dedup

commit 5e492634032f66a0ea3a17322265eca49efc2592
parent bbae2410b3c189917a266eb6fbca6781051e8951
Author: sin <sin@2f30.org>
Date:   Mon, 18 Feb 2019 19:37:51 +0000

Lock the index/store/cache file descriptors

This is to prevent two invocations of dedup to corrupt the store.

Diffstat:
M
TODO
 | 
1
-
M
dedup.c
 | 
6
++++++

2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/TODO b/TODO
@@ -1,3 +1,2 @@
 endianness agnostic
-file locking
 overflow checks
diff --git a/dedup.c b/dedup.c
@@ -1,4 +1,5 @@
 #include <sys/stat.h>
+#include <sys/file.h>
 #include <err.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -678,6 +679,11 @@ init(void)
 	if (cfd < 0)
 		err(1, "open %s", CACHEF);
 
+	if (flock(ifd, LOCK_NB | LOCK_EX) < 0 ||
+	    flock(sfd, LOCK_NB | LOCK_EX) < 0 ||
+	    flock(cfd, LOCK_NB | LOCK_EX) < 0)
+		errx(1, "busy lock");
+
 	if (fstat(ifd, &sb) < 0)
 		err(1, "fstat %s", INDEXF);
 	if (sb.st_size != 0) {