X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=pack-write.c;h=e59b197e5ebb301107f9a18b7765e18097a1c8e3;hb=a94eda65d37149e81356b6a263ce03015d3f5d73;hp=ae2e481e5554cfa66cf137d38c38f961b9aa8ec7;hpb=d1c7c27ea3d9c92be2c7a9c5fc72ba5f228c424a;p=git.git

diff --git a/pack-write.c b/pack-write.c
index ae2e481e5..e59b197e5 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -1,5 +1,147 @@
 #include "cache.h"
 #include "pack.h"
+#include "csum-file.h"
+
+uint32_t pack_idx_default_version = 1;
+uint32_t pack_idx_off32_limit = 0x7fffffff;
+
+static int sha1_compare(const void *_a, const void *_b)
+{
+	struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
+	struct pack_idx_entry *b = *(struct pack_idx_entry **)_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. The objects array passed in
+ * will be sorted by SHA1 on exit.
+ */
+const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, unsigned char *sha1)
+{
+	struct sha1file *f;
+	struct pack_idx_entry **sorted_by_sha, **list, **last;
+	off_t last_obj_offset = 0;
+	uint32_t array[256];
+	int i, fd;
+	SHA_CTX ctx;
+	uint32_t index_version;
+
+	if (nr_objects) {
+		sorted_by_sha = objects;
+		list = sorted_by_sha;
+		last = sorted_by_sha + nr_objects;
+		for (i = 0; i < nr_objects; ++i) {
+			if (objects[i]->offset > last_obj_offset)
+				last_obj_offset = objects[i]->offset;
+		}
+		qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
+		      sha1_compare);
+	}
+	else
+		sorted_by_sha = list = last = NULL;
+
+	if (!index_name) {
+		static char tmpfile[PATH_MAX];
+		snprintf(tmpfile, sizeof(tmpfile),
+			 "%s/tmp_idx_XXXXXX", get_object_directory());
+		fd = xmkstemp(tmpfile);
+		index_name = xstrdup(tmpfile);
+	} else {
+		unlink(index_name);
+		fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
+	}
+	if (fd < 0)
+		die("unable to create %s: %s", index_name, strerror(errno));
+	f = sha1fd(fd, index_name);
+
+	/* if last object's offset is >= 2^31 we should use index V2 */
+	index_version = (last_obj_offset >> 31) ? 2 : pack_idx_default_version;
+
+	/* index versions 2 and above need a header */
+	if (index_version >= 2) {
+		struct pack_idx_header hdr;
+		hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
+		hdr.idx_version = htonl(index_version);
+		sha1write(f, &hdr, sizeof(hdr));
+	}
+
+	/*
+	 * Write the first-level table (the list is sorted,
+	 * but we use a 256-entry lookup to be able to avoid
+	 * having to do eight extra binary search iterations).
+	 */
+	for (i = 0; i < 256; i++) {
+		struct pack_idx_entry **next = list;
+		while (next < last) {
+			struct pack_idx_entry *obj = *next;
+			if (obj->sha1[0] != i)
+				break;
+			next++;
+		}
+		array[i] = htonl(next - sorted_by_sha);
+		list = next;
+	}
+	sha1write(f, array, 256 * 4);
+
+	/* compute the SHA1 hash of sorted object names. */
+	SHA1_Init(&ctx);
+
+	/*
+	 * Write the actual SHA1 entries..
+	 */
+	list = sorted_by_sha;
+	for (i = 0; i < nr_objects; i++) {
+		struct pack_idx_entry *obj = *list++;
+		if (index_version < 2) {
+			uint32_t offset = htonl(obj->offset);
+			sha1write(f, &offset, 4);
+		}
+		sha1write(f, obj->sha1, 20);
+		SHA1_Update(&ctx, obj->sha1, 20);
+	}
+
+	if (index_version >= 2) {
+		unsigned int nr_large_offset = 0;
+
+		/* write the crc32 table */
+		list = sorted_by_sha;
+		for (i = 0; i < nr_objects; i++) {
+			struct pack_idx_entry *obj = *list++;
+			uint32_t crc32_val = htonl(obj->crc32);
+			sha1write(f, &crc32_val, 4);
+		}
+
+		/* write the 32-bit offset table */
+		list = sorted_by_sha;
+		for (i = 0; i < nr_objects; i++) {
+			struct pack_idx_entry *obj = *list++;
+			uint32_t offset = (obj->offset <= pack_idx_off32_limit) ?
+				obj->offset : (0x80000000 | nr_large_offset++);
+			offset = htonl(offset);
+			sha1write(f, &offset, 4);
+		}
+
+		/* write the large offset table */
+		list = sorted_by_sha;
+		while (nr_large_offset) {
+			struct pack_idx_entry *obj = *list++;
+			uint64_t offset = obj->offset;
+			if (offset > pack_idx_off32_limit) {
+				uint32_t split[2];
+				split[0] = htonl(offset >> 32);
+				split[1] = htonl(offset & 0xffffffff);
+				sha1write(f, split, 8);
+				nr_large_offset--;
+			}
+		}
+	}
+
+	sha1write(f, sha1, 20);
+	sha1close(f, NULL, 1);
+	SHA1_Final(sha1, &ctx);
+	return index_name;
+}
 
 void fixup_pack_header_footer(int pack_fd,
 			 unsigned char *pack_file_sha1,