Reorganize zstream API and fix wrap problems

There were some confusing issues mixing up the number of bytes
written to the zstream output buffer with the number of bytes
consumed from the zstream input.  This reorganizes the zstream
API and makes it easier to deflate an arbitrarily large input
while still using a fixed size output.

1 files changed, 98 insertions, 0 deletions

diff --git a/tests/core/zstream.c b/tests/core/zstream.c
new file mode 100644
index 000000000..63ff8c93a
--- /dev/null
+++ b/tests/core/zstream.c
@@ -0,0 +1,98 @@
+#include "clar_libgit2.h"
+#include "buffer.h"
+#include "zstream.h"
+
+static const char *data = "This is a test test test of This is a test";
+
+#define INFLATE_EXTRA 2
+
+static void assert_zlib_equal_(
+	const void *expected, size_t e_len,
+	const void *compressed, size_t c_len,
+	const char *msg, const char *file, int line)
+{
+	z_stream stream;
+	char *expanded = git__calloc(1, e_len + INFLATE_EXTRA);
+	cl_assert(expanded);
+
+	memset(&stream, 0, sizeof(stream));
+	stream.next_out  = (Bytef *)expanded;
+	stream.avail_out = (uInt)(e_len + INFLATE_EXTRA);
+	stream.next_in   = (Bytef *)compressed;
+	stream.avail_in  = (uInt)c_len;
+
+	cl_assert(inflateInit(&stream) == Z_OK);
+	cl_assert(inflate(&stream, Z_FINISH));
+	inflateEnd(&stream);
+
+	clar__assert_equal(
+		file, line, msg, 1,
+		"%d", (int)stream.total_out, (int)e_len);
+	clar__assert_equal(
+		file, line, "Buffer len was not exact match", 1,
+		"%d", (int)stream.avail_out, (int)INFLATE_EXTRA);
+
+	clar__assert(
+		memcmp(expanded, expected, e_len) == 0,
+		file, line, "uncompressed data did not match", NULL, 1);
+
+	git__free(expanded);
+}
+
+#define assert_zlib_equal(E,EL,C,CL) \
+	assert_zlib_equal_(E, EL, C, CL, #EL " != " #CL, __FILE__, (int)__LINE__)
+
+void test_core_zstream__basic(void)
+{
+	git_zstream z = GIT_ZSTREAM_INIT;
+	char out[128];
+	size_t outlen = sizeof(out);
+
+	cl_git_pass(git_zstream_init(&z));
+	cl_git_pass(git_zstream_set_input(&z, data, strlen(data) + 1));
+	cl_git_pass(git_zstream_get_output(out, &outlen, &z));
+	cl_assert(git_zstream_done(&z));
+	cl_assert(outlen > 0);
+	git_zstream_free(&z);
+
+	assert_zlib_equal(data, strlen(data) + 1, out, outlen);
+}
+
+void test_core_zstream__buffer(void)
+{
+	git_buf out = GIT_BUF_INIT;
+	cl_git_pass(git_zstream_deflatebuf(&out, data, strlen(data) + 1));
+	assert_zlib_equal(data, strlen(data) + 1, out.ptr, out.size);
+	git_buf_free(&out);
+}
+
+#define BIG_STRING_PART "Big Data IS Big - Long Data IS Long - We need a buffer larger than 1024 x 1024 to make sure we trigger chunked compression - Big Big Data IS Bigger than Big - Long Long Data IS Longer than Long"
+
+void test_core_zstream__big_data(void)
+{
+	git_buf in = GIT_BUF_INIT;
+	git_buf out = GIT_BUF_INIT;
+	size_t scan;
+
+	/* make a big string that's easy to compress */
+	while (in.size < 1024 * 1024)
+		cl_git_pass(git_buf_put(&in, BIG_STRING_PART, strlen(BIG_STRING_PART)));
+
+	cl_git_pass(git_zstream_deflatebuf(&out, in.ptr, in.size));
+	assert_zlib_equal(in.ptr, in.size, out.ptr, out.size);
+
+	git_buf_free(&out);
+
+	/* make a big string that's hard to compress */
+
+	srand(0xabad1dea);
+	for (scan = 0; scan < in.size; ++scan)
+		in.ptr[scan] = (char)rand();
+
+	cl_git_pass(git_zstream_deflatebuf(&out, in.ptr, in.size));
+	assert_zlib_equal(in.ptr, in.size, out.ptr, out.size);
+
+	git_buf_free(&out);
+
+	git_buf_free(&in);
+}