Let git-help prefer man-pages installed with this version of git

Prepend $(prefix)/share/man to the MANPATH environment variable before
invoking 'man' from help.c:show_man_page().  There may be other git
documentation in the user's MANPATH but the user is asking a specific
instance of git about its own documentation, so we'd better show the
documentation for _that_ instance of git.

Signed-off-by: Sergei Organov <osv@javad.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/help.c b/help.c
index 37a9c25db..f935887d3 100644
--- a/help.c
+++ b/help.c
@@ -239,6 +239,27 @@ void list_common_cmds_help(void)
 	}
 }
 
+static void setup_man_path(void)
+{
+	struct strbuf new_path;
+	const char *old_path = getenv("MANPATH");
+
+	strbuf_init(&new_path, 0);
+
+	/* We should always put ':' after our path. If there is no
+	 * old_path, the ':' at the end will let 'man' to try
+	 * system-wide paths after ours to find the manual page. If
+	 * there is old_path, we need ':' as delimiter. */
+	strbuf_addstr(&new_path, GIT_MAN_PATH);
+	strbuf_addch(&new_path, ':');
+	if (old_path)
+		strbuf_addstr(&new_path, old_path);
+
+	setenv("MANPATH", new_path.buf, 1);
+
+	strbuf_release(&new_path);
+}
+
 static void show_man_page(const char *git_cmd)
 {
 	const char *page;
@@ -254,6 +275,7 @@ static void show_man_page(const char *git_cmd)
 		page = p;
 	}
 
+	setup_man_path();
 	execlp("man", "man", page, NULL);
 }