Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7

1 files changed, 379 insertions, 0 deletions

diff --git a/pack-write.c b/pack-write.c
new file mode 100644
index 000000000000..29d17a9bec27
--- /dev/null
+++ b/pack-write.c
@@ -0,0 +1,379 @@
+#include "cache.h"
+#include "pack.h"
+#include "csum-file.h"
+
+void reset_pack_idx_option(struct pack_idx_option *opts)
+{
+	memset(opts, 0, sizeof(*opts));
+	opts->version = 2;
+	opts->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 oidcmp(&a->oid, &b->oid);
+}
+
+static int cmp_uint32(const void *a_, const void *b_)
+{
+	uint32_t a = *((uint32_t *)a_);
+	uint32_t b = *((uint32_t *)b_);
+
+	return (a < b) ? -1 : (a != b);
+}
+
+static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
+{
+	uint32_t ofsval;
+
+	if ((offset >> 31) || (opts->off32_limit < offset))
+		return 1;
+	if (!opts->anomaly_nr)
+		return 0;
+	ofsval = offset;
+	return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr,
+			 sizeof(ofsval), cmp_uint32);
+}
+
+/*
+ * 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, const struct pack_idx_option *opts,
+			   const unsigned char *sha1)
+{
+	struct hashfile *f;
+	struct pack_idx_entry **sorted_by_sha, **list, **last;
+	off_t last_obj_offset = 0;
+	uint32_t array[256];
+	int i, fd;
+	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, sha1_compare);
+	}
+	else
+		sorted_by_sha = list = last = NULL;
+
+	if (opts->flags & WRITE_IDX_VERIFY) {
+		assert(index_name);
+		f = hashfd_check(index_name);
+	} else {
+		if (!index_name) {
+			struct strbuf tmp_file = STRBUF_INIT;
+			fd = odb_mkstemp(&tmp_file, "pack/tmp_idx_XXXXXX");
+			index_name = strbuf_detach(&tmp_file, NULL);
+		} else {
+			unlink(index_name);
+			fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
+			if (fd < 0)
+				die_errno("unable to create '%s'", index_name);
+		}
+		f = hashfd(fd, index_name);
+	}
+
+	/* if last object's offset is >= 2^31 we should use index V2 */
+	index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->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);
+		hashwrite(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->oid.hash[0] != i)
+				break;
+			next++;
+		}
+		array[i] = htonl(next - sorted_by_sha);
+		list = next;
+	}
+	hashwrite(f, array, 256 * 4);
+
+	/*
+	 * 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);
+			hashwrite(f, &offset, 4);
+		}
+		hashwrite(f, obj->oid.hash, the_hash_algo->rawsz);
+		if ((opts->flags & WRITE_IDX_STRICT) &&
+		    (i && oideq(&list[-2]->oid, &obj->oid)))
+			die("The same object %s appears twice in the pack",
+			    oid_to_hex(&obj->oid));
+	}
+
+	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);
+			hashwrite(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;
+
+			offset = (need_large_offset(obj->offset, opts)
+				  ? (0x80000000 | nr_large_offset++)
+				  : obj->offset);
+			offset = htonl(offset);
+			hashwrite(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;
+			uint32_t split[2];
+
+			if (!need_large_offset(offset, opts))
+				continue;
+			split[0] = htonl(offset >> 32);
+			split[1] = htonl(offset & 0xffffffff);
+			hashwrite(f, split, 8);
+			nr_large_offset--;
+		}
+	}
+
+	hashwrite(f, sha1, the_hash_algo->rawsz);
+	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE |
+				    ((opts->flags & WRITE_IDX_VERIFY)
+				    ? 0 : CSUM_FSYNC));
+	return index_name;
+}
+
+off_t write_pack_header(struct hashfile *f, uint32_t nr_entries)
+{
+	struct pack_header hdr;
+
+	hdr.hdr_signature = htonl(PACK_SIGNATURE);
+	hdr.hdr_version = htonl(PACK_VERSION);
+	hdr.hdr_entries = htonl(nr_entries);
+	hashwrite(f, &hdr, sizeof(hdr));
+	return sizeof(hdr);
+}
+
+/*
+ * Update pack header with object_count and compute new SHA1 for pack data
+ * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
+ * is also returned in new_pack_sha1.
+ *
+ * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
+ * (without the header update) is computed and validated against the
+ * one provided in partial_pack_sha1.  The validation is performed at
+ * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
+ * data (i.e. from partial_pack_offset to the end) is then computed and
+ * returned in partial_pack_sha1.
+ *
+ * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
+ * partial_pack_sha1 can refer to the same buffer if the caller is not
+ * interested in the resulting SHA1 of pack data above partial_pack_offset.
+ */
+void fixup_pack_header_footer(int pack_fd,
+			 unsigned char *new_pack_hash,
+			 const char *pack_name,
+			 uint32_t object_count,
+			 unsigned char *partial_pack_hash,
+			 off_t partial_pack_offset)
+{
+	int aligned_sz, buf_sz = 8 * 1024;
+	git_hash_ctx old_hash_ctx, new_hash_ctx;
+	struct pack_header hdr;
+	char *buf;
+	ssize_t read_result;
+
+	the_hash_algo->init_fn(&old_hash_ctx);
+	the_hash_algo->init_fn(&new_hash_ctx);
+
+	if (lseek(pack_fd, 0, SEEK_SET) != 0)
+		die_errno("Failed seeking to start of '%s'", pack_name);
+	read_result = read_in_full(pack_fd, &hdr, sizeof(hdr));
+	if (read_result < 0)
+		die_errno("Unable to reread header of '%s'", pack_name);
+	else if (read_result != sizeof(hdr))
+		die_errno("Unexpected short read for header of '%s'",
+			  pack_name);
+	if (lseek(pack_fd, 0, SEEK_SET) != 0)
+		die_errno("Failed seeking to start of '%s'", pack_name);
+	the_hash_algo->update_fn(&old_hash_ctx, &hdr, sizeof(hdr));
+	hdr.hdr_entries = htonl(object_count);
+	the_hash_algo->update_fn(&new_hash_ctx, &hdr, sizeof(hdr));
+	write_or_die(pack_fd, &hdr, sizeof(hdr));
+	partial_pack_offset -= sizeof(hdr);
+
+	buf = xmalloc(buf_sz);
+	aligned_sz = buf_sz - sizeof(hdr);
+	for (;;) {
+		ssize_t m, n;
+		m = (partial_pack_hash && partial_pack_offset < aligned_sz) ?
+			partial_pack_offset : aligned_sz;
+		n = xread(pack_fd, buf, m);
+		if (!n)
+			break;
+		if (n < 0)
+			die_errno("Failed to checksum '%s'", pack_name);
+		the_hash_algo->update_fn(&new_hash_ctx, buf, n);
+
+		aligned_sz -= n;
+		if (!aligned_sz)
+			aligned_sz = buf_sz;
+
+		if (!partial_pack_hash)
+			continue;
+
+		the_hash_algo->update_fn(&old_hash_ctx, buf, n);
+		partial_pack_offset -= n;
+		if (partial_pack_offset == 0) {
+			unsigned char hash[GIT_MAX_RAWSZ];
+			the_hash_algo->final_fn(hash, &old_hash_ctx);
+			if (!hasheq(hash, partial_pack_hash))
+				die("Unexpected checksum for %s "
+				    "(disk corruption?)", pack_name);
+			/*
+			 * Now let's compute the SHA1 of the remainder of the
+			 * pack, which also means making partial_pack_offset
+			 * big enough not to matter anymore.
+			 */
+			the_hash_algo->init_fn(&old_hash_ctx);
+			partial_pack_offset = ~partial_pack_offset;
+			partial_pack_offset -= MSB(partial_pack_offset, 1);
+		}
+	}
+	free(buf);
+
+	if (partial_pack_hash)
+		the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx);
+	the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx);
+	write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz);
+	fsync_or_die(pack_fd, pack_name);
+}
+
+char *index_pack_lockfile(int ip_out)
+{
+	char packname[GIT_MAX_HEXSZ + 6];
+	const int len = the_hash_algo->hexsz + 6;
+
+	/*
+	 * The first thing we expect from index-pack's output
+	 * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
+	 * %40s is the newly created pack SHA1 name.  In the "keep"
+	 * case, we need it to remove the corresponding .keep file
+	 * later on.  If we don't get that then tough luck with it.
+	 */
+	if (read_in_full(ip_out, packname, len) == len && packname[len-1] == '\n') {
+		const char *name;
+		packname[len-1] = 0;
+		if (skip_prefix(packname, "keep\t", &name))
+			return xstrfmt("%s/pack/pack-%s.keep",
+				       get_object_directory(), name);
+	}
+	return NULL;
+}
+
+/*
+ * The per-object header is a pretty dense thing, which is
+ *  - first byte: low four bits are "size", then three bits of "type",
+ *    and the high bit is "size continues".
+ *  - each byte afterwards: low seven bits are size continuation,
+ *    with the high bit being "size continues"
+ */
+int encode_in_pack_object_header(unsigned char *hdr, int hdr_len,
+				 enum object_type type, uintmax_t size)
+{
+	int n = 1;
+	unsigned char c;
+
+	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
+		die("bad type %d", type);
+
+	c = (type << 4) | (size & 15);
+	size >>= 4;
+	while (size) {
+		if (n == hdr_len)
+			die("object size is too enormous to format");
+		*hdr++ = c | 0x80;
+		c = size & 0x7f;
+		size >>= 7;
+		n++;
+	}
+	*hdr = c;
+	return n;
+}
+
+struct hashfile *create_tmp_packfile(char **pack_tmp_name)
+{
+	struct strbuf tmpname = STRBUF_INIT;
+	int fd;
+
+	fd = odb_mkstemp(&tmpname, "pack/tmp_pack_XXXXXX");
+	*pack_tmp_name = strbuf_detach(&tmpname, NULL);
+	return hashfd(fd, *pack_tmp_name);
+}
+
+void finish_tmp_packfile(struct strbuf *name_buffer,
+			 const char *pack_tmp_name,
+			 struct pack_idx_entry **written_list,
+			 uint32_t nr_written,
+			 struct pack_idx_option *pack_idx_opts,
+			 unsigned char sha1[])
+{
+	const char *idx_tmp_name;
+	int basename_len = name_buffer->len;
+
+	if (adjust_shared_perm(pack_tmp_name))
+		die_errno("unable to make temporary pack file readable");
+
+	idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
+				      pack_idx_opts, sha1);
+	if (adjust_shared_perm(idx_tmp_name))
+		die_errno("unable to make temporary index file readable");
+
+	strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
+
+	if (rename(pack_tmp_name, name_buffer->buf))
+		die_errno("unable to rename temporary pack file");
+
+	strbuf_setlen(name_buffer, basename_len);
+
+	strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
+	if (rename(idx_tmp_name, name_buffer->buf))
+		die_errno("unable to rename temporary index file");
+
+	strbuf_setlen(name_buffer, basename_len);
+
+	free((void *)idx_tmp_name);
+}