Files
git-mirror/t/t4020-diff-external.sh
Jeff King 57c2b6cc86 diff: send external diff output to diff_options.file
Diff output usually goes to the process stdout, but it can be redirected
with the "--output" option. We store this in the "file" pointer of
diff_options, and all of the diff code should write there instead of to
stdout.

But there's one spot we missed: running an external diff cmd. We don't
redirect its output at all, so it just defaults to the stdout of the
parent process. We should instead point its stdout at our output file.
There are a few caveats to watch out for when doing so:

  - The stdout field takes a descriptor, not a FILE pointer. We can pull
    out the descriptor with fileno().

  - The run-command API always closes the stdout descriptor we pass to
    it. So we must duplicate it (otherwise we break the FILE pointer,
    since it now points to a closed descriptor).

  - We don't need to worry about closing our dup'd descriptor, since the
    point is that run-command will do it for us (even in the case of an
    error). But we do need to make sure we skip the dup() if we set
    no_stdout (because then run-command will not look at it at all).

  - When the output is going to stdout, it would not be wrong to dup()
    the descriptor, but we don't need to. We can skip that extra work
    with a simple pointer comparison.

  - It seems like you'd need to fflush() the descriptor before handing
    off a copy to the child process to prevent out-of-order writes. But
    that was true even before this patch! It works because run-command
    always calls fflush(NULL) before running the child.

The new test shows the breakage (and fix). The need for duplicating the
descriptor doesn't need a new test; that is covered by the later test
"GIT_EXTERNAL_DIFF with more than one changed files".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-10-24 10:15:21 -07:00

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#!/bin/sh
test_description='external diff interface test'
. ./test-lib.sh
test_expect_success setup '
test_tick &&
echo initial >file &&
git add file &&
git commit -m initial &&
test_tick &&
echo second >file &&
before=$(git hash-object file) &&
before=$(git rev-parse --short $before) &&
git add file &&
git commit -m second &&
test_tick &&
echo third >file
'
test_expect_success 'GIT_EXTERNAL_DIFF environment' '
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
EOF
GIT_EXTERNAL_DIFF=echo git diff >out &&
cut -d" " -f1,3- <out >actual &&
test_cmp expect actual
'
test_expect_success 'GIT_EXTERNAL_DIFF environment should apply only to diff' '
GIT_EXTERNAL_DIFF=echo git log -p -1 HEAD >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'GIT_EXTERNAL_DIFF environment and --no-ext-diff' '
GIT_EXTERNAL_DIFF=echo git diff --no-ext-diff >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'GIT_EXTERNAL_DIFF and --output' '
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
EOF
GIT_EXTERNAL_DIFF=echo git diff --output=out >stdout &&
cut -d" " -f1,3- <out >actual &&
test_must_be_empty stdout &&
test_cmp expect actual
'
test_expect_success SYMLINKS 'typechange diff' '
rm -f file &&
ln -s elif file &&
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 120000
EOF
GIT_EXTERNAL_DIFF=echo git diff >out &&
cut -d" " -f1,3-4,6- <out >actual &&
test_cmp expect actual &&
GIT_EXTERNAL_DIFF=echo git diff --no-ext-diff >actual &&
git diff >expect &&
test_cmp expect actual
'
test_expect_success 'diff.external' '
git reset --hard &&
echo third >file &&
test_config diff.external echo &&
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
EOF
git diff >out &&
cut -d" " -f1,3-4,6- <out >actual &&
test_cmp expect actual
'
test_expect_success 'diff.external should apply only to diff' '
test_config diff.external echo &&
git log -p -1 HEAD >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'diff.external and --no-ext-diff' '
test_config diff.external echo &&
git diff --no-ext-diff >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'diff attribute' '
git reset --hard &&
echo third >file &&
git config diff.parrot.command echo &&
echo >.gitattributes "file diff=parrot" &&
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
EOF
git diff >out &&
cut -d" " -f1,3-4,6- <out >actual &&
test_cmp expect actual
'
test_expect_success 'diff attribute should apply only to diff' '
git log -p -1 HEAD >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'diff attribute and --no-ext-diff' '
git diff --no-ext-diff >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'diff attribute' '
git config --unset diff.parrot.command &&
git config diff.color.command echo &&
echo >.gitattributes "file diff=color" &&
cat >expect <<-EOF &&
file $(git rev-parse --verify HEAD:file) 100644 $(test_oid zero) 100644
EOF
git diff >out &&
cut -d" " -f1,3-4,6- <out >actual &&
test_cmp expect actual
'
test_expect_success 'diff attribute should apply only to diff' '
git log -p -1 HEAD >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'diff attribute and --no-ext-diff' '
git diff --no-ext-diff >out &&
grep "^diff --git a/file b/file" out
'
test_expect_success 'GIT_EXTERNAL_DIFF trumps diff.external' '
>.gitattributes &&
test_config diff.external "echo ext-global" &&
cat >expect <<-EOF &&
ext-env file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
EOF
GIT_EXTERNAL_DIFF="echo ext-env" git diff >out &&
cut -d" " -f1-2,4- <out >actual &&
test_cmp expect actual
'
test_expect_success 'attributes trump GIT_EXTERNAL_DIFF and diff.external' '
test_config diff.foo.command "echo ext-attribute" &&
test_config diff.external "echo ext-global" &&
echo "file diff=foo" >.gitattributes &&
cat >expect <<-EOF &&
ext-attribute file $(git rev-parse --verify HEAD:file) 100644 file $(test_oid zero) 100644
EOF
GIT_EXTERNAL_DIFF="echo ext-env" git diff >out &&
cut -d" " -f1-2,4- <out >actual &&
test_cmp expect actual
'
test_expect_success 'no diff with -diff' '
echo >.gitattributes "file -diff" &&
git diff >out &&
grep Binary out
'
check_external_diff () {
expect_code=$1
expect_out=$2
expect_err=$3
command_code=$4
trust_exit_code=$5
shift 5
options="$@"
command="echo output; exit $command_code;"
desc="external diff '$command' with trustExitCode=$trust_exit_code"
with_options="${options:+ with }$options"
test_expect_success "$desc via attribute$with_options" "
test_config diff.foo.command \"$command\" &&
test_config diff.foo.trustExitCode $trust_exit_code &&
echo \"file diff=foo\" >.gitattributes &&
test_expect_code $expect_code git diff $options >out 2>err &&
test_cmp $expect_out out &&
test_cmp $expect_err err
"
test_expect_success "$desc via diff.external$with_options" "
test_config diff.external \"$command\" &&
test_config diff.trustExitCode $trust_exit_code &&
>.gitattributes &&
test_expect_code $expect_code git diff $options >out 2>err &&
test_cmp $expect_out out &&
test_cmp $expect_err err
"
test_expect_success "$desc via GIT_EXTERNAL_DIFF$with_options" "
>.gitattributes &&
test_expect_code $expect_code env \
GIT_EXTERNAL_DIFF=\"$command\" \
GIT_EXTERNAL_DIFF_TRUST_EXIT_CODE=$trust_exit_code \
git diff $options >out 2>err &&
test_cmp $expect_out out &&
test_cmp $expect_err err
"
}
test_expect_success 'setup output files' '
: >empty &&
echo output >output &&
echo "fatal: external diff died, stopping at file" >error
'
check_external_diff 0 output empty 0 off
check_external_diff 128 output error 1 off
check_external_diff 0 output empty 0 on
check_external_diff 0 output empty 1 on
check_external_diff 128 output error 2 on
check_external_diff 1 output empty 0 off --exit-code
check_external_diff 128 output error 1 off --exit-code
check_external_diff 0 output empty 0 on --exit-code
check_external_diff 1 output empty 1 on --exit-code
check_external_diff 128 output error 2 on --exit-code
check_external_diff 1 empty empty 0 off --quiet
check_external_diff 1 empty empty 1 off --quiet # we don't even call the program
check_external_diff 0 empty empty 0 on --quiet
check_external_diff 1 empty empty 1 on --quiet
check_external_diff 128 empty error 2 on --quiet
echo NULZbetweenZwords | tr "Z" "\000" > file
test_expect_success 'force diff with "diff"' '
after=$(git hash-object file) &&
after=$(git rev-parse --short $after) &&
echo >.gitattributes "file diff" &&
git diff >actual &&
sed -e "s/^index .*/index $before..$after 100644/" \
"$TEST_DIRECTORY"/t4020/diff.NUL >expected-diff &&
test_cmp expected-diff actual
'
test_expect_success 'GIT_EXTERNAL_DIFF with more than one changed files' '
echo anotherfile > file2 &&
git add file2 &&
git commit -m "added 2nd file" &&
echo modified >file2 &&
GIT_EXTERNAL_DIFF=echo git diff
'
test_expect_success 'GIT_EXTERNAL_DIFF path counter/total' '
write_script external-diff.sh <<-\EOF &&
echo $GIT_DIFF_PATH_COUNTER of $GIT_DIFF_PATH_TOTAL >>counter.txt
EOF
>counter.txt &&
cat >expect <<-\EOF &&
1 of 2
2 of 2
EOF
GIT_EXTERNAL_DIFF=./external-diff.sh git diff &&
test_cmp expect counter.txt
'
test_expect_success 'GIT_EXTERNAL_DIFF generates pretty paths' '
test_when_finished "git rm -f file.ext" &&
touch file.ext &&
git add file.ext &&
echo with extension > file.ext &&
cat >expect <<-EOF &&
file.ext
EOF
GIT_EXTERNAL_DIFF=echo git diff file.ext >out &&
basename $(cut -d" " -f2 <out) >actual &&
test_cmp expect actual
'
echo "#!$SHELL_PATH" >fake-diff.sh
cat >> fake-diff.sh <<\EOF
cat $2 >> crlfed.txt
EOF
chmod a+x fake-diff.sh
keep_only_cr () {
tr -dc '\015'
}
test_expect_success 'external diff with autocrlf = true' '
test_config core.autocrlf true &&
GIT_EXTERNAL_DIFF=./fake-diff.sh git diff &&
test $(wc -l <crlfed.txt) = $(keep_only_cr <crlfed.txt | wc -c)
'
test_expect_success 'diff --cached' '
test_config core.autocrlf true &&
git add file &&
git update-index --assume-unchanged file &&
echo second >file &&
git diff --cached >actual &&
test_cmp expected-diff actual
'
test_expect_success 'clean up crlf leftovers' '
git update-index --no-assume-unchanged file &&
rm -f file* &&
git reset --hard
'
test_expect_success 'submodule diff' '
git init sub &&
( cd sub && test_commit sub1 ) &&
git add sub &&
test_tick &&
git commit -m "add submodule" &&
( cd sub && test_commit sub2 ) &&
write_script gather_pre_post.sh <<-\EOF &&
echo "$1 $4" # path, mode
cat "$2" # old file
cat "$5" # new file
EOF
GIT_EXTERNAL_DIFF=./gather_pre_post.sh git diff >actual &&
cat >expected <<-EOF &&
sub 160000
Subproject commit $(git rev-parse HEAD:sub)
Subproject commit $(cd sub && git rev-parse HEAD)
EOF
test_cmp expected actual
'
test_done