3 files changed, 70 insertions, 0 deletions
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..0c3dbd8
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,16 @@
+VERSION=\"0.0.5\"
+CC = gcc
+CFLAGS = -Os -mtune=native -Wall -Wextra -pedantic
+DESTDIR = /usr/local/
+
+all: lock
+
+lock:
+	$(CC) $(CFLAGS) lock.c -o lock
+
+
+install: all
+	@install lock $(DESTDIR)/bin/
+
+clean:
+	rm lock
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;
+}
diff --git a/lock b/lock.sh
index 22191fe..22191fe 100755
--- a/lock
+++ b/lock.sh