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 features and behaviors related to the archived phase
=========================================================
$ cat << EOF >> $HGRCPATH
> [format]
> internal-phase=yes
> [extensions]
> strip=
> [experimental]
> EOF
$ hg init repo
$ cd repo
$ echo root > a
$ hg add a
$ hg ci -m 'root'
Test that bundle can unarchive a changeset
------------------------------------------
$ echo foo >> a
$ hg st
M a
$ hg ci -m 'unbundletesting'
$ hg log -G
@ changeset: 1:883aadbbf309
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
o changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg strip --soft --rev '.'
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/883aadbbf309-efc55adc-backup.hg
$ hg log -G
@ changeset: 0:c1863a3840c6
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg log -G --hidden
o changeset: 1:883aadbbf309
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
@ changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg unbundle .hg/strip-backup/883aadbbf309-efc55adc-backup.hg
adding changesets
adding manifests
adding file changes
added 0 changesets with 0 changes to 1 files
(run 'hg update' to get a working copy)
$ hg log -G
o changeset: 1:883aadbbf309
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
@ changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
Test that history rewriting command can use the archived phase when allowed to
------------------------------------------------------------------------------
$ hg up 'desc(unbundletesting)'
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo bar >> a
$ hg commit --amend --config experimental.cleanup-as-archived=yes
$ hg log -G
@ changeset: 2:d1e73e428f29
| tag: tip
| parent: 0:c1863a3840c6
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
o changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg log -G --hidden
@ changeset: 2:d1e73e428f29
| tag: tip
| parent: 0:c1863a3840c6
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
| o changeset: 1:883aadbbf309
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
o changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ ls -1 .hg/strip-backup/
883aadbbf309-efc55adc-amend.hg
883aadbbf309-efc55adc-backup.hg
$ hg unbundle .hg/strip-backup/883aadbbf309*amend.hg
adding changesets
adding manifests
adding file changes
added 0 changesets with 0 changes to 1 files
(run 'hg update' to get a working copy)
$ hg log -G
@ changeset: 2:d1e73e428f29
| tag: tip
| parent: 0:c1863a3840c6
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
| o changeset: 1:883aadbbf309
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: unbundletesting
|
o changeset: 0:c1863a3840c6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root