Merge branch 'nr/git-cd-to-a-directory'

Just like "make -C <directory>", make "git -C <directory> ..." to
go there before doing anything else.

* nr/git-cd-to-a-directory:
  t0056: "git -C" test updates
  git: run in a directory given with -C option

Documentation/git.txt

@@ -9,7 +9,7 @@ git - the stupid content tracker
 SYNOPSIS
 --------
 [verse]
-'git' [--version] [--help] [-c <name>=<value>]
+'git' [--version] [--help] [-C <path>] [-c <name>=<value>]
     [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
     [-p|--paginate|--no-pager] [--no-replace-objects] [--bare]
     [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]
@@ -395,6 +395,20 @@ displayed. See linkgit:git-help[1] for more information,
 because `git --help ...` is converted internally into `git
 help ...`.
 
+-C <path>::
+	Run as if git was started in '<path>' instead of the current working
+	directory.  When multiple `-C` options are given, each subsequent
+	non-absolute `-C <path>` is interpreted relative to the preceding `-C
+	<path>`.
++
+This option affects options that expect path name like `--git-dir` and
+`--work-tree` in that their interpretations of the path names would be
+made relative to the working directory caused by the `-C` option. For
+example the following invocations are equivalent:
+
+    git --git-dir=a.git --work-tree=b -C c status
+    git --git-dir=c/a.git --work-tree=c/b status
+
 -c <name>=<value>::
 	Pass a configuration parameter to the command. The value
 	given will override values from configuration files.

git.c

@@ -7,7 +7,7 @@
 #include "commit.h"
 
 const char git_usage_string[] =
-	"git [--version] [--help] [-c name=value]\n"
+	"git [--version] [--help] [-C <path>] [-c name=value]\n"
 	"           [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
 	"           [-p|--paginate|--no-pager] [--no-replace-objects] [--bare]\n"
 	"           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
@@ -165,6 +165,17 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			set_alternate_shallow_file((*argv)[0]);
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "-C")) {
+			if (*argc < 2) {
+				fprintf(stderr, "No directory given for -C.\n" );
+				usage(git_usage_string);
+			}
+			if (chdir((*argv)[1]))
+				die_errno("Cannot change to '%s'", (*argv)[1]);
+			if (envchanged)
+				*envchanged = 1;
+			(*argv)++;
+			(*argc)--;
 		} else {
 			fprintf(stderr, "Unknown option: %s\n", cmd);
 			usage(git_usage_string);

t/t0056-git-C.sh

@@ -0,0 +1,84 @@
+#!/bin/sh
+
+test_description='"-C <path>" option and its effects on other path-related options'
+
+. ./test-lib.sh
+
+test_expect_success '"git -C <path>" runs git from the directory <path>' '
+	test_create_repo dir1 &&
+	echo 1 >dir1/a.txt &&
+	msg="initial in dir1" &&
+	(cd dir1 && git add a.txt && git commit -m "$msg") &&
+	echo "$msg" >expected &&
+	git -C dir1 log --format=%s >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Multiple -C options: "-C dir1 -C dir2" is equivalent to "-C dir1/dir2"' '
+	test_create_repo dir1/dir2 &&
+	echo 1 >dir1/dir2/b.txt &&
+	git -C dir1/dir2 add b.txt &&
+	msg="initial in dir1/dir2" &&
+	echo "$msg" >expected &&
+	git -C dir1/dir2 commit -m "$msg" &&
+	git -C dir1 -C dir2 log --format=%s >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Effect on --git-dir option: "-C c --git-dir=a.git" is equivalent to "--git-dir c/a.git"' '
+	mkdir c &&
+	mkdir c/a &&
+	mkdir c/a.git &&
+	(cd c/a.git && git init --bare) &&
+	echo 1 >c/a/a.txt &&
+	git --git-dir c/a.git --work-tree=c/a add a.txt &&
+	git --git-dir c/a.git --work-tree=c/a commit -m "initial" &&
+	git --git-dir=c/a.git log -1 --format=%s >expected &&
+	git -C c --git-dir=a.git log -1 --format=%s >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Order should not matter: "--git-dir=a.git -C c" is equivalent to "-C c --git-dir=a.git"' '
+	git -C c --git-dir=a.git log -1 --format=%s >expected &&
+	git --git-dir=a.git -C c log -1 --format=%s >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Effect on --work-tree option: "-C c/a.git --work-tree=../a"  is equivalent to "--work-tree=c/a --git-dir=c/a.git"' '
+	rm c/a/a.txt &&
+	git --git-dir=c/a.git --work-tree=c/a status >expected &&
+	git -C c/a.git --work-tree=../a status >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Order should not matter: "--work-tree=../a -C c/a.git" is equivalent to "-C c/a.git --work-tree=../a"' '
+	git -C c/a.git --work-tree=../a status >expected &&
+	git --work-tree=../a -C c/a.git status >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Effect on --git-dir and --work-tree options - "-C c --git-dir=a.git --work-tree=a" is equivalent to "--git-dir=c/a.git --work-tree=c/a"' '
+	git --git-dir=c/a.git --work-tree=c/a status >expected &&
+	git -C c --git-dir=a.git --work-tree=a status >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Order should not matter: "-C c --git-dir=a.git --work-tree=a" is equivalent to "--git-dir=a.git -C c --work-tree=a"' '
+	git -C c --git-dir=a.git --work-tree=a status >expected &&
+	git --git-dir=a.git -C c --work-tree=a status >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Order should not matter: "-C c --git-dir=a.git --work-tree=a" is equivalent to "--git-dir=a.git --work-tree=a -C c"' '
+	git -C c --git-dir=a.git --work-tree=a status >expected &&
+	git --git-dir=a.git --work-tree=a -C c status >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'Relative followed by fullpath: "-C ./here -C /there" is equivalent to "-C /there"' '
+	echo "initial in dir1/dir2" >expected &&
+	git -C dir1 -C "$(pwd)/dir1/dir2" log --format=%s >actual &&
+	test_cmp expected actual
+'
+
+test_done