Factorise duplicated code.

Extract and factorise duplicated string glue code.
Cache strlen result to avoid duplicate calls.
[extended tests]

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4719)

test/bntest.c

@@ -79,6 +79,18 @@ static const char *findattr(STANZA *s, const char *key)
     return NULL;
 }
 
+/*
+ * Parse BIGNUM from sparse hex-strings, return |BN_hex2bn| result.
+ */
+static int parse_bigBN(BIGNUM **out, const char *bn_strings[])
+{
+    char *bigstring = glue_strings(bn_strings, NULL);
+    int ret = BN_hex2bn(out, bigstring);
+
+    OPENSSL_free(bigstring);
+    return ret;
+}
+
 /*
  * Parse BIGNUM, return number of bytes parsed.
  */
@@ -305,21 +317,6 @@ static const char *bn2strings[] = {
     NULL
 };
 
-static char *glue(const char *list[])
-{
-    size_t len = 0;
-    char *p, *save;
-    int i;
-
-    for (i = 0; list[i] != NULL; i++)
-        len += strlen(list[i]);
-    if (!TEST_ptr(p = save = OPENSSL_malloc(len + 1)))
-            return NULL;
-    for (i = 0; list[i] != NULL; i++)
-        p += strlen(strcpy(p, list[i]));
-    return save;
-}
-
 /*
  * Test constant-time modular exponentiation with 1024-bit inputs, which on
  * x86_64 cause a different code branch to be taken.
@@ -329,7 +326,6 @@ static int test_modexp_mont5(void)
     BIGNUM *a = NULL, *p = NULL, *m = NULL, *d = NULL, *e = NULL;
     BIGNUM *b = NULL, *n = NULL, *c = NULL;
     BN_MONT_CTX *mont = NULL;
-    char *bigstring;
     int st = 0;
 
     if (!TEST_ptr(a = BN_new())
@@ -375,12 +371,8 @@ static int test_modexp_mont5(void)
         goto err;
 
     /* Regression test for carry bug in sqr[x]8x_mont */
-    bigstring = glue(bn1strings);
-    BN_hex2bn(&n, bigstring);
-    OPENSSL_free(bigstring);
-    bigstring = glue(bn2strings);
-    BN_hex2bn(&a, bigstring);
-    OPENSSL_free(bigstring);
+    parse_bigBN(&n, bn1strings);
+    parse_bigBN(&a, bn2strings);
     BN_free(b);
     b = BN_dup(a);
     BN_MONT_CTX_set(mont, n, ctx);
@@ -405,7 +397,7 @@ static int test_modexp_mont5(void)
             "FCFFFFFFFFFF000000000000000000FF0302030000000000FFFFFFFFFFFFFFFF",
             "FF00FCFDFDFF030202FF00000000FFFFFFFFFFFFFFFFFF00FCFDFCFFFFFFFFFF",
             NULL
-	};
+        };
         static const char *nhex[] = {
                       "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
             "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
@@ -420,14 +412,10 @@ static int test_modexp_mont5(void)
             "FFFFFFFFFFFF000000000000000000000000000000000000FFFFFFFFFFFFFFFF",
             "FFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
             NULL
-	};
+        };
 
-        bigstring = glue(ahex);
-        BN_hex2bn(&a, bigstring);
-        OPENSSL_free(bigstring);
-        bigstring = glue(nhex);
-        BN_hex2bn(&n, bigstring);
-        OPENSSL_free(bigstring);
+        parse_bigBN(&a, ahex);
+        parse_bigBN(&n, nhex);
     }
     BN_free(b);
     b = BN_dup(a);

test/crltest.c

@@ -187,20 +187,11 @@ static X509 *test_leaf = NULL;
  * Glue an array of strings together.  Return a BIO and put the string
  * into |*out| so we can free it.
  */
-static BIO *glue(const char **pem, char **out)
+static BIO *glue2bio(const char **pem, char **out)
 {
-    char *dest;
-    int i;
     size_t s = 0;
 
-    /* Glue the strings together. */
-    for (i = 0; pem[i] != NULL; ++i)
-        s += strlen(pem[i]);
-    dest = *out = OPENSSL_malloc(s + 1);
-    if (dest == NULL)
-        return NULL;
-    for (i = 0; pem[i] != NULL; ++i)
-        dest += strlen(strcpy(dest, pem[i]));
+    *out = glue_strings(pem, &s);
     return BIO_new_mem_buf(*out, s);
 }
 
@@ -210,7 +201,7 @@ static BIO *glue(const char **pem, char **out)
 static X509_CRL *CRL_from_strings(const char **pem)
 {
     char *p;
-    BIO *b = glue(pem, &p);
+    BIO *b = glue2bio(pem, &p);
     X509_CRL *crl = PEM_read_bio_X509_CRL(b, NULL, NULL, NULL);
 
     OPENSSL_free(p);
@@ -224,7 +215,7 @@ static X509_CRL *CRL_from_strings(const char **pem)
 static X509 *X509_from_strings(const char **pem)
 {
     char *p;
-    BIO *b = glue(pem, &p);
+    BIO *b = glue2bio(pem, &p);
     X509 *x = PEM_read_bio_X509(b, NULL, NULL, NULL);
 
     OPENSSL_free(p);

test/testutil.h

@@ -440,4 +440,10 @@ int test_readstanza(STANZA *s);
  */
 void test_clearstanza(STANZA *s);
 
+/*
+ * Glue an array of strings together and return it as an allocated string.
+ * Optionally return the whole length of this string in |out_len|
+ */
+char *glue_strings(const char *list[], size_t *out_len);
+
 #endif                          /* HEADER_TESTUTIL_H */

test/testutil/driver.c

@@ -272,3 +272,28 @@ int run_tests(const char *test_prog_name)
     return EXIT_SUCCESS;
 }
 
+/*
+ * Glue an array of strings together and return it as an allocated string.
+ * Optionally return the whole length of this string in |out_len|
+ */
+char *glue_strings(const char *list[], size_t *out_len)
+{
+    size_t len = 0;
+    char *p, *ret;
+    int i;
+
+    for (i = 0; list[i] != NULL; i++)
+        len += strlen(list[i]);
+
+    if (out_len != NULL)
+        *out_len = len;
+
+    if (!TEST_ptr(ret = p = OPENSSL_malloc(len + 1)))
+        return NULL;
+
+    for (i = 0; list[i] != NULL; i++)
+        p += strlen(strcpy(p, list[i]));
+
+    return ret;
+}
+