Enable highlight executable path as a configuration option

Allow build-time/run-time configuration of the highlight executable
(must be the one from http://www.andre-simon.de due to assumptions
about parameters and output).  Defaults to previous behavior which
assumes that highlight is available on the server PATH. However, if
this is not the case, the path to the highlight executable can be
configured at build time as a configuration variable

    HIGHLIGHT_BIN = /path/to/highlight

or at runtime by configuring GITWEB_CONFIG

    $highlight_bin = /path/to/highlight

Signed-off-by: Christopher Wilson <cwilson@cdwilson.us>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/Makefile

@@ -35,6 +35,7 @@ GITWEB_FAVICON = static/git-favicon.png
 GITWEB_JS = static/gitweb.js
 GITWEB_SITE_HEADER =
 GITWEB_SITE_FOOTER =
+HIGHLIGHT_BIN = highlight
 
 # include user config
 -include ../config.mak.autogen
@@ -129,7 +130,8 @@ GITWEB_REPLACE = \
 	-e 's|++GITWEB_FAVICON++|$(GITWEB_FAVICON)|g' \
 	-e 's|++GITWEB_JS++|$(GITWEB_JS)|g' \
 	-e 's|++GITWEB_SITE_HEADER++|$(GITWEB_SITE_HEADER)|g' \
-	-e 's|++GITWEB_SITE_FOOTER++|$(GITWEB_SITE_FOOTER)|g'
+	-e 's|++GITWEB_SITE_FOOTER++|$(GITWEB_SITE_FOOTER)|g' \
+	-e 's|++HIGHLIGHT_BIN++|$(HIGHLIGHT_BIN)|g'
 
 GITWEB-BUILD-OPTIONS: FORCE
 	@rm -f $@+

gitweb/README

@@ -114,6 +114,11 @@ You can specify the following configuration variables when building GIT:
    when gitweb.cgi is executed, then the file specified in the environment
    variable will be loaded instead of the file specified when gitweb.cgi was
    created.  [Default: /etc/gitweb.conf]
+ * HIGHLIGHT_BIN
+   Path to the highlight executable to use (must be the one from
+   http://www.andre-simon.de due to assumptions about parameters and output).
+   Useful if highlight is not installed on your webserver's PATH.
+   [Default: highlight]
 
 
 Runtime gitweb configuration
@@ -236,7 +241,11 @@ not include variables usually directly set during build):
    If server load exceed this value then return "503 Service Unavailable" error.
    Server load is taken to be 0 if gitweb cannot determine its value.  Set it to
    undefined value to turn it off.  The default is 300.
-
+ * $highlight_bin
+   Path to the highlight executable to use (must be the one from
+   http://www.andre-simon.de due to assumptions about parameters and output).
+   Useful if highlight is not installed on your webserver's PATH.
+   [Default: highlight]
 
 Projects list file format
 ~~~~~~~~~~~~~~~~~~~~~~~~~

gitweb/gitweb.perl

@@ -165,6 +165,12 @@ our @diff_opts = ('-M'); # taken from git_commit
 # the gitweb domain.
 our $prevent_xss = 0;
 
+# Path to the highlight executable to use (must be the one from
+# http://www.andre-simon.de due to assumptions about parameters and output).
+# Useful if highlight is not installed on your webserver's PATH.
+# [Default: highlight]
+our $highlight_bin = "++HIGHLIGHT_BIN++";
+
 # information about snapshot formats that gitweb is capable of serving
 our %known_snapshot_formats = (
 	# name => {
@@ -3360,7 +3366,8 @@ sub run_highlighter {
 	close $fd
 		or die_error(404, "Reading blob failed");
 	open $fd, quote_command(git_cmd(), "cat-file", "blob", $hash)." | ".
-	          "highlight --xhtml --fragment --syntax $syntax |"
+	          quote_command($highlight_bin).
+	          " --xhtml --fragment --syntax $syntax |"
 		or die_error(500, "Couldn't open file or run syntax highlighter");
 	return $fd;
 }