##// 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:

r39719:337d6e0f default
r43163:97ada9b8 5.0.2 stable
Show More
bruterebase.py
74 lines | 2.2 KiB | text/x-python | PythonLexer
# bruterebase.py - brute force rebase testing
#
# Copyright 2017 Facebook, Inc.
#
# 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 mercurial import (
error,
registrar,
revsetlang,
)
from hgext import rebase
try:
xrange
except NameError:
xrange = range
cmdtable = {}
command = registrar.command(cmdtable)
@command(b'debugbruterebase')
def debugbruterebase(ui, repo, source, dest):
"""for every non-empty subset of source, run rebase -r subset -d dest
Print one line summary for each subset. Assume obsstore is enabled.
"""
srevs = list(repo.revs(source))
with repo.wlock(), repo.lock():
repolen = len(repo)
cl = repo.changelog
def getdesc(rev):
result = cl.changelogrevision(rev).description
if rev >= repolen:
result += b"'"
return result
for i in xrange(1, 2 ** len(srevs)):
subset = [rev for j, rev in enumerate(srevs) if i & (1 << j) != 0]
spec = revsetlang.formatspec(b'%ld', subset)
tr = repo.transaction(b'rebase')
tr._report = lambda x: 0 # hide "transaction abort"
ui.pushbuffer()
try:
rebase.rebase(ui, repo, dest=dest, rev=[spec])
except error.Abort as ex:
summary = b'ABORT: %s' % ex
except Exception as ex:
summary = b'CRASH: %s' % ex
else:
# short summary about new nodes
cl = repo.changelog
descs = []
for rev in xrange(repolen, len(repo)):
desc = b'%s:' % getdesc(rev)
for prev in cl.parentrevs(rev):
if prev > -1:
desc += getdesc(prev)
descs.append(desc)
descs.sort()
summary = b' '.join(descs)
ui.popbuffer()
repo.vfs.tryunlink(b'rebasestate')
subsetdesc = b''.join(getdesc(rev) for rev in subset)
ui.write((b'%s: %s\n') % (subsetdesc.rjust(len(srevs)), summary))
tr.abort()