dedup

commit f28b07e0a5e1b3adfd9b2ac9d252b499ae763918
parent 6d6cce9ed24f393e09afec8f45d3c2566210038d
Author: sin <sin@2f30.org>
Date:   Sun, 17 Feb 2019 22:03:43 +0000

Use a "double" buffer for compression

Diffstat:
M
dedup.c
 | 
43
++++++++++++++++++++++---------------------

1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/dedup.c b/dedup.c
@@ -394,35 +394,36 @@ lookup_blk(uint8_t *md)
 void
 dedup(int fd, char *msg)
 {
-	uint8_t *buf, *cbuf;
+	uint8_t *buf[2];
 	struct ent *ent;
 	SHA256_CTX ctx;
 	ssize_t n;
 
-	buf = alloc_buf(BLKSIZE);
-	cbuf = alloc_buf(comp_size(BLKSIZE));
+	buf[0] = alloc_buf(BLKSIZE);
+	buf[1] = alloc_buf(comp_size(BLKSIZE));
 	ent = alloc_ent();
 
 	SHA256_Init(&ctx);
-	while ((n = xread(fd, buf, BLKSIZE)) > 0) {
-		uint8_t *bp = buf;
+	while ((n = xread(fd, buf[0], BLKSIZE)) > 0) {
+		uint8_t *inp = buf[0]; /* input buf */
+		uint8_t *outp = buf[1]; /* compressed buf */
 
 		while (n > 0) {
 			uint8_t md[MDSIZE];
 			struct bdescr bdescr;
 			size_t blksize, csize;
 
-			blksize = chunk_blk(bp, n);
-			csize = comp(bp, cbuf, blksize, comp_size(BLKSIZE));
+			blksize = chunk_blk(inp, n);
+			csize = comp(inp, outp, blksize, comp_size(BLKSIZE));
 
 			memcpy(bdescr.md, md, sizeof(bdescr));
 			bdescr.offset = enthdr.store_size;
 			bdescr.size = csize;
 
-			hash_blk(cbuf, bdescr.size, bdescr.md);
+			hash_blk(outp, bdescr.size, bdescr.md);
 
 			/* Calculate file hash one block at a time */
-			SHA256_Update(&ctx, cbuf, bdescr.size);
+			SHA256_Update(&ctx, outp, bdescr.size);
 
 			ent = grow_ent(ent, ent->nblks + 1);
 
@@ -433,7 +434,7 @@ dedup(int fd, char *msg)
 				ent->bdescr[ent->nblks++] = bdescr;
 
 				/* Store block */
-				append_blk(cbuf, &bdescr);
+				append_blk(outp, &bdescr);
 
 				/* Create a cache entry for this block */
 				cent = alloc_cent();
@@ -443,7 +444,7 @@ dedup(int fd, char *msg)
 				ent->bdescr[ent->nblks++] = bdescr;
 			}
 
-			bp += blksize;
+			inp += blksize;
 			n -= blksize;
 		}
 	}
@@ -466,31 +467,31 @@ dedup(int fd, char *msg)
 	}
 
 	free(ent);
-	free(cbuf);
-	free(buf);
+	free(buf[1]);
+	free(buf[0]);
 }
 
 int
 extract(struct ent *ent, void *arg)
 {
-	uint8_t *buf, *cbuf;
+	uint8_t *buf[2];
 	struct extract_args *args = arg;
 	uint64_t i;
 
 	if (memcmp(ent->md, args->md, sizeof(ent->md)) != 0)
 		return WALK_CONTINUE;
 
-	buf = alloc_buf(BLKSIZE);
-	cbuf = alloc_buf(comp_size(BLKSIZE));
+	buf[0] = alloc_buf(BLKSIZE);
+	buf[1] = alloc_buf(comp_size(BLKSIZE));
 	for (i = 0; i < ent->nblks; i++) {
 		size_t blksize;
 
-		read_blk(cbuf, &ent->bdescr[i]);
-		blksize = decomp(cbuf, buf, ent->bdescr[i].size, BLKSIZE);
-		xwrite(args->fd, buf, blksize);
+		read_blk(buf[1], &ent->bdescr[i]);
+		blksize = decomp(buf[1], buf[0], ent->bdescr[i].size, BLKSIZE);
+		xwrite(args->fd, buf[0], blksize);
 	}
-	free(cbuf);
-	free(buf);
+	free(buf[1]);
+	free(buf[0]);
 	return WALK_STOP;
 }