X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Flockfile.c;fp=src%2Fcommon%2Flockfile.c;h=bf1ddf9e341c9f18ea3e08f4552f5fcd5c104357;hb=cea28ac8f3e9eb154a405efb645ed907ac086978;hp=a34838c553f13f795b8127d3d83947c95900b9be;hpb=f9431861198d04bfa0e14cbe65360412de67f40a;p=lttng-tools.git

diff --git a/src/common/lockfile.c b/src/common/lockfile.c
index a34838c55..bf1ddf9e3 100644
--- a/src/common/lockfile.c
+++ b/src/common/lockfile.c
@@ -12,49 +12,93 @@
 
 #include <assert.h>
 
+#include <fcntl.h>
+
 #ifdef HAVE_FLOCK
 
+#include <sys/file.h>
+
+static int lock_file(const char *filepath, int fd)
+{
+	int ret;
+
+	/*
+	 * Attempt to lock the file. If this fails, there is
+	 * already a process using the same lock file running
+	 * and we should exit.
+	 */
+	ret = flock(fd, LOCK_EX | LOCK_NB);
+	if (ret == -1) {
+		/* EWOULDBLOCK are expected if the file is locked: don't spam the logs. */
+		if (errno != EWOULDBLOCK) {
+			PERROR("Failed to apply lock on lock file: file_path=`%s`", filepath);
+		}
+	}
+
+	return ret;
+}
+
 #else /* HAVE_FLOCK */
 
-#include <fcntl.h>
+static int lock_file(const char *filepath, int fd)
+{
+	int ret;
+	struct flock lock = {};
+
+	lock.l_whence = SEEK_SET;
+	lock.l_type = F_WRLCK;
+
+	/*
+	 * Attempt to lock the file. If this fails, there is
+	 * already a process using the same lock file running
+	 * and we should exit.
+	 */
+	ret = fcntl(fd, F_SETLK, &lock);
+	if (ret == -1) {
+		/* EAGAIN and EACCESS are expected if the file is locked: don't spam the logs. */
+		if (errno != EAGAIN && errno != EACCES) {
+			PERROR("Failed to set lock on lock file: file_path=`%s`", filepath);
+		}
+	}
+
+	return ret;
+}
+
+#endif /* HAVE_FLOCK */
 
 int utils_create_lock_file(const char *filepath)
 {
-	int ret;
-	int fd;
-	struct flock lock;
+	int ret, fd;
 
 	assert(filepath);
 
-	memset(&lock, 0, sizeof(lock));
 	fd = open(filepath, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
 	if (fd < 0) {
-		PERROR("open lock file %s", filepath);
+		PERROR("Failed to open lock file `%s`", filepath);
 		fd = -1;
 		goto error;
 	}
 
 	/*
-	 * Attempt to lock the file. If this fails, there is
-	 * already a process using the same lock file running
-	 * and we should exit.
+	 * Attempt to lock the file. If this fails, there is already a process using the same lock
+	 * file running and we should exit.
+	 *
+	 * lock_file is chosen based on the build configuration, see implementations above.
 	 */
-	lock.l_whence = SEEK_SET;
-	lock.l_type = F_WRLCK;
-
-	ret = fcntl(fd, F_SETLK, &lock);
+	ret = lock_file(filepath, fd);
 	if (ret == -1) {
-		PERROR("fcntl lock file");
-		ERR("Could not get lock file %s, another instance is running.", filepath);
+		ERR("Could not get lock file `%s`, another instance is running.", filepath);
+
 		if (close(fd)) {
-			PERROR("close lock file");
+			PERROR("Failed to close lock file fd: fd=%d", fd);
 		}
+
 		fd = ret;
 		goto error;
 	}
 
+	DBG("Acquired lock file: file_path=`%s`", filepath);
+
 error:
 	return fd;
 }
-
-#endif /* HAVE_FLOCK */