delta/git.git, branch sb/pathspec-errors

pathspec: give better message for submodule related pathspec error

2017-01-09T23:19:22+00:00

Every once in a while someone complains to the mailing list to have
run into this weird assertion[1]. The usual response from the mailing
list is link to old discussions[2], and acknowledging the problem
stating it is known.

This patch accomplishes two things:

  1. Switch assert() to die("BUG") to give a more readable message.

  2. Take one of the cases where we hit a BUG and turn it into a normal
     "there was something wrong with the input" message.

     This assertion triggered for cases where there wasn't a programming
     bug, but just bogus input. In particular, if the user asks for a
     pathspec that is inside a submodule, we shouldn't assert() or
     die("BUG"); we should tell the user their request is bogus.

     The only reason we did not check for it, is the expensive nature
     of such a check, so callers avoid setting the flag
     PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE. However when we die due
     to bogus input, the expense of CPU cycles spent outweighs the user
     wondering what went wrong, so run that check unconditionally before
     dying with a more generic error message.

Note: There is a case (e.g. "git -C submodule add .") in which we call
strip_submodule_slash_expensive, as git-add requests it via the flag
PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE, but the assert used to
trigger nevertheless, because the flag PATHSPEC_LITERAL was not set,
such that we executed

	if (item->nowildcard_len < prefixlen)
		item->nowildcard_len = prefixlen;

and prefixlen was not adapted (e.g. it was computed from "submodule/")
So in the die_inside_submodule_path function we also need handle paths,
that were stripped before, i.e. are the exact submodule path. This
is why the conditions in die_inside_submodule_path are slightly
different than in strip_submodule_slash_expensive.

[1] https://www.google.com/search?q=item-%3Enowildcard_len
[2] http://git.661346.n2.nabble.com/assert-failed-in-submodule-edge-case-td7628687.html
    https://www.spinics.net/lists/git/msg249473.html

Helped-by: Jeff King 
Helped-by: Junio C Hamano 
Signed-off-by: Stefan Beller 
Signed-off-by: Junio C Hamano

pathspec: rename prefix_pathspec to init_pathspec_item

2017-01-09T02:04:18+00:00

Give a more relevant name to the prefix_pathspec function as it does
more than just prefix a pathspec element.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: small readability changes

2017-01-09T02:04:18+00:00

A few small changes to improve readability.  This is done by grouping related
assignments, adding blank lines, ensuring lines are <80 characters, and
adding additional comments.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: create strip submodule slash helpers

2017-01-09T02:04:18+00:00

Factor out the logic responsible for stripping the trailing slash on
pathspecs referencing submodules into its own function.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: create parse_element_magic helper

2017-01-09T02:04:18+00:00

Factor out the logic responsible for the magic in a pathspec element
into its own function.

Also avoid calling into the parsing functions when
`PATHSPEC_LITERAL_PATH` is specified since it causes magic to be
ignored and all paths to be treated as literals.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: create parse_long_magic function

2017-01-09T02:04:18+00:00

Factor out the logic responsible for parsing long magic into its own
function.  As well as hoist the prefix check logic outside of the inner
loop as there isn't anything that needs to be done after matching
"prefix:".

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: create parse_short_magic function

2017-01-09T02:04:17+00:00

Factor out the logic responsible for parsing short magic into its own
function.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: factor global magic into its own function

2017-01-09T02:04:17+00:00

Create helper functions to read the global magic environment variables
in additon to factoring out the global magic gathering logic into its
own function.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: simpler logic to prefix original pathspec elements

2017-01-09T02:04:17+00:00

The logic used to prefix an original pathspec element with 'prefix'
magic is more general purpose and can be used for more than just short
magic.  Remove the extra code paths and rename 'prefix_short_magic' to
'prefix_magic' to better indicate that it can be used in more general
situations.

Also, slightly change the logic which decides when to prefix the
original element in order to prevent a pathspec of "." from getting
converted to "" (empty string).

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano

pathspec: always show mnemonic and name in unsupported_magic

2017-01-09T02:04:17+00:00

For better clarity, always show the mnemonic and name of the unsupported
magic being used.  This lets users have a more clear understanding of
what magic feature isn't supported.  And if they supplied a mnemonic,
the user will be told what its corresponding name is which will allow
them to more easily search the man pages for that magic type.

This also avoids passing an extra parameter around the pathspec
initialization code.

Signed-off-by: Brandon Williams 
Reviewed-by: Nguyễn Thái Ngọc Duy 
Signed-off-by: Junio C Hamano