Add dm_create_lockfile to libdm to handle pidfiles for all daemons.

Switch dmeventd to use dm_create_lockfile and drop duplicate code.
Allow clvmd pidfile to be configurable.
Switch cmirrord and clvmd to use dm_create_lockfile.

1 files changed, 82 insertions, 0 deletions

diff --git a/libdm/libdm-file.c b/libdm/libdm-file.c
index 749ee4f6..ae2da76d 100644
--- a/libdm/libdm-file.c
+++ b/libdm/libdm-file.c
@@ -84,3 +84,85 @@ int dm_fclose(FILE *stream)
 
 	return prev_fail || fclose_fail ? EOF : 0;
 }
+
+int dm_create_lockfile(const char *lockfile)
+{
+	int fd, value;
+	size_t bufferlen;
+	ssize_t write_out;
+	struct flock lock;
+	char buffer[50];
+
+	if((fd = open(lockfile, O_CREAT | O_WRONLY,
+		      (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))) < 0) {
+		log_error("Cannot open lockfile [%s], error was [%s]",
+			  lockfile, strerror(errno));
+		return 0;
+	}
+
+	lock.l_type = F_WRLCK;
+	lock.l_start = 0;
+	lock.l_whence = SEEK_SET;
+	lock.l_len = 0;
+	if (fcntl(fd, F_SETLK, &lock) < 0) {
+		if (errno != EACCES && errno != EAGAIN)
+			log_error("Cannot lock lockfile [%s], error was [%s]",
+				   lockfile, strerror(errno));
+		else
+			log_error("process is already running");
+
+		goto fail;
+	}
+
+	if (ftruncate(fd, 0) < 0) {
+		log_error("Cannot truncate pidfile [%s], error was [%s]",
+			  lockfile, strerror(errno));
+
+		goto fail;
+	}
+
+	memset(buffer, 0, sizeof(buffer));
+	snprintf(buffer, sizeof(buffer)-1, "%u\n", getpid());
+
+	bufferlen = strlen(buffer);
+	write_out = write(fd, buffer, bufferlen);
+
+	if ((write_out < 0) || (write_out == 0 && errno)) {
+		log_error("Cannot write pid to pidfile [%s], error was [%s]",
+			  lockfile, strerror(errno));
+
+		goto fail;
+	}
+
+	if ((write_out == 0) || (write_out < bufferlen)) {
+		log_error("Cannot write pid to pidfile [%s], shortwrite of"
+			  "[%" PRIsize_t "] bytes, expected [%" PRIsize_t "]\n",
+			  lockfile, write_out, bufferlen);
+
+		goto fail;
+	}
+
+	if ((value = fcntl(fd, F_GETFD, 0)) < 0) {
+		log_error("Cannot get close-on-exec flag from pidfile [%s], "
+			  "error was [%s]", lockfile, strerror(errno));
+
+		goto fail;
+	}
+	value |= FD_CLOEXEC;
+	if (fcntl(fd, F_SETFD, value) < 0) {
+		log_error("Cannot set close-on-exec flag from pidfile [%s], "
+			  "error was [%s]", lockfile, strerror(errno));
+
+		goto fail;
+	}
+
+	return 1;
+
+fail:
+	if (close(fd))
+		stack;
+	if (unlink(lockfile))
+		stack;
+
+	return 0;
+}