X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Futils.c;h=ff6d1c22337200e69e24807b1c871530ce6ea09e;hp=b640b950e7e3d88ac95a966d60e76acaa1a88121;hb=c9cb3e7db56f4325ed97c068f8ced2c2c0366495;hpb=8bf28e6702eaffc5a3314ba0f7d10c76e59cd289

diff --git a/src/common/utils.c b/src/common/utils.c
index b640b950e..ff6d1c223 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -30,6 +30,7 @@
 #include <inttypes.h>
 #include <grp.h>
 #include <pwd.h>
+#include <sys/file.h>
 
 #include <common/common.h>
 #include <common/runas.h>
@@ -468,6 +469,44 @@ error:
 	return ret;
 }
 
+/*
+ * Create lock file to the given path and filename.
+ * Returns the associated file descriptor, -1 on error.
+ */
+LTTNG_HIDDEN
+int utils_create_lock_file(const char *filepath)
+{
+	int ret;
+	int fd;
+
+	assert(filepath);
+
+	fd = open(filepath, O_CREAT,
+		O_WRONLY | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
+	if (fd < 0) {
+		PERROR("open lock file %s", filepath);
+		ret = -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.
+	 */
+	ret = flock(fd, LOCK_EX | LOCK_NB);
+	if (ret) {
+		WARN("Could not get lock file %s, another instance is running.",
+			filepath);
+		close(fd);
+		fd = ret;
+		goto error;
+	}
+
+error:
+	return fd;
+}
+
 /*
  * Recursively create directory using the given path and mode.
  *