url: Improve CURLOPT_PROXY_CAPATH error handling

- Change CURLOPT_PROXY_CAPATH to return CURLE_NOT_BUILT_IN if the option
  is not supported, which is the same as what we already do for
  CURLOPT_CAPATH.

- Change the curl tool to handle CURLOPT_PROXY_CAPATH error
  CURLE_NOT_BUILT_IN as a warning instead of as an error, which is the
  same as what we already do for CURLOPT_CAPATH.

- Fix CAPATH docs to show that CURLE_NOT_BUILT_IN is returned when the
  respective CAPATH option is not supported by the SSL library.

Ref: https://github.com/curl/curl/pull/1257

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/url.c b/lib/url.c
index b8f7cfb9b..a78a2412f 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -583,8 +583,9 @@ CURLcode Curl_init_userdefined(struct UserDefined *set)
   if(result)
     return result;
 
-  result = setstropt(&set->str[STRING_SSL_CAPATH_PROXY],
-                     (char *) CURL_CA_PATH);
+  result = setstropt(&set->str[STRING_SSL_CAPATH_PROXY], CURL_CA_PATH);
+  if(result)
+    return result;
 #endif
 
   set->wildcardmatch  = FALSE;
@@ -2225,8 +2226,12 @@ CURLcode Curl_setopt(struct Curl_easy *data, CURLoption option,
     /* This does not work on windows. */
     result = setstropt(&data->set.str[STRING_SSL_CAPATH_ORIG],
                        va_arg(param, char *));
+#else
+    result = CURLE_NOT_BUILT_IN;
+#endif
     break;
   case CURLOPT_PROXY_CAPATH:
+#ifdef have_curlssl_ca_path /* not supported by all backends */
     /*
      * Set CA path info for SSL connection proxy. Specify directory name of the
      * CA certificates which have been prepared using openssl c_rehash utility.