builtin/cat-file.c             | 133 ++++++++++++++++++++++++
  t/t1006-cat-file.sh            | 178 ++++++++++++++++++++++++++++++++-
  3 files changed, 347 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index bef76f4dd06..e8da704477d 100644
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt

@@ -96,6 +96,32 @@ OPTIONS
  	need to specify the path, separated by whitespace.  See the
  	section `BATCH OUTPUT` below for details.
  
+--batch-command::

+	Enter a command mode that reads commands and arguments from stdin. May
+	only be combined with `--buffer`, `--textconv` or `--filters`. In the
+	case of `--textconv` or `--filters`, the input lines also need to specify
+	the path, separated by whitespace. See the section `BATCH OUTPUT` below
+	for details.
++
+`--batch-command` recognizes the following commands:
++
+--
+contents `<object>`::
+	Print object contents for object reference `<object>`. This corresponds to
+	the output of `--batch`.
+
+info `<object>`::
+	Print object info for object reference `<object>`. This corresponds to the
+	output of `--batch-check`.
+
+flush::
+	Used with `--buffer` to execute all preceding commands that were issued
+	since the beginning or since the last flush was issued. When `--buffer`
+	is used, no output will come until a `flush` is issued. When `--buffer`
+	is not used, commands are flushed each time without issuing `flush`.
+--
++

diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
index 145eee11df9..a501dbcc39b 100755
--- a/t/t1006-cat-file.sh
+++ b/t/t1006-cat-file.sh

@@ -177,6 +177,24 @@ $content"
  	test_cmp expect actual
      '
  
+    for opt in --buffer --no-buffer
+    do
+	test -z "$content" ||
+		test_expect_success "--batch-command $opt output of $type content is correct" '
+		maybe_remove_timestamp "$batch_output" $no_ts >expect &&
+		maybe_remove_timestamp "$(test_write_lines "contents $sha1" \
+		| git cat-file --batch-command $opt)" $no_ts >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "--batch-command $opt output of $type info is correct" '
+		echo "$sha1 $type $size" >expect &&
+		test_write_lines "info $sha1" \
+		| git cat-file --batch-command $opt >actual &&
+		test_cmp expect actual
+	'
+    done
+
      test_expect_success "custom --batch-check format" '
  	echo "$type $sha1" >expect &&
  	echo $sha1 | git cat-file --batch-check="%(objecttype) %(objectname)" >actual &&

@@ -213,6 +231,84 @@ $content"
      '
  }
  
+run_buffer_test_flush () {
+	type=$1
+	sha1=$2
+	size=$3
+
+	rm -f input output &&

+		test "$status" -ne 0 &&
+		test_must_be_empty output
+	) >input
+}
+
+
  hello_content="Hello World"
  hello_size=$(strlen "$hello_content")
  hello_sha1=$(echo_without_newline "$hello_content" | git hash-object --stdin)

@@ -224,6 +320,14 @@ test_expect_success "setup" '
  
  run_tests 'blob' $hello_sha1 $hello_size "$hello_content" "$hello_content"
  
+test_expect_success PIPE '--batch-command --buffer with flush for blob info' '
+       run_buffer_test_flush blob $hello_sha1 $hello_size
+'
+
+test_expect_success PIPE '--batch-command --buffer without flush for blob info' '
+       run_buffer_test_no_flush blob $hello_sha1 $hello_size false
+'
+
  test_expect_success '--batch-check without %(rest) considers whole line' '
  	echo "$hello_sha1 blob $hello_size" >expect &&
  	git update-index --add --cacheinfo 100644 $hello_sha1 "white space" &&

@@ -267,7 +371,7 @@ test_expect_success \
      "Reach a blob from a tag pointing to it" \
      "test '$hello_content' = \"\$(git cat-file blob $tag_sha1)\""
  
-for batch in batch batch-check
+for batch in batch batch-check batch-command
  do
      for opt in t s e p
      do

@@ -373,6 +477,43 @@ test_expect_success "--batch-check with multiple sha1s gives correct format" '
      "$(echo_without_newline "$batch_check_input" | git cat-file --batch-check)"
  '
  
+test_expect_success '--batch-command with multiple info calls gives correct format' '
+	cat >expect <<-EOF &&
+	$hello_sha1 blob $hello_size
+	$tree_sha1 tree $tree_size
+	$commit_sha1 commit $commit_size
+	$tag_sha1 tag $tag_size
+	deadbeef missing
+	EOF
+
+	test_write_lines "info $hello_sha1"\
+	"info $tree_sha1"\
+	"info $commit_sha1"\
+	"info $tag_sha1"\
+	"info deadbeef" | git cat-file --batch-command --buffer >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--batch-command with multiple command calls gives correct format' '
+	cat >expect <<-EOF &&
+	$hello_sha1 blob $hello_size
+	$hello_content
+	$commit_sha1 commit $commit_size
+	$commit_content
+	$tag_sha1 tag $tag_size
+	$tag_content
+	deadbeef missing
+	EOF
+
+	maybe_remove_timestamp "$(cat expect)" 1 >expect &&
+	maybe_remove_timestamp "$(test_write_lines "contents $hello_sha1"\
+	"contents $commit_sha1"\
+	"contents $tag_sha1"\
+	"contents deadbeef"\
+	"flush" | git cat-file --batch-command --buffer)" 1 >actual &&
+	test_cmp expect actual

+'
+
  test_expect_success 'setup blobs which are likely to delta' '
  	test-tool genrandom foo 10240 >foo &&
  	{ cat foo && echo plus; } >foo-plus &&

@@ -963,5 +1104,40 @@ test_expect_success 'cat-file --batch-all-objects --batch-check ignores replace'
  	echo "$orig commit $orig_size" >expect &&
  	test_cmp expect actual
  '
+test_expect_success 'batch-command empty command' '
+	echo "" >cmd &&
+	test_expect_code 128 git cat-file --batch-command <cmd 2>err &&
+	grep "^fatal:.*empty command in input.*" err
+'
+
+test_expect_success 'batch-command whitespace before command' '
+	echo " info deadbeef" >cmd &&
+	test_expect_code 128 git cat-file --batch-command <cmd 2>err &&
+	grep "^fatal:.*whitespace before command.*" err
+'
+
+test_expect_success 'batch-command unknown command' '
+	echo unknown_command >cmd &&
+	test_expect_code 128 git cat-file --batch-command <cmd 2>err &&
+	grep "^fatal:.*unknown command.*" err
+'
+
+test_expect_success 'batch-command missing arguments' '
+	echo "info" >cmd &&
+	test_expect_code 128 git cat-file --batch-command <cmd 2>err &&
+	grep "^fatal:.*info requires arguments.*" err
+'
+
+test_expect_success 'batch-command flush with arguments' '
+	echo "flush arg" >cmd &&
+	test_expect_code 128 git cat-file --batch-command --buffer <cmd 2>err &&
+	grep "^fatal:.*flush takes no arguments.*" err
+'
+
+test_expect_success 'batch-command flush without --buffer' '
+	echo "flush arg" >cmd &&
+	test_expect_code 128 git cat-file --batch-command <cmd 2>err &&
+	grep "^fatal:.*flush is only for --buffer mode.*" err
+'
  
  test_done