dedup

commit faf2fab2ac2febc631159913683d1c3dbc5166b3
parent 01c8fce481e7a253ac9a96c4bbc877aab2945586
Author: sin <sin@2f30.org>
Date:   Sun, 12 May 2019 16:36:27 +0100

Rework additional data handling

Diffstat:
M
snap.c
 | 
75
++++++++++++++++++++++++++++++++++++---------------------------------------

1 file changed, 36 insertions(+), 39 deletions(-)
diff --git a/snap.c b/snap.c
@@ -61,18 +61,12 @@ struct sctx {
 	struct shdr shdr;			/* snapshot header */
 };
 
-/* Read snapshot header */
+/* Unpack snapshot header */
 static int
-unpackshdr(int fd, struct shdr *shdr)
+unpackshdr(unsigned char *buf, struct shdr *shdr)
 {
-	unsigned char buf[SHDRSIZE];
 	int n;
 
-	if (xread(fd, buf, sizeof(buf)) != sizeof(buf)) {
-		seterr("failed to read snapshot header: %s", strerror(errno));
-		return -1;
-	}
-
 	n = unpack(buf, "'16'24qq",
 	           shdr->magic,
 	           shdr->header,
@@ -83,11 +77,10 @@ unpackshdr(int fd, struct shdr *shdr)
 	return n;
 }
 
-/* Write snapshot header */
+/* Pack snapshot header */
 static int
-packshdr(int fd, struct shdr *shdr)
+packshdr(unsigned char *buf, struct shdr *shdr)
 {
-	unsigned char buf[SHDRSIZE];
 	int n;
 
 	n = pack(buf, "'16'24qq",
@@ -97,36 +90,25 @@ packshdr(int fd, struct shdr *shdr)
 	         shdr->nbd);
 
 	assert(n == SHDRSIZE);
-	if (xwrite(fd, buf, n) != n) {
-		seterr("failed to write snapshot header: %s", strerror(errno));
-		return -1;
-	}
 	return n;
 }
 
 static int
 initmdhead(struct sctx *sctx)
 {
-	unsigned char ad[SHDRSIZE];
 	struct shdr *shdr;
 	uint64_t i;
 
-	if (lseek(sctx->fd, 0, SEEK_SET) < 0) {
-		seterr("lseek: %s", strerror(errno));
-		return -1;
-	}
-
-	if (xread(sctx->fd, ad, sizeof(ad)) != sizeof(ad)) {
-		seterr("failed to read snapshot header: %s\n", strerror(errno));
-		return -1;
-	}
-
 	shdr = &sctx->shdr;
 	if (sctx->crypto) {
+		unsigned char ad[SHDRSIZE];
 		crypto_secretstream_xchacha20poly1305_state state;
 		struct shdr *shdr;
 
 		shdr = &sctx->shdr;
+		if (packshdr(ad, shdr) < 0)
+			return -1;
+
 		if (crypto_secretstream_xchacha20poly1305_init_pull(&state,
 		                                                    shdr->header,
 		                                                    param.key) != 0) {
@@ -196,6 +178,7 @@ err0:
 int
 screat(char *path, int mode, struct sctx **sctx)
 {
+	unsigned char buf[SHDRSIZE];
 	struct shdr *shdr;
 	int crypto;
 	int fd;
@@ -249,18 +232,24 @@ screat(char *path, int mode, struct sctx **sctx)
 	shdr->flags = (VMAJ << VMAJSHIFT) | VMIN;
 	shdr->nbd = 0;
 
-	if (packshdr(fd, shdr) < 0) {
+	if (packshdr(buf, shdr) < 0) {
 		free(*sctx);
 		close(fd);
 		return -1;
 	}
 
+	if (xwrite(fd, buf, SHDRSIZE) != SHDRSIZE) {
+		seterr("failed to write snapshot header: %s", strerror(errno));
+		return -1;
+	}
+
 	return 0;
 }
 
 int
 sopen(char *path, int flags, int mode, struct sctx **sctx)
 {
+	unsigned char buf[SHDRSIZE];
 	struct shdr *shdr;
 	int crypto;
 	int fd;
@@ -312,7 +301,12 @@ sopen(char *path, int flags, int mode, struct sctx **sctx)
 
 	shdr = &(*sctx)->shdr;
 
-	if (unpackshdr(fd, shdr) < 0) {
+	if (xread(fd, buf, SHDRSIZE) != SHDRSIZE) {
+		seterr("failed to read snapshot header: %s", strerror(errno));
+		return -1;
+	}
+
+	if (unpackshdr(buf, shdr) < 0) {
 		free(sctx);
 		close(fd);
 		return -1;
@@ -419,23 +413,18 @@ ssync(struct sctx *sctx)
 
 	shdr = &sctx->shdr;
 	if (sctx->crypto) {
-		unsigned char ad[SHDRSIZE];
+		unsigned char hdr[SHDRSIZE];
 		crypto_secretstream_xchacha20poly1305_state state;
 
 		crypto_secretstream_xchacha20poly1305_init_push(&state,
 		                                                shdr->header,
 		                                                param.key);
 
-		if (packshdr(sctx->fd, shdr) < 0)
+		if (packshdr(hdr, shdr) < 0)
 			return -1;
 
-		if (lseek(sctx->fd, 0, SEEK_SET) < 0) {
-			seterr("lseek: %s", strerror(errno));
-			return -1;
-		}
-
-		if (xread(sctx->fd, ad, sizeof(ad)) != sizeof(ad)) {
-			seterr("failed to read snapshot header: %s\n", strerror(errno));
+		if (xwrite(sctx->fd, hdr, SHDRSIZE) != SHDRSIZE) {
+			seterr("failed to write snapshot header: %s", strerror(errno));
 			return -1;
 		}
 
@@ -451,7 +440,7 @@ ssync(struct sctx *sctx)
 			crypto_secretstream_xchacha20poly1305_push(&state,
 			                                           buf, NULL,
 			                                           mdnode->md, MDSIZE,
-			                                           ad, sizeof(ad), tag);
+			                                           hdr, SHDRSIZE, tag);
 			if (xwrite(sctx->fd, buf, sizeof(buf)) != sizeof(buf)) {
 				seterr("failed to write block hash: %s",
 				        strerror(errno));
@@ -459,8 +448,16 @@ ssync(struct sctx *sctx)
 			}
 		}
 	} else {
-		if (packshdr(sctx->fd, shdr) < 0)
+		unsigned char hdr[SHDRSIZE];
+
+		if (packshdr(hdr, shdr) < 0)
 			return -1;
+
+		if (xwrite(sctx->fd, hdr, SHDRSIZE) != SHDRSIZE) {
+			seterr("failed to write snapshot header: %s", strerror(errno));
+			return -1;
+		}
+
 		TAILQ_FOREACH(mdnode, &sctx->mdhead, e) {
 			if (xwrite(sctx->fd, mdnode->md, MDSIZE) != MDSIZE) {
 				seterr("failed to write block hash: %s",