dedup

commit 44ce796d4a5c9a22d136f4f4c37596254d70bee3
parent fe4061d87b77bf2789310758b799078da594f2bf
Author: sin <sin@2f30.org>
Date:   Tue, 20 Mar 2018 18:03:17 +0000

Minor refactoring

Diffstat:
M
dedup.c
 | 
20
+++++++++++++-------

1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/dedup.c b/dedup.c
@@ -19,7 +19,7 @@ struct enthdr {
 } __attribute__((packed));
 
 struct ent {
-	uint64_t sz;
+	uint64_t sz; /* size of entire entry structure */
 	unsigned char md[SHA256_DIGEST_LENGTH];
 	uint64_t nblks;
 	uint64_t blks[];
@@ -90,10 +90,12 @@ dump_blk(struct blk *blk)
 void
 append_ent(struct ent *ent)
 {
+	/* Update index header */
 	enthdr.nents++;
 	lseek(ifd, 0, SEEK_SET);
 	write(ifd, &enthdr, sizeof(enthdr));
 
+	/* Append entry */
 	lseek(ifd, 0, SEEK_END);
 	ent->sz = sizeof(*ent);
 	ent->sz += ent->nblks * sizeof(ent->blks[0]);
@@ -117,6 +119,7 @@ grow_ent(struct ent *ent, uint64_t nblks)
 	size_t sz;
 
 	sz = sizeof(*ent);
+	/* XXX: Smarter realloc strategy */
 	sz += nblks * sizeof(ent->blks[0]);
 	ent = realloc(ent, sz);
 	if (ent == NULL)
@@ -185,7 +188,10 @@ dedup(int fd)
 		hash_blk(&blk);
 		if (verbose)
 			dump_blk(&blk);
+
+		/* Rolling hash of input stream */
 		SHA256_Update(&ctx, blk.data, blk.sz);
+		/* Prepare for adding a new block index for this entry */
 		ent = grow_ent(ent, ent->nblks + 1);
 
 		if (lookup_blk(&blk, &blkidx) == -1) {
@@ -203,19 +209,19 @@ dedup(int fd)
 	if (n < 0)
 		err(1, "read");
 
+	/* Calculate hash and add this entry to the index */
 	SHA256_Final(ent->md, &ctx);
 	append_ent(ent);
 	free(ent);
 }
 
 void
-str2id(unsigned char *idstr, uint8_t *id)
+str2bin(unsigned char *s, uint8_t *d)
 {
-	size_t i, len = strlen(idstr) / 2;
-	char *p = idstr;
+	size_t i, len = strlen(s) / 2;
 
-	for (i = 0; i < len; i++, p += 2)
-		sscanf(p, "%2hhx", &id[i]);
+	for (i = 0; i < len; i++, s += 2)
+		sscanf(s, "%2hhx", &d[i]);
 }
 
 void
@@ -225,7 +231,7 @@ extract(unsigned char *id, int fd)
 	struct ent *ent;
 	uint64_t i;
 
-	str2id(id, md);
+	str2bin(id, md);
 	lseek(ifd, sizeof(enthdr), SEEK_SET);
 	for (i = 0; i < enthdr.nents; i++) {
 		ent = alloc_ent();