git/refs.c

/*
 * The backend-independent part of the reference module.
 */

#include "cache.h"
#include "config.h"
#include "hashmap.h"
#include "lockfile.h"
#include "iterator.h"
#include "refs.h"
#include "refs/refs-internal.h"
#include "run-command.h"
#include "object-store.h"
#include "object.h"
#include "tag.h"
#include "submodule.h"
#include "worktree.h"
#include "strvec.h"
#include "repository.h"
#include "sigchain.h"

/*
 * List of all available backends
 */
static struct ref_storage_be *refs_backends = &refs_be_files;

static struct ref_storage_be *find_ref_storage_backend(const char *name)
{
	struct ref_storage_be *be;
	for (be = refs_backends; be; be = be->next)
		if (!strcmp(be->name, name))
			return be;
	return NULL;
}

int ref_storage_backend_exists(const char *name)
{
	return find_ref_storage_backend(name) != NULL;
}

/*
 * How to handle various characters in refnames:
 * 0: An acceptable character for refs
 * 1: End-of-component
 * 2: ., look for a preceding . to reject .. in refs
 * 3: {, look for a preceding @ to reject @{ in refs
 * 4: A bad character: ASCII control characters, and
 *    ":", "?", "[", "\", "^", "~", SP, or TAB
 * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
 */
static unsigned char refname_disposition[256] = {
	1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
	4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
};

/*
 * Try to read one refname component from the front of refname.
 * Return the length of the component found, or -1 if the component is
 * not legal.  It is legal if it is something reasonable to have under
 * ".git/refs/"; We do not like it if:
 *
 * - it begins with ".", or
 * - it has double dots "..", or
 * - it has ASCII control characters, or
 * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
 * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
 * - it ends with a "/", or
 * - it ends with ".lock", or
 * - it contains a "@{" portion
 *
 * When sanitized is not NULL, instead of rejecting the input refname
 * as an error, try to come up with a usable replacement for the input
 * refname in it.
 */
static int check_refname_component(const char *refname, int *flags,
				   struct strbuf *sanitized)
{
	const char *cp;
	char last = '\0';
	size_t component_start = 0; /* garbage - not a reasonable initial value */

	if (sanitized)
		component_start = sanitized->len;

	for (cp = refname; ; cp++) {
		int ch = *cp & 255;
		unsigned char disp = refname_disposition[ch];

		if (sanitized && disp != 1)
			strbuf_addch(sanitized, ch);

		switch (disp) {
		case 1:
			goto out;
		case 2:
			if (last == '.') { /* Refname contains "..". */
				if (sanitized)
					/* collapse ".." to single "." */
					strbuf_setlen(sanitized, sanitized->len - 1);
				else
					return -1;
			}
			break;
		case 3:
			if (last == '@') { /* Refname contains "@{". */
				if (sanitized)
					sanitized->buf[sanitized->len-1] = '-';
				else
					return -1;
			}
			break;
		case 4:
			/* forbidden char */
			if (sanitized)
				sanitized->buf[sanitized->len-1] = '-';
			else
				return -1;
			break;
		case 5:
			if (!(*flags & REFNAME_REFSPEC_PATTERN)) {
				/* refspec can't be a pattern */
				if (sanitized)
					sanitized->buf[sanitized->len-1] = '-';
				else
					return -1;
			}

			/*
			 * Unset the pattern flag so that we only accept
			 * a single asterisk for one side of refspec.
			 */
			*flags &= ~ REFNAME_REFSPEC_PATTERN;
			break;
		}
		last = ch;
	}
out:
	if (cp == refname)
		return 0; /* Component has zero length. */

	if (refname[0] == '.') { /* Component starts with '.'. */
		if (sanitized)
			sanitized->buf[component_start] = '-';
		else
			return -1;
	}
	if (cp - refname >= LOCK_SUFFIX_LEN &&
	    !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN)) {
		if (!sanitized)
			return -1;
		/* Refname ends with ".lock". */
		while (strbuf_strip_suffix(sanitized, LOCK_SUFFIX)) {
			/* try again in case we have .lock.lock */
		}
	}
	return cp - refname;
}

static int check_or_sanitize_refname(const char *refname, int flags,
				     struct strbuf *sanitized)
{
	int component_len, component_count = 0;

	if (!strcmp(refname, "@")) {
		/* Refname is a single character '@'. */
		if (sanitized)
			strbuf_addch(sanitized, '-');
		else
			return -1;
	}

	while (1) {
		if (sanitized && sanitized->len)
			strbuf_complete(sanitized, '/');

		/* We are at the start of a path component. */
		component_len = check_refname_component(refname, &flags,
							sanitized);
		if (sanitized && component_len == 0)
			; /* OK, omit empty component */
		else if (component_len <= 0)
			return -1;

		component_count++;
		if (refname[component_len] == '\0')
			break;
		/* Skip to next component. */
		refname += component_len + 1;
	}

	if (refname[component_len - 1] == '.') {
		/* Refname ends with '.'. */
		if (sanitized)
			; /* omit ending dot */
		else
			return -1;
	}
	if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
		return -1; /* Refname has only one component. */
	return 0;
}

int check_refname_format(const char *refname, int flags)
{
	return check_or_sanitize_refname(refname, flags, NULL);
}

void sanitize_refname_component(const char *refname, struct strbuf *out)
{
	if (check_or_sanitize_refname(refname, REFNAME_ALLOW_ONELEVEL, out))
		BUG("sanitizing refname '%s' check returned error", refname);
}

int refname_is_safe(const char *refname)
{
	const char *rest;

	if (skip_prefix(refname, "refs/", &rest)) {
		char *buf;
		int result;
		size_t restlen = strlen(rest);

		/* rest must not be empty, or start or end with "/" */
		if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
			return 0;

		/*
		 * Does the refname try to escape refs/?
		 * For example: refs/foo/../bar is safe but refs/foo/../../bar
		 * is not.
		 */
		buf = xmallocz(restlen);
		result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
		free(buf);
		return result;
	}

	do {
		if (!isupper(*refname) && *refname != '_')
			return 0;
		refname++;
	} while (*refname);
	return 1;
}

/*
 * Return true if refname, which has the specified oid and flags, can
 * be resolved to an object in the database. If the referred-to object
 * does not exist, emit a warning and return false.
 */
int ref_resolves_to_object(const char *refname,
			   const struct object_id *oid,
			   unsigned int flags)
{
	if (flags & REF_ISBROKEN)
		return 0;
	if (!has_object_file(oid)) {
		error(_("%s does not point to a valid object!"), refname);
		return 0;
	}
	return 1;
}

char *refs_resolve_refdup(struct ref_store *refs,
			  const char *refname, int resolve_flags,
			  struct object_id *oid, int *flags)
{
	const char *result;

	result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
					 oid, flags);
	return xstrdup_or_null(result);
}

char *resolve_refdup(const char *refname, int resolve_flags,
		     struct object_id *oid, int *flags)
{
	return refs_resolve_refdup(get_main_ref_store(the_repository),
				   refname, resolve_flags,
				   oid, flags);
}

/* The argument to filter_refs */
struct ref_filter {
	const char *pattern;
	const char *prefix;
	each_ref_fn *fn;
	void *cb_data;
};

int refs_read_ref_full(struct ref_store *refs, const char *refname,
		       int resolve_flags, struct object_id *oid, int *flags)
{
	if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, oid, flags))
		return 0;
	return -1;
}

int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
{
	return refs_read_ref_full(get_main_ref_store(the_repository), refname,
				  resolve_flags, oid, flags);
}

int read_ref(const char *refname, struct object_id *oid)
{
	return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
}

int refs_ref_exists(struct ref_store *refs, const char *refname)
{
	return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING, NULL, NULL);
}

int ref_exists(const char *refname)
{
	return refs_ref_exists(get_main_ref_store(the_repository), refname);
}

static int filter_refs(const char *refname, const struct object_id *oid,
			   int flags, void *data)
{
	struct ref_filter *filter = (struct ref_filter *)data;

	if (wildmatch(filter->pattern, refname, 0))
		return 0;
	if (filter->prefix)
		skip_prefix(refname, filter->prefix, &refname);
	return filter->fn(refname, oid, flags, filter->cb_data);
}

enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
{
	struct object *o = lookup_unknown_object(the_repository, name);

	if (o->type == OBJ_NONE) {
		int type = oid_object_info(the_repository, name, NULL);
		if (type < 0 || !object_as_type(o, type, 0))
			return PEEL_INVALID;
	}

	if (o->type != OBJ_TAG)
		return PEEL_NON_TAG;

	o = deref_tag_noverify(o);
	if (!o)
		return PEEL_INVALID;

	oidcpy(oid, &o->oid);
	return PEEL_PEELED;
}

struct warn_if_dangling_data {
	FILE *fp;
	const char *refname;
	const struct string_list *refnames;
	const char *msg_fmt;
};

static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
				   int flags, void *cb_data)
{
	struct warn_if_dangling_data *d = cb_data;
	const char *resolves_to;

	if (!(flags & REF_ISSYMREF))
		return 0;

	resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
	if (!resolves_to
	    || (d->refname
		? strcmp(resolves_to, d->refname)
		: !string_list_has_string(d->refnames, resolves_to))) {
		return 0;
	}

	fprintf(d->fp, d->msg_fmt, refname);
	fputc('\n', d->fp);
	return 0;
}

void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
{
	struct warn_if_dangling_data data;

	data.fp = fp;
	data.refname = refname;
	data.refnames = NULL;
	data.msg_fmt = msg_fmt;
	for_each_rawref(warn_if_dangling_symref, &data);
}

void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
{
	struct warn_if_dangling_data data;

	data.fp = fp;
	data.refname = NULL;
	data.refnames = refnames;
	data.msg_fmt = msg_fmt;
	for_each_rawref(warn_if_dangling_symref, &data);
}

int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
{
	return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
}

int for_each_tag_ref(each_ref_fn fn, void *cb_data)
{
	return refs_for_each_tag_ref(get_main_ref_store(the_repository), fn, cb_data);
}

int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
{
	return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
}

int for_each_branch_ref(each_ref_fn fn, void *cb_data)
{
	return refs_for_each_branch_ref(get_main_ref_store(the_repository), fn, cb_data);
}

int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
{
	return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
}

int for_each_remote_ref(each_ref_fn fn, void *cb_data)
{
	return refs_for_each_remote_ref(get_main_ref_store(the_repository), fn, cb_data);
}

int head_ref_namespaced(each_ref_fn fn, void *cb_data)
{
	struct strbuf buf = STRBUF_INIT;
	int ret = 0;
	struct object_id oid;
	int flag;

	strbuf_addf(&buf, "%sHEAD", get_git_namespace());
	if (!read_ref_full(buf.buf, RESOLVE_REF_READING, &oid, &flag))
		ret = fn(buf.buf, &oid, flag, cb_data);
	strbuf_release(&buf);

	return ret;
}

void normalize_glob_ref(struct string_list_item *item, const char *prefix,
			const char *pattern)
{
	struct strbuf normalized_pattern = STRBUF_INIT;

	if (*pattern == '/')
		BUG("pattern must not start with '/'");

	if (prefix) {
		strbuf_addstr(&normalized_pattern, prefix);
	}
	else if (!starts_with(pattern, "refs/"))
		strbuf_addstr(&normalized_pattern, "refs/");
	strbuf_addstr(&normalized_pattern, pattern);
	strbuf_strip_suffix(&normalized_pattern, "/");

	item->string = strbuf_detach(&normalized_pattern, NULL);
	item->util = has_glob_specials(pattern) ? NULL : item->string;
	strbuf_release(&normalized_pattern);
}

int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
	const char *prefix, void *cb_data)
{
	struct strbuf real_pattern = STRBUF_INIT;
	struct ref_filter filter;
	int ret;

	if (!prefix && !starts_with(pattern, "refs/"))
		strbuf_addstr(&real_pattern, "refs/");
	else if (prefix)
		strbuf_addstr(&real_pattern, prefix);
	strbuf_addstr(&real_pattern, pattern);

	if (!has_glob_specials(pattern)) {
		/* Append implied '/' '*' if not present. */
		strbuf_complete(&real_pattern, '/');
		/* No need to check for '*', there is none. */
		strbuf_addch(&real_pattern, '*');
	}

	filter.pattern = real_pattern.buf;
	filter.prefix = prefix;
	filter.fn = fn;
	filter.cb_data = cb_data;
	ret = for_each_ref(filter_refs, &filter);

	strbuf_release(&real_pattern);
	return ret;
}

int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
{
	return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
}

const char *prettify_refname(const char *name)