Mercurial > hg
view tests/test-dirstate.t @ 42562:97ada9b8d51b stable 5.0.2
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.
author | Augie Fackler <augie@google.com> |
---|---|
date | Mon, 08 Jul 2019 13:12:20 -0400 |
parents | 4441705b7111 |
children | 87a34c767384 |
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------ Test dirstate._dirs refcounting $ hg init t $ cd t $ mkdir -p a/b/c/d $ touch a/b/c/d/x $ touch a/b/c/d/y $ touch a/b/c/d/z $ hg ci -Am m adding a/b/c/d/x adding a/b/c/d/y adding a/b/c/d/z $ hg mv a z moving a/b/c/d/x to z/b/c/d/x moving a/b/c/d/y to z/b/c/d/y moving a/b/c/d/z to z/b/c/d/z Test name collisions $ rm z/b/c/d/x $ mkdir z/b/c/d/x $ touch z/b/c/d/x/y $ hg add z/b/c/d/x/y abort: file 'z/b/c/d/x' in dirstate clashes with 'z/b/c/d/x/y' [255] $ rm -rf z/b/c/d $ touch z/b/c/d $ hg add z/b/c/d abort: directory 'z/b/c/d' already in dirstate [255] $ cd .. Issue1790: dirstate entry locked into unset if file mtime is set into the future Prepare test repo: $ hg init u $ cd u $ echo a > a $ hg add adding a $ hg ci -m1 Set mtime of a into the future: $ touch -t 202101011200 a Status must not set a's entry to unset (issue1790): $ hg status $ hg debugstate n 644 2 2021-01-01 12:00:00 a Test modulo storage/comparison of absurd dates: #if no-aix $ touch -t 195001011200 a $ hg st $ hg debugstate n 644 2 2018-01-19 15:14:08 a #endif Verify that exceptions during a dirstate change leave the dirstate coherent (issue4353) $ cat > ../dirstateexception.py <<EOF > from __future__ import absolute_import > from mercurial import ( > error, > extensions, > merge, > ) > > def wraprecordupdates(orig, repo, actions, branchmerge): > raise error.Abort("simulated error while recording dirstateupdates") > > def reposetup(ui, repo): > extensions.wrapfunction(merge, 'recordupdates', wraprecordupdates) > EOF $ hg rm a $ hg commit -m 'rm a' $ echo "[extensions]" >> .hg/hgrc $ echo "dirstateex=../dirstateexception.py" >> .hg/hgrc $ hg up 0 abort: simulated error while recording dirstateupdates [255] $ hg log -r . -T '{rev}\n' 1 $ hg status ? a