misc: Simplifies ssh_strreplace().

Signed-off-by: Sahana Prasad <sahana@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

src/misc.c

@@ -1797,29 +1797,29 @@ err:
  * @param[in]  replace      String to be replaced is stored in replace.
  *
  * @returns  src_replaced a pointer that points to the replaced string.
- * NULL if allocation fails.
+ * NULL if allocation fails or if src is NULL.
  */
 char *ssh_strreplace(char *src, const char *pattern, const char *replace)
 {
     char *p = NULL;
     char *src_replaced = NULL;
-    size_t len_replaced;
 
-    if (pattern == NULL || replace == NULL) {
-        return src;
+    if (src == NULL) {
+        return NULL;
     }
 
-    if ((p = strstr(src, pattern)) != NULL) {
+    if (pattern == NULL || replace == NULL) {
+        return strdup(src);
+    }
+
+    p = strstr(src, pattern);
+
+    if (p != NULL) {
         size_t offset = p - src;
-        size_t len  = strlen(src);
         size_t pattern_len = strlen(pattern);
         size_t replace_len = strlen(replace);
-
-        if (replace_len != pattern_len) {
-            len_replaced = strlen(src) + replace_len - pattern_len + 1;
-        } else {
-            len_replaced = strlen(src) + 1;
-        }
+        size_t len  = strlen(src);
+        size_t len_replaced = len + replace_len - pattern_len + 1;
 
         src_replaced = (char *)malloc(len_replaced);
 
@@ -1831,9 +1831,10 @@ char *ssh_strreplace(char *src, const char *pattern, const char *replace)
         memcpy(src_replaced, src, offset);
         memcpy(src_replaced + offset, replace, replace_len);
         memcpy(src_replaced + offset + replace_len, src + offset + pattern_len, len - offset - pattern_len);
+        return src_replaced; /* free in the caller */
+    } else {
+        return strdup(src);
     }
-
-    return src_replaced; /* free in the caller */
 }
 
 /** @} */