[PATCH 4/9] Make setup_work_tree() return new prefix

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

worktree setup inside setup_git_directory*() is not perfect. It does
not take core.worktree into account. So when you do setup_work_tree(),
the real work tree may be not the one setup_git_directory*() gives you.
You need a new prefix in that case.

This also effectively reverts dd5c8af (Fix
setup_git_directory_gently() with relative GIT_DIR & GIT_WORK_TREE).
The problem is IMHO that git-diff does not setup worktree when it
needs it, so setting up worktree from setup_git_directory_gently() is
a fix in a wrong place.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin-blame.c      |    4 +-
 builtin-diff-files.c |    4 ++-
 builtin-diff.c       |    4 ++-
 builtin-ls-files.c   |    8 ++--
 builtin-read-tree.c  |    2 +-
 builtin-rev-parse.c  |    2 +
 builtin-rm.c         |    2 +-
 cache.h              |    2 +-
 git.c                |    2 +-
 setup.c              |   84 ++++++++++++++++----------------------------------
 10 files changed, 45 insertions(+), 69 deletions(-)

diff --git a/builtin-blame.c b/builtin-blame.c
index bfd562d..f5a878b 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -2291,6 +2291,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 			/* (3) */
 			if (argc <= i)
 				usage(blame_usage);
+			prefix = setup_work_tree(prefix);
 			path = add_prefix(prefix, argv[i]);
 			if (i + 1 == argc - 1) {
 				final_commit_name = argv[i + 1];
@@ -2306,7 +2307,6 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 			else if (i != argc - 1)
 				usage(blame_usage); /* garbage at end */
 
-			setup_work_tree();
 			if (!has_path_in_work_tree(path))
 				die("cannot stat path %s: %s",
 				    path, strerror(errno));
@@ -2354,7 +2354,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		 * do not default to HEAD, but use the working tree
 		 * or "--contents".
 		 */
-		setup_work_tree();
+		setup_work_tree(prefix);
 		sb.final = fake_working_tree_commit(path, contents_from);
 		add_pending_object(&revs, &(sb.final->object), ":");
 	}
diff --git a/builtin-diff-files.c b/builtin-diff-files.c
index 4abe3c2..11671a8 100644
--- a/builtin-diff-files.c
+++ b/builtin-diff-files.c
@@ -26,8 +26,10 @@ int cmd_diff_files(int argc, const char **argv, const char *prefix)
 
 	if (!setup_diff_no_index(&rev, argc, argv, nongit, prefix))
 		argc = 0;
-	else
+	else {
+		rev.prefix = setup_work_tree(prefix);
 		argc = setup_revisions(argc, argv, &rev, NULL);
+	}
 	if (!rev.diffopt.output_format)
 		rev.diffopt.output_format = DIFF_FORMAT_RAW;
 	result = run_diff_files_cmd(&rev, argc, argv);
diff --git a/builtin-diff.c b/builtin-diff.c
index 444ff2f..254e5a0 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -244,8 +244,10 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 
 	if (!setup_diff_no_index(&rev, argc, argv, nongit, prefix))
 		argc = 0;
-	else
+	else {
+		rev.prefix = setup_work_tree(prefix);
 		argc = setup_revisions(argc, argv, &rev, NULL);
+	}
 	if (!rev.diffopt.output_format) {
 		rev.diffopt.output_format = DIFF_FORMAT_PATCH;
 		if (diff_setup_done(&rev.diffopt) < 0)
diff --git a/builtin-ls-files.c b/builtin-ls-files.c
index 25dbfb4..cf4c492 100644
--- a/builtin-ls-files.c
+++ b/builtin-ls-files.c
@@ -23,7 +23,7 @@ static int show_valid_bit;
 static int line_terminator = '\n';
 
 static int prefix_len;
-static int prefix_offset;
+static int prefix_offset = -1;
 static const char **pathspec;
 static int error_unmatch;
 static char *ps_matched;
@@ -435,8 +435,6 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 	struct dir_struct dir;
 
 	memset(&dir, 0, sizeof(dir));
-	if (prefix)
-		prefix_offset = strlen(prefix);
 	git_config(git_default_config);
 
 	for (i = 1; i < argc; i++) {
@@ -569,7 +567,9 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 	}
 
 	if (require_work_tree && !is_inside_work_tree())
-		setup_work_tree();
+		prefix = setup_work_tree(prefix);
+	if (prefix_offset == -1)
+		prefix_offset = prefix ? strlen(prefix) : 0;
 
 	pathspec = get_pathspec(prefix, argv + i);
 
diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 95318e3..0a398f9 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -220,7 +220,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		die("--exclude-per-directory is meaningless unless -u");
 
 	if (opts.merge)
-		setup_work_tree();
+		setup_work_tree(NULL);
 
 	if (opts.prefix) {
 		int pfxlen = strlen(opts.prefix);
diff --git a/builtin-rev-parse.c b/builtin-rev-parse.c
index 651b5e6..e82cac2 100644
--- a/builtin-rev-parse.c
+++ b/builtin-rev-parse.c
@@ -472,6 +472,8 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 				continue;
 			}
 			if (!strcmp(arg, "--show-prefix")) {
+				if (is_inside_work_tree())
+					prefix = setup_work_tree(prefix);
 				if (prefix)
 					puts(prefix);
 				continue;
diff --git a/builtin-rm.c b/builtin-rm.c
index c0a8bb6..2c15d66 100644
--- a/builtin-rm.c
+++ b/builtin-rm.c
@@ -156,7 +156,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 		usage_with_options(builtin_rm_usage, builtin_rm_options);
 
 	if (!index_only)
-		setup_work_tree();
+		prefix = setup_work_tree(prefix);
 
 	pathspec = get_pathspec(prefix, argv);
 	seen = NULL;
diff --git a/cache.h b/cache.h
index a5b9ffd..dc768db 100644
--- a/cache.h
+++ b/cache.h
@@ -282,7 +282,7 @@ extern const char *get_git_work_tree(void);
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
 extern const char **get_pathspec(const char *prefix, const char **pathspec);
-extern void setup_work_tree(void);
+extern const char *setup_work_tree(const char *prefix);
 extern const char *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
 extern const char *prefix_path(const char *prefix, int len, const char *path);
diff --git a/git.c b/git.c
index 4f804a2..90451ee 100644
--- a/git.c
+++ b/git.c
@@ -252,7 +252,7 @@ static int run_command(struct cmd_struct *p, int argc, const char **argv)
 	if (p->option & USE_PAGER)
 		setup_pager();
 	if (p->option & NEED_WORK_TREE)
-		setup_work_tree();
+		prefix = setup_work_tree(prefix);
 
 	trace_argv_printf(argv, "trace: built-in: git");
 
diff --git a/setup.c b/setup.c
index 89c81e5..6c908a5 100644
--- a/setup.c
+++ b/setup.c
@@ -262,38 +262,23 @@ int is_inside_work_tree(void)
 	return inside_work_tree;
 }
 
-/*
- * set_work_tree() is only ever called if you set GIT_DIR explicitely.
- * 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 *setup_work_tree(const char *prefix)
 {
-	const char *work_tree, *git_dir;
-	static int initialized = 0;
+	const char *work_tree;
+	static char buffer[PATH_MAX + 1];
+	char *rel;
 
-	if (initialized)
-		return;
+	get_git_dir(); /* ensure git_dir has been initialized as cwd will change */
 	work_tree = get_git_work_tree();
-	git_dir = get_git_dir();
-	if (!is_absolute_path(git_dir))
-		set_git_dir(make_absolute_path(git_dir));
-	if (!work_tree || chdir(work_tree))
+	if (!work_tree)
 		die("This operation must be run in a work tree");
-	initialized = 1;
+	if (prefix && chdir(prefix))
+		die ("Could not jump back into original cwd");
+	rel = get_relative_cwd(buffer, PATH_MAX, work_tree);
+	trace_printf("test: worktree = %s\n", rel ? rel : "NULL");
+	if (chdir(work_tree))
+		die("This operation must be run in a work tree");
+	return rel && *rel ? strcat(rel, "/") : NULL;
 }
 
 static int check_repository_format_gently(int *nongit_ok)
@@ -336,24 +321,21 @@ const char *setup_git_directory_gently(int *nongit_ok)
 			static char buffer[1024 + 1];
 			const char *retval;
 
+			/*
+			 * 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.
+			 */
 			if (!work_tree_env) {
-				retval = set_work_tree(gitdirenv);
-				/* config may override worktree */
-				if (check_repository_format_gently(nongit_ok))
-					return NULL;
-				return retval;
+				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;
 			}
-			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 ("Could not chdir to %s", work_tree_env);
-			strcat(buffer, "/");
-			return retval;
+			check_repository_format_gently(nongit_ok);
+			return NULL;
 		}
 		if (nongit_ok) {
 			*nongit_ok = 1;
@@ -462,17 +444,5 @@ int check_repository_format(void)
 
 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 ("Could not jump back into original cwd");
-		rel = get_relative_cwd(buffer, PATH_MAX, get_git_work_tree());
-		return rel && *rel ? strcat(rel, "/") : NULL;
-	}
-
-	return retval;
+	return setup_git_directory_gently(NULL);
 }
-- 
1.5.4.2.281.g28d0e