From c206275096c683fb6e5fc5adef28c44d1415833b Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Fri, 28 Jul 2017 15:25:45 -0400
Subject: connect: factor out "looks like command line option" check

We reject hostnames that start with a dash because they may
be confused for command-line options. Let's factor out that
notion into a helper function, as we'll use it in more
places. And while it's simple now, it's not clear if some
systems might need more complex logic to handle all cases.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 cache.h   | 8 ++++++++
 connect.c | 2 +-
 path.c    | 5 +++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/cache.h b/cache.h
index a50a61a197..4a537d686d 100644
--- a/cache.h
+++ b/cache.h
@@ -1076,6 +1076,14 @@ char *strip_path_suffix(const char *path, const char *suffix);
 int daemon_avoid_alias(const char *path);
 extern int is_ntfs_dotgit(const char *name);
 
+/*
+ * Returns true iff "str" could be confused as a command-line option when
+ * passed to a sub-program like "ssh". Note that this has nothing to do with
+ * shell-quoting, which should be handled separately; we're assuming here that
+ * the string makes it verbatim to the sub-program.
+ */
+int looks_like_command_line_option(const char *str);
+
 /**
  * Return a newly allocated string with the evaluation of
  * "$XDG_CONFIG_HOME/git/$filename" if $XDG_CONFIG_HOME is non-empty, otherwise
diff --git a/connect.c b/connect.c
index 27dafb48cf..378dfaae1c 100644
--- a/connect.c
+++ b/connect.c
@@ -791,7 +791,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 				return NULL;
 			}
 
-			if (ssh_host[0] == '-')
+			if (looks_like_command_line_option(ssh_host))
 				die("strange hostname '%s' blocked", ssh_host);
 
 			ssh = get_ssh_command();
diff --git a/path.c b/path.c
index 52d889c88e..4c054037cc 100644
--- a/path.c
+++ b/path.c
@@ -1252,6 +1252,11 @@ int is_ntfs_dotgit(const char *name)
 		}
 }
 
+int looks_like_command_line_option(const char *str)
+{
+	return str && str[0] == '-';
+}
+
 char *xdg_config_home(const char *filename)
 {
 	const char *home, *config_home;
-- 
2.14.0.434.g98096fd7a8