Definition

What is a patch? A patch is a change to an Ubuntu package that will resolve a bug report. These include:

• changes to the packaging of an Ubuntu package
• changes to the source code included in an Ubuntu package

These changes can appear in a few different formats:

diff

A diff is a plain text file that contains differences between the original file and changed file.

Example:

diff -Nurp ciso-1.0.0/ciso.h ciso-1.0.0-fixed/ciso.h
--- ciso-1.0.0/ciso.h    2006-11-03 12:53:02.000000000 -0800
+++ ciso-1.0.0-fixed/ciso.h    2008-11-27 13:32:01.000000000 -0800
@@ -28,9 +28,9 @@
 typedef struct ciso_header
 {
 unsigned char magic[4];         /* +00 : 'C','I','S','O'                 */
-unsigned long header_size;      /* +04 : header size (==0x18)            */
+uint32_t header_size;           /* +04 : header size (==0x18)            */
 unsigned long long total_bytes; /* +08 : number of original data size    */
-unsigned long block_size;       /* +10 : number of compressed block size */
+uint32_t block_size;            /* +10 : number of compressed block size */
 unsigned char ver;              /* +14 : version 01                      */
 unsigned char align;            /* +15 : align of index value            */
 unsigned char rsv_06[2];        /* +16 : reserved                        */

Here the file ciso.h is being changed in two places - notice the - in front of a line indicating it is being removed and the + indicating it is being added.

debdiff

A debdiff contains all the changes needed to build a different version of a package. The debdiff will probably include changes to the source of the package, in the form of a diff, in addition to files in the debian directory.

Shortened Example:

diff -u ciso-1.0.0/debian/rules ciso-1.0.0/debian/rules
--- ciso-1.0.0/debian/rules
+++ ciso-1.0.0/debian/rules
@@ -20,8 +20,10 @@
        CFLAGS += -O2
 endif
 
+include /usr/share/dpatch/dpatch.make
+
 configure: configure-stamp
-configure-stamp:
+configure-stamp: patch
        dh_testdir
        # Add here commands to configure the package.
 
@@ -39,7 +41,9 @@
 
        touch $@
 
-clean:
+clean: clean-patched unpatch
+
+clean-patched:
        dh_testdir
        dh_testroot
        rm -f build-stamp configure-stamp
@@ -86 +90 @@
-.PHONY: build clean binary-indep binary-arch binary install configure
+.PHONY: build clean clean-patched binary-indep binary-arch binary install configure
diff -u ciso-1.0.0/debian/control ciso-1.0.0/debian/control
--- ciso-1.0.0/debian/control
+++ ciso-1.0.0/debian/control
@@ -1,8 +1,9 @@
 Source: ciso
 Section: utils
 Priority: optional
-Maintainer: Gaëtan Petit <tenshu@gmail.com>
-Build-Depends: debhelper (>= 5), zlib1g-dev
+Maintainer: Ubuntu MOTU Developers <ubuntu-motu@lists.ubuntu.com>
+XSBC-Original-Maintainer: Gaëtan Petit <tenshu@gmail.com>
+Build-Depends: debhelper (>= 5), zlib1g-dev, dpatch
 Standards-Version: 3.7.2

Here the files debian/rules and debian/control are being modified.

Other

A patch could also be an image file, in the event that a package is missing a menu icon. Bug 274714 is a great example of this. In the debdiff the image, is uuencoded (converted from binary to text) and looks like:

--- system-cleaner-1.10.3.orig/debian/system-cleaner-gtk.png.uuencode
+++ system-cleaner-1.10.3/debian/system-cleaner-gtk.png.uuencode
@@ -0,0 +1,429 @@
+begin 644 system-cleaner-gtk.png
+MB5!.1PT*&@H````-24A$4@```!@````8"`8```#@=SWX````!'-"250("`@(
+M?`ADB`````EP2%ES```+$@``"Q(!TMU^_````"5T15AT4V]F='=A<F4`36%C

Patches in Launchpad

Attachments that are patches can be flagged in the Launchpad bug tracker, which then makes them show up in search results and on other reports. Attachments to bug reports appear in the attachments portlet on the right hand side of a bug report.

The third attachment has a star by it, which indicates that this attachment is flagged as a patch. However, these stars do not normally show up in Launchpad, they require the lp_patches Greasemonkey script.

Notice the "edit" link next to each attachment, it will take you to the following page:

Here you can set and unset the patch flag on a per attachment basis.

Workflow

Bugs with attachments

Bug reports that have attachments should be examined to see whether or not any of those attachments are patches. If an attachment qualifies as a patch it should be flagged as one. When flagging attachments as patches comment on the bug indicating that the attachment was flagged as a patch and why this is important.

Additionally, one could incorporate the patch into a debdiff for the package in the development release of Ubuntu or apply the patch to a bzr branch of the package and link the branch to the bug report.

Bugs with patches

Bug reports that have attachments flagged as patches should have the patches reviewed to ensure that they are in fact patches. If an attachment is incorrectly flagged as a patch when it is not one, unflag the attachment and comment on the bug report indicating that the attachment is not a patch and why it is important for them to be identified properly.

In the event that it is not a debdiff one could incorporate the patch into a debdiff for the latest release of Ubuntu or apply the patch to a bzr branch of the package and link the branch to the bug report.

If an attachment is a debdiff and applies to a recent version of the package the bug report needs to be sponsored to the appropriate archive. This is done by subscribing (NOT assigning) the appropriate sponsorship team to the bug. For packages in main and restricted the ubuntu-main-sponsors team should be subscribed. For packages in the universe and multiverse repositories the ubuntu-universe-sponsors team should be subscribed. You can view their queues at main-sponsors and universe-sponsors.