git/t/t4125-apply-ws-fuzz.sh
Patrick Steinhardt 3fc4eab466 apply: refactor struct image to use a struct strbuf
The `struct image` uses a character array to track the pre- or postimage
of a patch operation. This has multiple downsides:

  - It is somewhat hard to track memory ownership. In fact, we have
    several memory leaks in git-apply(1) because we do not (and cannot
    easily) free the buffer in all situations.

  - We have to reinvent the wheel and manually implement a lot of
    functionality that would already be provided by `struct strbuf`.

  - We have to carefully track whether `update_pre_post_images()` can do
    an in-place update of the postimage or whether it has to allocate a
    new buffer for it.

This is all rather cumbersome, and especially `update_pre_post_images()`
is really hard to understand as a consequence even though what it is
doing is rather trivial.

Refactor the code to use a `struct strbuf` instead, addressing all of
the above. Like this we can easily perform in-place updates in all
situations, the logic to perform those updates becomes way simpler and
the lifetime of the buffer becomes a ton easier to track.

This refactoring also plugs some leaking buffers as a side effect.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-09-17 13:53:30 -07:00

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#!/bin/sh
test_description='applying patch that has broken whitespaces in context'
TEST_PASSES_SANITIZE_LEAK=true
. ./test-lib.sh
test_expect_success setup '
>file &&
git add file &&
# file-0 is full of whitespace breakages
printf "%s \n" a bb c d eeee f ggg h >file-0 &&
# patch-0 creates a whitespace broken file
cat file-0 >file &&
git diff >patch-0 &&
git add file &&
# file-1 is still full of whitespace breakages,
# but has one line updated, without fixing any
# whitespaces.
# patch-1 records that change.
sed -e "s/d/D/" file-0 >file-1 &&
cat file-1 >file &&
git diff >patch-1 &&
# patch-all is the effect of both patch-0 and patch-1
>file &&
git add file &&
cat file-1 >file &&
git diff >patch-all &&
# patch-2 is the same as patch-1 but is based
# on a version that already has whitespace fixed,
# and does not introduce whitespace breakages.
sed -e "s/ \$//" patch-1 >patch-2 &&
# If all whitespace breakages are fixed the contents
# should look like file-fixed
sed -e "s/ \$//" file-1 >file-fixed
'
test_expect_success nofix '
>file &&
git add file &&
# Baseline. Applying without fixing any whitespace
# breakages.
git apply --whitespace=nowarn patch-0 &&
git apply --whitespace=nowarn patch-1 &&
# The result should obviously match.
test_cmp file-1 file
'
test_expect_success 'withfix (forward)' '
>file &&
git add file &&
# The first application will munge the context lines
# the second patch depends on. We should be able to
# adjust and still apply.
git apply --whitespace=fix patch-0 &&
git apply --whitespace=fix patch-1 &&
test_cmp file-fixed file
'
test_expect_success 'withfix (backward)' '
>file &&
git add file &&
# Now we have a whitespace breakages on our side.
git apply --whitespace=nowarn patch-0 &&
# And somebody sends in a patch based on image
# with whitespace already fixed.
git apply --whitespace=fix patch-2 &&
# The result should accept the whitespace fixed
# postimage. But the line with "h" is beyond context
# horizon and left unfixed.
sed -e /h/d file-fixed >fixed-head &&
sed -e /h/d file >file-head &&
test_cmp fixed-head file-head &&
sed -n -e /h/p file-fixed >fixed-tail &&
sed -n -e /h/p file >file-tail &&
! test_cmp fixed-tail file-tail
'
test_done