setopt: warn on Curl_set*opt() uses not using the return value

And switch the invokes that would "set" NULL to instead just plainly
free the pointer, as those were otherwise the invokes that would ignore
the return code. And possibly confuse static code analyzers.

Closes #13591

diff --git a/lib/setopt.c b/lib/setopt.c
index e4c8ebb95d8f8c199442033644503ebb466ab8bc..43256014c2ef51ff9d5ad2ed3a05420a520b6cce 100644 (file)
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -520,11 +520,12 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
            data.
         */
         char *p = Curl_memdup0(argptr, (size_t)data->set.postfieldsize);
-        (void) Curl_setstropt(&data->set.str[STRING_COPYPOSTFIELDS], NULL);
         if(!p)
           result = CURLE_OUT_OF_MEMORY;
-        else
+        else {
+          free(data->set.str[STRING_COPYPOSTFIELDS]);
           data->set.str[STRING_COPYPOSTFIELDS] = p;
+        }
       }
     }
 
@@ -538,7 +539,7 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
      */
     data->set.postfields = va_arg(param, void *);
     /* Release old copied data. */
-    (void) Curl_setstropt(&data->set.str[STRING_COPYPOSTFIELDS], NULL);
+    Curl_safefree(data->set.str[STRING_COPYPOSTFIELDS]);
     data->set.method = HTTPREQ_POST;
     break;
 
@@ -554,7 +555,7 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
     if(data->set.postfieldsize < bigsize &&
        data->set.postfields == data->set.str[STRING_COPYPOSTFIELDS]) {
       /* Previous CURLOPT_COPYPOSTFIELDS is no longer valid. */
-      (void) Curl_setstropt(&data->set.str[STRING_COPYPOSTFIELDS], NULL);
+      Curl_safefree(data->set.str[STRING_COPYPOSTFIELDS]);
       data->set.postfields = NULL;
     }
 
@@ -573,7 +574,7 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
     if(data->set.postfieldsize < bigsize &&
        data->set.postfields == data->set.str[STRING_COPYPOSTFIELDS]) {
       /* Previous CURLOPT_COPYPOSTFIELDS is no longer valid. */
-      (void) Curl_setstropt(&data->set.str[STRING_COPYPOSTFIELDS], NULL);
+      Curl_safefree(data->set.str[STRING_COPYPOSTFIELDS]);
       data->set.postfields = NULL;
     }
 
@@ -1860,7 +1861,7 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
     /*
      * flag to set engine as default.
      */
-    Curl_setstropt(&data->set.str[STRING_SSL_ENGINE], NULL);
+    Curl_safefree(data->set.str[STRING_SSL_ENGINE]);
     result = Curl_ssl_set_engine_default(data);
     break;
   case CURLOPT_CRLF:

diff --git a/lib/setopt.h b/lib/setopt.h
index 3c14a05e3749d07a50d3efb927bfe0c57503e114..b0237467bd67a6a9cf0c796e1b9b24977f312e73 100644 (file)
--- a/lib/setopt.h
+++ b/lib/setopt.h
@@ -24,9 +24,10 @@
  *
  ***************************************************************************/
 
-CURLcode Curl_setstropt(char **charp, const char *s);
+CURLcode Curl_setstropt(char **charp, const char *s) WARN_UNUSED_RESULT;
 CURLcode Curl_setblobopt(struct curl_blob **blobp,
-                         const struct curl_blob *blob);
-CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list arg);
+                         const struct curl_blob *blob) WARN_UNUSED_RESULT;
+CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list arg)
+  WARN_UNUSED_RESULT;
 
 #endif /* HEADER_CURL_SETOPT_H */