git / git

Cannot retrieve contributors at this time

2625 lines (2285 sloc) 64.5 KB

	/*
	* GIT - The information manager from hell
	*
	* Copyright (C) Linus Torvalds, 2005
	*
	* This handles basic git object files - packing, unpacking,
	* creation etc.
	*/
	#include "cache.h"
	#include "config.h"
	#include "string-list.h"
	#include "lockfile.h"
	#include "delta.h"
	#include "pack.h"
	#include "blob.h"
	#include "commit.h"
	#include "run-command.h"
	#include "tag.h"
	#include "tree.h"
	#include "tree-walk.h"
	#include "refs.h"
	#include "pack-revindex.h"
	#include "hash-lookup.h"
	#include "bulk-checkin.h"
	#include "repository.h"
	#include "replace-object.h"
	#include "streaming.h"
	#include "dir.h"
	#include "list.h"
	#include "mergesort.h"
	#include "quote.h"
	#include "packfile.h"
	#include "object-store.h"
	#include "promisor-remote.h"

	/* The maximum size for an object header. */
	#define MAX_HEADER_LEN 32


	#define EMPTY_TREE_SHA1_BIN_LITERAL \
	"\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
	"\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
	#define EMPTY_TREE_SHA256_BIN_LITERAL \
	"\x6e\xf1\x9b\x41\x22\x5c\x53\x69\xf1\xc1" \
	"\x04\xd4\x5d\x8d\x85\xef\xa9\xb0\x57\xb5" \
	"\x3b\x14\xb4\xb9\xb9\x39\xdd\x74\xde\xcc" \
	"\x53\x21"

	#define EMPTY_BLOB_SHA1_BIN_LITERAL \
	"\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
	"\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
	#define EMPTY_BLOB_SHA256_BIN_LITERAL \
	"\x47\x3a\x0f\x4c\x3b\xe8\xa9\x36\x81\xa2" \
	"\x67\xe3\xb1\xe9\xa7\xdc\xda\x11\x85\x43" \
	"\x6f\xe1\x41\xf7\x74\x91\x20\xa3\x03\x72" \
	"\x18\x13"

	static const struct object_id empty_tree_oid = {
	.hash = EMPTY_TREE_SHA1_BIN_LITERAL,
	.algo = GIT_HASH_SHA1,
	};
	static const struct object_id empty_blob_oid = {
	.hash = EMPTY_BLOB_SHA1_BIN_LITERAL,
	.algo = GIT_HASH_SHA1,
	};
	static const struct object_id null_oid_sha1 = {
	.hash = {0},
	.algo = GIT_HASH_SHA1,
	};
	static const struct object_id empty_tree_oid_sha256 = {
	.hash = EMPTY_TREE_SHA256_BIN_LITERAL,
	.algo = GIT_HASH_SHA256,
	};
	static const struct object_id empty_blob_oid_sha256 = {
	.hash = EMPTY_BLOB_SHA256_BIN_LITERAL,
	.algo = GIT_HASH_SHA256,
	};
	static const struct object_id null_oid_sha256 = {
	.hash = {0},
	.algo = GIT_HASH_SHA256,
	};

	static void git_hash_sha1_init(git_hash_ctx *ctx)
	{
	git_SHA1_Init(&ctx->sha1);
	}

	static void git_hash_sha1_clone(git_hash_ctx dst, const git_hash_ctx src)
	{
	git_SHA1_Clone(&dst->sha1, &src->sha1);
	}

	static void git_hash_sha1_update(git_hash_ctx ctx, const void data, size_t len)
	{
	git_SHA1_Update(&ctx->sha1, data, len);
	}

	static void git_hash_sha1_final(unsigned char hash, git_hash_ctx ctx)
	{
	git_SHA1_Final(hash, &ctx->sha1);
	}

	static void git_hash_sha1_final_oid(struct object_id oid, git_hash_ctx ctx)
	{
	git_SHA1_Final(oid->hash, &ctx->sha1);
	memset(oid->hash + GIT_SHA1_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA1_RAWSZ);
	oid->algo = GIT_HASH_SHA1;
	}


	static void git_hash_sha256_init(git_hash_ctx *ctx)
	{
	git_SHA256_Init(&ctx->sha256);
	}

	static void git_hash_sha256_clone(git_hash_ctx dst, const git_hash_ctx src)
	{
	git_SHA256_Clone(&dst->sha256, &src->sha256);
	}

	static void git_hash_sha256_update(git_hash_ctx ctx, const void data, size_t len)
	{
	git_SHA256_Update(&ctx->sha256, data, len);
	}

	static void git_hash_sha256_final(unsigned char hash, git_hash_ctx ctx)
	{
	git_SHA256_Final(hash, &ctx->sha256);
	}

	static void git_hash_sha256_final_oid(struct object_id oid, git_hash_ctx ctx)
	{
	git_SHA256_Final(oid->hash, &ctx->sha256);
	/*
	* This currently does nothing, so the compiler should optimize it out,
	* but keep it in case we extend the hash size again.
	*/
	memset(oid->hash + GIT_SHA256_RAWSZ, 0, GIT_MAX_RAWSZ - GIT_SHA256_RAWSZ);
	oid->algo = GIT_HASH_SHA256;
	}

	static void git_hash_unknown_init(git_hash_ctx *ctx)
	{
	BUG("trying to init unknown hash");
	}

	static void git_hash_unknown_clone(git_hash_ctx dst, const git_hash_ctx src)
	{
	BUG("trying to clone unknown hash");
	}

	static void git_hash_unknown_update(git_hash_ctx ctx, const void data, size_t len)
	{
	BUG("trying to update unknown hash");
	}

	static void git_hash_unknown_final(unsigned char hash, git_hash_ctx ctx)
	{
	BUG("trying to finalize unknown hash");
	}

	static void git_hash_unknown_final_oid(struct object_id oid, git_hash_ctx ctx)
	{
	BUG("trying to finalize unknown hash");
	}


	const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
	{
	NULL,
	0x00000000,
	0,
	0,
	0,
	git_hash_unknown_init,
	git_hash_unknown_clone,
	git_hash_unknown_update,
	git_hash_unknown_final,
	git_hash_unknown_final_oid,
	NULL,
	NULL,
	NULL,
	},
	{
	"sha1",
	/* "sha1", big-endian */
	0x73686131,
	GIT_SHA1_RAWSZ,
	GIT_SHA1_HEXSZ,
	GIT_SHA1_BLKSZ,
	git_hash_sha1_init,
	git_hash_sha1_clone,
	git_hash_sha1_update,
	git_hash_sha1_final,
	git_hash_sha1_final_oid,
	&empty_tree_oid,
	&empty_blob_oid,
	&null_oid_sha1,
	},
	{
	"sha256",
	/* "s256", big-endian */
	0x73323536,
	GIT_SHA256_RAWSZ,
	GIT_SHA256_HEXSZ,
	GIT_SHA256_BLKSZ,
	git_hash_sha256_init,
	git_hash_sha256_clone,
	git_hash_sha256_update,
	git_hash_sha256_final,
	git_hash_sha256_final_oid,
	&empty_tree_oid_sha256,
	&empty_blob_oid_sha256,
	&null_oid_sha256,
	}
	};

	const struct object_id *null_oid(void)
	{
	return the_hash_algo->null_oid;
	}

	const char *empty_tree_oid_hex(void)
	{
	static char buf[GIT_MAX_HEXSZ + 1];
	return oid_to_hex_r(buf, the_hash_algo->empty_tree);
	}

	const char *empty_blob_oid_hex(void)
	{
	static char buf[GIT_MAX_HEXSZ + 1];
	return oid_to_hex_r(buf, the_hash_algo->empty_blob);
	}

	int hash_algo_by_name(const char *name)
	{
	int i;
	if (!name)
	return GIT_HASH_UNKNOWN;
	for (i = 1; i < GIT_HASH_NALGOS; i++)
	if (!strcmp(name, hash_algos[i].name))
	return i;
	return GIT_HASH_UNKNOWN;
	}

	int hash_algo_by_id(uint32_t format_id)
	{
	int i;
	for (i = 1; i < GIT_HASH_NALGOS; i++)
	if (format_id == hash_algos[i].format_id)
	return i;
	return GIT_HASH_UNKNOWN;
	}

	int hash_algo_by_length(int len)
	{
	int i;
	for (i = 1; i < GIT_HASH_NALGOS; i++)
	if (len == hash_algos[i].rawsz)
	return i;
	return GIT_HASH_UNKNOWN;
	}

	/*
	* This is meant to hold a small number of objects that you would
	* want read_object_file() to be able to return, but yet you do not want
	* to write them into the object store (e.g. a browse-only
	* application).
	*/
	static struct cached_object {
	struct object_id oid;
	enum object_type type;
	void *buf;
	unsigned long size;
	} *cached_objects;
	static int cached_object_nr, cached_object_alloc;

	static struct cached_object empty_tree = {
	{ EMPTY_TREE_SHA1_BIN_LITERAL },
	OBJ_TREE,
	"",
	0
	};

	static struct cached_object find_cached_object(const struct object_id oid)
	{
	int i;
	struct cached_object *co = cached_objects;

	for (i = 0; i < cached_object_nr; i++, co++) {
	if (oideq(&co->oid, oid))
	return co;
	}
	if (oideq(oid, the_hash_algo->empty_tree))
	return &empty_tree;
	return NULL;
	}


	static int get_conv_flags(unsigned flags)
	{
	if (flags & HASH_RENORMALIZE)
	return CONV_EOL_RENORMALIZE;
	else if (flags & HASH_WRITE_OBJECT)
	return global_conv_flags_eol \| CONV_WRITE_OBJECT;
	else
	return 0;
	}


	int mkdir_in_gitdir(const char *path)
	{
	if (mkdir(path, 0777)) {
	int saved_errno = errno;
	struct stat st;
	struct strbuf sb = STRBUF_INIT;

	if (errno != EEXIST)
	return -1;
	/*
	* Are we looking at a path in a symlinked worktree
	* whose original repository does not yet have it?
	* e.g. .git/rr-cache pointing at its original
	* repository in which the user hasn't performed any
	* conflict resolution yet?
	*/
	if (lstat(path, &st) \|\| !S_ISLNK(st.st_mode) \|\|
	strbuf_readlink(&sb, path, st.st_size) \|\|
	!is_absolute_path(sb.buf) \|\|
	mkdir(sb.buf, 0777)) {
	strbuf_release(&sb);
	errno = saved_errno;
	return -1;
	}
	strbuf_release(&sb);
	}
	return adjust_shared_perm(path);
	}

	static enum scld_error safe_create_leading_directories_1(char *path, int share)
	{
	char *next_component = path + offset_1st_component(path);
	enum scld_error ret = SCLD_OK;

	while (ret == SCLD_OK && next_component) {
	struct stat st;
	char *slash = next_component, slash_character;

	while (slash && !is_dir_sep(slash))
	slash++;

	if (!*slash)
	break;

	next_component = slash + 1;
	while (is_dir_sep(*next_component))
	next_component++;
	if (!*next_component)
	break;

	slash_character = *slash;
	*slash = '\0';
	if (!stat(path, &st)) {
	/* path exists */
	if (!S_ISDIR(st.st_mode)) {
	errno = ENOTDIR;
	ret = SCLD_EXISTS;
	}
	} else if (mkdir(path, 0777)) {
	if (errno == EEXIST &&
	!stat(path, &st) && S_ISDIR(st.st_mode))
	; /* somebody created it since we checked */
	else if (errno == ENOENT)
	/*
	* Either mkdir() failed because
	* somebody just pruned the containing
	* directory, or stat() failed because
	* the file that was in our way was
	* just removed. Either way, inform
	* the caller that it might be worth
	* trying again:
	*/
	ret = SCLD_VANISHED;
	else
	ret = SCLD_FAILED;
	} else if (share && adjust_shared_perm(path)) {
	ret = SCLD_PERMS;
	}
	*slash = slash_character;
	}
	return ret;
	}

	enum scld_error safe_create_leading_directories(char *path)
	{
	return safe_create_leading_directories_1(path, 1);
	}

	enum scld_error safe_create_leading_directories_no_share(char *path)
	{
	return safe_create_leading_directories_1(path, 0);
	}

	enum scld_error safe_create_leading_directories_const(const char *path)
	{
	int save_errno;
	/* path points to cache entries, so xstrdup before messing with it */
	char *buf = xstrdup(path);
	enum scld_error result = safe_create_leading_directories(buf);

	save_errno = errno;
	free(buf);
	errno = save_errno;
	return result;
	}

	int raceproof_create_file(const char path, create_file_fn fn, void cb)
	{
	/*
	* The number of times we will try to remove empty directories
	* in the way of path. This is only 1 because if another
	* process is racily creating directories that conflict with
	* us, we don't want to fight against them.
	*/
	int remove_directories_remaining = 1;

	/*
	* The number of times that we will try to create the
	* directories containing path. We are willing to attempt this
	* more than once, because another process could be trying to
	* clean up empty directories at the same time as we are
	* trying to create them.
	*/
	int create_directories_remaining = 3;

	/* A scratch copy of path, filled lazily if we need it: */
	struct strbuf path_copy = STRBUF_INIT;

	int ret, save_errno;

	/* Sanity check: */
	assert(*path);

	retry_fn:
	ret = fn(path, cb);
	save_errno = errno;
	if (!ret)
	goto out;

	if (errno == EISDIR && remove_directories_remaining-- > 0) {
	/*
	* A directory is in the way. Maybe it is empty; try
	* to remove it:
	*/
	if (!path_copy.len)
	strbuf_addstr(&path_copy, path);

	if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
	goto retry_fn;
	} else if (errno == ENOENT && create_directories_remaining-- > 0) {
	/*
	* Maybe the containing directory didn't exist, or
	* maybe it was just deleted by a process that is
	* racing with us to clean up empty directories. Try
	* to create it:
	*/
	enum scld_error scld_result;

	if (!path_copy.len)
	strbuf_addstr(&path_copy, path);

	do {
	scld_result = safe_create_leading_directories(path_copy.buf);
	if (scld_result == SCLD_OK)
	goto retry_fn;
	} while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
	}

	out:
	strbuf_release(&path_copy);
	errno = save_errno;
	return ret;
	}

	static void fill_loose_path(struct strbuf buf, const struct object_id oid)
	{
	int i;
	for (i = 0; i < the_hash_algo->rawsz; i++) {
	static char hex[] = "0123456789abcdef";
	unsigned int val = oid->hash[i];
	strbuf_addch(buf, hex[val >> 4]);
	strbuf_addch(buf, hex[val & 0xf]);
	if (!i)
	strbuf_addch(buf, '/');
	}
	}

	static const char odb_loose_path(struct object_directory odb,
	struct strbuf *buf,
	const struct object_id *oid)
	{
	strbuf_reset(buf);
	strbuf_addstr(buf, odb->path);
	strbuf_addch(buf, '/');
	fill_loose_path(buf, oid);
	return buf->buf;
	}

	const char loose_object_path(struct repository r, struct strbuf *buf,
	const struct object_id *oid)
	{
	return odb_loose_path(r->objects->odb, buf, oid);
	}

	/*
	* Return non-zero iff the path is usable as an alternate object database.
	*/
	static int alt_odb_usable(struct raw_object_store *o,
	struct strbuf *path,
	const char normalized_objdir, khiter_t pos)
	{
	int r;

	/* Detect cases where alternate disappeared */
	if (!is_directory(path->buf)) {
	error(_("object directory %s does not exist; "
	"check .git/objects/info/alternates"),
	path->buf);
	return 0;
	}

	/*
	* Prevent the common mistake of listing the same
	* thing twice, or object directory itself.
	*/
	if (!o->odb_by_path) {
	khiter_t p;

	o->odb_by_path = kh_init_odb_path_map();
	assert(!o->odb->next);
	p = kh_put_odb_path_map(o->odb_by_path, o->odb->path, &r);
	assert(r == 1); /* never used */
	kh_value(o->odb_by_path, p) = o->odb;
	}
	if (fspatheq(path->buf, normalized_objdir))
	return 0;
	*pos = kh_put_odb_path_map(o->odb_by_path, path->buf, &r);
	/* r: 0 = exists, 1 = never used, 2 = deleted */
	return r == 0 ? 0 : 1;
	}

	/*
	* Prepare alternate object database registry.
	*
	* The variable alt_odb_list points at the list of struct
	* object_directory. The elements on this list come from
	* non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
	* environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
	* whose contents is similar to that environment variable but can be
	* LF separated. Its base points at a statically allocated buffer that
	* contains "/the/directory/corresponding/to/.git/objects/...", while
	* its name points just after the slash at the end of ".git/objects/"
	* in the example above, and has enough space to hold all hex characters
	* of the object ID, an extra slash for the first level indirection, and
	* the terminating NUL.
	*/
	static void read_info_alternates(struct repository *r,
	const char *relative_base,
	int depth);
	static int link_alt_odb_entry(struct repository r, const struct strbuf entry,
	const char relative_base, int depth, const char normalized_objdir)
	{
	struct object_directory *ent;
	struct strbuf pathbuf = STRBUF_INIT;
	khiter_t pos;

	if (!is_absolute_path(entry->buf) && relative_base) {
	strbuf_realpath(&pathbuf, relative_base, 1);
	strbuf_addch(&pathbuf, '/');
	}
	strbuf_addbuf(&pathbuf, entry);

	if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
	error(_("unable to normalize alternate object path: %s"),
	pathbuf.buf);
	strbuf_release(&pathbuf);
	return -1;
	}

	/*
	* The trailing slash after the directory name is given by
	* this function at the end. Remove duplicates.
	*/
	while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
	strbuf_setlen(&pathbuf, pathbuf.len - 1);

	if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir, &pos)) {
	strbuf_release(&pathbuf);
	return -1;
	}

	CALLOC_ARRAY(ent, 1);
	/* pathbuf.buf is already in r->objects->odb_by_path */
	ent->path = strbuf_detach(&pathbuf, NULL);

	/* add the alternate entry */
	*r->objects->odb_tail = ent;
	r->objects->odb_tail = &(ent->next);
	ent->next = NULL;
	assert(r->objects->odb_by_path);
	kh_value(r->objects->odb_by_path, pos) = ent;

	/* recursively add alternates */
	read_info_alternates(r, ent->path, depth + 1);

	return 0;
	}

	static const char parse_alt_odb_entry(const char string,
	int sep,
	struct strbuf *out)
	{
	const char *end;

	strbuf_reset(out);

	if (*string == '#') {
	/* comment; consume up to next separator */
	end = strchrnul(string, sep);
	} else if (*string == '"' && !unquote_c_style(out, string, &end)) {
	/*
	* quoted path; unquote_c_style has copied the
	* data for us and set "end". Broken quoting (e.g.,
	* an entry that doesn't end with a quote) falls
	* back to the unquoted case below.
	*/
	} else {
	/* normal, unquoted path */
	end = strchrnul(string, sep);
	strbuf_add(out, string, end - string);
	}

	if (*end)
	end++;
	return end;
	}

	static void link_alt_odb_entries(struct repository r, const char alt,
	int sep, const char *relative_base, int depth)
	{
	struct strbuf objdirbuf = STRBUF_INIT;
	struct strbuf entry = STRBUF_INIT;

	if (!alt \|\| !*alt)
	return;

	if (depth > 5) {
	error(_("%s: ignoring alternate object stores, nesting too deep"),
	relative_base);
	return;
	}

	strbuf_add_absolute_path(&objdirbuf, r->objects->odb->path);
	if (strbuf_normalize_path(&objdirbuf) < 0)
	die(_("unable to normalize object directory: %s"),
	objdirbuf.buf);

	while (*alt) {
	alt = parse_alt_odb_entry(alt, sep, &entry);
	if (!entry.len)
	continue;
	link_alt_odb_entry(r, &entry,
	relative_base, depth, objdirbuf.buf);
	}
	strbuf_release(&entry);
	strbuf_release(&objdirbuf);
	}

	static void read_info_alternates(struct repository *r,
	const char *relative_base,
	int depth)
	{
	char *path;
	struct strbuf buf = STRBUF_INIT;

	path = xstrfmt("%s/info/alternates", relative_base);
	if (strbuf_read_file(&buf, path, 1024) < 0) {
	warn_on_fopen_errors(path);
	free(path);
	return;
	}

	link_alt_odb_entries(r, buf.buf, '\n', relative_base, depth);
	strbuf_release(&buf);
	free(path);
	}

	void add_to_alternates_file(const char *reference)
	{
	struct lock_file lock = LOCK_INIT;
	char *alts = git_pathdup("objects/info/alternates");
	FILE in, out;
	int found = 0;

	hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
	out = fdopen_lock_file(&lock, "w");
	if (!out)
	die_errno(_("unable to fdopen alternates lockfile"));

	in = fopen(alts, "r");
	if (in) {
	struct strbuf line = STRBUF_INIT;

	while (strbuf_getline(&line, in) != EOF) {
	if (!strcmp(reference, line.buf)) {
	found = 1;
	break;
	}
	fprintf_or_die(out, "%s\n", line.buf);
	}

	strbuf_release(&line);
	fclose(in);
	}
	else if (errno != ENOENT)
	die_errno(_("unable to read alternates file"));

	if (found) {
	rollback_lock_file(&lock);
	} else {
	fprintf_or_die(out, "%s\n", reference);
	if (commit_lock_file(&lock))
	die_errno(_("unable to move new alternates file into place"));
	if (the_repository->objects->loaded_alternates)
	link_alt_odb_entries(the_repository, reference,
	'\n', NULL, 0);
	}
	free(alts);
	}

	void add_to_alternates_memory(const char *reference)
	{
	/*
	* Make sure alternates are initialized, or else our entry may be
	* overwritten when they are.
	*/
	prepare_alt_odb(the_repository);

	link_alt_odb_entries(the_repository, reference,
	'\n', NULL, 0);
	}

	/*
	* Compute the exact path an alternate is at and returns it. In case of
	* error NULL is returned and the human readable error is added to `err`
	* `path` may be relative and should point to $GIT_DIR.
	* `err` must not be null.
	*/
	char compute_alternate_path(const char path, struct strbuf *err)
	{
	char *ref_git = NULL;
	const char *repo;
	int seen_error = 0;

	ref_git = real_pathdup(path, 0);
	if (!ref_git) {
	seen_error = 1;
	strbuf_addf(err, _("path '%s' does not exist"), path);
	goto out;
	}

	repo = read_gitfile(ref_git);
	if (!repo)
	repo = read_gitfile(mkpath("%s/.git", ref_git));
	if (repo) {
	free(ref_git);
	ref_git = xstrdup(repo);
	}

	if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
	char *ref_git_git = mkpathdup("%s/.git", ref_git);
	free(ref_git);
	ref_git = ref_git_git;
	} else if (!is_directory(mkpath("%s/objects", ref_git))) {
	struct strbuf sb = STRBUF_INIT;
	seen_error = 1;
	if (get_common_dir(&sb, ref_git)) {
	strbuf_addf(err,
	_("reference repository '%s' as a linked "
	"checkout is not supported yet."),
	path);
	goto out;
	}

	strbuf_addf(err, _("reference repository '%s' is not a "
	"local repository."), path);
	goto out;
	}

	if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
	strbuf_addf(err, _("reference repository '%s' is shallow"),
	path);
	seen_error = 1;
	goto out;
	}

	if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
	strbuf_addf(err,
	_("reference repository '%s' is grafted"),
	path);
	seen_error = 1;
	goto out;
	}

	out:
	if (seen_error) {
	FREE_AND_NULL(ref_git);
	}

	return ref_git;
	}

	static void fill_alternate_refs_command(struct child_process *cmd,
	const char *repo_path)
	{
	const char *value;

	if (!git_config_get_value("core.alternateRefsCommand", &value)) {
	cmd->use_shell = 1;

	strvec_push(&cmd->args, value);
	strvec_push(&cmd->args, repo_path);
	} else {
	cmd->git_cmd = 1;

	strvec_pushf(&cmd->args, "--git-dir=%s", repo_path);
	strvec_push(&cmd->args, "for-each-ref");
	strvec_push(&cmd->args, "--format=%(objectname)");

	if (!git_config_get_value("core.alternateRefsPrefixes", &value)) {
	strvec_push(&cmd->args, "--");
	strvec_split(&cmd->args, value);
	}
	}

	cmd->env = local_repo_env;
	cmd->out = -1;
	}

	static void read_alternate_refs(const char *path,
	alternate_ref_fn *cb,
	void *data)
	{
	struct child_process cmd = CHILD_PROCESS_INIT;
	struct strbuf line = STRBUF_INIT;
	FILE *fh;

	fill_alternate_refs_command(&cmd, path);

	if (start_command(&cmd))
	return;

	fh = xfdopen(cmd.out, "r");
	while (strbuf_getline_lf(&line, fh) != EOF) {
	struct object_id oid;
	const char *p;

	if (parse_oid_hex(line.buf, &oid, &p) \|\| *p) {
	warning(_("invalid line while parsing alternate refs: %s"),
	line.buf);
	break;
	}

	cb(&oid, data);
	}

	fclose(fh);
	finish_command(&cmd);
	strbuf_release(&line);
	}

	struct alternate_refs_data {
	alternate_ref_fn *fn;
	void *data;
	};

	static int refs_from_alternate_cb(struct object_directory *e,
	void *data)
	{
	struct strbuf path = STRBUF_INIT;
	size_t base_len;
	struct alternate_refs_data *cb = data;

	if (!strbuf_realpath(&path, e->path, 0))
	goto out;
	if (!strbuf_strip_suffix(&path, "/objects"))
	goto out;
	base_len = path.len;

	/* Is this a git repository with refs? */
	strbuf_addstr(&path, "/refs");
	if (!is_directory(path.buf))
	goto out;
	strbuf_setlen(&path, base_len);

	read_alternate_refs(path.buf, cb->fn, cb->data);

	out:
	strbuf_release(&path);
	return 0;
	}

	void for_each_alternate_ref(alternate_ref_fn fn, void *data)
	{
	struct alternate_refs_data cb;
	cb.fn = fn;
	cb.data = data;
	foreach_alt_odb(refs_from_alternate_cb, &cb);
	}

	int foreach_alt_odb(alt_odb_fn fn, void *cb)
	{
	struct object_directory *ent;
	int r = 0;

	prepare_alt_odb(the_repository);
	for (ent = the_repository->objects->odb->next; ent; ent = ent->next) {
	r = fn(ent, cb);
	if (r)
	break;
	}
	return r;
	}

	void prepare_alt_odb(struct repository *r)
	{
	if (r->objects->loaded_alternates)
	return;

	link_alt_odb_entries(r, r->objects->alternate_db, PATH_SEP, NULL, 0);

	read_info_alternates(r, r->objects->odb->path, 0);
	r->objects->loaded_alternates = 1;
	}

	/* Returns 1 if we have successfully freshened the file, 0 otherwise. */
	static int freshen_file(const char *fn)
	{
	return !utime(fn, NULL);
	}

	/*
	* All of the check_and_freshen functions return 1 if the file exists and was
	* freshened (if freshening was requested), 0 otherwise. If they return
	* 0, you should not assume that it is safe to skip a write of the object (it
	* either does not exist on disk, or has a stale mtime and may be subject to
	* pruning).
	*/
	int check_and_freshen_file(const char *fn, int freshen)
	{
	if (access(fn, F_OK))
	return 0;
	if (freshen && !freshen_file(fn))
	return 0;
	return 1;
	}

	static int check_and_freshen_odb(struct object_directory *odb,
	const struct object_id *oid,
	int freshen)
	{
	static struct strbuf path = STRBUF_INIT;
	odb_loose_path(odb, &path, oid);
	return check_and_freshen_file(path.buf, freshen);
	}

	static int check_and_freshen_local(const struct object_id *oid, int freshen)
	{
	return check_and_freshen_odb(the_repository->objects->odb, oid, freshen);
	}

	static int check_and_freshen_nonlocal(const struct object_id *oid, int freshen)
	{
	struct object_directory *odb;

	prepare_alt_odb(the_repository);
	for (odb = the_repository->objects->odb->next; odb; odb = odb->next) {
	if (check_and_freshen_odb(odb, oid, freshen))
	return 1;
	}
	return 0;
	}

	static int check_and_freshen(const struct object_id *oid, int freshen)
	{
	return check_and_freshen_local(oid, freshen) \|\|
	check_and_freshen_nonlocal(oid, freshen);
	}

	int has_loose_object_nonlocal(const struct object_id *oid)
	{
	return check_and_freshen_nonlocal(oid, 0);
	}

	static int has_loose_object(const struct object_id *oid)
	{
	return check_and_freshen(oid, 0);
	}

	static void mmap_limit_check(size_t length)
	{
	static size_t limit = 0;
	if (!limit) {
	limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
	if (!limit)
	limit = SIZE_MAX;
	}
	if (length > limit)
	die(_("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX),
	(uintmax_t)length, (uintmax_t)limit);
	}

	void xmmap_gently(void start, size_t length,
	int prot, int flags, int fd, off_t offset)
	{
	void *ret;

	mmap_limit_check(length);
	ret = mmap(start, length, prot, flags, fd, offset);
	if (ret == MAP_FAILED && !length)
	ret = NULL;
	return ret;
	}

	const char *mmap_os_err(void)
	{
	static const char blank[] = "";
	#if defined(__linux__)
	if (errno == ENOMEM) {
	/* this continues an existing error message: */
	static const char enomem[] =
	", check sys.vm.max_map_count and/or RLIMIT_DATA";
	return enomem;
	}
	#endif /* OS-specific bits */
	return blank;
	}

	void xmmap(void start, size_t length,
	int prot, int flags, int fd, off_t offset)
	{
	void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
	if (ret == MAP_FAILED)
	die_errno(_("mmap failed%s"), mmap_os_err());
	return ret;
	}

	/*
	* With an in-core object data in "map", rehash it to make sure the
	* object name actually matches "oid" to detect object corruption.
	* With "map" == NULL, try reading the object named with "oid" using
	* the streaming interface and rehash it to do the same.
	*/
	int check_object_signature(struct repository r, const struct object_id oid,
	void map, unsigned long size, const char type)
	{
	struct object_id real_oid;
	enum object_type obj_type;
	struct git_istream *st;
	git_hash_ctx c;
	char hdr[MAX_HEADER_LEN];
	int hdrlen;

	if (map) {
	hash_object_file(r->hash_algo, map, size, type, &real_oid);
	return !oideq(oid, &real_oid) ? -1 : 0;
	}

	st = open_istream(r, oid, &obj_type, &size, NULL);
	if (!st)
	return -1;

	/* Generate the header */
	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(obj_type), (uintmax_t)size) + 1;

	/* Sha1.. */
	r->hash_algo->init_fn(&c);
	r->hash_algo->update_fn(&c, hdr, hdrlen);
	for (;;) {
	char buf[1024 * 16];
	ssize_t readlen = read_istream(st, buf, sizeof(buf));

	if (readlen < 0) {
	close_istream(st);
	return -1;
	}
	if (!readlen)
	break;
	r->hash_algo->update_fn(&c, buf, readlen);
	}
	r->hash_algo->final_oid_fn(&real_oid, &c);
	close_istream(st);
	return !oideq(oid, &real_oid) ? -1 : 0;
	}

	int git_open_cloexec(const char *name, int flags)
	{
	int fd;
	static int o_cloexec = O_CLOEXEC;

	fd = open(name, flags \| o_cloexec);
	if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
	/* Try again w/o O_CLOEXEC: the kernel might not support it */
	o_cloexec &= ~O_CLOEXEC;
	fd = open(name, flags \| o_cloexec);
	}

	#if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
	{
	static int fd_cloexec = FD_CLOEXEC;

	if (!o_cloexec && 0 <= fd && fd_cloexec) {
	/* Opened w/o O_CLOEXEC? try with fcntl(2) to add it */
	int flags = fcntl(fd, F_GETFD);
	if (fcntl(fd, F_SETFD, flags \| fd_cloexec))
	fd_cloexec = 0;
	}
	}
	#endif
	return fd;
	}

	/*
	* Find "oid" as a loose object in the local repository or in an alternate.
	* Returns 0 on success, negative on failure.
	*
	* The "path" out-parameter will give the path of the object we found (if any).
	* Note that it may point to static storage and is only valid until another
	* call to stat_loose_object().
	*/
	static int stat_loose_object(struct repository r, const struct object_id oid,
	struct stat st, const char *path)
	{
	struct object_directory *odb;
	static struct strbuf buf = STRBUF_INIT;

	prepare_alt_odb(r);
	for (odb = r->objects->odb; odb; odb = odb->next) {
	*path = odb_loose_path(odb, &buf, oid);
	if (!lstat(*path, st))
	return 0;
	}

	return -1;
	}

	/*
	* Like stat_loose_object(), but actually open the object and return the
	* descriptor. See the caveats on the "path" parameter above.
	*/
	static int open_loose_object(struct repository *r,
	const struct object_id oid, const char *path)
	{
	int fd;
	struct object_directory *odb;
	int most_interesting_errno = ENOENT;
	static struct strbuf buf = STRBUF_INIT;

	prepare_alt_odb(r);
	for (odb = r->objects->odb; odb; odb = odb->next) {
	*path = odb_loose_path(odb, &buf, oid);
	fd = git_open(*path);
	if (fd >= 0)
	return fd;

	if (most_interesting_errno == ENOENT)
	most_interesting_errno = errno;
	}
	errno = most_interesting_errno;
	return -1;
	}

	static int quick_has_loose(struct repository *r,
	const struct object_id *oid)
	{
	struct object_directory *odb;

	prepare_alt_odb(r);
	for (odb = r->objects->odb; odb; odb = odb->next) {
	if (oidtree_contains(odb_loose_cache(odb, oid), oid))
	return 1;
	}
	return 0;
	}

	/*
	* Map the loose object at "path" if it is not NULL, or the path found by
	* searching for a loose object named "oid".
	*/
	static void map_loose_object_1(struct repository r, const char *path,
	const struct object_id oid, unsigned long size)
	{
	void *map;
	int fd;

	if (path)
	fd = git_open(path);
	else
	fd = open_loose_object(r, oid, &path);
	map = NULL;
	if (fd >= 0) {
	struct stat st;

	if (!fstat(fd, &st)) {
	*size = xsize_t(st.st_size);
	if (!*size) {
	/* mmap() is forbidden on empty files */
	error(_("object file %s is empty"), path);
	close(fd);
	return NULL;
	}
	map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
	}
	close(fd);
	}
	return map;
	}

	void map_loose_object(struct repository r,
	const struct object_id *oid,
	unsigned long *size)
	{
	return map_loose_object_1(r, NULL, oid, size);
	}

	static int unpack_loose_short_header(git_zstream *stream,
	unsigned char *map, unsigned long mapsize,
	void *buffer, unsigned long bufsiz)
	{
	int ret;

	/* Get the data stream */
	memset(stream, 0, sizeof(*stream));
	stream->next_in = map;
	stream->avail_in = mapsize;
	stream->next_out = buffer;
	stream->avail_out = bufsiz;

	git_inflate_init(stream);
	obj_read_unlock();
	ret = git_inflate(stream, 0);
	obj_read_lock();

	return ret;
	}

	int unpack_loose_header(git_zstream *stream,
	unsigned char *map, unsigned long mapsize,
	void *buffer, unsigned long bufsiz)
	{
	int status = unpack_loose_short_header(stream, map, mapsize,
	buffer, bufsiz);

	if (status < Z_OK)
	return status;

	/* Make sure we have the terminating NUL */
	if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
	return -1;
	return 0;
	}

	static int unpack_loose_header_to_strbuf(git_zstream stream, unsigned char map,
	unsigned long mapsize, void *buffer,
	unsigned long bufsiz, struct strbuf *header)
	{
	int status;

	status = unpack_loose_short_header(stream, map, mapsize, buffer, bufsiz);
	if (status < Z_OK)
	return -1;

	/*
	* Check if entire header is unpacked in the first iteration.
	*/
	if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
	return 0;

	/*
	* buffer[0..bufsiz] was not large enough. Copy the partial
	* result out to header, and then append the result of further
	* reading the stream.
	*/
	strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
	stream->next_out = buffer;
	stream->avail_out = bufsiz;

	do {
	obj_read_unlock();
	status = git_inflate(stream, 0);
	obj_read_lock();
	strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
	if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
	return 0;
	stream->next_out = buffer;
	stream->avail_out = bufsiz;
	} while (status != Z_STREAM_END);
	return -1;
	}

	static void unpack_loose_rest(git_zstream stream,
	void *buffer, unsigned long size,
	const struct object_id *oid)
	{
	int bytes = strlen(buffer) + 1;
	unsigned char *buf = xmallocz(size);
	unsigned long n;
	int status = Z_OK;

	n = stream->total_out - bytes;
	if (n > size)
	n = size;
	memcpy(buf, (char *) buffer + bytes, n);
	bytes = n;
	if (bytes <= size) {
	/*
	* The above condition must be (bytes <= size), not
	* (bytes < size). In other words, even though we
	* expect no more output and set avail_out to zero,
	* the input zlib stream may have bytes that express
	* "this concludes the stream", and we do want to
	* eat that input.
	*
	* Otherwise we would not be able to test that we
	* consumed all the input to reach the expected size;
	* we also want to check that zlib tells us that all
	* went well with status == Z_STREAM_END at the end.
	*/
	stream->next_out = buf + bytes;
	stream->avail_out = size - bytes;
	while (status == Z_OK) {
	obj_read_unlock();
	status = git_inflate(stream, Z_FINISH);
	obj_read_lock();
	}
	}
	if (status == Z_STREAM_END && !stream->avail_in) {
	git_inflate_end(stream);
	return buf;
	}

	if (status < 0)
	error(_("corrupt loose object '%s'"), oid_to_hex(oid));
	else if (stream->avail_in)
	error(_("garbage at end of loose object '%s'"),
	oid_to_hex(oid));
	free(buf);
	return NULL;
	}

	/*
	* We used to just use "sscanf()", but that's actually way
	* too permissive for what we want to check. So do an anal
	* object header parse by hand.
	*/
	static int parse_loose_header_extended(const char hdr, struct object_info oi,
	unsigned int flags)
	{
	const char *type_buf = hdr;
	unsigned long size;
	int type, type_len = 0;

	/*
	* The type can be of any size but is followed by
	* a space.
	*/
	for (;;) {
	char c = *hdr++;
	if (!c)
	return -1;
	if (c == ' ')
	break;
	type_len++;
	}

	type = type_from_string_gently(type_buf, type_len, 1);
	if (oi->type_name)
	strbuf_add(oi->type_name, type_buf, type_len);
	/*
	* Set type to 0 if its an unknown object and
	* we're obtaining the type using '--allow-unknown-type'
	* option.
	*/
	if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
	type = 0;
	else if (type < 0)
	die(_("invalid object type"));
	if (oi->typep)
	*oi->typep = type;

	/*
	* The length must follow immediately, and be in canonical
	* decimal format (ie "010" is not valid).
	*/
	size = *hdr++ - '0';
	if (size > 9)
	return -1;
	if (size) {
	for (;;) {
	unsigned long c = *hdr - '0';
	if (c > 9)
	break;
	hdr++;
	size = size * 10 + c;
	}
	}

	if (oi->sizep)
	*oi->sizep = size;

	/*
	* The length must be followed by a zero byte
	*/
	return *hdr ? -1 : type;
	}

	int parse_loose_header(const char hdr, unsigned long sizep)
	{
	struct object_info oi = OBJECT_INFO_INIT;

	oi.sizep = sizep;
	return parse_loose_header_extended(hdr, &oi, 0);
	}

	static int loose_object_info(struct repository *r,
	const struct object_id *oid,
	struct object_info *oi, int flags)
	{
	int status = 0;
	unsigned long mapsize;
	void *map;
	git_zstream stream;
	char hdr[MAX_HEADER_LEN];
	struct strbuf hdrbuf = STRBUF_INIT;
	unsigned long size_scratch;

	if (oi->delta_base_oid)
	oidclr(oi->delta_base_oid);

	/*
	* If we don't care about type or size, then we don't
	* need to look inside the object at all. Note that we
	* do not optimize out the stat call, even if the
	* caller doesn't care about the disk-size, since our
	* return value implicitly indicates whether the
	* object even exists.
	*/
	if (!oi->typep && !oi->type_name && !oi->sizep && !oi->contentp) {
	const char *path;
	struct stat st;
	if (!oi->disk_sizep && (flags & OBJECT_INFO_QUICK))
	return quick_has_loose(r, oid) ? 0 : -1;
	if (stat_loose_object(r, oid, &st, &path) < 0)
	return -1;
	if (oi->disk_sizep)
	*oi->disk_sizep = st.st_size;
	return 0;
	}

	map = map_loose_object(r, oid, &mapsize);
	if (!map)
	return -1;

	if (!oi->sizep)
	oi->sizep = &size_scratch;

	if (oi->disk_sizep)
	*oi->disk_sizep = mapsize;
	if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
	if (unpack_loose_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
	status = error(_("unable to unpack %s header with --allow-unknown-type"),
	oid_to_hex(oid));
	} else if (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
	status = error(_("unable to unpack %s header"),
	oid_to_hex(oid));
	if (status < 0)
	; /* Do nothing */
	else if (hdrbuf.len) {
	if ((status = parse_loose_header_extended(hdrbuf.buf, oi, flags)) < 0)
	status = error(_("unable to parse %s header with --allow-unknown-type"),
	oid_to_hex(oid));
	} else if ((status = parse_loose_header_extended(hdr, oi, flags)) < 0)
	status = error(_("unable to parse %s header"), oid_to_hex(oid));

	if (status >= 0 && oi->contentp) {
	*oi->contentp = unpack_loose_rest(&stream, hdr,
	*oi->sizep, oid);
	if (!*oi->contentp) {
	git_inflate_end(&stream);
	status = -1;
	}
	} else
	git_inflate_end(&stream);

	munmap(map, mapsize);
	if (status && oi->typep)
	*oi->typep = status;
	if (oi->sizep == &size_scratch)
	oi->sizep = NULL;
	strbuf_release(&hdrbuf);
	oi->whence = OI_LOOSE;
	return (status < 0) ? status : 0;
	}

	int obj_read_use_lock = 0;
	pthread_mutex_t obj_read_mutex;

	void enable_obj_read_lock(void)
	{
	if (obj_read_use_lock)
	return;

	obj_read_use_lock = 1;
	init_recursive_mutex(&obj_read_mutex);
	}

	void disable_obj_read_lock(void)
	{
	if (!obj_read_use_lock)
	return;

	obj_read_use_lock = 0;
	pthread_mutex_destroy(&obj_read_mutex);
	}

	int fetch_if_missing = 1;

	static int do_oid_object_info_extended(struct repository *r,
	const struct object_id *oid,
	struct object_info *oi, unsigned flags)
	{
	static struct object_info blank_oi = OBJECT_INFO_INIT;
	struct cached_object *co;
	struct pack_entry e;
	int rtype;
	const struct object_id *real = oid;
	int already_retried = 0;


	if (flags & OBJECT_INFO_LOOKUP_REPLACE)
	real = lookup_replace_object(r, oid);

	if (is_null_oid(real))
	return -1;

	if (!oi)
	oi = &blank_oi;

	co = find_cached_object(real);
	if (co) {
	if (oi->typep)
	*(oi->typep) = co->type;
	if (oi->sizep)
	*(oi->sizep) = co->size;
	if (oi->disk_sizep)
	*(oi->disk_sizep) = 0;
	if (oi->delta_base_oid)
	oidclr(oi->delta_base_oid);
	if (oi->type_name)
	strbuf_addstr(oi->type_name, type_name(co->type));
	if (oi->contentp)
	*oi->contentp = xmemdupz(co->buf, co->size);
	oi->whence = OI_CACHED;
	return 0;
	}

	while (1) {
	if (find_pack_entry(r, real, &e))
	break;

	if (flags & OBJECT_INFO_IGNORE_LOOSE)
	return -1;

	/* Most likely it's a loose object. */
	if (!loose_object_info(r, real, oi, flags))
	return 0;

	/* Not a loose object; someone else may have just packed it. */
	if (!(flags & OBJECT_INFO_QUICK)) {
	reprepare_packed_git(r);
	if (find_pack_entry(r, real, &e))
	break;
	}

	/* Check if it is a missing object */
	if (fetch_if_missing && repo_has_promisor_remote(r) &&
	!already_retried &&
	!(flags & OBJECT_INFO_SKIP_FETCH_OBJECT)) {
	/*
	* TODO Investigate checking promisor_remote_get_direct()
	* TODO return value and stopping on error here.
	*/
	promisor_remote_get_direct(r, real, 1);
	already_retried = 1;
	continue;
	}

	return -1;
	}

	if (oi == &blank_oi)
	/*
	* We know that the caller doesn't actually need the
	* information below, so return early.
	*/
	return 0;
	rtype = packed_object_info(r, e.p, e.offset, oi);
	if (rtype < 0) {
	mark_bad_packed_object(e.p, real->hash);
	return do_oid_object_info_extended(r, real, oi, 0);
	} else if (oi->whence == OI_PACKED) {
	oi->u.packed.offset = e.offset;
	oi->u.packed.pack = e.p;
	oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA \|\|
	rtype == OBJ_OFS_DELTA);
	}

	return 0;
	}

	int oid_object_info_extended(struct repository r, const struct object_id oid,
	struct object_info *oi, unsigned flags)
	{
	int ret;
	obj_read_lock();
	ret = do_oid_object_info_extended(r, oid, oi, flags);
	obj_read_unlock();
	return ret;
	}


	/* returns enum object_type or negative */
	int oid_object_info(struct repository *r,
	const struct object_id *oid,
	unsigned long *sizep)
	{
	enum object_type type;
	struct object_info oi = OBJECT_INFO_INIT;

	oi.typep = &type;
	oi.sizep = sizep;
	if (oid_object_info_extended(r, oid, &oi,
	OBJECT_INFO_LOOKUP_REPLACE) < 0)
	return -1;
	return type;
	}

	static void read_object(struct repository r,
	const struct object_id oid, enum object_type type,
	unsigned long *size)
	{
	struct object_info oi = OBJECT_INFO_INIT;
	void *content;
	oi.typep = type;
	oi.sizep = size;
	oi.contentp = &content;

	if (oid_object_info_extended(r, oid, &oi, 0) < 0)
	return NULL;
	return content;
	}

	int pretend_object_file(void *buf, unsigned long len, enum object_type type,
	struct object_id *oid)
	{
	struct cached_object *co;

	hash_object_file(the_hash_algo, buf, len, type_name(type), oid);
	if (has_object_file_with_flags(oid, OBJECT_INFO_QUICK \| OBJECT_INFO_SKIP_FETCH_OBJECT) \|\|
	find_cached_object(oid))
	return 0;
	ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
	co = &cached_objects[cached_object_nr++];
	co->size = len;
	co->type = type;
	co->buf = xmalloc(len);
	memcpy(co->buf, buf, len);
	oidcpy(&co->oid, oid);
	return 0;
	}

	/*
	* This function dies on corrupt objects; the callers who want to
	* deal with them should arrange to call read_object() and give error
	* messages themselves.
	*/
	void read_object_file_extended(struct repository r,
	const struct object_id *oid,
	enum object_type *type,
	unsigned long *size,
	int lookup_replace)
	{
	void *data;
	const struct packed_git *p;
	const char *path;
	struct stat st;
	const struct object_id *repl = lookup_replace ?
	lookup_replace_object(r, oid) : oid;

	errno = 0;
	data = read_object(r, repl, type, size);
	if (data)
	return data;

	obj_read_lock();
	if (errno && errno != ENOENT)
	die_errno(_("failed to read object %s"), oid_to_hex(oid));

	/* die if we replaced an object with one that does not exist */
	if (repl != oid)
	die(_("replacement %s not found for %s"),
	oid_to_hex(repl), oid_to_hex(oid));

	if (!stat_loose_object(r, repl, &st, &path))
	die(_("loose object %s (stored in %s) is corrupt"),
	oid_to_hex(repl), path);

	if ((p = has_packed_and_bad(r, repl->hash)) != NULL)
	die(_("packed object %s (stored in %s) is corrupt"),
	oid_to_hex(repl), p->pack_name);
	obj_read_unlock();

	return NULL;
	}

	void read_object_with_reference(struct repository r,
	const struct object_id *oid,
	const char *required_type_name,
	unsigned long *size,
	struct object_id *actual_oid_return)
	{
	enum object_type type, required_type;
	void *buffer;
	unsigned long isize;
	struct object_id actual_oid;

	required_type = type_from_string(required_type_name);
	oidcpy(&actual_oid, oid);
	while (1) {
	int ref_length = -1;
	const char *ref_type = NULL;

	buffer = repo_read_object_file(r, &actual_oid, &type, &isize);
	if (!buffer)
	return NULL;
	if (type == required_type) {
	*size = isize;
	if (actual_oid_return)
	oidcpy(actual_oid_return, &actual_oid);
	return buffer;
	}
	/* Handle references */
	else if (type == OBJ_COMMIT)
	ref_type = "tree ";
	else if (type == OBJ_TAG)
	ref_type = "object ";
	else {
	free(buffer);
	return NULL;
	}
	ref_length = strlen(ref_type);

	if (ref_length + the_hash_algo->hexsz > isize \|\|
	memcmp(buffer, ref_type, ref_length) \|\|
	get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
	free(buffer);
	return NULL;
	}
	free(buffer);
	/* Now we have the ID of the referred-to object in
	* actual_oid. Check again. */
	}
	}

	static void write_object_file_prepare(const struct git_hash_algo *algo,
	const void *buf, unsigned long len,
	const char type, struct object_id oid,
	char hdr, int hdrlen)
	{
	git_hash_ctx c;

	/* Generate the header */
	hdrlen = xsnprintf(hdr, hdrlen, "%s %"PRIuMAX , type, (uintmax_t)len)+1;

	/* Sha1.. */
	algo->init_fn(&c);
	algo->update_fn(&c, hdr, *hdrlen);
	algo->update_fn(&c, buf, len);
	algo->final_oid_fn(oid, &c);
	}

	/*
	* Move the just written object into its final resting place.
	*/
	int finalize_object_file(const char tmpfile, const char filename)
	{
	int ret = 0;

	if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
	goto try_rename;
	else if (link(tmpfile, filename))
	ret = errno;

	/*
	* Coda hack - coda doesn't like cross-directory links,
	* so we fall back to a rename, which will mean that it
	* won't be able to check collisions, but that's not a
	* big deal.
	*
	* The same holds for FAT formatted media.
	*
	* When this succeeds, we just return. We have nothing
	* left to unlink.
	*/
	if (ret && ret != EEXIST) {
	try_rename:
	if (!rename(tmpfile, filename))
	goto out;
	ret = errno;
	}
	unlink_or_warn(tmpfile);
	if (ret) {
	if (ret != EEXIST) {
	return error_errno(_("unable to write file %s"), filename);
	}
	/* FIXME!!! Collision check here ? */
	}

	out:
	if (adjust_shared_perm(filename))
	return error(_("unable to set permission to '%s'"), filename);
	return 0;
	}

	static int write_buffer(int fd, const void *buf, size_t len)
	{
	if (write_in_full(fd, buf, len) < 0)
	return error_errno(_("file write error"));
	return 0;
	}

	int hash_object_file(const struct git_hash_algo algo, const void buf,
	unsigned long len, const char *type,
	struct object_id *oid)
	{
	char hdr[MAX_HEADER_LEN];
	int hdrlen = sizeof(hdr);
	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
	return 0;
	}

	/* Finalize a file on disk, and close it. */
	static void close_loose_object(int fd)
	{
	if (fsync_object_files)
	fsync_or_die(fd, "loose object file");
	if (close(fd) != 0)
	die_errno(_("error when closing loose object file"));
	}

	/* Size of directory component, including the ending '/' */
	static inline int directory_size(const char *filename)
	{
	const char *s = strrchr(filename, '/');
	if (!s)
	return 0;
	return s - filename + 1;
	}

	/*
	* This creates a temporary file in the same directory as the final
	* 'filename'
	*
	* We want to avoid cross-directory filename renames, because those
	* can have problems on various filesystems (FAT, NFS, Coda).
	*/
	static int create_tmpfile(struct strbuf tmp, const char filename)
	{
	int fd, dirlen = directory_size(filename);

	strbuf_reset(tmp);
	strbuf_add(tmp, filename, dirlen);
	strbuf_addstr(tmp, "tmp_obj_XXXXXX");
	fd = git_mkstemp_mode(tmp->buf, 0444);
	if (fd < 0 && dirlen && errno == ENOENT) {
	/*
	* Make sure the directory exists; note that the contents
	* of the buffer are undefined after mkstemp returns an
	* error, so we have to rewrite the whole buffer from
	* scratch.
	*/
	strbuf_reset(tmp);
	strbuf_add(tmp, filename, dirlen - 1);
	if (mkdir(tmp->buf, 0777) && errno != EEXIST)
	return -1;
	if (adjust_shared_perm(tmp->buf))
	return -1;

	/* Try again */
	strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
	fd = git_mkstemp_mode(tmp->buf, 0444);
	}
	return fd;
	}

	static int write_loose_object(const struct object_id oid, char hdr,
	int hdrlen, const void *buf, unsigned long len,
	time_t mtime)
	{
	int fd, ret;
	unsigned char compressed[4096];
	git_zstream stream;
	git_hash_ctx c;
	struct object_id parano_oid;
	static struct strbuf tmp_file = STRBUF_INIT;
	static struct strbuf filename = STRBUF_INIT;

	loose_object_path(the_repository, &filename, oid);

	fd = create_tmpfile(&tmp_file, filename.buf);
	if (fd < 0) {
	if (errno == EACCES)
	return error(_("insufficient permission for adding an object to repository database %s"), get_object_directory());
	else
	return error_errno(_("unable to create temporary file"));
	}

	/* Set it up */
	git_deflate_init(&stream, zlib_compression_level);
	stream.next_out = compressed;
	stream.avail_out = sizeof(compressed);
	the_hash_algo->init_fn(&c);

	/* First header.. */
	stream.next_in = (unsigned char *)hdr;
	stream.avail_in = hdrlen;
	while (git_deflate(&stream, 0) == Z_OK)
	; /* nothing */
	the_hash_algo->update_fn(&c, hdr, hdrlen);

	/* Then the data itself.. */
	stream.next_in = (void *)buf;
	stream.avail_in = len;
	do {
	unsigned char *in0 = stream.next_in;
	ret = git_deflate(&stream, Z_FINISH);
	the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
	if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
	die(_("unable to write loose object file"));
	stream.next_out = compressed;
	stream.avail_out = sizeof(compressed);
	} while (ret == Z_OK);

	if (ret != Z_STREAM_END)
	die(_("unable to deflate new object %s (%d)"), oid_to_hex(oid),
	ret);
	ret = git_deflate_end_gently(&stream);
	if (ret != Z_OK)
	die(_("deflateEnd on object %s failed (%d)"), oid_to_hex(oid),
	ret);
	the_hash_algo->final_oid_fn(&parano_oid, &c);
	if (!oideq(oid, &parano_oid))
	die(_("confused by unstable object source data for %s"),
	oid_to_hex(oid));

	close_loose_object(fd);

	if (mtime) {
	struct utimbuf utb;
	utb.actime = mtime;
	utb.modtime = mtime;
	if (utime(tmp_file.buf, &utb) < 0)
	warning_errno(_("failed utime() on %s"), tmp_file.buf);
	}

	return finalize_object_file(tmp_file.buf, filename.buf);
	}

	static int freshen_loose_object(const struct object_id *oid)
	{
	return check_and_freshen(oid, 1);
	}

	static int freshen_packed_object(const struct object_id *oid)
	{
	struct pack_entry e;
	if (!find_pack_entry(the_repository, oid, &e))
	return 0;
	if (e.p->freshened)
	return 1;
	if (!freshen_file(e.p->pack_name))
	return 0;
	e.p->freshened = 1;
	return 1;
	}

	int write_object_file(const void buf, unsigned long len, const char type,
	struct object_id *oid)
	{
	char hdr[MAX_HEADER_LEN];
	int hdrlen = sizeof(hdr);

	/* Normally if we have it in the pack then we do not bother writing
	* it out into .git/objects/??/?{38} file.
	*/
	write_object_file_prepare(the_hash_algo, buf, len, type, oid, hdr,
	&hdrlen);
	if (freshen_packed_object(oid) \|\| freshen_loose_object(oid))
	return 0;
	return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
	}

	int hash_object_file_literally(const void *buf, unsigned long len,
	const char type, struct object_id oid,
	unsigned flags)
	{
	char *header;
	int hdrlen, status = 0;

	/* type string, SP, %lu of the length plus NUL must fit this */
	hdrlen = strlen(type) + MAX_HEADER_LEN;
	header = xmalloc(hdrlen);
	write_object_file_prepare(the_hash_algo, buf, len, type, oid, header,
	&hdrlen);

	if (!(flags & HASH_WRITE_OBJECT))
	goto cleanup;
	if (freshen_packed_object(oid) \|\| freshen_loose_object(oid))
	goto cleanup;
	status = write_loose_object(oid, header, hdrlen, buf, len, 0);

	cleanup:
	free(header);
	return status;
	}

	int force_object_loose(const struct object_id *oid, time_t mtime)
	{
	void *buf;
	unsigned long len;
	enum object_type type;
	char hdr[MAX_HEADER_LEN];
	int hdrlen;
	int ret;

	if (has_loose_object(oid))
	return 0;
	buf = read_object(the_repository, oid, &type, &len);
	if (!buf)
	return error(_("cannot read object for %s"), oid_to_hex(oid));
	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1;
	ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
	free(buf);

	return ret;
	}

	int has_object(struct repository r, const struct object_id oid,
	unsigned flags)
	{
	int quick = !(flags & HAS_OBJECT_RECHECK_PACKED);
	unsigned object_info_flags = OBJECT_INFO_SKIP_FETCH_OBJECT \|
	(quick ? OBJECT_INFO_QUICK : 0);

	if (!startup_info->have_repository)
	return 0;
	return oid_object_info_extended(r, oid, NULL, object_info_flags) >= 0;
	}

	int repo_has_object_file_with_flags(struct repository *r,
	const struct object_id *oid, int flags)
	{
	if (!startup_info->have_repository)
	return 0;
	return oid_object_info_extended(r, oid, NULL, flags) >= 0;
	}

	int repo_has_object_file(struct repository *r,
	const struct object_id *oid)
	{
	return repo_has_object_file_with_flags(r, oid, 0);
	}

	static void check_tree(const void *buf, size_t size)
	{
	struct tree_desc desc;
	struct name_entry entry;

	init_tree_desc(&desc, buf, size);
	while (tree_entry(&desc, &entry))
	/* do nothing
	* tree_entry() will die() on malformed entries */
	;
	}

	static void check_commit(const void *buf, size_t size)
	{
	struct commit c;
	memset(&c, 0, sizeof(c));
	if (parse_commit_buffer(the_repository, &c, buf, size, 0))
	die(_("corrupt commit"));
	}

	static void check_tag(const void *buf, size_t size)
	{
	struct tag t;
	memset(&t, 0, sizeof(t));
	if (parse_tag_buffer(the_repository, &t, buf, size))
	die(_("corrupt tag"));
	}

	static int index_mem(struct index_state *istate,
	struct object_id oid, void buf, size_t size,
	enum object_type type,
	const char *path, unsigned flags)
	{
	int ret, re_allocated = 0;
	int write_object = flags & HASH_WRITE_OBJECT;

	if (!type)
	type = OBJ_BLOB;

	/*
	* Convert blobs to git internal format
	*/
	if ((type == OBJ_BLOB) && path) {
	struct strbuf nbuf = STRBUF_INIT;
	if (convert_to_git(istate, path, buf, size, &nbuf,
	get_conv_flags(flags))) {
	buf = strbuf_detach(&nbuf, &size);
	re_allocated = 1;
	}
	}
	if (flags & HASH_FORMAT_CHECK) {
	if (type == OBJ_TREE)
	check_tree(buf, size);
	if (type == OBJ_COMMIT)
	check_commit(buf, size);
	if (type == OBJ_TAG)
	check_tag(buf, size);
	}

	if (write_object)
	ret = write_object_file(buf, size, type_name(type), oid);
	else
	ret = hash_object_file(the_hash_algo, buf, size,
	type_name(type), oid);
	if (re_allocated)
	free(buf);
	return ret;
	}

	static int index_stream_convert_blob(struct index_state *istate,
	struct object_id *oid,
	int fd,
	const char *path,
	unsigned flags)
	{
	int ret;
	const int write_object = flags & HASH_WRITE_OBJECT;
	struct strbuf sbuf = STRBUF_INIT;

	assert(path);
	assert(would_convert_to_git_filter_fd(istate, path));

	convert_to_git_filter_fd(istate, path, fd, &sbuf,
	get_conv_flags(flags));

	if (write_object)
	ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
	oid);
	else
	ret = hash_object_file(the_hash_algo, sbuf.buf, sbuf.len,
	type_name(OBJ_BLOB), oid);
	strbuf_release(&sbuf);
	return ret;
	}

	static int index_pipe(struct index_state istate, struct object_id oid,
	int fd, enum object_type type,
	const char *path, unsigned flags)
	{
	struct strbuf sbuf = STRBUF_INIT;
	int ret;

	if (strbuf_read(&sbuf, fd, 4096) >= 0)
	ret = index_mem(istate, oid, sbuf.buf, sbuf.len, type, path, flags);
	else
	ret = -1;
	strbuf_release(&sbuf);
	return ret;
	}

	#define SMALL_FILE_SIZE (32*1024)

	static int index_core(struct index_state *istate,
	struct object_id *oid, int fd, size_t size,
	enum object_type type, const char *path,
	unsigned flags)
	{
	int ret;

	if (!size) {
	ret = index_mem(istate, oid, "", size, type, path, flags);
	} else if (size <= SMALL_FILE_SIZE) {
	char *buf = xmalloc(size);
	ssize_t read_result = read_in_full(fd, buf, size);
	if (read_result < 0)
	ret = error_errno(_("read error while indexing %s"),
	path ? path : "<unknown>");
	else if (read_result != size)
	ret = error(_("short read while indexing %s"),
	path ? path : "<unknown>");
	else
	ret = index_mem(istate, oid, buf, size, type, path, flags);
	free(buf);
	} else {
	void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	ret = index_mem(istate, oid, buf, size, type, path, flags);
	munmap(buf, size);
	}
	return ret;
	}

	/*
	* This creates one packfile per large blob unless bulk-checkin
	* machinery is "plugged".
	*
	* This also bypasses the usual "convert-to-git" dance, and that is on
	* purpose. We could write a streaming version of the converting
	* functions and insert that before feeding the data to fast-import
	* (or equivalent in-core API described above). However, that is
	* somewhat complicated, as we do not know the size of the filter
	* result, which we need to know beforehand when writing a git object.
	* Since the primary motivation for trying to stream from the working
	* tree file and to avoid mmaping it in core is to deal with large
	* binary blobs, they generally do not want to get any conversion, and
	* callers should avoid this code path when filters are requested.
	*/
	static int index_stream(struct object_id *oid, int fd, size_t size,
	enum object_type type, const char *path,
	unsigned flags)
	{
	return index_bulk_checkin(oid, fd, size, type, path, flags);
	}

	int index_fd(struct index_state istate, struct object_id oid,
	int fd, struct stat *st,
	enum object_type type, const char *path, unsigned flags)
	{
	int ret;

	/*
	* Call xsize_t() only when needed to avoid potentially unnecessary
	* die() for large files.
	*/
	if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(istate, path))
	ret = index_stream_convert_blob(istate, oid, fd, path, flags);
	else if (!S_ISREG(st->st_mode))
	ret = index_pipe(istate, oid, fd, type, path, flags);
	else if (st->st_size <= big_file_threshold \|\| type != OBJ_BLOB \|\|
	(path && would_convert_to_git(istate, path)))
	ret = index_core(istate, oid, fd, xsize_t(st->st_size),
	type, path, flags);
	else
	ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
	flags);
	close(fd);
	return ret;
	}

	int index_path(struct index_state istate, struct object_id oid,
	const char path, struct stat st, unsigned flags)
	{
	int fd;
	struct strbuf sb = STRBUF_INIT;
	int rc = 0;

	switch (st->st_mode & S_IFMT) {
	case S_IFREG:
	fd = open(path, O_RDONLY);
	if (fd < 0)
	return error_errno("open(\"%s\")", path);
	if (index_fd(istate, oid, fd, st, OBJ_BLOB, path, flags) < 0)
	return error(_("%s: failed to insert into database"),
	path);
	break;
	case S_IFLNK:
	if (strbuf_readlink(&sb, path, st->st_size))
	return error_errno("readlink(\"%s\")", path);
	if (!(flags & HASH_WRITE_OBJECT))
	hash_object_file(the_hash_algo, sb.buf, sb.len,
	blob_type, oid);
	else if (write_object_file(sb.buf, sb.len, blob_type, oid))
	rc = error(_("%s: failed to insert into database"), path);
	strbuf_release(&sb);
	break;
	case S_IFDIR:
	return resolve_gitlink_ref(path, "HEAD", oid);
	default:
	return error(_("%s: unsupported file type"), path);
	}
	return rc;
	}

	int read_pack_header(int fd, struct pack_header *header)
	{
	if (read_in_full(fd, header, sizeof(header)) != sizeof(header))
	/* "eof before pack header was fully read" */
	return PH_ERROR_EOF;

	if (header->hdr_signature != htonl(PACK_SIGNATURE))
	/* "protocol error (pack signature mismatch detected)" */
	return PH_ERROR_PACK_SIGNATURE;
	if (!pack_version_ok(header->hdr_version))
	/* "protocol error (pack version unsupported)" */
	return PH_ERROR_PROTOCOL;
	return 0;
	}

	void assert_oid_type(const struct object_id *oid, enum object_type expect)
	{
	enum object_type type = oid_object_info(the_repository, oid, NULL);
	if (type < 0)
	die(_("%s is not a valid object"), oid_to_hex(oid));
	if (type != expect)
	die(_("%s is not a valid '%s' object"), oid_to_hex(oid),
	type_name(expect));
	}

	int for_each_file_in_obj_subdir(unsigned int subdir_nr,
	struct strbuf *path,
	each_loose_object_fn obj_cb,
	each_loose_cruft_fn cruft_cb,
	each_loose_subdir_fn subdir_cb,
	void *data)
	{
	size_t origlen, baselen;
	DIR *dir;
	struct dirent *de;
	int r = 0;
	struct object_id oid;

	if (subdir_nr > 0xff)
	BUG("invalid loose object subdirectory: %x", subdir_nr);

	origlen = path->len;
	strbuf_complete(path, '/');
	strbuf_addf(path, "%02x", subdir_nr);

	dir = opendir(path->buf);
	if (!dir) {
	if (errno != ENOENT)
	r = error_errno(_("unable to open %s"), path->buf);
	strbuf_setlen(path, origlen);
	return r;
	}

	oid.hash[0] = subdir_nr;
	strbuf_addch(path, '/');
	baselen = path->len;

	while ((de = readdir_skip_dot_and_dotdot(dir))) {
	size_t namelen;

	namelen = strlen(de->d_name);
	strbuf_setlen(path, baselen);
	strbuf_add(path, de->d_name, namelen);
	if (namelen == the_hash_algo->hexsz - 2 &&
	!hex_to_bytes(oid.hash + 1, de->d_name,
	the_hash_algo->rawsz - 1)) {
	oid_set_algo(&oid, the_hash_algo);
	if (obj_cb) {
	r = obj_cb(&oid, path->buf, data);
	if (r)
	break;
	}
	continue;
	}

	if (cruft_cb) {
	r = cruft_cb(de->d_name, path->buf, data);
	if (r)
	break;
	}
	}
	closedir(dir);

	strbuf_setlen(path, baselen - 1);
	if (!r && subdir_cb)
	r = subdir_cb(subdir_nr, path->buf, data);

	strbuf_setlen(path, origlen);

	return r;
	}

	int for_each_loose_file_in_objdir_buf(struct strbuf *path,
	each_loose_object_fn obj_cb,
	each_loose_cruft_fn cruft_cb,
	each_loose_subdir_fn subdir_cb,
	void *data)
	{
	int r = 0;
	int i;

	for (i = 0; i < 256; i++) {
	r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
	subdir_cb, data);
	if (r)
	break;
	}

	return r;
	}

	int for_each_loose_file_in_objdir(const char *path,
	each_loose_object_fn obj_cb,
	each_loose_cruft_fn cruft_cb,
	each_loose_subdir_fn subdir_cb,
	void *data)
	{
	struct strbuf buf = STRBUF_INIT;
	int r;

	strbuf_addstr(&buf, path);
	r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
	subdir_cb, data);
	strbuf_release(&buf);

	return r;
	}

	int for_each_loose_object(each_loose_object_fn cb, void *data,
	enum for_each_object_flags flags)
	{
	struct object_directory *odb;

	prepare_alt_odb(the_repository);
	for (odb = the_repository->objects->odb; odb; odb = odb->next) {
	int r = for_each_loose_file_in_objdir(odb->path, cb, NULL,
	NULL, data);
	if (r)
	return r;

	if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
	break;
	}

	return 0;
	}

	static int append_loose_object(const struct object_id oid, const char path,
	void *data)
	{
	oidtree_insert(data, oid);
	return 0;
	}

	struct oidtree odb_loose_cache(struct object_directory odb,
	const struct object_id *oid)
	{
	int subdir_nr = oid->hash[0];
	struct strbuf buf = STRBUF_INIT;
	size_t word_bits = bitsizeof(odb->loose_objects_subdir_seen[0]);
	size_t word_index = subdir_nr / word_bits;
	size_t mask = 1u << (subdir_nr % word_bits);
	uint32_t *bitmap;

	if (subdir_nr < 0 \|\|
	subdir_nr >= bitsizeof(odb->loose_objects_subdir_seen))
	BUG("subdir_nr out of range");

	bitmap = &odb->loose_objects_subdir_seen[word_index];
	if (*bitmap & mask)
	return odb->loose_objects_cache;
	if (!odb->loose_objects_cache) {
	ALLOC_ARRAY(odb->loose_objects_cache, 1);
	oidtree_init(odb->loose_objects_cache);
	}
	strbuf_addstr(&buf, odb->path);
	for_each_file_in_obj_subdir(subdir_nr, &buf,
	append_loose_object,
	NULL, NULL,
	odb->loose_objects_cache);
	*bitmap \|= mask;
	strbuf_release(&buf);
	return odb->loose_objects_cache;
	}

	void odb_clear_loose_cache(struct object_directory *odb)
	{
	oidtree_clear(odb->loose_objects_cache);
	FREE_AND_NULL(odb->loose_objects_cache);
	memset(&odb->loose_objects_subdir_seen, 0,
	sizeof(odb->loose_objects_subdir_seen));
	}

	static int check_stream_oid(git_zstream *stream,
	const char *hdr,
	unsigned long size,
	const char *path,
	const struct object_id *expected_oid)
	{
	git_hash_ctx c;
	struct object_id real_oid;
	unsigned char buf[4096];
	unsigned long total_read;
	int status = Z_OK;

	the_hash_algo->init_fn(&c);
	the_hash_algo->update_fn(&c, hdr, stream->total_out);

	/*
	* We already read some bytes into hdr, but the ones up to the NUL
	* do not count against the object's content size.
	*/
	total_read = stream->total_out - strlen(hdr) - 1;

	/*
	* This size comparison must be "<=" to read the final zlib packets;
	* see the comment in unpack_loose_rest for details.
	*/
	while (total_read <= size &&
	(status == Z_OK \|\|
	(status == Z_BUF_ERROR && !stream->avail_out))) {
	stream->next_out = buf;
	stream->avail_out = sizeof(buf);
	if (size - total_read < stream->avail_out)
	stream->avail_out = size - total_read;
	status = git_inflate(stream, Z_FINISH);
	the_hash_algo->update_fn(&c, buf, stream->next_out - buf);
	total_read += stream->next_out - buf;
	}
	git_inflate_end(stream);

	if (status != Z_STREAM_END) {
	error(_("corrupt loose object '%s'"), oid_to_hex(expected_oid));
	return -1;
	}
	if (stream->avail_in) {
	error(_("garbage at end of loose object '%s'"),
	oid_to_hex(expected_oid));
	return -1;
	}

	the_hash_algo->final_oid_fn(&real_oid, &c);
	if (!oideq(expected_oid, &real_oid)) {
	error(_("hash mismatch for %s (expected %s)"), path,
	oid_to_hex(expected_oid));
	return -1;
	}

	return 0;
	}

	int read_loose_object(const char *path,
	const struct object_id *expected_oid,
	enum object_type *type,
	unsigned long *size,
	void **contents)
	{
	int ret = -1;
	void *map = NULL;
	unsigned long mapsize;
	git_zstream stream;
	char hdr[MAX_HEADER_LEN];

	*contents = NULL;

	map = map_loose_object_1(the_repository, path, NULL, &mapsize);
	if (!map) {
	error_errno(_("unable to mmap %s"), path);
	goto out;
	}

	if (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
	error(_("unable to unpack header of %s"), path);
	goto out;
	}

	*type = parse_loose_header(hdr, size);
	if (*type < 0) {
	error(_("unable to parse header of %s"), path);
	git_inflate_end(&stream);
	goto out;
	}

	if (type == OBJ_BLOB && size > big_file_threshold) {
	if (check_stream_oid(&stream, hdr, *size, path, expected_oid) < 0)
	goto out;
	} else {
	contents = unpack_loose_rest(&stream, hdr, size, expected_oid);
	if (!*contents) {
	error(_("unable to unpack contents of %s"), path);
	git_inflate_end(&stream);
	goto out;
	}
	if (check_object_signature(the_repository, expected_oid,
	contents, size,
	type_name(*type))) {
	error(_("hash mismatch for %s (expected %s)"), path,
	oid_to_hex(expected_oid));
	free(*contents);
	goto out;
	}
	}

	ret = 0; /* everything checks out */

	out:
	if (map)
	munmap(map, mapsize);
	return ret;
	}

Apr	AUG	Jan
	15
2020	2021	2023

git / git

git/object-file.c