t1016-compatObjectFormat: add tests to verify the conversion between objects

For now my strategy is simple.  Create two identical repositories one
in each format.  Use fixed timestamps. Verify the dynamically computed
compatibility objects from one repository match the objects stored in
the other repository.

A general limitation of this strategy is that the git when generating
signed tags and commits with compatObjectFormat enabled will generate
a signature for both formats.  To overcome this limitation I have
added "test-tool delete-gpgsig" that when fed an signed commit or tag
with two signatures deletes one of the signatures.

With that in place I can have "git commit" and  "git tag" generate
signed objects, have my tool delete one, and feed the new object
into "git hash-object" to create the kinds of commits and tags
git without compatObjectFormat enabled will generate.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 64 insertions, 0 deletions

diff --git a/t/helper/test-delete-gpgsig.c b/t/helper/test-delete-gpgsig.c
new file mode 100644
index 0000000000..e36831af03
--- /dev/null
+++ b/t/helper/test-delete-gpgsig.c
@@ -0,0 +1,62 @@
+#include "test-tool.h"
+#include "gpg-interface.h"
+#include "strbuf.h"
+
+
+int cmd__delete_gpgsig(int argc, const char **argv)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *pattern = "gpgsig";
+	const char *bufptr, *tail, *eol;
+	int deleting = 0;
+	size_t plen;
+
+	if (argc >= 2) {
+		pattern = argv[1];
+		argv++;
+		argc--;
+	}
+
+	plen = strlen(pattern);
+	strbuf_read(&buf, 0, 0);
+
+	if (!strcmp(pattern, "trailer")) {
+		size_t payload_size = parse_signed_buffer(buf.buf, buf.len);
+		fwrite(buf.buf, 1, payload_size, stdout);
+		fflush(stdout);
+		return 0;
+	}
+
+	bufptr = buf.buf;
+	tail = bufptr + buf.len;
+
+	while (bufptr < tail) {
+		/* Find the end of the line */
+		eol = memchr(bufptr, '\n', tail - bufptr);
+		if (!eol)
+			eol = tail;
+
+		/* Drop continuation lines */
+		if (deleting && (bufptr < eol) && (bufptr[0] == ' ')) {
+			bufptr = eol + 1;
+			continue;
+		}
+		deleting = 0;
+
+		/* Does the line match the prefix? */
+		if (((bufptr + plen) < eol) &&
+		    !memcmp(bufptr, pattern, plen) &&
+		    (bufptr[plen] == ' ')) {
+			deleting = 1;
+			bufptr = eol + 1;
+			continue;
+		}
+
+		/* Print all other lines */
+		fwrite(bufptr, 1, (eol - bufptr) + 1, stdout);
+		bufptr = eol + 1;
+	}
+	fflush(stdout);
+
+	return 0;
+}
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index abe8a785eb..8b6c84f202 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -21,6 +21,7 @@ static struct test_cmd cmds[] = {
 	{ "csprng", cmd__csprng },
 	{ "ctype", cmd__ctype },
 	{ "date", cmd__date },
+	{ "delete-gpgsig", cmd__delete_gpgsig },
 	{ "delta", cmd__delta },
 	{ "dir-iterator", cmd__dir_iterator },
 	{ "drop-caches", cmd__drop_caches },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index ea2672436c..76baaece35 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -15,6 +15,7 @@ int cmd__csprng(int argc, const char **argv);
 int cmd__ctype(int argc, const char **argv);
 int cmd__date(int argc, const char **argv);
 int cmd__delta(int argc, const char **argv);
+int cmd__delete_gpgsig(int argc, const char **argv);
 int cmd__dir_iterator(int argc, const char **argv);
 int cmd__drop_caches(int argc, const char **argv);
 int cmd__dump_cache_tree(int argc, const char **argv);