web--browse: use custom commands defined at config time

Currently "git web--browse" is restricted to a set of commands defined
in the script. You can subvert the "browser.<tool>.path" to force "git
web--browse" to use a different command, but if you have a command
whose invocation syntax does not match one of the current tools then
you would have to write a wrapper script for it.

This patch adds a git config variable "browser.<tool>.cmd" which
allows a more flexible browser choice.

If you run "git web--browse" with -t/--tool, -b/--browser or the
"web.browser" config variable set to an unrecognized tool then "git
web--browse" will query the "browser.<tool>.cmd" config variable. If
this variable exists, then "git web--browse" will treat the specified
tool as a custom command and will use a shell eval to run the command
with the URLs added as extra parameters.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-web--browse.sh

@@ -23,12 +23,18 @@ USAGE='[--browser=browser|--tool=browser] [--config=conf.var] url/file ...'
 NONGIT_OK=Yes
 . git-sh-setup
 
+valid_custom_tool()
+{
+	browser_cmd="$(git config "browser.$1.cmd")"
+	test -n "$browser_cmd"
+}
+
 valid_tool() {
 	case "$1" in
 		firefox | iceweasel | konqueror | w3m | links | lynx | dillo | open)
 			;; # happy
 		*)
-			return 1
+			valid_custom_tool "$1" || return 1
 			;;
 	esac
 }
@@ -122,7 +128,7 @@ else
 
     init_browser_path "$browser"
 
-    if ! type "$browser_path" > /dev/null 2>&1; then
+    if test -z "$browser_cmd" && ! type "$browser_path" > /dev/null 2>&1; then
 	die "The browser $browser is not available as '$browser_path'."
     fi
 fi
@@ -157,4 +163,9 @@ case "$browser" in
     dillo)
 	"$browser_path" "$@" &
 	;;
+    *)
+	if test -n "$browser_cmd"; then
+	    ( eval $browser_cmd "$@" )
+	fi
+	;;
 esac