c version of lock

1 files changed, 54 insertions, 0 deletions

diff --git a/lock.c b/lock.c
new file mode 100644
index 0000000..12d560b
--- /dev/null
+++ b/lock.c
@@ -0,0 +1,54 @@
+/* See LICENSE for licence details. */

+

+#include <string.h>

+#include <errno.h>

+#include <stdio.h>

+#include <unistd.h>

+#include <sys/stat.h>

+#include <stdlib.h>

+

+int main(int argc, char **argv){

+	size_t pathlen, argvlen;

+	char *path;

+

+	if(argc != 2){

+		fprintf(stderr, "Please supply one argument: the lock directory.\n");

+		return EXIT_FAILURE;

+	}

+

+	if(access(argv[1], F_OK)){

+		/* create lock */

+		if(mkdir(argv[1], S_IRUSR | S_IXUSR)){

+			fprintf(stderr, "Failed to create lock %s.\n", argv[1]);

+			return EXIT_FAILURE;

+		}

+		return EXIT_SUCCESS;

+	}

+	

+	/* prepare path */

+	argvlen = strlen(argv[1]);

+	pathlen = argvlen + sizeof("/..") + 1;

+	path = malloc(pathlen);

+	if(path == NULL) {

+		fprintf(stderr, "Error: %s\n", strerror(errno));

+		return EXIT_FAILURE;

+	}

+	

+	memcpy(path, argv[1], argvlen);

+	memcpy(path + argvlen, "/..\0", sizeof("/..") + 1);

+

+	if(access(path, F_OK)){

+		/* invalid lock */

+		fprintf(stderr, "%s is not a lock directory.\n", argv[1]);

+		free(path);

+		return EXIT_FAILURE;

+	}

+	

+	/* lock exists */

+	for(; !access(path, F_OK) ;){

+		sleep(1);

+	}

+

+	free(path);

+	return EXIT_SUCCESS;

+}