Re: [PATCH] git-svn: fix ls-tree usage with dash-prefixed paths

> Eric Wong <normalperson@yhbt.net> writes:
> 
> > To find the blob object name given a tree and pathname, we were
> > incorrectly calling "git ls-tree" with a "--" argument followed
> > by the pathname of the file we wanted to get.
> >
> >   git ls-tree <TREE> -- --dashed/path/name.c
> >
> > Unlike many command-line interfaces, the "--" alone does not
> > symbolize the end of non-option arguments on the command-line.
> >
> > ls-tree interprets the "--" as a prefix to match against, thus
> > the entire contents of the --dashed/* hierarchy would be
> > returned because the "--" matches "--dashed" and every path
> > under it.
> 
> The above makes only half a sense to me.  In an empty directory:

>     $ git add .
>     $ git ls-files
>     --dashed/path/name
>     $ git commit -a -m initial
>     [master (root-commit) cd44284] initial
>      0 files changed, 0 insertions(+), 0 deletions(-)
>      create mode 100644 --dashed/path/name
>     $ git ls-tree HEAD^{tree} --
>     $ git ls-tree HEAD^{tree} -- --dashed/path/name
>     100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	--dashed/path/name
>     $ mkdir ./--
>     $ >./--/eman
>     $ git add .
>     $ git commit -m second
>     [master 80f8ef9] second
>      0 files changed, 0 insertions(+), 0 deletions(-)
>      create mode 100644 --/eman
>     $ git ls-tree HEAD^{tree} -- --dashed/path
>     100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391	--/eman
>     040000 tree 23e59e0c91294c39ac7c5a2e39efb01d878de9a0	--dashed/path

>     $ exit
> 
> Perhaps the problem repository had a pathname that is exactly -- (in
> addition to --dashed/), and ls-tree emitted everything under --/
> hierarchy?  In other words, your fix to git-svn may be correct and I am
> reading your problem description above incorrectly?

> As the command always takes exactly one tree, it could be argued that it
> is not a bug that it does not honour the usual -- convention, even though
> I am tempted to think it is of a very dark shade of gray.  It is certainly
> something that we would have done differently if we were implementing the
> command today.

> "Fixing" ls-tree would be trivial to ignore the first "--" if it precedes
> other pathspecs (see below), but the command is a plumbing, and such a
> change will break existing scripts that have relied on the existing
> behaviour since 2005, so I do not think it is worth the risk of causing
> such silent breakages to them.  Besides, with such a "fix", fixing of user
> scripts will become much more cumbersome, as they need to detect the
> version of git and drive ls-tree differently.