Add regress for CBB_discard_child().

Converted from BoringSSL.

1 files changed, 56 insertions, 2 deletions

diff --git a/src/regress/lib/libssl/bytestring/bytestringtest.c b/src/regress/lib/libssl/bytestring/bytestringtest.c
index 5275269902..a260ede2a2 100644
--- a/src/regress/lib/libssl/bytestring/bytestringtest.c
+++ b/src/regress/lib/libssl/bytestring/bytestringtest.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bytestringtest.c,v 1.10 2015/10/25 20:15:06 doug Exp $        */
+/*      $OpenBSD: bytestringtest.c,v 1.11 2017/11/28 16:35:05 jsing Exp $       */
 /*
  * Copyright (c) 2014, Google Inc.
  *
@@ -350,9 +350,9 @@ test_cbb_prefixed(void)
 {
         static const uint8_t kExpected[] = {0, 1, 1, 0, 2, 2, 3, 0, 0, 3,
             4, 5, 6, 5, 4, 1, 0, 1, 2};
+        CBB cbb, contents, inner_contents, inner_inner_contents;
         uint8_t *buf = NULL;
         size_t buf_len;
-        CBB cbb, contents, inner_contents, inner_inner_contents;
         int ret = 0;
 
         CHECK(CBB_init(&cbb, 0));
@@ -383,6 +383,59 @@ err:
 }
 
 static int
+test_cbb_discard_child(void)
+{
+        static const uint8_t kExpected[] = {
+                0xaa,
+                0,
+                1, 0xbb,
+                0, 2, 0xcc, 0xcc,
+                0, 0, 3, 0xdd, 0xdd, 0xdd,
+                1, 0xff,
+        };
+        CBB cbb, contents, inner_contents, inner_inner_contents;
+        uint8_t *buf = NULL;
+        size_t buf_len;
+        int ret = 0;
+
+        CHECK(CBB_init(&cbb, 0));
+        CHECK_GOTO(CBB_add_u8(&cbb, 0xaa));
+
+        // Discarding |cbb|'s children preserves the byte written.
+        CBB_discard_child(&cbb);
+
+        CHECK_GOTO(CBB_add_u8_length_prefixed(&cbb, &contents));
+        CHECK_GOTO(CBB_add_u8_length_prefixed(&cbb, &contents));
+        CHECK_GOTO(CBB_add_u8(&contents, 0xbb));
+        CHECK_GOTO(CBB_add_u16_length_prefixed(&cbb, &contents));
+        CHECK_GOTO(CBB_add_u16(&contents, 0xcccc));
+        CHECK_GOTO(CBB_add_u24_length_prefixed(&cbb, &contents));
+        CHECK_GOTO(CBB_add_u24(&contents, 0xdddddd));
+        CHECK_GOTO(CBB_add_u8_length_prefixed(&cbb, &contents));
+        CHECK_GOTO(CBB_add_u8(&contents, 0xff));
+        CHECK_GOTO(CBB_add_u8_length_prefixed(&contents, &inner_contents));
+        CHECK_GOTO(CBB_add_u8(&inner_contents, 0x42));
+        CHECK_GOTO(CBB_add_u16_length_prefixed(&inner_contents,
+            &inner_inner_contents));
+        CHECK_GOTO(CBB_add_u8(&inner_inner_contents, 0x99));
+
+        // Discard everything from |inner_contents| down.
+        CBB_discard_child(&contents);
+
+        CHECK_GOTO(CBB_finish(&cbb, &buf, &buf_len));
+
+        ret = (buf_len == sizeof(kExpected)
+            && memcmp(buf, kExpected, buf_len) == 0);
+
+        if (0) {
+err:
+                CBB_cleanup(&cbb);
+        }
+        free(buf);
+        return ret;
+}
+
+static int
 test_cbb_misuse(void)
 {
         CBB cbb, child, contents;
@@ -805,6 +858,7 @@ main(void)
         failed |= !test_cbb_basic();
         failed |= !test_cbb_fixed();
         failed |= !test_cbb_finish_child();
+        failed |= !test_cbb_discard_child();
         failed |= !test_cbb_misuse();
         failed |= !test_cbb_prefixed();
         failed |= !test_cbb_asn1();