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.
============================================
Testing obsolescence markers push: Cases C.1
============================================
Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).
This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.
Category C: advanced case
TestCase 1: Multiple pruned changeset atop each other
Variants:
# a: explicite push
# b: bare push
C.1 Multiple pruned changeset atop each other
=============================================
.. {{{
.. ⊗ B
.. |
.. ⊗ A
.. |
.. ● O
.. }}}
..
.. Marker exist from:
..
.. * A (prune)
.. * B (prune)
..
.. Commands run:
..
.. * hg push -r O
.. * hg push
..
.. Expected exchange:
..
.. * A (prune)
.. * B (prune)
Setup
-----
$ . $TESTDIR/testlib/exchange-obsmarker-util.sh
Initial
$ setuprepos C.1
creating test repo for test case C.1
- pulldest
- main
- pushdest
cd into `main` and proceed with env setup
$ cd main
$ mkcommit A
$ mkcommit B
$ hg prune -qd '0 0' '.~1'
1 new orphan changesets
$ hg prune -qd '0 0' .
$ hg log -G --hidden
x f6fbb35d8ac9 (draft): B
|
x f5bc6836db60 (draft): A
|
@ a9bdc8b26820 (public): O
$ inspect_obsmarkers
obsstore content
================
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
$ cd ..
$ cd ..
$ cp -R C.1 C.1.a
$ cp -R C.1 C.1.b
Actual Test (explicit push)
---------------------------
$ dotest C.1.a O
## Running testcase C.1.a
# testing echange of "O" (a9bdc8b26820)
## initial state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
# obstore: pulldest
## pushing "O" from main to pushdest
pushing to pushdest
searching for changes
no changes found
remote: 2 new obsolescence markers
## post push state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
## pulling "a9bdc8b26820" from main into pulldest
pulling from main
no changes found
2 new obsolescence markers
## post pull state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
Actual Test (bare push)
-------------------------------------
$ dotest C.1.b
## Running testcase C.1.b
## initial state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
# obstore: pulldest
## pushing from main to pushdest
pushing to pushdest
searching for changes
no changes found
remote: 2 new obsolescence markers
## post push state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
## pulling from main into pulldest
pulling from main
searching for changes
no changes found
2 new obsolescence markers
## post pull state
# obstore: main
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
f5bc6836db60e308a17ba08bf050154ba9c4fad7 0 {a9bdc8b26820b1b87d585b82eb0ceb4a2ecdbc04} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
f6fbb35d8ac958bbe70035e4c789c18471cdc0af 0 {f5bc6836db60e308a17ba08bf050154ba9c4fad7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}