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.
$ hg init rep; cd rep
$ touch empty-file
$ "$PYTHON" -c 'for x in range(10000): print(x)' > large-file
$ hg addremove
adding empty-file
adding large-file
$ hg commit -m A
$ rm large-file empty-file
$ "$PYTHON" -c 'for x in range(10,10000): print(x)' > another-file
$ hg addremove -s50
adding another-file
removing empty-file
removing large-file
recording removal of large-file as rename to another-file (99% similar)
$ hg commit -m B
comparing two empty files caused ZeroDivisionError in the past
$ hg update -C 0
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ rm empty-file
$ touch another-empty-file
$ hg addremove -s50
adding another-empty-file
removing empty-file
$ cd ..
$ hg init rep2; cd rep2
$ "$PYTHON" -c 'for x in range(10000): print(x)' > large-file
$ "$PYTHON" -c 'for x in range(50): print(x)' > tiny-file
$ hg addremove
adding large-file
adding tiny-file
$ hg commit -m A
$ "$PYTHON" -c 'for x in range(70): print(x)' > small-file
$ rm tiny-file
$ rm large-file
$ hg addremove -s50
removing large-file
adding small-file
removing tiny-file
recording removal of tiny-file as rename to small-file (82% similar)
$ hg commit -m B
should be sorted by path for stable result
$ for i in `"$PYTHON" $TESTDIR/seq.py 0 9`; do
> cp small-file $i
> done
$ rm small-file
$ hg addremove
adding 0
adding 1
adding 2
adding 3
adding 4
adding 5
adding 6
adding 7
adding 8
adding 9
removing small-file
recording removal of small-file as rename to 0 (100% similar)
recording removal of small-file as rename to 1 (100% similar)
recording removal of small-file as rename to 2 (100% similar)
recording removal of small-file as rename to 3 (100% similar)
recording removal of small-file as rename to 4 (100% similar)
recording removal of small-file as rename to 5 (100% similar)
recording removal of small-file as rename to 6 (100% similar)
recording removal of small-file as rename to 7 (100% similar)
recording removal of small-file as rename to 8 (100% similar)
recording removal of small-file as rename to 9 (100% similar)
$ hg commit -m '10 same files'
pick one from many identical files
$ cp 0 a
$ rm `"$PYTHON" $TESTDIR/seq.py 0 9`
$ hg addremove
removing 0
removing 1
removing 2
removing 3
removing 4
removing 5
removing 6
removing 7
removing 8
removing 9
adding a
recording removal of 0 as rename to a (100% similar)
$ hg revert -aq
pick one from many similar files
$ cp 0 a
$ for i in `"$PYTHON" $TESTDIR/seq.py 0 9`; do
> echo $i >> $i
> done
$ hg commit -m 'make them slightly different'
$ rm `"$PYTHON" $TESTDIR/seq.py 0 9`
$ hg addremove -s50
removing 0
removing 1
removing 2
removing 3
removing 4
removing 5
removing 6
removing 7
removing 8
removing 9
adding a
recording removal of 0 as rename to a (99% similar)
$ hg commit -m 'always the same file should be selected'
should all fail
$ hg addremove -s foo
abort: similarity must be a number
[255]
$ hg addremove -s -1
abort: similarity must be between 0 and 100
[255]
$ hg addremove -s 1e6
abort: similarity must be between 0 and 100
[255]
$ cd ..
Issue1527: repeated addremove causes Abort
$ hg init rep3; cd rep3
$ mkdir d
$ echo a > d/a
$ hg add d/a
$ hg commit -m 1
$ mv d/a d/b
$ hg addremove -s80
removing d/a
adding d/b
recording removal of d/a as rename to d/b (100% similar)
$ hg debugstate
r 0 0 1970-01-01 00:00:00 d/a
a 0 -1 unset d/b
copy: d/a -> d/b
$ mv d/b c
no copies found here (since the target isn't in d
$ hg addremove -s80 d
removing d/b
copies here
$ hg addremove -s80
adding c
recording removal of d/a as rename to c (100% similar)
$ cd ..