dirstate-v2: no longer register the data-file during transaction
If the data file change during the transaction, we cannot truncate it.
The content of the file itself is fine as it will get backed up at the same time
as the docket.
Leaving the trailing data at the end of failed transaction is fine. The
dirstate-v2 format supports it. The dead data will simply we written over if
necessary.
Setup:
$ cat > eval.py <<EOF
> import filecmp
> from mercurial import commands, context, pycompat, registrar
> cmdtable = {}
> command = registrar.command(cmdtable)
> @command(b'eval', [], b'hg eval CMD')
> def eval_(ui, repo, *cmds, **opts):
> cmd = b" ".join(cmds)
> res = pycompat.bytestr(eval(cmd, globals(), locals()))
> ui.warn(b"%s" % res)
> EOF
$ echo "[extensions]" >> $HGRCPATH
$ echo "eval=`pwd`/eval.py" >> $HGRCPATH
Arbitraryfilectx.cmp does not follow symlinks:
$ mkdir case1
$ cd case1
$ hg init
#if symlink
$ printf "A" > real_A
$ printf "foo" > A
$ printf "foo" > B
$ ln -s A sym_A
$ hg add .
adding A
adding B
adding real_A
adding sym_A
$ hg commit -m "base"
#else
$ hg import -q --bypass - <<EOF
> # HG changeset patch
> # User test
> # Date 0 0
> base
>
> diff --git a/A b/A
> new file mode 100644
> --- /dev/null
> +++ b/A
> @@ -0,0 +1,1 @@
> +foo
> \ No newline at end of file
> diff --git a/B b/B
> new file mode 100644
> --- /dev/null
> +++ b/B
> @@ -0,0 +1,1 @@
> +foo
> \ No newline at end of file
> diff --git a/real_A b/real_A
> new file mode 100644
> --- /dev/null
> +++ b/real_A
> @@ -0,0 +1,1 @@
> +A
> \ No newline at end of file
> diff --git a/sym_A b/sym_A
> new file mode 120000
> --- /dev/null
> +++ b/sym_A
> @@ -0,0 +1,1 @@
> +A
> \ No newline at end of file
> EOF
$ hg up -q
#endif
These files are different and should return True (different):
(Note that filecmp.cmp's return semantics are inverted from ours, so we invert
for simplicity):
$ hg eval "context.arbitraryfilectx(b'A', repo).cmp(repo[None][b'real_A'])"
True (no-eol)
$ hg eval "not filecmp.cmp(b'A', b'real_A')"
True (no-eol)
These files are identical and should return False (same):
$ hg eval "context.arbitraryfilectx(b'A', repo).cmp(repo[None][b'A'])"
False (no-eol)
$ hg eval "context.arbitraryfilectx(b'A', repo).cmp(repo[None][b'B'])"
False (no-eol)
$ hg eval "not filecmp.cmp(b'A', b'B')"
False (no-eol)
This comparison should also return False, since A and sym_A are substantially
the same in the eyes of ``filectx.cmp``, which looks at data only.
$ hg eval "context.arbitraryfilectx(b'real_A', repo).cmp(repo[None][b'sym_A'])"
False (no-eol)
A naive use of filecmp on those two would wrongly return True, since it follows
the symlink to "A", which has different contents.
#if symlink
$ hg eval "not filecmp.cmp(b'real_A', b'sym_A')"
True (no-eol)
#else
$ hg eval "not filecmp.cmp(b'real_A', b'sym_A')"
False (no-eol)
#endif