Convert git diff to svn patch compatible format.

git-svn-diff.py

#!/usr/bin/python

# Author: Chen Yufei
# Convert git diff to svn patch compatible format.

import subprocess
import sys
import re

def check_output(cmd):
    return subprocess.check_output(cmd, shell=True)

# Get the tracking branch (if we're on a branch)
tracking_branch = check_output("git svn info | grep URL | sed -e 's/.*\/branches\///'").strip()

# If the tracking branch has 'URL' at the beginning, then the sed wasn't successful and
# we'll fall back to the svn-remote config option
if tracking_branch[0:3] == 'URL':
    tracking_branch = check_output("git config --get svn-remote.svn.fetch | sed -e 's/.*:refs\/remotes\///'").strip()

# Get the highest revision number
revision = check_output("git svn info | awk '/Last Changed Rev:/ { print $4 }'").strip()

# Then do the diff from the highest revision on the current branch
# and masssage into SVN format
rev_list = check_output('git rev-list --date-order --max-count=1 %s' % tracking_branch)
diff_output = check_output("git diff --no-prefix %s" % rev_list)

re_diff_git = re.compile('^diff --git [^ ]+ ([^ ]+$)')
re_diff_file_mode = re.compile('.+ file mode [0-9]+$')
re_diff_stat = re.compile('^(@@ -[^ ]+ \+[^ ]+ @@).*$')

def is_diff_header(line, i):
    if re_diff_git.match(line[i]):
        if re_diff_file_mode.match(line[i+1]):
            i += 1
        if line[i+1].startswith('index ') and \
            line[i+2].startswith('--- ') and \
            line[i+3].startswith('+++ '):
            return True
    return False

def convert_print_diff_header(line, i):
    num_line = 4
    print re_diff_git.sub(r'Index: \1', line[i])

    if re_diff_file_mode.match(line[i+1]):
        i += 1
        num_line += 1

    print '==================================================================='
    if line[i+2] == '--- /dev/null':
        filename = line[i+3][len('+++ '):]
        print '--- %s\t(revision 0)' % filename
    else:
        print '%s\t(revision %s)' % (line[i+2], revision)

    if line[i+3] == '+++ /dev/null':
        filename = line[i+2][len('--- '):]
        print '+++ %s\t(working copy)' % filename
    else:
        print '%s\t(working copy)' % line[i+3]

    return num_line

i = 0
diff = diff_output.split('\n')

while i < len(diff):
    if is_diff_header(diff, i):
        i += convert_print_diff_header(diff, i)
    elif re_diff_stat.match(diff[i]):
        print re_diff_stat.sub(r'\1', diff[i])
        i += 1
    else:
        if i == (len(diff) - 1):
            # last line
            sys.stdout.write(diff[i])
        else:
            print diff[i]
        i += 1