[PATCH 02/24] gitweb: Prepare for splitting gitweb

[Jakub Narebski <jnareb@gmail.com>]

Prepare gitweb for having been split into modules that are to be
installed alongside gitweb in 'lib/' subdirectory, by adding

  use lib __DIR__.'/lib';

to gitweb.perl (to main gitweb script), and preparing for putting
modules (relative path) in $(GITWEB_MODULES) in gitweb/Makefile.

This preparatory work allows to add new module to gitweb by simply
adding

  GITWEB_MODULES += <module>

to gitweb/Makefile (assuming that the module is in 'gitweb/lib/'
directory).

While at it pass GITWEBLIBDIR in addition to GITWEB_TEST_INSTALLED to
allow testing installed version of gitweb and installed version of
modules (for future tests which would check individual (sub)modules).


Using __DIR__ from Dir::Self module (not in core, that's why currently
gitweb includes excerpt of code from Dir::Self defining __DIR__) was
chosen over using FindBin-based solution (in core since perl 5.00307,
while gitweb itself requires at least perl 5.8.0) because FindBin uses
BEGIN block, which is a problem under mod_perl and other persistent
Perl environments (thought there are workarounds).

At Pavan Kumar Sankara suggestion gitweb/Makefile uses

  install [OPTION]... SOURCE... DIRECTORY

format (2nd format) with single SOURCE rather than

  install [OPTION]... SOURCE DEST

format (1st format) because of security reasons (race conditions).
Modern GNU install has `-T' / `--no-target-directory' option, but we
cannot rely that the $(INSTALL) we are using supports this option.

The install-modules target in gitweb/Makefile uses shell 'for' loop,
instead of make's $(foreach) function, to avoid possible problem with
generating a command line that exceeded the maximum argument list
length.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
In previous version there was a BUG: shell variables should not be in
single quotes.

This is fixed version, the same as in

  [PATCHv7.4 0/4] Gitweb caching v7.4
  Message-ID: <1291404335-25541-1-git-send-email-jnareb@gmail.com>
  http://thread.gmane.org/gmane.comp.version-control.git/162830

series, which are a bit fixed up and a tiny bit cleaned up version of
"Gitweb caching v7" series from John 'Warthog9' Hawley:

  http://thread.gmane.org/gmane.comp.version-control.git/160147


Sidenote: this patch can serve as a way to introduce infrastructure
required for splitting gitweb into modules for better maintability.
This issue was to be first part (first milestone) for "Integrated web
client for git" GSoC2010 project by Pavan Kumar Sankara (with Christian
Couder as mentor, and Petr 'Pasky' Baudis as co-mentor)... which
unfortunately failed middterm evaluations.

As you can see later in series it makes it very easy to add new gitweb
modules which are to be installed.  Just add

  GITWEB_MODULES += Module/Foo.pm

to gitweb/Makefile for Module::Foo (present in gitweb/lib/Module/Foo.pm)
and 'install-gitweb' target would automatically install it along with
gitweb.



 gitweb/Makefile    |   17 +++++++++++++++--
 gitweb/gitweb.perl |    8 ++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/gitweb/Makefile b/gitweb/Makefile
index 0a6ac00..e6029e1 100644
--- a/gitweb/Makefile
+++ b/gitweb/Makefile
@@ -57,6 +57,7 @@ PERL_PATH  ?= /usr/bin/perl
 bindir_SQ = $(subst ','\'',$(bindir))#'
 gitwebdir_SQ = $(subst ','\'',$(gitwebdir))#'
 gitwebstaticdir_SQ = $(subst ','\'',$(gitwebdir)/static)#'
+gitweblibdir_SQ = $(subst ','\'',$(gitwebdir)/lib)#'
 SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))#'
 PERL_PATH_SQ  = $(subst ','\'',$(PERL_PATH))#'
 DESTDIR_SQ    = $(subst ','\'',$(DESTDIR))#'
@@ -153,20 +154,32 @@ test:
 
 test-installed:
 	GITWEB_TEST_INSTALLED='$(DESTDIR_SQ)$(gitwebdir_SQ)' \
+	GITWEBLIBDIR='$(DESTDIR_SQ)$(gitweblibdir_SQ)' \
 		$(MAKE) -C ../t gitweb-test
 
 ### Installation rules
 
-install: all
+install: all install-modules
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(gitwebdir_SQ)'
 	$(INSTALL) -m 755 $(GITWEB_PROGRAMS) '$(DESTDIR_SQ)$(gitwebdir_SQ)'
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(gitwebstaticdir_SQ)'
 	$(INSTALL) -m 644 $(GITWEB_FILES) '$(DESTDIR_SQ)$(gitwebstaticdir_SQ)'
 
+install-modules:
+	install_dirs="$(sort $(dir $(GITWEB_MODULES)))" && \
+	for dir in $$install_dirs; do \
+		test -d '$(DESTDIR_SQ)$(gitweblibdir_SQ)'/"$$dir" || \
+		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(gitweblibdir_SQ)'/"$$dir"; \
+	done
+	gitweb_modules="$(GITWEB_MODULES)" && \
+	for mod in $$gitweb_modules; do \
+		$(INSTALL) -m 644 "lib/$$mod" '$(DESTDIR_SQ)$(gitweblibdir_SQ)'/"$$(dirname $$mod)"; \
+	done
+
 ### Cleaning rules
 
 clean:
 	$(RM) gitweb.cgi static/gitweb.min.js static/gitweb.min.css GITWEB-BUILD-OPTIONS
 
-.PHONY: all clean install test test-installed .FORCE-GIT-VERSION-FILE FORCE
+.PHONY: all clean install install-modules test test-installed .FORCE-GIT-VERSION-FILE FORCE
 
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 679f2da..cfa511c 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -10,6 +10,14 @@
 use 5.008;
 use strict;
 use warnings;
+
+use File::Spec;
+# __DIR__ is taken from Dir::Self __DIR__ fragment
+sub __DIR__ () {
+	File::Spec->rel2abs(join '', (File::Spec->splitpath(__FILE__))[0, 1]);
+}
+use lib __DIR__ . '/lib';
+
 use CGI qw(:standard :escapeHTML -nosticky);
 use CGI::Util qw(unescape);
 use CGI::Carp qw(fatalsToBrowser set_message);
-- 
1.7.3