Add a test for a names_do_all function

Make sure that if we change the namemap part way through calling a
names_do_all function it still works.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14250)

test/evp_extra_test.c

diff --git a/test/evp_extra_test.c b/test/evp_extra_test.c
index 2d32eb9..a2490a9 100644
--- a/test/evp_extra_test.c
+++ b/test/evp_extra_test.c
@@ -2439,6 +2439,53 @@
     return ret;
 }
 
+static int success = 1;
+static void md_names(const char *name, void *vctx)
+{
+    OSSL_LIB_CTX *ctx = (OSSL_LIB_CTX *)vctx;
+    /* Force a namemap update */
+    EVP_CIPHER *aes128 = EVP_CIPHER_fetch(ctx, "AES-128-CBC", NULL);
+
+    if (!TEST_ptr(aes128))
+        success = 0;
+
+    EVP_CIPHER_free(aes128);
+}
+
+/*
+ * Test that changing the namemap in a user callback works in a names_do_all
+ * function.
+ */
+static int test_names_do_all(void)
+{
+    /* We use a custom libctx so that we know the state of the namemap */
+    OSSL_LIB_CTX *ctx = OSSL_LIB_CTX_new();
+    EVP_MD *sha256 = NULL;
+    int testresult = 0;
+
+    if (!TEST_ptr(ctx))
+        goto err;
+
+    sha256 = EVP_MD_fetch(ctx, "SHA2-256", NULL);
+    if (!TEST_ptr(sha256))
+        goto err;
+
+    /*
+     * We loop through all the names for a given digest. This should still work
+     * even if the namemap changes part way through.
+     */
+    if (!TEST_true(EVP_MD_names_do_all(sha256, md_names, ctx)))
+        goto err;
+
+    if (!TEST_true(success))
+        goto err;
+
+    testresult = 1;
+ err:
+    EVP_MD_free(sha256);
+    OSSL_LIB_CTX_free(ctx);
+    return testresult;
+}
 
 int setup_tests(void)
 {
@@ -2513,6 +2560,8 @@
     ADD_ALL_TESTS(test_evp_iv, 10);
     ADD_TEST(test_EVP_rsa_pss_with_keygen_bits);
 
+    ADD_TEST(test_names_do_all);
+
     return 1;
 }