X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=setup.c;h=7a3618fab774c0c26a99c6e23b4fcf726e5dc1ad;hb=d3f2475c01d9e90dbadacbe2c35854f6d11e6409;hp=0717a98d16b8be3cb70b33b6dea7040694130a0b;hpb=03f94ae9f909952ed5a78917ab319a312889354b;p=git.git

diff --git a/setup.c b/setup.c
index 0717a98d1..7a3618fab 100644
--- a/setup.c
+++ b/setup.c
@@ -4,13 +4,16 @@
 static int inside_git_dir = -1;
 static int inside_work_tree = -1;
 
-const char *prefix_path(const char *prefix, int len, const char *path)
+char *prefix_path(const char *prefix, int len, const char *path)
 {
 	const char *orig = path;
-	char *sanitized = xmalloc(len + strlen(path) + 1);
-	if (is_absolute_path(orig))
-		strcpy(sanitized, path);
-	else {
+	char *sanitized;
+	if (is_absolute_path(orig)) {
+		const char *temp = real_path(path);
+		sanitized = xmalloc(len + strlen(temp) + 1);
+		strcpy(sanitized, temp);
+	} else {
+		sanitized = xmalloc(len + strlen(path) + 1);
 		if (len)
 			memcpy(sanitized, prefix, len);
 		strcpy(sanitized + len, path);
@@ -18,14 +21,15 @@ const char *prefix_path(const char *prefix, int len, const char *path)
 	if (normalize_path_copy(sanitized, sanitized))
 		goto error_out;
 	if (is_absolute_path(orig)) {
-		size_t len, total;
+		size_t root_len, len, total;
 		const char *work_tree = get_git_work_tree();
 		if (!work_tree)
 			goto error_out;
 		len = strlen(work_tree);
+		root_len = offset_1st_component(work_tree);
 		total = strlen(sanitized) + 1;
 		if (strncmp(sanitized, work_tree, len) ||
-		    (sanitized[len] != '\0' && sanitized[len] != '/')) {
+		    (len > root_len && sanitized[len] != '\0' && sanitized[len] != '/')) {
 		error_out:
 			die("'%s' is outside repository", orig);
 		}
@@ -36,34 +40,6 @@ const char *prefix_path(const char *prefix, int len, const char *path)
 	return sanitized;
 }
 
-/*
- * Unlike prefix_path, this should be used if the named file does
- * not have to interact with index entry; i.e. name of a random file
- * on the filesystem.
- */
-const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
-{
-	static char path[PATH_MAX];
-#ifndef WIN32
-	if (!pfx || !*pfx || is_absolute_path(arg))
-		return arg;
-	memcpy(path, pfx, pfx_len);
-	strcpy(path + pfx_len, arg);
-#else
-	char *p;
-	/* don't add prefix to absolute paths, but still replace '\' by '/' */
-	if (is_absolute_path(arg))
-		pfx_len = 0;
-	else
-		memcpy(path, pfx, pfx_len);
-	strcpy(path + pfx_len, arg);
-	for (p = path + pfx_len; *p; p++)
-		if (*p == '\\')
-			*p = '/';
-#endif
-	return path;
-}
-
 int check_filename(const char *prefix, const char *arg)
 {
 	const char *name;
@@ -81,8 +57,17 @@ static void NORETURN die_verify_filename(const char *prefix, const char *arg)
 {
 	unsigned char sha1[20];
 	unsigned mode;
-	/* try a detailed diagnostic ... */
-	get_sha1_with_mode_1(arg, sha1, &mode, 0, prefix);
+
+	/*
+	 * Saying "'(icase)foo' does not exist in the index" when the
+	 * user gave us ":(icase)foo" is just stupid.  A magic pathspec
+	 * begins with a colon and is followed by a non-alnum; do not
+	 * let get_sha1_with_mode_1(only_to_die=1) to even trigger.
+	 */
+	if (!(arg[0] == ':' && !isalnum(arg[1])))
+		/* try a detailed diagnostic ... */
+		get_sha1_with_mode_1(arg, sha1, &mode, 1, prefix);
+
 	/* ... or fall back the most general message. */
 	die("ambiguous argument '%s': unknown revision or path not in the working tree.\n"
 	    "Use '--' to separate paths from revisions", arg);
@@ -122,6 +107,105 @@ void verify_non_filename(const char *prefix, const char *arg)
 	    "Use '--' to separate filenames from revisions", arg);
 }
 
+/*
+ * Magic pathspec
+ *
+ * NEEDSWORK: These need to be moved to dir.h or even to a new
+ * pathspec.h when we restructure get_pathspec() users to use the
+ * "struct pathspec" interface.
+ *
+ * Possible future magic semantics include stuff like:
+ *
+ *	{ PATHSPEC_NOGLOB, '!', "noglob" },
+ *	{ PATHSPEC_ICASE, '\0', "icase" },
+ *	{ PATHSPEC_RECURSIVE, '*', "recursive" },
+ *	{ PATHSPEC_REGEXP, '\0', "regexp" },
+ *
+ */
+#define PATHSPEC_FROMTOP    (1<<0)
+
+static struct pathspec_magic {
+	unsigned bit;
+	char mnemonic; /* this cannot be ':'! */
+	const char *name;
+} pathspec_magic[] = {
+	{ PATHSPEC_FROMTOP, '/', "top" },
+};
+
+/*
+ * Take an element of a pathspec and check for magic signatures.
+ * Append the result to the prefix.
+ *
+ * For now, we only parse the syntax and throw out anything other than
+ * "top" magic.
+ *
+ * NEEDSWORK: This needs to be rewritten when we start migrating
+ * get_pathspec() users to use the "struct pathspec" interface.  For
+ * example, a pathspec element may be marked as case-insensitive, but
+ * the prefix part must always match literally, and a single stupid
+ * string cannot express such a case.
+ */
+static const char *prefix_pathspec(const char *prefix, int prefixlen, const char *elt)
+{
+	unsigned magic = 0;
+	const char *copyfrom = elt;
+	int i;
+
+	if (elt[0] != ':') {
+		; /* nothing to do */
+	} else if (elt[1] == '(') {
+		/* longhand */
+		const char *nextat;
+		for (copyfrom = elt + 2;
+		     *copyfrom && *copyfrom != ')';
+		     copyfrom = nextat) {
+			size_t len = strcspn(copyfrom, ",)");
+			if (copyfrom[len] == ')')
+				nextat = copyfrom + len;
+			else
+				nextat = copyfrom + len + 1;
+			if (!len)
+				continue;
+			for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++)
+				if (strlen(pathspec_magic[i].name) == len &&
+				    !strncmp(pathspec_magic[i].name, copyfrom, len)) {
+					magic |= pathspec_magic[i].bit;
+					break;
+				}
+			if (ARRAY_SIZE(pathspec_magic) <= i)
+				die("Invalid pathspec magic '%.*s' in '%s'",
+				    (int) len, copyfrom, elt);
+		}
+		if (*copyfrom == ')')
+			copyfrom++;
+	} else {
+		/* shorthand */
+		for (copyfrom = elt + 1;
+		     *copyfrom && *copyfrom != ':';
+		     copyfrom++) {
+			char ch = *copyfrom;
+
+			if (!is_pathspec_magic(ch))
+				break;
+			for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++)
+				if (pathspec_magic[i].mnemonic == ch) {
+					magic |= pathspec_magic[i].bit;
+					break;
+				}
+			if (ARRAY_SIZE(pathspec_magic) <= i)
+				die("Unimplemented pathspec magic '%c' in '%s'",
+				    ch, elt);
+		}
+		if (*copyfrom == ':')
+			copyfrom++;
+	}
+
+	if (magic & PATHSPEC_FROMTOP)
+		return xstrdup(copyfrom);
+	else
+		return prefix_path(prefix, prefixlen, copyfrom);
+}
+
 const char **get_pathspec(const char *prefix, const char **pathspec)
 {
 	const char *entry = *pathspec;
@@ -143,8 +227,7 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
 	dst = pathspec;
 	prefixlen = prefix ? strlen(prefix) : 0;
 	while (*src) {
-		const char *p = prefix_path(prefix, prefixlen, *src);
-		*(dst++) = p;
+		*(dst++) = prefix_pathspec(prefix, prefixlen, *src);
 		src++;
 	}
 	*dst = NULL;
@@ -164,11 +247,13 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
  *    a proper "ref:", or a regular file HEAD that has a properly
  *    formatted sha1 object name.
  */
-static int is_git_directory(const char *suspect)
+int is_git_directory(const char *suspect)
 {
 	char path[PATH_MAX];
 	size_t len = strlen(suspect);
 
+	if (PATH_MAX <= len + strlen("/objects"))
+		die("Too long path: %.*s", 60, suspect);
 	strcpy(path, suspect);
 	if (getenv(DB_ENVIRONMENT)) {
 		if (access(getenv(DB_ENVIRONMENT), X_OK))
@@ -205,24 +290,6 @@ int is_inside_work_tree(void)
 	return inside_work_tree;
 }
 
-/*
- * set_work_tree() is only ever called if you set GIT_DIR explicitly.
- * The old behaviour (which we retain here) is to set the work tree root
- * to the cwd, unless overridden by the config, the command line, or
- * GIT_WORK_TREE.
- */
-static const char *set_work_tree(const char *dir)
-{
-	char buffer[PATH_MAX + 1];
-
-	if (!getcwd(buffer, sizeof(buffer)))
-		die ("Could not get the current working directory");
-	git_work_tree_cfg = xstrdup(buffer);
-	inside_work_tree = 1;
-
-	return NULL;
-}
-
 void setup_work_tree(void)
 {
 	const char *work_tree, *git_dir;
@@ -233,16 +300,36 @@ void setup_work_tree(void)
 	work_tree = get_git_work_tree();
 	git_dir = get_git_dir();
 	if (!is_absolute_path(git_dir))
-		git_dir = make_absolute_path(git_dir);
+		git_dir = real_path(get_git_dir());
 	if (!work_tree || chdir(work_tree))
 		die("This operation must be run in a work tree");
-	set_git_dir(make_relative_path(git_dir, work_tree));
+
+	/*
+	 * Make sure subsequent git processes find correct worktree
+	 * if $GIT_WORK_TREE is set relative
+	 */
+	if (getenv(GIT_WORK_TREE_ENVIRONMENT))
+		setenv(GIT_WORK_TREE_ENVIRONMENT, ".", 1);
+
+	set_git_dir(relative_path(git_dir, work_tree));
 	initialized = 1;
 }
 
-static int check_repository_format_gently(int *nongit_ok)
+static int check_repository_format_gently(const char *gitdir, int *nongit_ok)
 {
-	git_config(check_repository_format_version, NULL);
+	char repo_config[PATH_MAX+1];
+
+	/*
+	 * git_config() can't be used here because it calls git_pathdup()
+	 * to get $GIT_CONFIG/config. That call will make setup_git_env()
+	 * set git_dir to ".git".
+	 *
+	 * We are in gitdir setup, no git dir has been found useable yet.
+	 * Use a gentler version of git_config() to check if this repo
+	 * is a good one.
+	 */
+	snprintf(repo_config, PATH_MAX, "%s/config", gitdir);
+	git_config_early(check_repository_format_version, NULL, repo_config);
 	if (GIT_REPO_VERSION < repository_format_version) {
 		if (!nongit_ok)
 			die ("Expected git repo version <= %d, found %d",
@@ -260,14 +347,14 @@ static int check_repository_format_gently(int *nongit_ok)
  * Try to read the location of the git directory from the .git file,
  * return path to git directory if found.
  */
-const char *read_gitfile_gently(const char *path)
+const char *read_gitfile(const char *path)
 {
 	char *buf;
 	char *dir;
 	const char *slash;
 	struct stat st;
 	int fd;
-	size_t len;
+	ssize_t len;
 
 	if (stat(path, &st))
 		return NULL;
@@ -304,24 +391,207 @@ const char *read_gitfile_gently(const char *path)
 
 	if (!is_git_directory(dir))
 		die("Not a git repository: %s", dir);
-	path = make_absolute_path(dir);
+	path = real_path(dir);
 
 	free(buf);
 	return path;
 }
 
+static const char *setup_explicit_git_dir(const char *gitdirenv,
+					  char *cwd, int len,
+					  int *nongit_ok)
+{
+	const char *work_tree_env = getenv(GIT_WORK_TREE_ENVIRONMENT);
+	const char *worktree;
+	char *gitfile;
+	int offset;
+
+	if (PATH_MAX - 40 < strlen(gitdirenv))
+		die("'$%s' too big", GIT_DIR_ENVIRONMENT);
+
+	gitfile = (char*)read_gitfile(gitdirenv);
+	if (gitfile) {
+		gitfile = xstrdup(gitfile);
+		gitdirenv = gitfile;
+	}
+
+	if (!is_git_directory(gitdirenv)) {
+		if (nongit_ok) {
+			*nongit_ok = 1;
+			free(gitfile);
+			return NULL;
+		}
+		die("Not a git repository: '%s'", gitdirenv);
+	}
+
+	if (check_repository_format_gently(gitdirenv, nongit_ok)) {
+		free(gitfile);
+		return NULL;
+	}
+
+	/* #3, #7, #11, #15, #19, #23, #27, #31 (see t1510) */
+	if (work_tree_env)
+		set_git_work_tree(work_tree_env);
+	else if (is_bare_repository_cfg > 0) {
+		if (git_work_tree_cfg) /* #22.2, #30 */
+			die("core.bare and core.worktree do not make sense");
+
+		/* #18, #26 */
+		set_git_dir(gitdirenv);
+		free(gitfile);
+		return NULL;
+	}
+	else if (git_work_tree_cfg) { /* #6, #14 */
+		if (is_absolute_path(git_work_tree_cfg))
+			set_git_work_tree(git_work_tree_cfg);
+		else {
+			char core_worktree[PATH_MAX];
+			if (chdir(gitdirenv))
+				die_errno("Could not chdir to '%s'", gitdirenv);
+			if (chdir(git_work_tree_cfg))
+				die_errno("Could not chdir to '%s'", git_work_tree_cfg);
+			if (!getcwd(core_worktree, PATH_MAX))
+				die_errno("Could not get directory '%s'", git_work_tree_cfg);
+			if (chdir(cwd))
+				die_errno("Could not come back to cwd");
+			set_git_work_tree(core_worktree);
+		}
+	}
+	else /* #2, #10 */
+		set_git_work_tree(".");
+
+	/* set_git_work_tree() must have been called by now */
+	worktree = get_git_work_tree();
+
+	/* both get_git_work_tree() and cwd are already normalized */
+	if (!strcmp(cwd, worktree)) { /* cwd == worktree */
+		set_git_dir(gitdirenv);
+		free(gitfile);
+		return NULL;
+	}
+
+	offset = dir_inside_of(cwd, worktree);
+	if (offset >= 0) {	/* cwd inside worktree? */
+		set_git_dir(real_path(gitdirenv));
+		if (chdir(worktree))
+			die_errno("Could not chdir to '%s'", worktree);
+		cwd[len++] = '/';
+		cwd[len] = '\0';
+		free(gitfile);
+		return cwd + offset;
+	}
+
+	/* cwd outside worktree */
+	set_git_dir(gitdirenv);
+	free(gitfile);
+	return NULL;
+}
+
+static const char *setup_discovered_git_dir(const char *gitdir,
+					    char *cwd, int offset, int len,
+					    int *nongit_ok)
+{
+	if (check_repository_format_gently(gitdir, nongit_ok))
+		return NULL;
+
+	/* --work-tree is set without --git-dir; use discovered one */
+	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
+		if (offset != len && !is_absolute_path(gitdir))
+			gitdir = xstrdup(real_path(gitdir));
+		if (chdir(cwd))
+			die_errno("Could not come back to cwd");
+		return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
+	}
+
+	/* #16.2, #17.2, #20.2, #21.2, #24, #25, #28, #29 (see t1510) */
+	if (is_bare_repository_cfg > 0) {
+		set_git_dir(offset == len ? gitdir : real_path(gitdir));
+		if (chdir(cwd))
+			die_errno("Could not come back to cwd");
+		return NULL;
+	}
+
+	/* #0, #1, #5, #8, #9, #12, #13 */
+	set_git_work_tree(".");
+	if (strcmp(gitdir, DEFAULT_GIT_DIR_ENVIRONMENT))
+		set_git_dir(gitdir);
+	inside_git_dir = 0;
+	inside_work_tree = 1;
+	if (offset == len)
+		return NULL;
+
+	/* Make "offset" point to past the '/', and add a '/' at the end */
+	offset++;
+	cwd[len++] = '/';
+	cwd[len] = 0;
+	return cwd + offset;
+}
+
+/* #16.1, #17.1, #20.1, #21.1, #22.1 (see t1510) */
+static const char *setup_bare_git_dir(char *cwd, int offset, int len, int *nongit_ok)
+{
+	int root_len;
+
+	if (check_repository_format_gently(".", nongit_ok))
+		return NULL;
+
+	/* --work-tree is set without --git-dir; use discovered one */
+	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
+		const char *gitdir;
+
+		gitdir = offset == len ? "." : xmemdupz(cwd, offset);
+		if (chdir(cwd))
+			die_errno("Could not come back to cwd");
+		return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
+	}
+
+	inside_git_dir = 1;
+	inside_work_tree = 0;
+	if (offset != len) {
+		if (chdir(cwd))
+			die_errno("Cannot come back to cwd");
+		root_len = offset_1st_component(cwd);
+		cwd[offset > root_len ? offset : root_len] = '\0';
+		set_git_dir(cwd);
+	}
+	else
+		set_git_dir(".");
+	return NULL;
+}
+
+static const char *setup_nongit(const char *cwd, int *nongit_ok)
+{
+	if (!nongit_ok)
+		die("Not a git repository (or any of the parent directories): %s", DEFAULT_GIT_DIR_ENVIRONMENT);
+	if (chdir(cwd))
+		die_errno("Cannot come back to cwd");
+	*nongit_ok = 1;
+	return NULL;
+}
+
+static dev_t get_device_or_die(const char *path, const char *prefix)
+{
+	struct stat buf;
+	if (stat(path, &buf))
+		die_errno("failed to stat '%s%s%s'",
+				prefix ? prefix : "",
+				prefix ? "/" : "", path);
+	return buf.st_dev;
+}
+
 /*
  * We cannot decide in this function whether we are in the work tree or
  * not, since the config can only be read _after_ this function was called.
  */
-const char *setup_git_directory_gently(int *nongit_ok)
+static const char *setup_git_directory_gently_1(int *nongit_ok)
 {
-	const char *work_tree_env = getenv(GIT_WORK_TREE_ENVIRONMENT);
 	const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
 	static char cwd[PATH_MAX+1];
-	const char *gitdirenv;
-	const char *gitfile_dir;
+	const char *gitdirenv, *ret;
+	char *gitfile;
 	int len, offset, ceil_offset;
+	dev_t current_device = 0;
+	int one_filesystem = 1;
 
 	/*
 	 * Let's assume that we are in a git repository.
@@ -331,47 +601,18 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	if (nongit_ok)
 		*nongit_ok = 0;
 
+	if (!getcwd(cwd, sizeof(cwd)-1))
+		die_errno("Unable to read current working directory");
+	offset = len = strlen(cwd);
+
 	/*
 	 * If GIT_DIR is set explicitly, we're not going
 	 * to do any discovery, but we still do repository
 	 * validation.
 	 */
 	gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
-	if (gitdirenv) {
-		if (PATH_MAX - 40 < strlen(gitdirenv))
-			die("'$%s' too big", GIT_DIR_ENVIRONMENT);
-		if (is_git_directory(gitdirenv)) {
-			static char buffer[1024 + 1];
-			const char *retval;
-
-			if (!work_tree_env) {
-				retval = set_work_tree(gitdirenv);
-				/* config may override worktree */
-				if (check_repository_format_gently(nongit_ok))
-					return NULL;
-				return retval;
-			}
-			if (check_repository_format_gently(nongit_ok))
-				return NULL;
-			retval = get_relative_cwd(buffer, sizeof(buffer) - 1,
-					get_git_work_tree());
-			if (!retval || !*retval)
-				return NULL;
-			set_git_dir(make_absolute_path(gitdirenv));
-			if (chdir(work_tree_env) < 0)
-				die_errno ("Could not chdir to '%s'", work_tree_env);
-			strcat(buffer, "/");
-			return retval;
-		}
-		if (nongit_ok) {
-			*nongit_ok = 1;
-			return NULL;
-		}
-		die("Not a git repository: '%s'", gitdirenv);
-	}
-
-	if (!getcwd(cwd, sizeof(cwd)-1))
-		die_errno("Unable to read current working directory");
+	if (gitdirenv)
+		return setup_explicit_git_dir(gitdirenv, cwd, len, nongit_ok);
 
 	ceil_offset = longest_ancestor_length(cwd, env_ceiling_dirs);
 	if (ceil_offset < 0 && has_dos_drive_prefix(cwd))
@@ -388,56 +629,69 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	 * - ../../.git/
 	 *   etc.
 	 */
-	offset = len = strlen(cwd);
+	one_filesystem = !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0);
+	if (one_filesystem)
+		current_device = get_device_or_die(".", NULL);
 	for (;;) {
-		gitfile_dir = read_gitfile_gently(DEFAULT_GIT_DIR_ENVIRONMENT);
-		if (gitfile_dir) {
-			if (set_git_dir(gitfile_dir))
-				die("Repository setup failed");
-			break;
+		gitfile = (char*)read_gitfile(DEFAULT_GIT_DIR_ENVIRONMENT);
+		if (gitfile)
+			gitdirenv = gitfile = xstrdup(gitfile);
+		else {
+			if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
+				gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
 		}
-		if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
-			break;
-		if (is_git_directory(".")) {
-			inside_git_dir = 1;
-			if (!work_tree_env)
-				inside_work_tree = 0;
-			if (offset != len) {
-				cwd[offset] = '\0';
-				set_git_dir(cwd);
-			} else
-				set_git_dir(".");
-			check_repository_format_gently(nongit_ok);
-			return NULL;
+
+		if (gitdirenv) {
+			ret = setup_discovered_git_dir(gitdirenv,
+						       cwd, offset, len,
+						       nongit_ok);
+			free(gitfile);
+			return ret;
 		}
+		free(gitfile);
+
+		if (is_git_directory("."))
+			return setup_bare_git_dir(cwd, offset, len, nongit_ok);
+
 		while (--offset > ceil_offset && cwd[offset] != '/');
-		if (offset <= ceil_offset) {
-			if (nongit_ok) {
-				if (chdir(cwd))
-					die_errno("Cannot come back to cwd");
-				*nongit_ok = 1;
-				return NULL;
+		if (offset <= ceil_offset)
+			return setup_nongit(cwd, nongit_ok);
+		if (one_filesystem) {
+			dev_t parent_device = get_device_or_die("..", cwd);
+			if (parent_device != current_device) {
+				if (nongit_ok) {
+					if (chdir(cwd))
+						die_errno("Cannot come back to cwd");
+					*nongit_ok = 1;
+					return NULL;
+				}
+				cwd[offset] = '\0';
+				die("Not a git repository (or any parent up to mount parent %s)\n"
+				"Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).", cwd);
 			}
-			die("Not a git repository (or any of the parent directories): %s", DEFAULT_GIT_DIR_ENVIRONMENT);
 		}
-		if (chdir(".."))
+		if (chdir("..")) {
+			cwd[offset] = '\0';
 			die_errno("Cannot change to '%s/..'", cwd);
+		}
 	}
+}
 
-	inside_git_dir = 0;
-	if (!work_tree_env)
-		inside_work_tree = 1;
-	git_work_tree_cfg = xstrndup(cwd, offset);
-	if (check_repository_format_gently(nongit_ok))
-		return NULL;
-	if (offset == len)
-		return NULL;
+const char *setup_git_directory_gently(int *nongit_ok)
+{
+	const char *prefix;
 
-	/* Make "offset" point to past the '/', and add a '/' at the end */
-	offset++;
-	cwd[len++] = '/';
-	cwd[len] = 0;
-	return cwd + offset;
+	prefix = setup_git_directory_gently_1(nongit_ok);
+	if (prefix)
+		setenv("GIT_PREFIX", prefix, 1);
+	else
+		setenv("GIT_PREFIX", "", 1);
+
+	if (startup_info) {
+		startup_info->have_repository = !nongit_ok || !*nongit_ok;
+		startup_info->prefix = prefix;
+	}
+	return prefix;
 }
 
 int git_config_perm(const char *var, const char *value)
@@ -513,24 +767,23 @@ int check_repository_format_version(const char *var, const char *value, void *cb
 
 int check_repository_format(void)
 {
-	return check_repository_format_gently(NULL);
+	return check_repository_format_gently(get_git_dir(), NULL);
 }
 
+/*
+ * Returns the "prefix", a path to the current working directory
+ * relative to the work tree root, or NULL, if the current working
+ * directory is not a strict subdirectory of the work tree root. The
+ * prefix always ends with a '/' character.
+ */
 const char *setup_git_directory(void)
 {
-	const char *retval = setup_git_directory_gently(NULL);
-
-	/* If the work tree is not the default one, recompute prefix */
-	if (inside_work_tree < 0) {
-		static char buffer[PATH_MAX + 1];
-		char *rel;
-		if (retval && chdir(retval))
-			die_errno ("Could not jump back into original cwd");
-		rel = get_relative_cwd(buffer, PATH_MAX, get_git_work_tree());
-		if (rel && *rel && chdir(get_git_work_tree()))
-			die_errno ("Could not jump to working directory");
-		return rel && *rel ? strcat(rel, "/") : NULL;
-	}
+	return setup_git_directory_gently(NULL);
+}
 
-	return retval;
+const char *resolve_gitdir(const char *suspect)
+{
+	if (is_git_directory(suspect))
+		return suspect;
+	return read_gitfile(suspect);
 }