
+
+ /*
+ * Busy-loop trying to lock the file.
+ */
+ 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 the file and re-open it. It may
+ * have been deleted. If it was deleted,
+ * then the new file should now be unlocked.
+ */
+ close(ef->entries[i].fd);
+ ef->entries[i].fd = open(filename, O_RDWR | 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;
+ }
+
+ /*
+ * See which file it really is.
+ */
+ if (fstat(ef->entries[i].fd, &st) < 0) {
+ fr_strerror_printf("Failed to stat file %s: %s", filename, strerror(errno));
+ goto error;
+ }
+
+ /*
+ * Maybe the file was unlinked from the file system, OR
+ * the file we opened is NOT the one we had cached. If
+ * so, close the file and re-open it from scratch.
+ */
+ if ((st.st_nlink == 0) ||
+ (st.st_dev != ef->entries[i].st_dev) ||
+ (st.st_ino != ef->entries[i].st_ino)) {
+ close(ef->entries[i].fd);
+ goto reopen;
+ }
+
+ /*
+ * Sometimes the file permissions are changed externally.
+ * just be sure to update the permission if necessary.
+ */
+ if ((st.st_mode & ~S_IFMT) != permissions) {
+ char str_need[10], oct_need[5];
+ char str_have[10], oct_have[5];
+
+ rad_mode_to_oct(oct_need, permissions);
+ rad_mode_to_str(str_need, permissions);
+
+ rad_mode_to_oct(oct_have, st.st_mode & ~S_IFMT);
+ rad_mode_to_str(str_have, st.st_mode & ~S_IFMT);
+
+ WARN("File %s permissions are %s (%s) not %s (%s))", filename,
+ oct_have, str_have, oct_need, str_need);
+
+ if (((st.st_mode | permissions) != st.st_mode) &&
+ (fchmod(ef->entries[i].fd, (st.st_mode & ~S_IFMT) | permissions) < 0)) {
+ rad_mode_to_oct(oct_need, (st.st_mode & ~S_IFMT) | permissions);
+ rad_mode_to_str(str_need, (st.st_mode & ~S_IFMT) | permissions);
+
+ WARN("Failed resetting file %s permissions to %s (%s): %s",
+ filename, oct_need, str_need, fr_syserror(errno));
+ }
+ }
+
+ /*
+ * If we're appending, seek to the end of the file before
+ * returning the FD to the caller.
+ */
+ (void) lseek(ef->entries[i].fd, 0, SEEK_END);
+
+ /*
+ * Return holding the mutex for the entry.
+ */
+ ef->entries[i].last_used = now;
+
+ return ef->entries[i].fd;
+}
+
+/** 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;
+
+ /*
+ * No locking: just close the file.
+ */
+ if (!ef->locking) {
+ close(fd);
+ return 0;
+ }
+
+ /*
+ * Unlock the bytes that we had previously locked.
+ */
+ for (i = 0; i < ef->max_entries; i++) {
+ if (ef->entries[i].fd == fd) {
+ (void) lseek(ef->entries[i].fd, 0, SEEK_SET);
+ (void) rad_unlockfd(ef->entries[i].fd, 0);
+
+ 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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 01:10:02 +0000