INTRODUCTION
------------
Patchtool is a tool aimed to simplify common operations with patchfiles. It
was designed using real world's experience with the subject and expected to be
very handy for an active porter.


MODES OF OPERATION
------------------
The tool has the following two basic modes of operation:
o generation/update of patchfiles. In this mode user provides list of working
  files for which patchfiles are to be generated and the tool generates or
  updates corresponding patches automatically guessing if there is an original
  version (.orig file, rcs(1)) or it is a completely new file;

o automatic update of the existing patchfiles. In this mode user provides a
  list of patchfiles or directories containing patchfiles and the tool
  re-generates specified patches. In this mode the tool tries hard to guess
  whether the patchfile in question is already up to date or not and updates
  only those patchfiles, which are found to be outdated.

The following options are supported:
  -a -- automatically save resulting diff into a patchfile;
  -f -- don't ask any question if target patchfile already exists and is to be
        replaced;
  -u -- run tool in the "update" mode (see above);
  -i -- perform requiested operation (generate or update) even if the
	patchfile seems to be up-to-date based on last modification time of
	all files involved.

The tool supports dozen environment variables that can be used to override
default settings. You can find complete list at the top of patchtool.py,
following are the most useful ones:
PT_CVS_ID	-- CVS id to be added at the top of each patchfile generated
		   ("FreeBSD");
PT_DIFF_ARGS	-- diff(1) args used to generate patchfile ("-du");
PT_DIFF_SUFX	-- suffix used to save original version of the file (".orig");


KNOWN BUGS AND LIMITATIONS
--------------------------
o It is assumed that each patchfile contains exactly one diff, so the tool
  may remove useful diffs when there are several diffs merged into one
  patchfile. Actually I don't think that it is a bug, because Porter's
  Handbook clearly demands to follow a "one diff - one patchfile" rule.
  Perhaps portlint(1) should be extended to warn about such abuses;

o only '+++' supported as the prefix for the name of target file in the
  patchfile. Neither '***' nor 'Index:' are not recognised/supported yet;

o please keep in mind that when you are trying to do automatic update and
  some of the patches are for auto-generated/mangled files (e.g. configure
  script in the situation when USE_LIBTOOL is used) then you would end up
  with some of patchfiles containing bogus hunks;

o by default the tool tries to recognise saved original version on the file
  first by probing file with '.orig' suffix added and if it fails then by
  probing file with ',v' suffix added. If you use other suffix to save
  original version, for example '~', then set PT_DIFF_SUFX environment
  variable to match your settings, otherwise the tool will not function
  properly.


REPORTING BUGS AND PROPOSING ENHANCEMENTS
-----------------------------------------
The author of the tool is Maxim Sobolev <sobomax@FreeBSD.org>. Any bug
reports, patches, proposals or suggestions are encouraged. You can do it
either contacting author directly at the e-mail above or submitting a FreeBSD
problem report.


EXAMPLES
--------
Following are several sample sessions which show common usage patterns for
this tool.

1. Generation mode (usefull when creating new port).
$ cd /somewhere/foo ; make
[compilation blows with error in src/bar/baz.c]
$ cd work/foo-1.0/src/bar
[digged here and there and finally have found that the problem in baz.c]
$ cp baz.c baz.c.orig
$ vi baz.c
[fixing it]
$ patchtool baz.c
[reading diff]
$ patchtool -a baz.c
Generating patchfile: patch-src_bar_baz.c...ok
$ cd ../../../../
$ make
[works as expected, wow!]
$ make install clean
$ send-pr
[...]

2. Generation mode when target patchfile already exists (Minor port update).
$ cd /somewhere/foo ; make
[...]
1 out of 4 hunks failed--saving rejects to Makefile.rej
>> Patch patch-aa failed to apply cleanly.
*** Error code 1
$ cd work/foo-1.0
[examining Makefile.rej]
$ vi Makefile
[merging changes by hand]
$ patchtool Makefile
[reading diff]
$ patchtool -a Makefile
Target patchfile "patch-aa" already exists, do you want to  replace it? [y/N]: y
Generating patchfile: patch-aa...ok
$ cd ../../
$ make clean
$ make install clean
$ send-pr
[...]

3. "Gross" update mode (Major update, when several existing patches do not apply
   cleanly).
$ cd /somewhere/foo
$ vi Makefile
[increase PORTVERSION]
$ make fetch makesum patch
[several patches are failing to apply cleanly]
$ cd work/foo-1.0
[doing merging work, finally all changes are merged] 
$ cd ../../ ; make all install
[compile and works like a charm]
$ pwd
/somewhere/foo
$ patchtool -u ./
Updating patchfile: patch-aa
Updating patchfile: patch-as
Updating patchfile: patch-foo.c
Updating patchfile: patch-foo_bar.c
$ make clean
$ send-pr
[...]