tool: improve --stderr handling

- freopen stderr with the user-specified file (--stderr file) instead of
  using a separate 'errors' stream.

- In tool_setup.h override stdio.h's stderr macro as global variable
  tool_stderr.

Both freopen and overriding the stderr macro are necessary because if
the user-specified filename is "-" then stdout is assigned to
tool_stderr and no freopen takes place. See the PR for more information.

Ref: https://github.com/curl/curl/issues/10491

Closes https://github.com/curl/curl/pull/10673

1 files changed, 16 insertions, 23 deletions

diff --git a/src/tool_operate.c b/src/tool_operate.c
index f694f088d..4e2b82114 100644
--- a/src/tool_operate.c
+++ b/src/tool_operate.c
@@ -306,7 +306,7 @@ static CURLcode pre_transfer(struct GlobalConfig *global,
     if((per->infd == -1) || fstat(per->infd, &fileinfo))
 #endif
     {
-      helpf(global->errors, "Can't open '%s'!\n", per->uploadfile);
+      helpf(stderr, "Can't open '%s'!\n", per->uploadfile);
       if(per->infd != -1) {
         close(per->infd);
         per->infd = STDIN_FILENO;
@@ -404,10 +404,10 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
     if(!config->synthetic_error && result &&
        (!global->silent || global->showerror)) {
       const char *msg = per->errorbuffer;
-      fprintf(global->errors, "curl: (%d) %s\n", result,
+      fprintf(stderr, "curl: (%d) %s\n", result,
               (msg && msg[0]) ? msg : curl_easy_strerror(result));
       if(result == CURLE_PEER_FAILED_VERIFICATION)
-        fputs(CURL_CA_CERT_ERRORMSG, global->errors);
+        fputs(CURL_CA_CERT_ERRORMSG, stderr);
     }
     else if(config->failwithbody) {
       /* if HTTP response >= 400, return error */
@@ -415,7 +415,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
       curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &code);
       if(code >= 400) {
         if(!global->silent || global->showerror)
-          fprintf(global->errors,
+          fprintf(stderr,
                   "curl: (%d) The requested URL returned error: %ld\n",
                   CURLE_HTTP_RETURNED_ERROR, code);
         result = CURLE_HTTP_RETURNED_ERROR;
@@ -448,7 +448,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
       /* something went wrong in the writing process */
       result = CURLE_WRITE_ERROR;
       if(!global->silent || global->showerror)
-        fprintf(global->errors, "curl: (%d) Failed writing body\n", result);
+        fprintf(stderr, "curl: (%d) Failed writing body\n", result);
     }
   }
 
@@ -589,8 +589,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
         /* We have written data to an output file, we truncate file
          */
         if(!global->silent)
-          fprintf(global->errors, "Throwing away %"
-                  CURL_FORMAT_CURL_OFF_T " bytes\n",
+          fprintf(stderr, "Throwing away %"  CURL_FORMAT_CURL_OFF_T " bytes\n",
                   outs->bytes);
         fflush(outs->stream);
         /* truncate file at the position where we started appending */
@@ -599,8 +598,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
           /* when truncate fails, we can't just append as then we'll
              create something strange, bail out */
           if(!global->silent || global->showerror)
-            fprintf(global->errors,
-                    "curl: (23) Failed to truncate file\n");
+            fprintf(stderr, "curl: (23) Failed to truncate file\n");
           return CURLE_WRITE_ERROR;
         }
         /* now seek to the end of the file, the position where we
@@ -615,8 +613,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
 #endif
         if(rc) {
           if(!global->silent || global->showerror)
-            fprintf(global->errors,
-                    "curl: (23) Failed seeking to end of file\n");
+            fprintf(stderr, "curl: (23) Failed seeking to end of file\n");
           return CURLE_WRITE_ERROR;
         }
         outs->bytes = 0; /* clear for next round */
@@ -641,7 +638,7 @@ static CURLcode post_per_transfer(struct GlobalConfig *global,
       /* something went wrong in the writing process */
       result = CURLE_WRITE_ERROR;
       if(!global->silent || global->showerror)
-        fprintf(global->errors, "curl: (%d) Failed writing body\n", result);
+        fprintf(stderr, "curl: (%d) Failed writing body\n", result);
     }
     if(result && config->rm_partial) {
       notef(global, "Removing output file: %s\n", outs->filename);
@@ -801,7 +798,7 @@ static CURLcode single_transfer(struct GlobalConfig *global,
       /* Unless explicitly shut off */
       result = glob_url(&inglob, infiles, &state->infilenum,
                         (!global->silent || global->showerror)?
-                        global->errors:NULL);
+                        stderr:NULL);
       if(result)
         break;
       config->state.inglob = inglob;
@@ -837,7 +834,7 @@ static CURLcode single_transfer(struct GlobalConfig *global,
              expressions and return total number of URLs in pattern set */
           result = glob_url(&state->urls, urlnode->url, &state->urlnum,
                             (!global->silent || global->showerror)?
-                            global->errors:NULL);
+                            stderr:NULL);
           if(result)
             break;
           urlnum = state->urlnum;
@@ -1096,7 +1093,7 @@ static CURLcode single_transfer(struct GlobalConfig *global,
              file output call */
 
           if(config->create_dirs) {
-            result = create_dir_hierarchy(per->outfile, global->errors);
+            result = create_dir_hierarchy(per->outfile, stderr);
             /* create_dir_hierarchy shows error upon CURLE_WRITE_ERROR */
             if(result)
               break;
@@ -1240,9 +1237,6 @@ static CURLcode single_transfer(struct GlobalConfig *global,
           }
         }
 
-        if(!global->errors)
-          global->errors = stderr;
-
         if((!per->outfile || !strcmp(per->outfile, "-")) &&
            !config->use_ascii) {
           /* We get the output to stdout and we have not got the ASCII/text
@@ -1851,7 +1845,7 @@ static CURLcode single_transfer(struct GlobalConfig *global,
         my_setopt(curl, CURLOPT_TIMEVALUE_LARGE, config->condtime);
         my_setopt_str(curl, CURLOPT_CUSTOMREQUEST, config->customrequest);
         customrequest_helper(config, config->httpreq, config->customrequest);
-        my_setopt(curl, CURLOPT_STDERR, global->errors);
+        my_setopt(curl, CURLOPT_STDERR, stderr);
 
         /* three new ones in libcurl 7.3: */
         my_setopt_str(curl, CURLOPT_INTERFACE, config->iface);
@@ -2517,8 +2511,7 @@ static CURLcode transfer_per_config(struct GlobalConfig *global,
 
   /* Check we have a url */
   if(!config->url_list || !config->url_list->url) {
-    helpf(global->errors, "(%d) no URL specified!\n",
-          CURLE_FAILED_INIT);
+    helpf(stderr, "(%d) no URL specified!\n", CURLE_FAILED_INIT);
     return CURLE_FAILED_INIT;
   }
 
@@ -2576,7 +2569,7 @@ static CURLcode transfer_per_config(struct GlobalConfig *global,
           if(!config->capath) {
             curl_free(env);
             curl_easy_cleanup(curltls);
-            helpf(global->errors, "out of memory\n");
+            helpf(stderr, "out of memory\n");
             return CURLE_OUT_OF_MEMORY;
           }
           capath_from_env = true;
@@ -2694,7 +2687,7 @@ CURLcode operate(struct GlobalConfig *global, int argc, argv_item_t argv[])
 
     /* If we had no arguments then make sure a url was specified in .curlrc */
     if((argc < 2) && (!global->first->url_list)) {
-      helpf(global->errors, NULL);
+      helpf(stderr, NULL);
       result = CURLE_FAILED_INIT;
     }
   }