[PATCH v4 1/2] bundle: lost objects when removing duplicate pendings

[Jiang Xin <worldhello.net@gmail.com>]

From: Jiang Xin <zhiyou.jx@alibaba-inc.com>

`git rev-list` will list one commit for the following command:

    $ git rev-list 'main^!'
    <tip-commit-of-main-branch>

But providing the same rev-list args to `git bundle`, fail to create
a bundle file.

    $ git bundle create - 'main^!'
    # v2 git bundle
    -<OID> <one-line-message>

    fatal: Refusing to create empty bundle.

This is because when removing duplicate objects in function
`object_array_remove_duplicates()`, one unique pending object which has
the same name is deleted by mistake.  The revision arg 'main^!' in the
above example is parsed by `handle_revision_arg()`, and at lease two
different objects will be appended to `revs.pending`, one points to the
parent commit of the "main" branch, and the other points to the tip
commit of the "main" branch.  These two objects have the same name
"main".  Only one object is left with the name "main" after calling the
function `object_array_remove_duplicates()`.

And what's worse, when adding boundary commits into pending list, we use
one-line commit message as names, and the arbitory names may surprise
git-bundle.

Only comparing objects themselves (".item") is also not good enough,
because user may want to create a bundle with two identical objects but
with different reference names, such as: "HEAD" and "refs/heads/main".

Add new function `contains_object()` which compare both the address and
the name of the object.

Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
---
 object.c               |  10 +-
 t/t6020-bundle-misc.sh | 477 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 483 insertions(+), 4 deletions(-)
 create mode 100755 t/t6020-bundle-misc.sh

diff --git a/object.c b/object.c
index 68f80b0b3d..98017bed8e 100644
--- a/object.c
+++ b/object.c
@@ -412,15 +412,16 @@ void object_array_clear(struct object_array *array)
 }
 
 /*
- * Return true iff array already contains an entry with name.
+ * Return true if array already contains an entry.
  */
-static int contains_name(struct object_array *array, const char *name)
+static int contains_object(struct object_array *array,
+			   const struct object *item, const char *name)
 {
 	unsigned nr = array->nr, i;
 	struct object_array_entry *object = array->objects;
 
 	for (i = 0; i < nr; i++, object++)
-		if (!strcmp(object->name, name))
+		if (item == object->item && !strcmp(object->name, name))
 			return 1;
 	return 0;
 }
@@ -432,7 +433,8 @@ void object_array_remove_duplicates(struct object_array *array)
 
 	array->nr = 0;
 	for (src = 0; src < nr; src++) {
-		if (!contains_name(array, objects[src].name)) {
+		if (!contains_object(array, objects[src].item,
+				     objects[src].name)) {
 			if (src != array->nr)
 				objects[array->nr] = objects[src];
 			array->nr++;
diff --git a/t/t6020-bundle-misc.sh b/t/t6020-bundle-misc.sh
new file mode 100755
index 0000000000..c4447ca88f
--- /dev/null
+++ b/t/t6020-bundle-misc.sh
@@ -0,0 +1,477 @@
+#!/bin/sh
+#
+# Copyright (c) 2021 Jiang Xin
+#
+
+test_description='Test git-bundle'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+# Check count of objects in a bundle file.
+# We can use "--thin" opiton to check thin pack, which must be fixed by
+# command `git-index-pack --fix-thin --stdin`.
+test_bundle_object_count () {
+	thin= &&
+	if test "$1" = "--thin"
+	then
+		thin=yes
+		shift
+	fi &&
+	if test $# -ne 2
+	then
+		echo >&2 "args should be: <bundle> <count>"
+		return 1
+	fi
+	bundle=$1 &&
+	pack=${bundle%.bdl}.pack &&
+	convert_bundle_to_pack <"$bundle" >"$pack" &&
+	if test -n "$thin"
+	then
+		test_must_fail git index-pack "$pack" &&
+		mv "$pack" "$pack"-thin &&
+		cat "$pack"-thin |
+			git index-pack --stdin --fix-thin "$pack"
+	else
+		git index-pack "$pack"
+	fi &&
+	git verify-pack -v "$pack" >verify.out
+	if test $? -ne 0
+	then
+		echo >&2 "error: fail to convert $bundle to $pack"
+		return 1
+	fi
+	count=$(grep -c "^$OID_REGEX " verify.out) &&
+	test $2 = $count && return 0
+	echo >&2 "error: object count for $bundle is $count, not $2"
+	return 1
+}
+
+# Display the pack data contained in the bundle file, bypassing the
+# header that contains the signature, prerequisites and references.
+convert_bundle_to_pack () {
+	while read x && test -n "$x"
+	do
+		:;
+	done
+	cat
+}
+
+# Create a commit or tag and set the variable with the object ID.
+test_commit_setvar () {
+	notick= &&
+	signoff= &&
+	indir= &&
+	merge= &&
+	tag= &&
+	var= &&
+	while test $# != 0
+	do
+		case "$1" in
+		--merge)
+			merge=yes
+			;;
+		--tag)
+			tag=yes
+			;;
+		--notick)
+			notick=yes
+			;;
+		--signoff)
+			signoff="$1"
+			;;
+		-C)
+			indir="$2"
+			shift
+			;;
+		-*)
+			echo >&2 "error: unknown option $1"
+			return 1
+			;;
+		*)
+			test -n "$var" && break
+			var=$1
+			;;
+		esac
+		shift
+	done &&
+	indir=${indir:+"$indir"/} &&
+	if test $# -eq 0
+	then
+		echo >&2 "no args provided"
+		return 1
+	fi &&
+	if test -z "$notick"
+	then
+		test_tick
+	fi &&
+	if test -n "$merge"
+	then
+		git ${indir:+ -C "$indir"} merge --no-edit --no-ff \
+			${2:+-m "$2"} "$1" &&
+		oid=$(git ${indir:+ -C "$indir"} rev-parse HEAD)
+	elif test -n "$tag"
+	then
+		git ${indir:+ -C "$indir"} tag -m "$1" "$1" &&
+		oid=$(git ${indir:+ -C "$indir"} rev-parse "$1")
+	else
+		file=${2:-"$1.t"} &&
+		echo "${3-$1}" > "$indir$file" &&
+		git ${indir:+ -C "$indir"} add "$file" &&
+		git ${indir:+ -C "$indir"} commit $signoff -m "$1" &&
+		oid=$(git ${indir:+ -C "$indir"} rev-parse HEAD)
+	fi &&
+	eval $var=$oid
+}
+
+
+# Format the output of git commands to make a user-friendly and stable
+# text.  We can easily prepare the expect text without having to worry
+# about future changes of the commit ID and spaces of the output.
+make_user_friendly_and_stable_output () {
+	sed \
+		-e "s/$A/<COMMIT-A>/" \
+		-e "s/$B/<COMMIT-B>/" \
+		-e "s/$C/<COMMIT-C>/" \
+		-e "s/$D/<COMMIT-D>/" \
+		-e "s/$E/<COMMIT-E>/" \
+		-e "s/$F/<COMMIT-F>/" \
+		-e "s/$G/<COMMIT-G>/" \
+		-e "s/$H/<COMMIT-H>/" \
+		-e "s/$I/<COMMIT-I>/" \
+		-e "s/$J/<COMMIT-J>/" \
+		-e "s/$K/<COMMIT-K>/" \
+		-e "s/$L/<COMMIT-L>/" \
+		-e "s/$M/<COMMIT-M>/" \
+		-e "s/$N/<COMMIT-N>/" \
+		-e "s/$O/<COMMIT-O>/" \
+		-e "s/$P/<COMMIT-P>/" \
+		-e "s/$TAG1/<TAG-1>/" \
+		-e "s/$TAG2/<TAG-2>/" \
+		-e "s/$TAG3/<TAG-3>/" \
+		-e "s/$(echo $A | cut -c1-7)[0-9a-f]*/<OID-A>/g" \
+		-e "s/$(echo $B | cut -c1-7)[0-9a-f]*/<OID-B>/g" \
+		-e "s/$(echo $C | cut -c1-7)[0-9a-f]*/<OID-C>/g" \
+		-e "s/$(echo $D | cut -c1-7)[0-9a-f]*/<OID-D>/g" \
+		-e "s/$(echo $E | cut -c1-7)[0-9a-f]*/<OID-E>/g" \
+		-e "s/$(echo $F | cut -c1-7)[0-9a-f]*/<OID-F>/g" \
+		-e "s/$(echo $G | cut -c1-7)[0-9a-f]*/<OID-G>/g" \
+		-e "s/$(echo $H | cut -c1-7)[0-9a-f]*/<OID-H>/g" \
+		-e "s/$(echo $I | cut -c1-7)[0-9a-f]*/<OID-I>/g" \
+		-e "s/$(echo $J | cut -c1-7)[0-9a-f]*/<OID-J>/g" \
+		-e "s/$(echo $K | cut -c1-7)[0-9a-f]*/<OID-K>/g" \
+		-e "s/$(echo $L | cut -c1-7)[0-9a-f]*/<OID-L>/g" \
+		-e "s/$(echo $M | cut -c1-7)[0-9a-f]*/<OID-M>/g" \
+		-e "s/$(echo $N | cut -c1-7)[0-9a-f]*/<OID-N>/g" \
+		-e "s/$(echo $O | cut -c1-7)[0-9a-f]*/<OID-O>/g" \
+		-e "s/$(echo $P | cut -c1-7)[0-9a-f]*/<OID-P>/g" \
+		-e "s/$(echo $TAG1 | cut -c1-7)[0-9a-f]*/<OID-TAG-1>/g" \
+		-e "s/$(echo $TAG2 | cut -c1-7)[0-9a-f]*/<OID-TAG-2>/g" \
+		-e "s/$(echo $TAG3 | cut -c1-7)[0-9a-f]*/<OID-TAG-3>/g" \
+		-e "s/ *\$//"
+}
+
+#            (C)   (D, pull/1/head, topic/1)
+#             o --- o
+#            /       \                              (L)
+#           /         \        o (H, topic/2)             (M, tag:v2)
+#          /    (F)    \      /                                 (N, tag:v3)
+#         /      o --------- o (G, pull/2/head)      o --- o --- o (release)
+#        /      /        \    \                      /       \
+#  o --- o --- o -------- o -- o ------------------ o ------- o --- o (main)
+# (A)   (B)  (E, tag:v1) (I)  (J)                  (K)       (O)   (P)
+#
+test_expect_success 'setup' '
+	# Try to make a stable fixed width for abbreviated commit ID,
+	# this fixed-width oid will be replaced with "<OID>".
+	git config core.abbrev 7 &&
+
+	# branch main: commit A & B
+	test_commit_setvar A "Commit A" main.txt &&
+	test_commit_setvar B "Commit B" main.txt &&
+
+	# branch topic/1: commit C & D, refs/pull/1/head
+	git checkout -b topic/1 &&
+	test_commit_setvar C "Commit C" topic-1.txt &&
+	test_commit_setvar D "Commit D" topic-1.txt &&
+	git update-ref refs/pull/1/head HEAD &&
+
+	# branch topic/1: commit E, tag v1
+	git checkout main &&
+	test_commit_setvar E "Commit E" main.txt &&
+	test_commit_setvar TAG1 --tag v1 &&
+
+	# branch topic/2: commit F & G, refs/pull/2/head
+	git checkout -b topic/2 &&
+	test_commit_setvar F "Commit F" topic-2.txt &&
+	test_commit_setvar G "Commit G" topic-2.txt &&
+	git update-ref refs/pull/2/head HEAD &&
+	test_commit_setvar H "Commit H" topic-2.txt &&
+
+	# branch main: merge commit I & J
+	git checkout main &&
+	test_commit_setvar I --merge topic/1 "Merge commit I" &&
+	test_commit_setvar J --merge refs/pull/2/head "Merge commit J" &&
+
+	# branch main: commit K
+	git checkout main &&
+	test_commit_setvar K "Commit K" main.txt &&
+
+	# branch release:
+	git checkout -b release &&
+	test_commit_setvar L "Commit L" release.txt &&
+	test_commit_setvar M "Commit M" release.txt &&
+	test_commit_setvar TAG2 --tag v2 &&
+	test_commit_setvar N "Commit N" release.txt &&
+	test_commit_setvar TAG3 --tag v3 &&
+
+	# branch main: merge commit O, commit P
+	git checkout main &&
+	test_commit_setvar O --merge tags/v2 "Merge commit O" &&
+	test_commit_setvar P "Commit P" main.txt
+'
+
+test_expect_success 'create bundle from special rev: main^!' '
+	git bundle create special-rev.bdl "main^!" &&
+
+	git bundle list-heads special-rev.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-P> refs/heads/main
+		EOF
+	test_i18ncmp expect actual &&
+
+	git bundle verify special-rev.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		The bundle contains this ref:
+		<COMMIT-P> refs/heads/main
+		The bundle requires this ref:
+		<COMMIT-O>
+		EOF
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count special-rev.bdl 3
+'
+
+test_expect_success 'create bundle with --max-count option' '
+	git bundle create max-count.bdl --max-count 1 \
+		main \
+		"^release" \
+		refs/tags/v1 \
+		refs/pull/1/head \
+		refs/pull/2/head &&
+
+	git bundle list-heads max-count.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-P> refs/heads/main
+		<TAG-1> refs/tags/v1
+		EOF
+	test_i18ncmp expect actual &&
+
+	git bundle verify max-count.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		The bundle contains these 2 refs:
+		<COMMIT-P> refs/heads/main
+		<TAG-1> refs/tags/v1
+		The bundle requires this ref:
+		<COMMIT-O>
+		EOF
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count max-count.bdl 4
+'
+
+test_expect_success 'create bundle with --since option' '
+	since="Thu Apr 7 15:26:13 2005 -0700" &&
+	git log -1 --pretty="%ad" $M >actual &&
+	echo "$since" >expect &&
+	test_cmp expect actual &&
+
+	git bundle create since.bdl \
+		--since "$since" --all &&
+
+	git bundle list-heads since.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-P> refs/heads/main
+		<COMMIT-N> refs/heads/release
+		<TAG-2> refs/tags/v2
+		<TAG-3> refs/tags/v3
+		<COMMIT-P> HEAD
+		EOF
+	test_i18ncmp expect actual &&
+
+	git bundle verify since.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		The bundle contains these 5 refs:
+		<COMMIT-P> refs/heads/main
+		<COMMIT-N> refs/heads/release
+		<TAG-2> refs/tags/v2
+		<TAG-3> refs/tags/v3
+		<COMMIT-P> HEAD
+		The bundle requires these 2 refs:
+		<COMMIT-L>
+		<COMMIT-K>
+		EOF
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count --thin since.bdl 16
+'
+
+test_expect_success 'create bundle 1 - no prerequisites' '
+	git bundle create 1.bdl topic/1 topic/2 &&
+
+	cat >expect <<-EOF &&
+		The bundle contains these 2 refs:
+		<COMMIT-D> refs/heads/topic/1
+		<COMMIT-H> refs/heads/topic/2
+		The bundle records a complete history.
+		EOF
+
+	# verify bundle, which has no prerequisites
+	git bundle verify 1.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count 1.bdl 24
+'
+
+test_expect_success 'create bundle 2 - has prerequisites' '
+	git bundle create 2.bdl \
+		--ignore-missing \
+		^topic/deleted \
+		^$D \
+		^topic/2 \
+		release &&
+
+	cat >expect <<-EOF &&
+		The bundle contains this ref:
+		<COMMIT-N> refs/heads/release
+		The bundle requires these 3 refs:
+		<COMMIT-D>
+		<COMMIT-E>
+		<COMMIT-G>
+		EOF
+
+	git bundle verify 2.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count 2.bdl 16
+'
+
+test_expect_success 'fail to verify bundle without prerequisites' '
+	git init --bare test1.git &&
+
+	cat >expect <<-EOF &&
+		error: Repository lacks these prerequisite commits:
+		error: <COMMIT-D>
+		error: <COMMIT-E>
+		error: <COMMIT-G>
+		EOF
+
+	test_must_fail git -C test1.git bundle verify ../2.bdl 2>&1 |
+		make_user_friendly_and_stable_output >actual &&
+	test_i18ncmp expect actual
+'
+
+test_expect_success 'create bundle 3 - two refs, same object' '
+	git bundle create --version=3 3.bdl \
+		^release \
+		^topic/1 \
+		^topic/2 \
+		main \
+		HEAD &&
+
+	cat >expect <<-EOF &&
+		The bundle contains these 2 refs:
+		<COMMIT-P> refs/heads/main
+		<COMMIT-P> HEAD
+		The bundle requires these 2 refs:
+		<COMMIT-M>
+		<COMMIT-K>
+		EOF
+
+	git bundle verify 3.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count 3.bdl 4
+'
+
+test_expect_success 'create bundle 4 - with tags' '
+	git bundle create 4.bdl \
+		^main \
+		^release \
+		^topic/1 \
+		^topic/2 \
+		--all &&
+
+	cat >expect <<-EOF &&
+		The bundle contains these 3 refs:
+		<TAG-1> refs/tags/v1
+		<TAG-2> refs/tags/v2
+		<TAG-3> refs/tags/v3
+		The bundle records a complete history.
+		EOF
+
+	git bundle verify 4.bdl |
+		make_user_friendly_and_stable_output >actual &&
+	test_i18ncmp expect actual &&
+
+	test_bundle_object_count 4.bdl 3
+'
+
+test_expect_success 'clone from bundle' '
+	git clone --mirror 1.bdl mirror.git &&
+	git -C mirror.git show-ref |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-D> refs/heads/topic/1
+		<COMMIT-H> refs/heads/topic/2
+		EOF
+	test_cmp expect actual &&
+
+	git -C mirror.git fetch ../2.bdl "+refs/*:refs/*" &&
+	git -C mirror.git show-ref |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-N> refs/heads/release
+		<COMMIT-D> refs/heads/topic/1
+		<COMMIT-H> refs/heads/topic/2
+		EOF
+	test_cmp expect actual &&
+
+	git -C mirror.git fetch ../3.bdl "+refs/*:refs/*" &&
+	git -C mirror.git show-ref |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-P> refs/heads/main
+		<COMMIT-N> refs/heads/release
+		<COMMIT-D> refs/heads/topic/1
+		<COMMIT-H> refs/heads/topic/2
+		EOF
+	test_cmp expect actual &&
+
+	git -C mirror.git fetch ../4.bdl "+refs/*:refs/*" &&
+	git -C mirror.git show-ref |
+		make_user_friendly_and_stable_output >actual &&
+	cat >expect <<-EOF &&
+		<COMMIT-P> refs/heads/main
+		<COMMIT-N> refs/heads/release
+		<COMMIT-D> refs/heads/topic/1
+		<COMMIT-H> refs/heads/topic/2
+		<TAG-1> refs/tags/v1
+		<TAG-2> refs/tags/v2
+		<TAG-3> refs/tags/v3
+		EOF
+	test_cmp expect actual
+'
+
+test_done
-- 
2.30.0.2.g06d2f50715