builtin/cat-file.c: support NUL-delimited input with `-z`

When callers are using `cat-file` via one of the stdin-driven `--batch`
modes, all input is newline-delimited. This presents a problem when
callers wish to ask about, e.g. tree-entries that have a newline
character present in their filename.

To support this niche scenario, introduce a new `-z` mode to the
`--batch`, `--batch-check`, and `--batch-command` suite of options that
instructs `cat-file` to treat its input as NUL-delimited, allowing the
individual commands themselves to have newlines present.

The refactoring here is slightly unfortunate, since we turn loops like:

    while (strbuf_getline(&buf, stdin) != EOF)

into:

    while (1) {
        int ret;
        if (opt->nul_terminated)
            ret = strbuf_getline_nul(&input, stdin);
        else
            ret = strbuf_getline(&input, stdin);

        if (ret == EOF)
            break;
    }

It's tempting to think that we could use `strbuf_getwholeline()` and
specify either `\n` or `\0` as the terminating character. But for input
on platforms that include a CR character preceeding the LF, this
wouldn't quite be the same, since `strbuf_getline(...)` will trim any
trailing CR, while `strbuf_getwholeline(&buf, stdin, '\n')` will not.

In the future, we could clean this up further by introducing a variant
of `strbuf_getwholeline()` that addresses the aforementioned gap, but
that approach felt too heavy-handed for this pair of uses.

Some tests are added in t1006 to ensure that `cat-file` produces the
same output in `--batch`, `--batch-check`, and `--batch-command` modes
with and without the new `-z` option.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-cat-file.txt b/Documentation/git-cat-file.txt
index 24a811f0ef64b0f411c23a3598e7bc73e6a2e7ee..3515350ed623e9cb88431140b37a4ef805742ec9 100644 (file)
--- a/Documentation/git-cat-file.txt
+++ b/Documentation/git-cat-file.txt
@@ -14,7 +14,7 @@ SYNOPSIS
 'git cat-file' (-t | -s) [--allow-unknown-type] <object>
 'git cat-file' (--batch | --batch-check | --batch-command) [--batch-all-objects]
             [--buffer] [--follow-symlinks] [--unordered]
-            [--textconv | --filters]
+            [--textconv | --filters] [-z]
 'git cat-file' (--textconv | --filters)
             [<rev>:<path|tree-ish> | --path=<path|tree-ish> <rev>]
 
@@ -207,6 +207,11 @@ respectively print:
        /etc/passwd
 --
 
+-z::
+       Only meaningful with `--batch`, `--batch-check`, or
+       `--batch-command`; input is NUL-delimited instead of
+       newline-delimited.
+
 
 OUTPUT
 ------

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index f42782e955f35bdfa9a78c217337863364bce1d5..c3602d15df621ae3223e4f91c71854c807ffcbcb 100644 (file)
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -31,6 +31,7 @@ struct batch_options {
        int all_objects;
        int unordered;
        int transform_mode; /* may be 'w' or 'c' for --filters or --textconv */
+       int nul_terminated;
        const char *format;
 };
 
@@ -614,12 +615,20 @@ static void batch_objects_command(struct batch_options *opt,
        struct queued_cmd *queued_cmd = NULL;
        size_t alloc = 0, nr = 0;
 
-       while (!strbuf_getline(&input, stdin)) {
-               int i;
+       while (1) {
+               int i, ret;
                const struct parse_cmd *cmd = NULL;
                const char *p = NULL, *cmd_end;
                struct queued_cmd call = {0};
 
+               if (opt->nul_terminated)
+                       ret = strbuf_getline_nul(&input, stdin);
+               else
+                       ret = strbuf_getline(&input, stdin);
+
+               if (ret)
+                       break;
+
                if (!input.len)
                        die(_("empty command in input"));
                if (isspace(*input.buf))
@@ -763,7 +772,16 @@ static int batch_objects(struct batch_options *opt)
                goto cleanup;
        }
 
-       while (strbuf_getline(&input, stdin) != EOF) {
+       while (1) {
+               int ret;
+               if (opt->nul_terminated)
+                       ret = strbuf_getline_nul(&input, stdin);
+               else
+                       ret = strbuf_getline(&input, stdin);
+
+               if (ret == EOF)
+                       break;
+
                if (data.split_on_whitespace) {
                        /*
                         * Split at first whitespace, tying off the beginning
@@ -866,6 +884,7 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
                        N_("like --batch, but don't emit <contents>"),
                        PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
                        batch_option_callback),
+               OPT_BOOL('z', NULL, &batch.nul_terminated, N_("stdin is NUL-terminated")),
                OPT_CALLBACK_F(0, "batch-command", &batch, N_("format"),
                        N_("read commands from stdin"),
                        PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
@@ -921,6 +940,9 @@ int cmd_cat_file(int argc, const char **argv, const char *prefix)
        else if (batch.all_objects)
                usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
                               "--batch-all-objects");
+       else if (batch.nul_terminated)
+               usage_msg_optf(_("'%s' requires a batch mode"), usage, options,
+                              "-z");
 
        /* Batch defaults */
        if (batch.buffer_output < 0)

diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
index 01c053576513cd03dd07e806157d9b9cd8379e07..23b8942edba45c32822886ee93acef9b5474ea02 100755 (executable)
--- a/t/t1006-cat-file.sh
+++ b/t/t1006-cat-file.sh
@@ -88,7 +88,8 @@ done
 
 for opt in --buffer \
        --follow-symlinks \
-       --batch-all-objects
+       --batch-all-objects \
+       -z
 do
        test_expect_success "usage: bad option combination: $opt without batch mode" '
                test_incompatible_usage git cat-file $opt &&
@@ -100,6 +101,10 @@ echo_without_newline () {
     printf '%s' "$*"
 }
 
+echo_without_newline_nul () {
+       echo_without_newline "$@" | tr '\n' '\0'
+}
+
 strlen () {
     echo_without_newline "$1" | wc -c | sed -e 's/^ *//'
 }
@@ -398,6 +403,12 @@ test_expect_success '--batch with multiple sha1s gives correct format' '
        test "$(maybe_remove_timestamp "$batch_output" 1)" = "$(maybe_remove_timestamp "$(echo_without_newline "$batch_input" | git cat-file --batch)" 1)"
 '
 
+test_expect_success '--batch, -z with multiple sha1s gives correct format' '
+       echo_without_newline_nul "$batch_input" >in &&
+       test "$(maybe_remove_timestamp "$batch_output" 1)" = \
+       "$(maybe_remove_timestamp "$(git cat-file --batch -z <in)" 1)"
+'
+
 batch_check_input="$hello_sha1
 $tree_sha1
 $commit_sha1
@@ -418,6 +429,24 @@ test_expect_success "--batch-check with multiple sha1s gives correct format" '
     "$(echo_without_newline "$batch_check_input" | git cat-file --batch-check)"
 '
 
+test_expect_success "--batch-check, -z with multiple sha1s gives correct format" '
+    echo_without_newline_nul "$batch_check_input" >in &&
+    test "$batch_check_output" = "$(git cat-file --batch-check -z <in)"
+'
+
+test_expect_success FUNNYNAMES '--batch-check, -z with newline in input' '
+       touch -- "newline${LF}embedded" &&
+       git add -- "newline${LF}embedded" &&
+       git commit -m "file with newline embedded" &&
+       test_tick &&
+
+       printf "HEAD:newline${LF}embedded" >in &&
+       git cat-file --batch-check -z <in >actual &&
+
+       echo "$(git rev-parse "HEAD:newline${LF}embedded") blob 0" >expect &&
+       test_cmp expect actual
+'
+
 batch_command_multiple_info="info $hello_sha1
 info $tree_sha1
 info $commit_sha1
@@ -436,6 +465,11 @@ test_expect_success '--batch-command with multiple info calls gives correct form
        echo "$batch_command_multiple_info" >in &&
        git cat-file --batch-command --buffer <in >actual &&
 
+       test_cmp expect actual &&
+
+       echo "$batch_command_multiple_info" | tr "\n" "\0" >in &&
+       git cat-file --batch-command --buffer -z <in >actual &&
+
        test_cmp expect actual
 '
 
@@ -459,6 +493,12 @@ test_expect_success '--batch-command with multiple command calls gives correct f
        echo "$batch_command_multiple_contents" >in &&
        git cat-file --batch-command --buffer <in >actual_raw &&
 
+       remove_timestamp <actual_raw >actual &&
+       test_cmp expect actual &&
+
+       echo "$batch_command_multiple_contents" | tr "\n" "\0" >in &&
+       git cat-file --batch-command --buffer -z <in >actual_raw &&
+
        remove_timestamp <actual_raw >actual &&
        test_cmp expect actual
 '