From 1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5 Mon Sep 17 00:00:00 2001
From: Vincent Ambo <Vincent Ambo>
Date: Sat, 11 Jan 2020 23:36:56 +0000
Subject: Squashed 'third_party/git/' content from commit cb71568594

git-subtree-dir: third_party/git
git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7
---
 builtin/unpack-objects.c | 597 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 597 insertions(+)
 create mode 100644 builtin/unpack-objects.c

(limited to 'builtin/unpack-objects.c')

diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
new file mode 100644
index 000000000000..a87a4bfd2c55
--- /dev/null
+++ b/builtin/unpack-objects.c
@@ -0,0 +1,597 @@
+#include "builtin.h"
+#include "cache.h"
+#include "config.h"
+#include "object-store.h"
+#include "object.h"
+#include "delta.h"
+#include "pack.h"
+#include "blob.h"
+#include "commit.h"
+#include "tag.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "progress.h"
+#include "decorate.h"
+#include "fsck.h"
+
+static int dry_run, quiet, recover, has_errors, strict;
+static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict]";
+
+/* We always read in 4kB chunks. */
+static unsigned char buffer[4096];
+static unsigned int offset, len;
+static off_t consumed_bytes;
+static off_t max_input_size;
+static git_hash_ctx ctx;
+static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
+
+/*
+ * When running under --strict mode, objects whose reachability are
+ * suspect are kept in core without getting written in the object
+ * store.
+ */
+struct obj_buffer {
+	char *buffer;
+	unsigned long size;
+};
+
+static struct decoration obj_decorate;
+
+static struct obj_buffer *lookup_object_buffer(struct object *base)
+{
+	return lookup_decoration(&obj_decorate, base);
+}
+
+static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
+{
+	struct obj_buffer *obj;
+	obj = xcalloc(1, sizeof(struct obj_buffer));
+	obj->buffer = buffer;
+	obj->size = size;
+	if (add_decoration(&obj_decorate, object, obj))
+		die("object %s tried to add buffer twice!", oid_to_hex(&object->oid));
+}
+
+/*
+ * Make sure at least "min" bytes are available in the buffer, and
+ * return the pointer to the buffer.
+ */
+static void *fill(int min)
+{
+	if (min <= len)
+		return buffer + offset;
+	if (min > sizeof(buffer))
+		die("cannot fill %d bytes", min);
+	if (offset) {
+		the_hash_algo->update_fn(&ctx, buffer, offset);
+		memmove(buffer, buffer + offset, len);
+		offset = 0;
+	}
+	do {
+		ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
+		if (ret <= 0) {
+			if (!ret)
+				die("early EOF");
+			die_errno("read error on input");
+		}
+		len += ret;
+	} while (len < min);
+	return buffer;
+}
+
+static void use(int bytes)
+{
+	if (bytes > len)
+		die("used more bytes than were available");
+	len -= bytes;
+	offset += bytes;
+
+	/* make sure off_t is sufficiently large not to wrap */
+	if (signed_add_overflows(consumed_bytes, bytes))
+		die("pack too large for current definition of off_t");
+	consumed_bytes += bytes;
+	if (max_input_size && consumed_bytes > max_input_size)
+		die(_("pack exceeds maximum allowed size"));
+}
+
+static void *get_data(unsigned long size)
+{
+	git_zstream stream;
+	void *buf = xmallocz(size);
+
+	memset(&stream, 0, sizeof(stream));
+
+	stream.next_out = buf;
+	stream.avail_out = size;
+	stream.next_in = fill(1);
+	stream.avail_in = len;
+	git_inflate_init(&stream);
+
+	for (;;) {
+		int ret = git_inflate(&stream, 0);
+		use(len - stream.avail_in);
+		if (stream.total_out == size && ret == Z_STREAM_END)
+			break;
+		if (ret != Z_OK) {
+			error("inflate returned %d", ret);
+			FREE_AND_NULL(buf);
+			if (!recover)
+				exit(1);
+			has_errors = 1;
+			break;
+		}
+		stream.next_in = fill(1);
+		stream.avail_in = len;
+	}
+	git_inflate_end(&stream);
+	return buf;
+}
+
+struct delta_info {
+	struct object_id base_oid;
+	unsigned nr;
+	off_t base_offset;
+	unsigned long size;
+	void *delta;
+	struct delta_info *next;
+};
+
+static struct delta_info *delta_list;
+
+static void add_delta_to_list(unsigned nr, const struct object_id *base_oid,
+			      off_t base_offset,
+			      void *delta, unsigned long size)
+{
+	struct delta_info *info = xmalloc(sizeof(*info));
+
+	oidcpy(&info->base_oid, base_oid);
+	info->base_offset = base_offset;
+	info->size = size;
+	info->delta = delta;
+	info->nr = nr;
+	info->next = delta_list;
+	delta_list = info;
+}
+
+struct obj_info {
+	off_t offset;
+	struct object_id oid;
+	struct object *obj;
+};
+
+/* Remember to update object flag allocation in object.h */
+#define FLAG_OPEN (1u<<20)
+#define FLAG_WRITTEN (1u<<21)
+
+static struct obj_info *obj_list;
+static unsigned nr_objects;
+
+/*
+ * Called only from check_object() after it verified this object
+ * is Ok.
+ */
+static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
+{
+	struct object_id oid;
+
+	if (write_object_file(obj_buf->buffer, obj_buf->size,
+			      type_name(obj->type), &oid) < 0)
+		die("failed to write object %s", oid_to_hex(&obj->oid));
+	obj->flags |= FLAG_WRITTEN;
+}
+
+/*
+ * At the very end of the processing, write_rest() scans the objects
+ * that have reachability requirements and calls this function.
+ * Verify its reachability and validity recursively and write it out.
+ */
+static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
+{
+	struct obj_buffer *obj_buf;
+
+	if (!obj)
+		return 1;
+
+	if (obj->flags & FLAG_WRITTEN)
+		return 0;
+
+	if (type != OBJ_ANY && obj->type != type)
+		die("object type mismatch");
+
+	if (!(obj->flags & FLAG_OPEN)) {
+		unsigned long size;
+		int type = oid_object_info(the_repository, &obj->oid, &size);
+		if (type != obj->type || type <= 0)
+			die("object of unexpected type");
+		obj->flags |= FLAG_WRITTEN;
+		return 0;
+	}
+
+	obj_buf = lookup_object_buffer(obj);
+	if (!obj_buf)
+		die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
+	if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
+		die("fsck error in packed object");
+	fsck_options.walk = check_object;
+	if (fsck_walk(obj, NULL, &fsck_options))
+		die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
+	write_cached_object(obj, obj_buf);
+	return 0;
+}
+
+static void write_rest(void)
+{
+	unsigned i;
+	for (i = 0; i < nr_objects; i++) {
+		if (obj_list[i].obj)
+			check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
+	}
+}
+
+static void added_object(unsigned nr, enum object_type type,
+			 void *data, unsigned long size);
+
+/*
+ * Write out nr-th object from the list, now we know the contents
+ * of it.  Under --strict, this buffers structured objects in-core,
+ * to be checked at the end.
+ */
+static void write_object(unsigned nr, enum object_type type,
+			 void *buf, unsigned long size)
+{
+	if (!strict) {
+		if (write_object_file(buf, size, type_name(type),
+				      &obj_list[nr].oid) < 0)
+			die("failed to write object");
+		added_object(nr, type, buf, size);
+		free(buf);
+		obj_list[nr].obj = NULL;
+	} else if (type == OBJ_BLOB) {
+		struct blob *blob;
+		if (write_object_file(buf, size, type_name(type),
+				      &obj_list[nr].oid) < 0)
+			die("failed to write object");
+		added_object(nr, type, buf, size);
+		free(buf);
+
+		blob = lookup_blob(the_repository, &obj_list[nr].oid);
+		if (blob)
+			blob->object.flags |= FLAG_WRITTEN;
+		else
+			die("invalid blob object");
+		obj_list[nr].obj = NULL;
+	} else {
+		struct object *obj;
+		int eaten;
+		hash_object_file(buf, size, type_name(type), &obj_list[nr].oid);
+		added_object(nr, type, buf, size);
+		obj = parse_object_buffer(the_repository, &obj_list[nr].oid,
+					  type, size, buf,
+					  &eaten);
+		if (!obj)
+			die("invalid %s", type_name(type));
+		add_object_buffer(obj, buf, size);
+		obj->flags |= FLAG_OPEN;
+		obj_list[nr].obj = obj;
+	}
+}
+
+static void resolve_delta(unsigned nr, enum object_type type,
+			  void *base, unsigned long base_size,
+			  void *delta, unsigned long delta_size)
+{
+	void *result;
+	unsigned long result_size;
+
+	result = patch_delta(base, base_size,
+			     delta, delta_size,
+			     &result_size);
+	if (!result)
+		die("failed to apply delta");
+	free(delta);
+	write_object(nr, type, result, result_size);
+}
+
+/*
+ * We now know the contents of an object (which is nr-th in the pack);
+ * resolve all the deltified objects that are based on it.
+ */
+static void added_object(unsigned nr, enum object_type type,
+			 void *data, unsigned long size)
+{
+	struct delta_info **p = &delta_list;
+	struct delta_info *info;
+
+	while ((info = *p) != NULL) {
+		if (oideq(&info->base_oid, &obj_list[nr].oid) ||
+		    info->base_offset == obj_list[nr].offset) {
+			*p = info->next;
+			p = &delta_list;
+			resolve_delta(info->nr, type, data, size,
+				      info->delta, info->size);
+			free(info);
+			continue;
+		}
+		p = &info->next;
+	}
+}
+
+static void unpack_non_delta_entry(enum object_type type, unsigned long size,
+				   unsigned nr)
+{
+	void *buf = get_data(size);
+
+	if (!dry_run && buf)
+		write_object(nr, type, buf, size);
+	else
+		free(buf);
+}
+
+static int resolve_against_held(unsigned nr, const struct object_id *base,
+				void *delta_data, unsigned long delta_size)
+{
+	struct object *obj;
+	struct obj_buffer *obj_buffer;
+	obj = lookup_object(the_repository, base);
+	if (!obj)
+		return 0;
+	obj_buffer = lookup_object_buffer(obj);
+	if (!obj_buffer)
+		return 0;
+	resolve_delta(nr, obj->type, obj_buffer->buffer,
+		      obj_buffer->size, delta_data, delta_size);
+	return 1;
+}
+
+static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
+			       unsigned nr)
+{
+	void *delta_data, *base;
+	unsigned long base_size;
+	struct object_id base_oid;
+
+	if (type == OBJ_REF_DELTA) {
+		hashcpy(base_oid.hash, fill(the_hash_algo->rawsz));
+		use(the_hash_algo->rawsz);
+		delta_data = get_data(delta_size);
+		if (dry_run || !delta_data) {
+			free(delta_data);
+			return;
+		}
+		if (has_object_file(&base_oid))
+			; /* Ok we have this one */
+		else if (resolve_against_held(nr, &base_oid,
+					      delta_data, delta_size))
+			return; /* we are done */
+		else {
+			/* cannot resolve yet --- queue it */
+			oidclr(&obj_list[nr].oid);
+			add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
+			return;
+		}
+	} else {
+		unsigned base_found = 0;
+		unsigned char *pack, c;
+		off_t base_offset;
+		unsigned lo, mid, hi;
+
+		pack = fill(1);
+		c = *pack;
+		use(1);
+		base_offset = c & 127;
+		while (c & 128) {
+			base_offset += 1;
+			if (!base_offset || MSB(base_offset, 7))
+				die("offset value overflow for delta base object");
+			pack = fill(1);
+			c = *pack;
+			use(1);
+			base_offset = (base_offset << 7) + (c & 127);
+		}
+		base_offset = obj_list[nr].offset - base_offset;
+		if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
+			die("offset value out of bound for delta base object");
+
+		delta_data = get_data(delta_size);
+		if (dry_run || !delta_data) {
+			free(delta_data);
+			return;
+		}
+		lo = 0;
+		hi = nr;
+		while (lo < hi) {
+			mid = lo + (hi - lo) / 2;
+			if (base_offset < obj_list[mid].offset) {
+				hi = mid;
+			} else if (base_offset > obj_list[mid].offset) {
+				lo = mid + 1;
+			} else {
+				oidcpy(&base_oid, &obj_list[mid].oid);
+				base_found = !is_null_oid(&base_oid);
+				break;
+			}
+		}
+		if (!base_found) {
+			/*
+			 * The delta base object is itself a delta that
+			 * has not been resolved yet.
+			 */
+			oidclr(&obj_list[nr].oid);
+			add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
+			return;
+		}
+	}
+
+	if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
+		return;
+
+	base = read_object_file(&base_oid, &type, &base_size);
+	if (!base) {
+		error("failed to read delta-pack base object %s",
+		      oid_to_hex(&base_oid));
+		if (!recover)
+			exit(1);
+		has_errors = 1;
+		return;
+	}
+	resolve_delta(nr, type, base, base_size, delta_data, delta_size);
+	free(base);
+}
+
+static void unpack_one(unsigned nr)
+{
+	unsigned shift;
+	unsigned char *pack;
+	unsigned long size, c;
+	enum object_type type;
+
+	obj_list[nr].offset = consumed_bytes;
+
+	pack = fill(1);
+	c = *pack;
+	use(1);
+	type = (c >> 4) & 7;
+	size = (c & 15);
+	shift = 4;
+	while (c & 0x80) {
+		pack = fill(1);
+		c = *pack;
+		use(1);
+		size += (c & 0x7f) << shift;
+		shift += 7;
+	}
+
+	switch (type) {
+	case OBJ_COMMIT:
+	case OBJ_TREE:
+	case OBJ_BLOB:
+	case OBJ_TAG:
+		unpack_non_delta_entry(type, size, nr);
+		return;
+	case OBJ_REF_DELTA:
+	case OBJ_OFS_DELTA:
+		unpack_delta_entry(type, size, nr);
+		return;
+	default:
+		error("bad object type %d", type);
+		has_errors = 1;
+		if (recover)
+			return;
+		exit(1);
+	}
+}
+
+static void unpack_all(void)
+{
+	int i;
+	struct progress *progress = NULL;
+	struct pack_header *hdr = fill(sizeof(struct pack_header));
+
+	nr_objects = ntohl(hdr->hdr_entries);
+
+	if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
+		die("bad pack file");
+	if (!pack_version_ok(hdr->hdr_version))
+		die("unknown pack file version %"PRIu32,
+			ntohl(hdr->hdr_version));
+	use(sizeof(struct pack_header));
+
+	if (!quiet)
+		progress = start_progress(_("Unpacking objects"), nr_objects);
+	obj_list = xcalloc(nr_objects, sizeof(*obj_list));
+	for (i = 0; i < nr_objects; i++) {
+		unpack_one(i);
+		display_progress(progress, i + 1);
+	}
+	stop_progress(&progress);
+
+	if (delta_list)
+		die("unresolved deltas left after unpacking");
+}
+
+int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	struct object_id oid;
+
+	read_replace_refs = 0;
+
+	git_config(git_default_config, NULL);
+
+	quiet = !isatty(2);
+
+	for (i = 1 ; i < argc; i++) {
+		const char *arg = argv[i];
+
+		if (*arg == '-') {
+			if (!strcmp(arg, "-n")) {
+				dry_run = 1;
+				continue;
+			}
+			if (!strcmp(arg, "-q")) {
+				quiet = 1;
+				continue;
+			}
+			if (!strcmp(arg, "-r")) {
+				recover = 1;
+				continue;
+			}
+			if (!strcmp(arg, "--strict")) {
+				strict = 1;
+				continue;
+			}
+			if (skip_prefix(arg, "--strict=", &arg)) {
+				strict = 1;
+				fsck_set_msg_types(&fsck_options, arg);
+				continue;
+			}
+			if (starts_with(arg, "--pack_header=")) {
+				struct pack_header *hdr;
+				char *c;
+
+				hdr = (struct pack_header *)buffer;
+				hdr->hdr_signature = htonl(PACK_SIGNATURE);
+				hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
+				if (*c != ',')
+					die("bad %s", arg);
+				hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
+				if (*c)
+					die("bad %s", arg);
+				len = sizeof(*hdr);
+				continue;
+			}
+			if (skip_prefix(arg, "--max-input-size=", &arg)) {
+				max_input_size = strtoumax(arg, NULL, 10);
+				continue;
+			}
+			usage(unpack_usage);
+		}
+
+		/* We don't take any non-flag arguments now.. Maybe some day */
+		usage(unpack_usage);
+	}
+	the_hash_algo->init_fn(&ctx);
+	unpack_all();
+	the_hash_algo->update_fn(&ctx, buffer, offset);
+	the_hash_algo->final_fn(oid.hash, &ctx);
+	if (strict) {
+		write_rest();
+		if (fsck_finish(&fsck_options))
+			die(_("fsck error in pack objects"));
+	}
+	if (!hasheq(fill(the_hash_algo->rawsz), oid.hash))
+		die("final sha1 did not match");
+	use(the_hash_algo->rawsz);
+
+	/* Write the last part of the buffer to stdout */
+	while (len) {
+		int ret = xwrite(1, buffer + offset, len);
+		if (ret <= 0)
+			break;
+		len -= ret;
+		offset += ret;
+	}
+
+	/* All done */
+	return has_errors;
+}
-- 
cgit 1.4.1