lock.c: Truls Beckens was right #2

also, what the hell?

Fixed the obvious stuff and returned atomicity to the locking - no, access() isn't safe when you want that.

1 files changed, 10 insertions, 29 deletions

diff --git a/lock.c b/lock.c
index 68245ac..aaac35a 100644
--- a/lock.c
+++ b/lock.c
@@ -1,4 +1,5 @@
 /* See LICENSE for licence details. */

+#include <errno.h>

 #include <string.h>

 #include <stdio.h>

 #include <unistd.h>

@@ -14,39 +15,19 @@ int main(int argc, char **argv){
 		return EXIT_FAILURE;

 	}

 

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

-		/* create lock */

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

+	/* create lock */

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

+		if(errno && errno != EEXIST) {

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

 			return EXIT_FAILURE;

 		}

+		/* lock exists */

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

+			sleep(1);

+		}

+		return EXIT_SUCCESS;

+	} else

 		return EXIT_SUCCESS;

 	}

 	

-	/* prepare path */

-	argvlen = strlen(argv[1]);

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

-	path = malloc(pathlen);

-	if(path == NULL) {

-		fprintf(stderr, "malloc() failed\n");

-		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;

 }