dedup

commit d0b30d153d3b50be6952cfdf5613239ad46d576f
parent 6f277b62999ea260b734120ad894fa3d16357daf
Author: sin <sin@2f30.org>
Date:   Wed, 21 Mar 2018 09:44:12 +0000

Wrapper to check for read/write failures

Diffstat:
M
dedup.c
 | 
46
+++++++++++++++++++++++++++++++++-------------

1 file changed, 33 insertions(+), 13 deletions(-)
diff --git a/dedup.c b/dedup.c
@@ -88,19 +88,41 @@ dump_blk(struct blk *blk)
 	fprintf(stderr, "blk->sz: %lld\n", (unsigned long long)blk->sz);
 }
 
+ssize_t
+xread(int fd, void *buf, size_t nbytes)
+{
+	ssize_t n;
+
+	n = read(fd, buf, nbytes);
+	if (n < 0)
+		err(1, "read");
+	return n;
+}
+
+ssize_t
+xwrite(int fd, const void *buf, size_t nbytes)
+{
+	ssize_t n;
+
+	n = write(fd, buf, nbytes);
+	if (n < 0)
+		err(1, "write");
+	return n;
+}
+
 void
 append_ent(struct ent *ent)
 {
 	/* Update index header */
 	enthdr.nents++;
 	lseek(ifd, 0, SEEK_SET);
-	write(ifd, &enthdr, sizeof(enthdr));
+	xwrite(ifd, &enthdr, sizeof(enthdr));
 
 	/* Append entry */
 	lseek(ifd, 0, SEEK_END);
 	ent->sz = sizeof(*ent);
 	ent->sz += ent->nblks * sizeof(ent->blks[0]);
-	write(ifd, ent, ent->sz);
+	xwrite(ifd, ent, ent->sz);
 }
 
 struct ent *
@@ -142,14 +164,14 @@ void
 read_blk(struct blk *blk, off_t blkidx)
 {
 	lseek(sfd, blkidx * sizeof(*blk), SEEK_SET);
-	read(sfd, blk, sizeof(*blk));
+	xread(sfd, blk, sizeof(*blk));
 }
 
 void
 append_blk(struct blk *blk)
 {
 	lseek(sfd, 0, SEEK_END);
-	write(sfd, blk, sizeof(*blk));
+	xwrite(sfd, blk, sizeof(*blk));
 }
 
 int
@@ -182,7 +204,7 @@ dedup(int fd)
 
 	ent = alloc_ent();
 	SHA256_Init(&ctx);
-	while ((n = read(fd, blk.data, BLKSIZ)) > 0) {
+	while ((n = xread(fd, blk.data, BLKSIZ)) > 0) {
 		uint64_t blkidx;
 
 		blk.sz = n;
@@ -207,8 +229,6 @@ dedup(int fd)
 			ent->blks[ent->nblks++] = blkidx;
 		}
 	}
-	if (n < 0)
-		err(1, "read");
 
 	/* Calculate hash and add this entry to the index */
 	SHA256_Final(ent->md, &ctx);
@@ -236,9 +256,9 @@ extract(unsigned char *id, int fd)
 	lseek(ifd, sizeof(enthdr), SEEK_SET);
 	for (i = 0; i < enthdr.nents; i++) {
 		ent = alloc_ent();
-		read(ifd, ent, sizeof(*ent));
+		xread(ifd, ent, sizeof(*ent));
 		ent = grow_ent(ent, ent->nblks);
-		read(ifd, ent->blks, ent->nblks * sizeof(ent->blks[0]));
+		xread(ifd, ent->blks, ent->nblks * sizeof(ent->blks[0]));
 		if (memcmp(ent->md, md, sizeof(ent->md)) == 0) {
 			uint64_t j;
 
@@ -246,7 +266,7 @@ extract(unsigned char *id, int fd)
 				struct blk blk;
 
 				read_blk(&blk, ent->blks[j]);
-				write(1, blk.data, blk.sz);
+				xwrite(1, blk.data, blk.sz);
 			}
 			break;
 		}
@@ -270,7 +290,7 @@ init(void)
 	if (fstat(ifd, &sb) == -1)
 		err(1, "stat index");
 	if (sb.st_size != 0)
-		read(ifd, &enthdr, sizeof(enthdr));
+		xread(ifd, &enthdr, sizeof(enthdr));
 }
 
 void
@@ -292,9 +312,9 @@ dump_index(void)
 	lseek(ifd, sizeof(enthdr), SEEK_SET);
 	for (i = 0; i < enthdr.nents; i++) {
 		ent = alloc_ent();
-		read(ifd, ent, sizeof(*ent));
+		xread(ifd, ent, sizeof(*ent));
 		ent = grow_ent(ent, ent->nblks);
-		read(ifd, ent->blks, ent->nblks * sizeof(ent->blks[0]));
+		xread(ifd, ent->blks, ent->nblks * sizeof(ent->blks[0]));
 		dump_ent(ent);
 		free(ent);
 	}