[PATCH] clean up pack index handling a bit

Especially with the new index format to come, it is more appropriate
to encapsulate more into check_packed_git_idx() and assume less of the
index format in struct packed_git.

To that effect, the index_base is renamed to index_data with void * type
so it is not used directly but other pointers initialized with it. This
allows for a couple pointer cast removal, as well as providing a better
generic name to grep for when adding support for new index versions or
formats.

And index_data is declared const too while at it.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 42 insertions, 44 deletions

diff --git a/sha1_file.c b/sha1_file.c
index 5691448d7..110d69621 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -432,16 +432,15 @@ void pack_report()
 		pack_mapped, peak_pack_mapped);
 }
 
-static int check_packed_git_idx(const char *path,
-	unsigned long *idx_size_,
-	void **idx_map_)
+static int check_packed_git_idx(const char *path,  struct packed_git *p)
 {
 	void *idx_map;
-	uint32_t *index;
+	struct pack_idx_header *hdr;
 	size_t idx_size;
-	uint32_t nr, i;
+	uint32_t nr, i, *index;
 	int fd = open(path, O_RDONLY);
 	struct stat st;
+
 	if (fd < 0)
 		return -1;
 	if (fstat(fd, &st)) {
@@ -456,15 +455,12 @@ static int check_packed_git_idx(const char *path,
 	idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);
 
-	index = idx_map;
-	*idx_map_ = idx_map;
-	*idx_size_ = idx_size;
-
 	/* a future index format would start with this, as older git
 	 * binaries would fail the non-monotonic index check below.
 	 * give a nicer warning to the user if we can.
 	 */
-	if (index[0] == htonl(PACK_IDX_SIGNATURE)) {
+	hdr = idx_map;
+	if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 		munmap(idx_map, idx_size);
 		return error("index file %s is a newer version"
 			" and is not supported by this binary"
@@ -473,6 +469,7 @@ static int check_packed_git_idx(const char *path,
 	}
 
 	nr = 0;
+	index = idx_map;
 	for (i = 0; i < 256; i++) {
 		uint32_t n = ntohl(index[i]);
 		if (n < nr) {
@@ -494,6 +491,9 @@ static int check_packed_git_idx(const char *path,
 		return error("wrong index file size in %s", path);
 	}
 
+	p->index_version = 1;
+	p->index_data = idx_map;
+	p->index_size = idx_size;
 	return 0;
 }
 
@@ -614,7 +614,7 @@ static int open_packed_git_1(struct packed_git *p)
 		return error("end of packfile %s is unavailable", p->pack_name);
 	if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 		return error("packfile %s signature is unavailable", p->pack_name);
-	idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
+	idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 	if (hashcmp(sha1, idx_sha1))
 		return error("packfile %s does not match index", p->pack_name);
 	return 0;
@@ -710,38 +710,37 @@ unsigned char* use_pack(struct packed_git *p,
 	return win->base + offset;
 }
 
-struct packed_git *add_packed_git(char *path, int path_len, int local)
+struct packed_git *add_packed_git(const char *path, int path_len, int local)
 {
 	struct stat st;
-	struct packed_git *p;
-	unsigned long idx_size;
-	void *idx_map;
-	unsigned char sha1[20];
+	struct packed_git *p = xmalloc(sizeof(*p) + path_len + 2);
 
-	if (check_packed_git_idx(path, &idx_size, &idx_map))
+	/*
+	 * Make sure a corresponding .pack file exists and that
+	 * the index looks sane.
+	 */
+	path_len -= strlen(".idx");
+	if (path_len < 1)
 		return NULL;
-
-	/* do we have a corresponding .pack file? */
-	strcpy(path + path_len - 4, ".pack");
-	if (stat(path, &st) || !S_ISREG(st.st_mode)) {
-		munmap(idx_map, idx_size);
+	memcpy(p->pack_name, path, path_len);
+	strcpy(p->pack_name + path_len, ".pack");
+	if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode) ||
+	    check_packed_git_idx(path, p)) {
+		free(p);
 		return NULL;
 	}
+
 	/* ok, it looks sane as far as we can check without
 	 * actually mapping the pack file.
 	 */
-	p = xmalloc(sizeof(*p) + path_len + 2);
-	strcpy(p->pack_name, path);
-	p->index_size = idx_size;
 	p->pack_size = st.st_size;
-	p->index_base = idx_map;
 	p->next = NULL;
 	p->windows = NULL;
 	p->pack_fd = -1;
 	p->pack_local = local;
 	p->mtime = st.st_mtime;
-	if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
-		hashcpy(p->sha1, sha1);
+	if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
+		hashclr(p->sha1);
 	return p;
 }
 
@@ -751,23 +750,19 @@ struct packed_git *parse_pack_index(unsigned char *sha1)
 	return parse_pack_index_file(sha1, path);
 }
 
-struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
+struct packed_git *parse_pack_index_file(const unsigned char *sha1,
+					 const char *idx_path)
 {
-	struct packed_git *p;
-	unsigned long idx_size;
-	void *idx_map;
-	char *path;
+	const char *path = sha1_pack_name(sha1);
+	struct packed_git *p = xmalloc(sizeof(*p) + strlen(path) + 2);
 
-	if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
+	if (check_packed_git_idx(idx_path, p)) {
+		free(p);
 		return NULL;
+	}
 
-	path = sha1_pack_name(sha1);
-
-	p = xmalloc(sizeof(*p) + strlen(path) + 2);
 	strcpy(p->pack_name, path);
-	p->index_size = idx_size;
 	p->pack_size = 0;
-	p->index_base = idx_map;
 	p->next = NULL;
 	p->windows = NULL;
 	p->pack_fd = -1;
@@ -1423,24 +1418,27 @@ uint32_t num_packed_objects(const struct packed_git *p)
 int nth_packed_object_sha1(const struct packed_git *p, uint32_t n,
 			   unsigned char* sha1)
 {
-	void *index = p->index_base + 256;
+	const unsigned char *index = p->index_data;
+	index += 4 * 256;
 	if (num_packed_objects(p) <= n)
 		return -1;
-	hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
+	hashcpy(sha1, index + 24 * n + 4);
 	return 0;
 }
 
 off_t find_pack_entry_one(const unsigned char *sha1,
 				  struct packed_git *p)
 {
-	uint32_t *level1_ofs = p->index_base;
+	const uint32_t *level1_ofs = p->index_data;
 	int hi = ntohl(level1_ofs[*sha1]);
 	int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
-	void *index = p->index_base + 256;
+	const unsigned char *index = p->index_data;
+
+	index += 4 * 256;
 
 	do {
 		int mi = (lo + hi) / 2;
-		int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
+		int cmp = hashcmp(index + 24 * mi + 4, sha1);
 		if (!cmp)
 			return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
 		if (cmp > 0)