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Re: fast-import bug?

From
Dave Abrahams <dave@boostpro.com>
Date
Jun 23, 2013, 02:16 UTC
Message-ID
<m2txkp1shb.fsf@cube.gateway.2wire.net>
In-Reply-To
<20130622102157.GE4676@serenity.lan>
on Sat Jun 22 2013, John Keeping <john-AT-keeping.me.uk> wrote:
Show 28 quoted lines
> On Fri, Jun 21, 2013 at 02:21:47AM -0700, Dave Abrahams wrote:
>> The docs for fast-import seem to imply that I can use "ls" to get the
>> SHA1 of a commit for which I have a mark:
>> 
>>        Reading from a named tree
>>            The <dataref> can be a mark reference (:<idnum>) or the full 40-byte
>
>>            SHA-1 of a Git tag, commit, or tree object, preexisting or waiting to
>>            be written. The path is relative to the top level of the tree named by
>>            <dataref>.
>> 
>>                        'ls' SP <dataref> SP <path> LF
>> 
>>        See filemodify above for a detailed description of <path>.
>> 
>>        Output uses the same format as git ls-tree <tree> -- <path>:
>> 
>>            <mode> SP ('blob' | 'tree' | 'commit') SP <dataref> HT <path> LF
>> 
>>        The <dataref> represents the blob, tree, or commit object at <path> and
>>                                                    ^^^^^^
>>        can be used in later cat-blob, filemodify, or ls commands.
>> 
>> but I can't get it to work.  It's not entirely clear it's supposed to
>> work.  What path would I pass?  Passing an empty path simply causes git
>> to report "missing ".
>
> Which version of Git are you using?  
,----[ git --version ]
| git version 1.8.3.1
`----
> I just tried this and get the error
> "fatal: Empty path component found in input", 
I get that too.
> which seems to be from commit 178e1de (fast-import: don't allow 'ls'
> of path with empty components, 2012-03-09), which is included in Git
> 1.7.9.5.

Yes, that's at least part of the issue. I notice git-fast-import rejects the root path "" for other commands, e.g. when used as the source of a filecopy we get the same issue. I also note that the docs don't make it clear that quoting the path is mandatory if it might turn out to be empty.

> It seems to be slightly more complicated than that though, because after
> allowing empty trees I get the "missing" message for the root tree.

Yeah, I've tried to patch Git to solve this but ran into that problem and gave up.

> This seems to be because its mode is 0 and not S_IFDIR.
Aha.
> With the patch below, things are working as I expect 
Awesome; works for me, too!
> but I don't understand why the mode of the root is not set correctly
> at this point.  Perhaps someone more familiar with fast-import will
> have some insight...

Yeah... there's no bug tracker for Git, right? So if nobody pays attention to this thread, the problem will persist?

Show 47 quoted lines
> -- >8 --
> diff --git a/fast-import.c b/fast-import.c
> index 23f625f..bcce651 100644
> --- a/fast-import.c
> +++ b/fast-import.c
> @@ -1626,6 +1626,15 @@ del_entry:
>  	return 1;
>  }
>
> +static void copy_tree_entry(struct tree_entry *dst, struct tree_entry *src)
> +{
> +	memcpy(dst, src, sizeof(*dst));
> +	if (src->tree && is_null_sha1(src->versions[1].sha1))
> +		dst->tree = dup_tree_content(src->tree);
> +	else
> +		dst->tree = NULL;
> +}
> +
>  static int tree_content_get(
>  	struct tree_entry *root,
>  	const char *p,
> @@ -1651,11 +1660,7 @@ static int tree_content_get(
>  		e = t->entries[i];
>  		if (e->name->str_len == n && !strncmp_icase(p, e->name->str_dat, n)) {
>  			if (!slash1) {
> -				memcpy(leaf, e, sizeof(*leaf));
> -				if (e->tree && is_null_sha1(e->versions[1].sha1))
> -					leaf->tree = dup_tree_content(e->tree);
> -				else
> -					leaf->tree = NULL;
> +				copy_tree_entry(leaf, e);
>  				return 1;
>  			}
>  			if (!S_ISDIR(e->versions[1].mode))
> @@ -3065,7 +3070,11 @@ static void parse_ls(struct branch *b)
>  			die("Garbage after path in: %s", command_buf.buf);
>  		p = uq.buf;
>  	}
> -	tree_content_get(root, p, &leaf);
> +	if (!*p) {
> +		copy_tree_entry(&leaf, root);
> +		leaf.versions[1].mode = S_IFDIR;
> +	} else
> +		tree_content_get(root, p, &leaf);
>  	/*
>  	 * A directory in preparation would have a sha1 of zero
>  	 * until it is saved.  Save, for simplicity.
-- 
Dave Abrahams
Previous: John KeepingNext: John Keeping
Message 3 of 6 in “fast-import bug?”
  1. Dave AbrahamsJun 21, 2013
  2. John KeepingJun 22, 2013
  3. Dave AbrahamsJun 23, 2013
  4. John KeepingJun 23, 2013
  5. Dave AbrahamsJun 23, 2013
  6. John KeepingJun 23, 2013

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