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.
Issue746: renaming files brought by the second parent of a merge was
broken.
Create source repository:
$ hg init t
$ cd t
$ echo a > a
$ hg ci -Am a
adding a
$ cd ..
Fork source repository:
$ hg clone t t2
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd t2
$ echo b > b
$ hg ci -Am b
adding b
Update source repository:
$ cd ../t
$ echo a >> a
$ hg ci -m a2
Merge repositories:
$ hg pull ../t2
pulling from ../t2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets d2ae7f538514
1 local changesets published
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st
M b
Rename b as c:
$ hg mv b c
$ hg st
A c
R b
Rename back c as b:
$ hg mv c b
$ hg st
M b
$ cd ..
Issue 1476: renaming a first parent file into another first parent
file while none of them belong to the second parent was broken
$ hg init repo1476
$ cd repo1476
$ echo a > a
$ hg ci -Am adda
adding a
$ echo b1 > b1
$ echo b2 > b2
$ hg ci -Am changea
adding b1
adding b2
$ hg up -C 0
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo c1 > c1
$ echo c2 > c2
$ hg ci -Am addcandd
adding c1
adding c2
created new head
Merge heads:
$ hg merge
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg mv -Af c1 c2
Commit issue 1476:
$ hg ci -m merge
$ hg log -r tip -C -v | grep copies
copies: c2 (c1)
$ hg rollback
repository tip rolled back to revision 2 (undo commit)
working directory now based on revisions 2 and 1
$ hg up -C .
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
Merge heads again:
$ hg merge
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg mv -Af b1 b2
Commit issue 1476 with a rename on the other side:
$ hg ci -m merge
$ hg log -r tip -C -v | grep copies
copies: b2 (b1)
$ cd ..