Fix and document BIO_FLAGS_NONCLEAR_RST behavior on memory BIO

The BIO_FLAGS_NONCLEAR_RST flag behavior was not properly documented
and it also caused the length to be incorrectly set after the reset
operation.

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/9179)

1 files changed, 40 insertions, 0 deletions

diff --git a/test/bio_memleak_test.c b/test/bio_memleak_test.c
index fab5ce73cf..dab61f6f9a 100644
--- a/test/bio_memleak_test.c
+++ b/test/bio_memleak_test.c
@@ -181,6 +181,45 @@ finish:
     return ok;
 }
 
+static int test_bio_nonclear_rst(void)
+{
+    int ok = 0;
+    BIO *bio = NULL;
+    char data[16];
+
+    bio = BIO_new(BIO_s_mem());
+    if (!TEST_ptr(bio))
+        goto finish;
+    if (!TEST_int_eq(BIO_puts(bio, "Hello World\n"), 12))
+        goto finish;
+
+    BIO_set_flags(bio, BIO_FLAGS_NONCLEAR_RST);
+
+    if (!TEST_int_eq(BIO_read(bio, data, 16), 12))
+        goto finish;
+    if (!TEST_mem_eq(data, 12, "Hello World\n", 12))
+        goto finish;
+    if (!TEST_int_gt(BIO_reset(bio), 0))
+        goto finish;
+
+    if (!TEST_int_eq(BIO_read(bio, data, 16), 12))
+        goto finish;
+    if (!TEST_mem_eq(data, 12, "Hello World\n", 12))
+        goto finish;
+
+    BIO_clear_flags(bio, BIO_FLAGS_NONCLEAR_RST);
+    if (!TEST_int_gt(BIO_reset(bio), 0))
+        goto finish;
+
+    if (!TEST_int_lt(BIO_read(bio, data, 16), 1))
+        goto finish;
+
+    ok = 1;
+
+finish:
+    BIO_free(bio);
+    return ok;
+}
 
 int global_init(void)
 {
@@ -196,5 +235,6 @@ int setup_tests(void)
     ADD_TEST(test_bio_new_mem_buf);
     ADD_TEST(test_bio_rdonly_mem_buf);
     ADD_TEST(test_bio_rdwr_rdonly);
+    ADD_TEST(test_bio_nonclear_rst);
     return 1;
 }