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.
------ 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