The match_pathspec_item() function takes "prefix" value, allowing a
caller to chop off the common leading prefix of pathspec pattern
strings from the path and only use the remainder of the path to
match the pathspec patterns (after chopping the same leading prefix
of them, of course).
This "common leading prefix" optimization has two main features:
* discard the entries in the in-core index that are outside of the
common leading prefix; if you are doing "ls-files one/a one/b",
we know all matches must be from "one/", so first the code
discards all entries outside the "one/" directory from the
in-core index. This allows us to work on a smaller dataset.
* allow skipping the comparison of the leading bytes when matching
pathspec with path. When "ls-files" finds the path "one/a/1" in
the in-core index given "one/a" and "one/b" as the pathspec,
knowing that common leading prefix "one/" was found lets the
pathspec matchinery not to bother comparing "one/" part, and
allows it to feed "a/1" down, as long as the pathspec element
"one/a" gets corresponding adjustment to "a".
When the "attr" pathspec magic is in effect, however, the current
code breaks down.
The attributes, other than the ones that are built-in and the ones
that come from the $GIT_DIR/info/attributes file and the top-level
.gitattributes file, are lazily read from the filesystem on-demand,
as we encounter each path and ask if it matches the pathspec. For
example, if you say "git ls-files "(attr:label)sub/" in a repository
with a file "sub/file" that is given the 'label' attribute in
"sub/.gitattributes":
* The common prefix optimization finds that "sub/" is the common
prefix and prunes the in-core index so that it has only entries
inside that directory. This is desirable.
* The code then walks the in-core index, finds "sub/file", and
eventually asks do_match_pathspec() if it matches the given
pathspec.
* do_match_pathspec() calls match_pathspec_item() _after_ stripping
the common prefix "sub/" from the path, giving it "file", plus
the length of the common prefix (4-bytes), so that the pathspec
element "(attr:label)sub/" can be treated as if it were "(attr:label)".
The last one is what breaks the match in the current code, as the
pathspec subsystem ends up asking the attribute subsystem to find
the attribute attached to the path "file". We need to ask about the
attributes on "sub/file" when calling match_pathspec_attrs(); this
can be done by looking at "prefix" bytes before the beginning of
"name", which is the same trick already used by another piece of the
code in the same match_pathspec_item() function.
Unfortunately this was not discovered so far because the code works
with slightly different arguments, e.g.
$ git ls-files "(attr:label)sub"
$ git ls-files "(attr:label)sub/" "no/such/dir/"
would have reported "sub/file" as a path with the 'label' attribute
just fine, because neither would trigger the common prefix
optimization.
Reported-by: Matthew Hughes <mhughes@uw.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test coverage on attribute magic combined with path pattern
was a bit thin. Let's add a few and make sure "(attr:X)sub" and
"(attr:X)sub/" behave the same.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This lets us use :(attr) with "git grep <tree-ish>" or "git log".
:(attr) requires another round of checking before we can declare that
a path is matched. This is done after path matching since we have lots
of optimization to take a shortcut when things don't match.
Note that if :(attr) is present, we can't return
all_entries_interesting / all_entries_not_interesting anymore because
we can't be certain about that. Not until match_pathspec_attrs() can
tell us "yes all these paths satisfy :(attr)".
Second note. Even though we walk a specific tree, we use attributes
from _worktree_ (or falling back to the index), not from .gitattributes
files on that tree. This by itself is not necessarily wrong, but the
user just have to be aware of this.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit b0db704652 (pathspec: allow querying for attributes -
2017-03-13) adds new pathspec magic 'attr' but only with
match_pathspec(). "git add" has some pathspec related code that still
does not know about 'attr' and will bail out:
$ git add ':(attr:foo)'
fatal: BUG:dir.c:1584: unsupported magic 40
A better solution would be making this code support 'attr'. But I
don't know how much work is needed (I'm not familiar with this new
magic). For now, let's simply reject this magic with a friendlier
message:
$ git add ':(attr:foo)'
fatal: :(attr:foo): pathspec magic not supported by this command: 'attr'
Update t6135 so that the expected error message is from the
"graceful" rejection codepath, not "oops, we were supposed to reject
the request to trigger this magic" codepath.
Reported-by: smaudet@sebastianaudet.com
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In our own .gitattributes file we have attributes such as:
*.[ch] whitespace=indent,trail,space
When querying for attributes we want to be able to ask for the exact
value, i.e.
git ls-files :(attr:whitespace=indent,trail,space)
should work, but the commas are used in the attr magic to introduce
the next attr, such that this query currently fails with
fatal: Invalid pathspec magic 'trail' in ':(attr:whitespace=indent,trail,space)'
This change allows escaping characters by a backslash, such that the query
git ls-files :(attr:whitespace=indent\,trail\,space)
will match all path that have the value "indent,trail,space" for the
whitespace attribute. To accomplish this, we need to modify two places.
First `parse_long_magic` needs to not stop early upon seeing a comma or
closing paren that is escaped. As a second step we need to remove any
escaping from the attr value.
Based on a patch by Stefan Beller <sbeller@google.com>
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The pathspec mechanism is extended via the new
":(attr:eol=input)pattern/to/match" syntax to filter paths so that it
requires paths to not just match the given pattern but also have the
specified attrs attached for them to be chosen.
Based on a patch by Stefan Beller <sbeller@google.com>
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
