##// END OF EJS Templates
posix: always seek to EOF when opening a file in append mode...
posix: always seek to EOF when opening a file in append mode Python 3 already does this, so skip it there. Consider the program: #include <stdio.h> int main() { FILE *f = fopen("narf", "w"); fprintf(f, "narf\n"); fclose(f); f = fopen("narf", "a"); printf("%ld\n", ftell(f)); fprintf(f, "troz\n"); printf("%ld\n", ftell(f)); return 0; } on macOS, FreeBSD, and Linux with glibc, this program prints 5 10 but on musl libc (Alpine Linux and probably others) this prints 0 10 By my reading of https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html this is technically correct, specifically: > Opening a file with append mode (a as the first character in the > mode argument) shall cause all subsequent writes to the file to be > forced to the then current end-of-file, regardless of intervening > calls to fseek(). in other words, the file position doesn't really matter in append-mode files, and we can't depend on it being at all meaningful unless we perform a seek() before tell() after open(..., 'a'). Experimentally after a .write() we can do a .tell() and it'll always be reasonable, but I'm unclear from reading the specification if that's a smart thing to rely on. This matches what we do on Windows and what Python 3 does for free, so let's just be consistent. Thanks to Yuya for the idea.

File last commit:

r41700:78b270a5 default
r43163:97ada9b8 5.0.2 stable
Show More
diffutil.py
108 lines | 4.5 KiB | text/x-python | PythonLexer
# diffutil.py - utility functions related to diff and patch
#
# Copyright 2006 Brendan Cully <brendan@kublai.com>
# Copyright 2007 Chris Mason <chris.mason@oracle.com>
# Copyright 2018 Octobus <octobus@octobus.net>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
from .i18n import _
from . import (
mdiff,
pycompat,
)
def diffallopts(ui, opts=None, untrusted=False, section='diff',
configprefix=''):
'''return diffopts with all features supported and parsed'''
return difffeatureopts(ui, opts=opts, untrusted=untrusted, section=section,
git=True, whitespace=True, formatchanging=True,
configprefix=configprefix)
def difffeatureopts(ui, opts=None, untrusted=False, section='diff', git=False,
whitespace=False, formatchanging=False, configprefix=''):
'''return diffopts with only opted-in features parsed
Features:
- git: git-style diffs
- whitespace: whitespace options like ignoreblanklines and ignorews
- formatchanging: options that will likely break or cause correctness issues
with most diff parsers
'''
def get(key, name=None, getter=ui.configbool, forceplain=None):
if opts:
v = opts.get(key)
# diffopts flags are either None-default (which is passed
# through unchanged, so we can identify unset values), or
# some other falsey default (eg --unified, which defaults
# to an empty string). We only want to override the config
# entries from hgrc with command line values if they
# appear to have been set, which is any truthy value,
# True, or False.
if v or isinstance(v, bool):
return v
if forceplain is not None and ui.plain():
return forceplain
return getter(section, configprefix + (name or key),
untrusted=untrusted)
# core options, expected to be understood by every diff parser
buildopts = {
'nodates': get('nodates'),
'showfunc': get('show_function', 'showfunc'),
'context': get('unified', getter=ui.config),
}
buildopts['xdiff'] = ui.configbool('experimental', 'xdiff')
if git:
buildopts['git'] = get('git')
# since this is in the experimental section, we need to call
# ui.configbool directory
buildopts['showsimilarity'] = ui.configbool('experimental',
'extendedheader.similarity')
# need to inspect the ui object instead of using get() since we want to
# test for an int
hconf = ui.config('experimental', 'extendedheader.index')
if hconf is not None:
hlen = None
try:
# the hash config could be an integer (for length of hash) or a
# word (e.g. short, full, none)
hlen = int(hconf)
if hlen < 0 or hlen > 40:
msg = _("invalid length for extendedheader.index: '%d'\n")
ui.warn(msg % hlen)
except ValueError:
# default value
if hconf == 'short' or hconf == '':
hlen = 12
elif hconf == 'full':
hlen = 40
elif hconf != 'none':
msg = _("invalid value for extendedheader.index: '%s'\n")
ui.warn(msg % hconf)
finally:
buildopts['index'] = hlen
if whitespace:
buildopts['ignorews'] = get('ignore_all_space', 'ignorews')
buildopts['ignorewsamount'] = get('ignore_space_change',
'ignorewsamount')
buildopts['ignoreblanklines'] = get('ignore_blank_lines',
'ignoreblanklines')
buildopts['ignorewseol'] = get('ignore_space_at_eol', 'ignorewseol')
if formatchanging:
buildopts['text'] = opts and opts.get('text')
binary = None if opts is None else opts.get('binary')
buildopts['nobinary'] = (not binary if binary is not None
else get('nobinary', forceplain=False))
buildopts['noprefix'] = get('noprefix', forceplain=False)
buildopts['worddiff'] = get('word_diff', 'word-diff', forceplain=False)
return mdiff.diffopts(**pycompat.strkwargs(buildopts))