1 files changed, 214 insertions, 117 deletions

diff --git a/index-pack.c b/index-pack.c
index 80bc6cb45..e33f60524 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -13,63 +13,93 @@ static const char index_pack_usage[] =
 struct object_entry
 {
 	unsigned long offset;
+	unsigned long size;
+	unsigned int hdr_size;
 	enum object_type type;
 	enum object_type real_type;
 	unsigned char sha1[20];
 };
 
+union delta_base {
+	unsigned char sha1[20];
+	unsigned long offset;
+};
+
+/*
+ * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
+ * to memcmp() only the first 20 bytes.
+ */
+#define UNION_BASE_SZ	20
+
 struct delta_entry
 {
 	struct object_entry *obj;
-	unsigned char base_sha1[20];
+	union delta_base base;
 };
 
 static const char *pack_name;
-static unsigned char *pack_base;
-static unsigned long pack_size;
 static struct object_entry *objects;
 static struct delta_entry *deltas;
 static int nr_objects;
 static int nr_deltas;
 
-static void open_pack_file(void)
+/* We always read in 4kB chunks. */
+static unsigned char input_buffer[4096];
+static unsigned long input_offset, input_len, consumed_bytes;
+static SHA_CTX input_ctx;
+static int input_fd;
+
+/*
+ * Make sure at least "min" bytes are available in the buffer, and
+ * return the pointer to the buffer.
+ */
+static void * fill(int min)
 {
-	int fd;
-	struct stat st;
+	if (min <= input_len)
+		return input_buffer + input_offset;
+	if (min > sizeof(input_buffer))
+		die("cannot fill %d bytes", min);
+	if (input_offset) {
+		SHA1_Update(&input_ctx, input_buffer, input_offset);
+		memcpy(input_buffer, input_buffer + input_offset, input_len);
+		input_offset = 0;
+	}
+	do {
+		int ret = xread(input_fd, input_buffer + input_len,
+				sizeof(input_buffer) - input_len);
+		if (ret <= 0) {
+			if (!ret)
+				die("early EOF");
+			die("read error on input: %s", strerror(errno));
+		}
+		input_len += ret;
+	} while (input_len < min);
+	return input_buffer;
+}
+
+static void use(int bytes)
+{
+	if (bytes > input_len)
+		die("used more bytes than were available");
+	input_len -= bytes;
+	input_offset += bytes;
+	consumed_bytes += bytes;
+}
 
-	fd = open(pack_name, O_RDONLY);
-	if (fd < 0)
+static void open_pack_file(void)
+{
+	input_fd = open(pack_name, O_RDONLY);
+	if (input_fd < 0)
 		die("cannot open packfile '%s': %s", pack_name,
 		    strerror(errno));
-	if (fstat(fd, &st)) {
-		int err = errno;
-		close(fd);
-		die("cannot fstat packfile '%s': %s", pack_name,
-		    strerror(err));
-	}
-	pack_size = st.st_size;
-	pack_base = mmap(NULL, pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (pack_base == MAP_FAILED) {
-		int err = errno;
-		close(fd);
-		die("cannot mmap packfile '%s': %s", pack_name,
-		    strerror(err));
-	}
-	close(fd);
+	SHA1_Init(&input_ctx);
 }
 
 static void parse_pack_header(void)
 {
-	const struct pack_header *hdr;
-	unsigned char sha1[20];
-	SHA_CTX ctx;
-
-	/* Ensure there are enough bytes for the header and final SHA1 */
-	if (pack_size < sizeof(struct pack_header) + 20)
-		die("packfile '%s' is too small", pack_name);
+	struct pack_header *hdr = fill(sizeof(struct pack_header));
 
 	/* Header consistency check */
-	hdr = (void *)pack_base;
 	if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 		die("packfile '%s' signature mismatch", pack_name);
 	if (!pack_version_ok(hdr->hdr_version))
@@ -77,13 +107,8 @@ static void parse_pack_header(void)
 		    pack_name, ntohl(hdr->hdr_version));
 
 	nr_objects = ntohl(hdr->hdr_entries);
-
-	/* Check packfile integrity */
-	SHA1_Init(&ctx);
-	SHA1_Update(&ctx, pack_base, pack_size - 20);
-	SHA1_Final(sha1, &ctx);
-	if (hashcmp(sha1, pack_base + pack_size - 20))
-		die("packfile '%s' SHA1 mismatch", pack_name);
+	use(sizeof(struct pack_header));
+	/*fprintf(stderr, "Indexing %d objects\n", nr_objects);*/
 }
 
 static void bad_object(unsigned long offset, const char *format,
@@ -101,86 +126,121 @@ static void bad_object(unsigned long offset, const char *format, ...)
 	    pack_name, offset, buf);
 }
 
-static void *unpack_entry_data(unsigned long offset,
-			       unsigned long *current_pos, unsigned long size)
+static void *unpack_entry_data(unsigned long offset, unsigned long size)
 {
-	unsigned long pack_limit = pack_size - 20;
-	unsigned long pos = *current_pos;
 	z_stream stream;
 	void *buf = xmalloc(size);
 
 	memset(&stream, 0, sizeof(stream));
 	stream.next_out = buf;
 	stream.avail_out = size;
-	stream.next_in = pack_base + pos;
-	stream.avail_in = pack_limit - pos;
+	stream.next_in = fill(1);
+	stream.avail_in = input_len;
 	inflateInit(&stream);
 
 	for (;;) {
 		int ret = inflate(&stream, 0);
-		if (ret == Z_STREAM_END)
+		use(input_len - stream.avail_in);
+		if (stream.total_out == size && ret == Z_STREAM_END)
 			break;
 		if (ret != Z_OK)
 			bad_object(offset, "inflate returned %d", ret);
+		stream.next_in = fill(1);
+		stream.avail_in = input_len;
 	}
 	inflateEnd(&stream);
-	if (stream.total_out != size)
-		bad_object(offset, "size mismatch (expected %lu, got %lu)",
-			   size, stream.total_out);
-	*current_pos = pack_limit - stream.avail_in;
 	return buf;
 }
 
-static void *unpack_raw_entry(unsigned long offset,
-			      enum object_type *obj_type,
-			      unsigned long *obj_size,
-			      unsigned char *delta_base,
-			      unsigned long *next_obj_offset)
+static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
 {
-	unsigned long pack_limit = pack_size - 20;
-	unsigned long pos = offset;
-	unsigned char c;
-	unsigned long size;
+	unsigned char *p, c;
+	unsigned long size, base_offset;
 	unsigned shift;
-	enum object_type type;
-	void *data;
 
-	c = pack_base[pos++];
-	type = (c >> 4) & 7;
+	obj->offset = consumed_bytes;
+
+	p = fill(1);
+	c = *p;
+	use(1);
+	obj->type = (c >> 4) & 7;
 	size = (c & 15);
 	shift = 4;
 	while (c & 0x80) {
-		if (pos >= pack_limit)
-			bad_object(offset, "object extends past end of pack");
-		c = pack_base[pos++];
+		p = fill(1);
+		c = *p;
+		use(1);
 		size += (c & 0x7fUL) << shift;
 		shift += 7;
 	}
+	obj->size = size;
 
-	switch (type) {
-	case OBJ_DELTA:
-		if (pos + 20 >= pack_limit)
-			bad_object(offset, "object extends past end of pack");
-		hashcpy(delta_base, pack_base + pos);
-		pos += 20;
-		/* fallthru */
+	switch (obj->type) {
+	case OBJ_REF_DELTA:
+		hashcpy(delta_base->sha1, fill(20));
+		use(20);
+		break;
+	case OBJ_OFS_DELTA:
+		memset(delta_base, 0, sizeof(*delta_base));
+		p = fill(1);
+		c = *p;
+		use(1);
+		base_offset = c & 127;
+		while (c & 128) {
+			base_offset += 1;
+			if (!base_offset || base_offset & ~(~0UL >> 7))
+				bad_object(obj->offset, "offset value overflow for delta base object");
+			p = fill(1);
+			c = *p;
+			use(1);
+			base_offset = (base_offset << 7) + (c & 127);
+		}
+		delta_base->offset = obj->offset - base_offset;
+		if (delta_base->offset >= obj->offset)
+			bad_object(obj->offset, "delta base offset is out of bound");
+		break;
 	case OBJ_COMMIT:
 	case OBJ_TREE:
 	case OBJ_BLOB:
 	case OBJ_TAG:
-		data = unpack_entry_data(offset, &pos, size);
 		break;
 	default:
-		bad_object(offset, "bad object type %d", type);
+		bad_object(obj->offset, "bad object type %d", obj->type);
 	}
+	obj->hdr_size = consumed_bytes - obj->offset;
 
-	*obj_type = type;
-	*obj_size = size;
-	*next_obj_offset = pos;
+	return unpack_entry_data(obj->offset, obj->size);
+}
+
+static void * get_data_from_pack(struct object_entry *obj)
+{
+	unsigned long from = obj[0].offset + obj[0].hdr_size;
+	unsigned long len = obj[1].offset - from;
+	unsigned pg_offset = from % getpagesize();
+	unsigned char *map, *data;
+	z_stream stream;
+	int st;
+
+	map = mmap(NULL, len + pg_offset, PROT_READ, MAP_PRIVATE,
+		   input_fd, from - pg_offset);
+	if (map == MAP_FAILED)
+		die("cannot mmap packfile '%s': %s", pack_name, strerror(errno));
+	data = xmalloc(obj->size);
+	memset(&stream, 0, sizeof(stream));
+	stream.next_out = data;
+	stream.avail_out = obj->size;
+	stream.next_in = map + pg_offset;
+	stream.avail_in = len;
+	inflateInit(&stream);
+	while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
+	inflateEnd(&stream);
+	if (st != Z_STREAM_END || stream.total_out != obj->size)
+		die("serious inflate inconsistency");
+	munmap(map, len + pg_offset);
 	return data;
 }
 
-static int find_delta(const unsigned char *base_sha1)
+static int find_delta(const union delta_base *base)
 {
 	int first = 0, last = nr_deltas;
 
@@ -189,7 +249,7 @@ static int find_delta(const unsigned char *base_sha1)
                 struct delta_entry *delta = &deltas[next];
                 int cmp;
 
-                cmp = hashcmp(base_sha1, delta->base_sha1);
+                cmp = memcmp(base, &delta->base, UNION_BASE_SZ);
                 if (!cmp)
                         return next;
                 if (cmp < 0) {
@@ -201,18 +261,18 @@ static int find_delta(const unsigned char *base_sha1)
         return -first-1;
 }
 
-static int find_deltas_based_on_sha1(const unsigned char *base_sha1,
-				     int *first_index, int *last_index)
+static int find_delta_childs(const union delta_base *base,
+			     int *first_index, int *last_index)
 {
-	int first = find_delta(base_sha1);
+	int first = find_delta(base);
 	int last = first;
 	int end = nr_deltas - 1;
 
 	if (first < 0)
 		return -1;
-	while (first > 0 && !hashcmp(deltas[first - 1].base_sha1, base_sha1))
+	while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
 		--first;
-	while (last < end && !hashcmp(deltas[last + 1].base_sha1, base_sha1))
+	while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
 		++last;
 	*first_index = first;
 	*last_index = last;
@@ -252,25 +312,34 @@ static void resolve_delta(struct delta_entry *delta, void *base_data,
 	unsigned long delta_size;
 	void *result;
 	unsigned long result_size;
-	enum object_type delta_type;
-	unsigned char base_sha1[20];
-	unsigned long next_obj_offset;
+	union delta_base delta_base;
 	int j, first, last;
 
 	obj->real_type = type;
-	delta_data = unpack_raw_entry(obj->offset, &delta_type,
-				      &delta_size, base_sha1,
-				      &next_obj_offset);
+	delta_data = get_data_from_pack(obj);
+	delta_size = obj->size;
 	result = patch_delta(base_data, base_size, delta_data, delta_size,
 			     &result_size);
 	free(delta_data);
 	if (!result)
 		bad_object(obj->offset, "failed to apply delta");
 	sha1_object(result, result_size, type, obj->sha1);
-	if (!find_deltas_based_on_sha1(obj->sha1, &first, &last)) {
+
+	hashcpy(delta_base.sha1, obj->sha1);
+	if (!find_delta_childs(&delta_base, &first, &last)) {
+		for (j = first; j <= last; j++)
+			if (deltas[j].obj->type == OBJ_REF_DELTA)
+				resolve_delta(&deltas[j], result, result_size, type);
+	}
+
+	memset(&delta_base, 0, sizeof(delta_base));
+	delta_base.offset = obj->offset;
+	if (!find_delta_childs(&delta_base, &first, &last)) {
 		for (j = first; j <= last; j++)
-			resolve_delta(&deltas[j], result, result_size, type);
+			if (deltas[j].obj->type == OBJ_OFS_DELTA)
+				resolve_delta(&deltas[j], result, result_size, type);
 	}
+
 	free(result);
 }
 
@@ -278,16 +347,16 @@ static int compare_delta_entry(const void *a, const void *b)
 {
 	const struct delta_entry *delta_a = a;
 	const struct delta_entry *delta_b = b;
-	return hashcmp(delta_a->base_sha1, delta_b->base_sha1);
+	return memcmp(&delta_a->base, &delta_b->base, UNION_BASE_SZ);
 }
 
-static void parse_pack_objects(void)
+/* Parse all objects and return the pack content SHA1 hash */
+static void parse_pack_objects(unsigned char *sha1)
 {
 	int i;
-	unsigned long offset = sizeof(struct pack_header);
-	unsigned char base_sha1[20];
+	struct delta_entry *delta = deltas;
 	void *data;
-	unsigned long data_size;
+	struct stat st;
 
 	/*
 	 * First pass:
@@ -297,22 +366,32 @@ static void parse_pack_objects(void)
 	 */
 	for (i = 0; i < nr_objects; i++) {
 		struct object_entry *obj = &objects[i];
-		obj->offset = offset;
-		data = unpack_raw_entry(offset, &obj->type, &data_size,
-					base_sha1, &offset);
+		data = unpack_raw_entry(obj, &delta->base);
 		obj->real_type = obj->type;
-		if (obj->type == OBJ_DELTA) {
-			struct delta_entry *delta = &deltas[nr_deltas++];
+		if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
+			nr_deltas++;
 			delta->obj = obj;
-			hashcpy(delta->base_sha1, base_sha1);
+			delta++;
 		} else
-			sha1_object(data, data_size, obj->type, obj->sha1);
+			sha1_object(data, obj->size, obj->type, obj->sha1);
 		free(data);
 	}
-	if (offset != pack_size - 20)
+	objects[i].offset = consumed_bytes;
+
+	/* Check pack integrity */
+	SHA1_Update(&input_ctx, input_buffer, input_offset);
+	SHA1_Final(sha1, &input_ctx);
+	if (hashcmp(fill(20), sha1))
+		die("packfile '%s' SHA1 mismatch", pack_name);
+	use(20);
+
+	/* If input_fd is a file, we should have reached its end now. */
+	if (fstat(input_fd, &st))
+		die("cannot fstat packfile '%s': %s", pack_name, strerror(errno));
+	if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes)
 		die("packfile '%s' has junk at the end", pack_name);
 
-	/* Sort deltas by base SHA1 for fast searching */
+	/* Sort deltas by base SHA1/offset for fast searching */
 	qsort(deltas, nr_deltas, sizeof(struct delta_entry),
 	      compare_delta_entry);
 
@@ -326,22 +405,36 @@ static void parse_pack_objects(void)
 	 */
 	for (i = 0; i < nr_objects; i++) {
 		struct object_entry *obj = &objects[i];
-		int j, first, last;
+		union delta_base base;
+		int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;
 
-		if (obj->type == OBJ_DELTA)
+		if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
 			continue;
-		if (find_deltas_based_on_sha1(obj->sha1, &first, &last))
+		hashcpy(base.sha1, obj->sha1);
+		ref = !find_delta_childs(&base, &ref_first, &ref_last);
+		memset(&base, 0, sizeof(base));
+		base.offset = obj->offset;
+		ofs = !find_delta_childs(&base, &ofs_first, &ofs_last);
+		if (!ref && !ofs)
 			continue;
-		data = unpack_raw_entry(obj->offset, &obj->type, &data_size,
-					base_sha1, &offset);
-		for (j = first; j <= last; j++)
-			resolve_delta(&deltas[j], data, data_size, obj->type);
+		data = get_data_from_pack(obj);
+		if (ref)
+			for (j = ref_first; j <= ref_last; j++)
+				if (deltas[j].obj->type == OBJ_REF_DELTA)
+					resolve_delta(&deltas[j], data,
+						      obj->size, obj->type);
+		if (ofs)
+			for (j = ofs_first; j <= ofs_last; j++)
+				if (deltas[j].obj->type == OBJ_OFS_DELTA)
+					resolve_delta(&deltas[j], data,
+						      obj->size, obj->type);
 		free(data);
 	}
 
 	/* Check for unresolved deltas */
 	for (i = 0; i < nr_deltas; i++) {
-		if (deltas[i].obj->real_type == OBJ_DELTA)
+		if (deltas[i].obj->real_type == OBJ_REF_DELTA ||
+		    deltas[i].obj->real_type == OBJ_OFS_DELTA)
 			die("packfile '%s' has unresolved deltas",  pack_name);
 	}
 }
@@ -353,6 +446,10 @@ static int sha1_compare(const void *_a, const void *_b)
 	return hashcmp(a->sha1, b->sha1);
 }
 
+/*
+ * On entry *sha1 contains the pack content SHA1 hash, on exit it is
+ * the SHA1 hash of sorted object names.
+ */
 static void write_index_file(const char *index_name, unsigned char *sha1)
 {
 	struct sha1file *f;
@@ -412,7 +509,7 @@ static void write_index_file(const char *index_name, unsigned char *sha1)
 		sha1write(f, obj->sha1, 20);
 		SHA1_Update(&ctx, obj->sha1, 20);
 	}
-	sha1write(f, pack_base + pack_size - 20, 20);
+	sha1write(f, sha1, 20);
 	sha1close(f, NULL, 1);
 	free(sorted_by_sha);
 	SHA1_Final(sha1, &ctx);
@@ -458,9 +555,9 @@ int main(int argc, char **argv)
 
 	open_pack_file();
 	parse_pack_header();
-	objects = xcalloc(nr_objects, sizeof(struct object_entry));
+	objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
 	deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
-	parse_pack_objects();
+	parse_pack_objects(sha1);
 	free(deltas);
 	write_index_file(index_name, sha1);
 	free(objects);