add --html-path to get the location of installed HTML docs

This can be used in GUIs to open installed HTML documentation in the
browser.

Signed-off-by: Markus Heidelberg <markus.heidelberg@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 7513c57..2ce5e6b 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -9,7 +9,7 @@
 SYNOPSIS
 --------
 [verse]
-'git' [--version] [--exec-path[=GIT_EXEC_PATH]]
+'git' [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path]
     [-p|--paginate|--no-pager]
     [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE]
     [--help] COMMAND [ARGS]
@@ -178,6 +178,10 @@
 	environment variable. If no path is given, 'git' will print
 	the current setting and then exit.
 
+--html-path::
+	Print the path to wherever your git HTML documentation is installed
+	and exit.
+
 -p::
 --paginate::
 	Pipe all output into 'less' (or if set, $PAGER).
diff --git a/Makefile b/Makefile
index 7867eac..bcf7cbb 100644
--- a/Makefile
+++ b/Makefile
@@ -1191,6 +1191,7 @@
 
 git.o: git.c common-cmds.h GIT-CFLAGS
 	$(QUIET_CC)$(CC) -DGIT_VERSION='"$(GIT_VERSION)"' \
+		'-DGIT_HTML_PATH="$(htmldir_SQ)"' \
 		$(ALL_CFLAGS) -c $(filter %.c,$^)
 
 git$X: git.o $(BUILTIN_OBJS) $(GITLIBS)
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index e72ce24..fdc5a24 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1870,6 +1870,7 @@
 			--bare
 			--version
 			--exec-path
+			--html-path
 			--work-tree=
 			--help
 			"
diff --git a/git.c b/git.c
index c2b181e..ff72e22 100644
--- a/git.c
+++ b/git.c
@@ -5,7 +5,7 @@
 #include "run-command.h"
 
 const char git_usage_string[] =
-	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
+	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
 
 const char git_more_info_string[] =
 	"See 'git help COMMAND' for more information on a specific command.";
@@ -75,6 +75,9 @@
 				puts(git_exec_path());
 				exit(0);
 			}
+		} else if (!strcmp(cmd, "--html-path")) {
+			puts(system_path(GIT_HTML_PATH));
+			exit(0);
 		} else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
 			use_pager = 1;
 		} else if (!strcmp(cmd, "--no-pager")) {
diff --git a/perl/Git.pm b/perl/Git.pm
index 7d7f2b1..291ff5b 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -56,7 +56,7 @@
 @EXPORT_OK = qw(command command_oneline command_noisy
                 command_output_pipe command_input_pipe command_close_pipe
                 command_bidi_pipe command_close_bidi_pipe
-                version exec_path hash_object git_cmd_try
+                version exec_path html_path hash_object git_cmd_try
                 remote_refs
                 temp_acquire temp_release temp_reset temp_path);
 
@@ -492,6 +492,16 @@
 sub exec_path { command_oneline('--exec-path') }
 
 
+=item html_path ()
+
+Return path to the Git html documentation (the same as
+C<git --html-path>). Useful mostly only internally.
+
+=cut
+
+sub html_path { command_oneline('--html-path') }
+
+
 =item repo_path ()
 
 Return path to the git repository. Must be called on a repository instance.