diff options
| -rwxr-xr-x | bin/jsonpatch | 72 |
1 files changed, 68 insertions, 4 deletions
diff --git a/bin/jsonpatch b/bin/jsonpatch index 8db17a1..3f01738 100755 --- a/bin/jsonpatch +++ b/bin/jsonpatch @@ -1,12 +1,11 @@ #!/usr/bin/env python # -*- coding: utf-8 -*- -from __future__ import print_function - import sys import os.path import json import jsonpatch +import tempfile import argparse @@ -15,9 +14,14 @@ parser = argparse.ArgumentParser( parser.add_argument('ORIGINAL', type=argparse.FileType('r'), help='Original file') parser.add_argument('PATCH', type=argparse.FileType('r'), - help='Patch file') + nargs='?', default=sys.stdin, + help='Patch file (read from stdin if omitted)') parser.add_argument('--indent', type=int, default=None, help='Indent output by n spaces') +parser.add_argument('-b', '--backup', action='store_true', + help='Back up ORIGINAL if modifying in-place') +parser.add_argument('-i', '--in-place', action='store_true', + help='Modify ORIGINAL in-place instead of to stdout') parser.add_argument('-v', '--version', action='version', version='%(prog)s ' + jsonpatch.__version__) @@ -35,7 +39,67 @@ def patch_files(): doc = json.load(args.ORIGINAL) patch = json.load(args.PATCH) result = jsonpatch.apply_patch(doc, patch) - print(json.dumps(result, indent=args.indent)) + + if args.in_place: + dirname = os.path.abspath(os.path.dirname(args.ORIGINAL.name)) + + try: + # Attempt to replace the file atomically. We do this by + # creating a temporary file in the same directory as the + # original file so we can atomically move the new file over + # the original later. (This is done in the same directory + # because atomic renames do not work across mount points.) + + fd, pathname = tempfile.mkstemp(dir=dirname) + fp = os.fdopen(fd, 'w') + atomic = True + + except OSError: + # We failed to create the temporary file for an atomic + # replace, so fall back to non-atomic mode by backing up + # the original (if desired) and writing a new file. + + if args.backup: + os.rename(args.ORIGINAL.name, args.ORIGINAL.name + '.orig') + fp = open(args.ORIGINAL.name, 'w') + atomic = False + + else: + # Since we're not replacing the original file in-place, write + # the modified JSON to stdout instead. + + fp = sys.stdout + + # By this point we have some sort of file object we can write the + # modified JSON to. + + json.dump(result, fp, indent=args.indent) + fp.write('\n') + + if args.in_place: + # Close the new file. If we aren't replacing atomically, this + # is our last step, since everything else is already in place. + + fp.close() + + if atomic: + try: + # Complete the atomic replace by linking the original + # to a backup (if desired), fixing up the permissions + # on the temporary file, and moving it into place. + + if args.backup: + os.link(args.ORIGINAL.name, args.ORIGINAL.name + '.orig') + os.chmod(pathname, os.stat(args.ORIGINAL.name).st_mode) + os.rename(pathname, args.ORIGINAL.name) + + except OSError: + # In the event we could not actually do the atomic + # replace, unlink the original to move it out of the + # way and finally move the temporary file into place. + + os.unlink(args.ORIGINAL.name) + os.rename(pathname, args.ORIGINAL.name) if __name__ == "__main__": |