Mercurial: The Definitive Guide

MQ Cookbook

Managing “Trivial” Patches

Because the overhead of dropping files into a new Mercurial repository is so low, it makes a lot of sense to manage patches this way even if you simply want to make a few changes to a source tarball that you downloaded.

Begin by downloading and unpacking the source tarball, and turning it into a Mercurial repository.

$ download netplug-1.2.5.tar.bz2
$ tar jxf netplug-1.2.5.tar.bz2
$ cd netplug-1.2.5
$ hg init
$ hg commit -q --addremove --message netplug-1.2.5
$ cd ..
$ hg clone netplug-1.2.5 netplug
updating working directory
18 files updated, 0 files merged, 0 files removed, 0 files unresolved

Continue by creating a patch stack and making your changes.

$ cd netplug
$ hg qinit
$ hg qnew -m 'fix build problem with gcc 4' build-fix.patch
$ perl -pi -e 's/int addr_len/socklen_t addr_len/' netlink.c
$ hg qrefresh
$ hg tip -p
changeset:   1:3174f1d41d77
tag:         qtip
tag:         build-fix.patch
tag:         tip
tag:         qbase
user:        Bryan O'Sullivan <[e-mail]>
date:        Tue May 05 06:44:41 2009 +0000
summary:     fix build problem with gcc 4

diff -r 566cfe2faac9 -r 3174f1d41d77 netlink.c
--- a/netlink.c	Tue May 05 06:44:41 2009 +0000
+++ b/netlink.c	Tue May 05 06:44:41 2009 +0000
@@ -275,7 +275,7 @@
         exit(1);
     }
 
-    int addr_len = sizeof(addr);
+    socklen_t addr_len = sizeof(addr);
 
     if (getsockname(fd, (struct sockaddr *) &addr, &addr_len) == -1) {
         do_log(LOG_ERR, "Could not get socket details: %m");

Let’s say a few weeks or months pass, and your package author releases a new version. ...