write extended attributes by using fsetxattr

Instead of reopening the downloaded file, fsetxattr uses the (already
open) file descriptor to attach extended attributes. This makes the
procedure more robust against errors caused by moved or deleted files.

src/main.c

@@ -5633,9 +5633,17 @@ operate(struct Configurable *config, int argc, argv_item_t argv[])
             }
           }
         }
-
         if(outfile && !curlx_strequal(outfile, "-") && outs.stream) {
-          int rc = fclose(outs.stream);
+          int rc;
+
+          if(config->xattr) {
+            rc = fwrite_xattr(curl, fileno(outs.stream) );
+            if(rc)
+              warnf(config, "Error setting extended attributes: %s\n",
+                    strerror(errno) );
+          }
+
+          rc = fclose(outs.stream);
           if(!res && rc) {
             /* something went wrong in the writing process */
             res = CURLE_WRITE_ERROR;
@@ -5643,13 +5651,6 @@ operate(struct Configurable *config, int argc, argv_item_t argv[])
           }
         }
 
-        if(config->xattr && outs.filename) {
-          int err = write_xattr(curl, outs.filename );
-          if(err)
-            warnf( config, "Error setting extended attributes: %s\n",
-                   strerror(errno) );
-        }
-
 #ifdef HAVE_UTIME
         /* Important that we set the time _after_ the file has been
            closed, as is done above here */

src/xattr.c

@@ -25,7 +25,7 @@
 #include <curl/curl.h>
 #include "xattr.h"
 
-#ifdef HAVE_SETXATTR
+#ifdef HAVE_FSETXATTR
 #include <sys/types.h>
 #include <string.h>
 #include <sys/xattr.h> /* include header from libc, not from libattr */
@@ -46,7 +46,7 @@ static const struct xattr_mapping {
 /* store metadata from the curl request alongside the downloaded
  * file using extended attributes
  */
-int write_xattr(CURL *curl, const char *filename)
+int fwrite_xattr(CURL *curl, int fd)
 {
   int i = 0;
   int err = 0;
@@ -55,17 +55,17 @@ int write_xattr(CURL *curl, const char *filename)
     char *value = NULL;
     CURLcode rc = curl_easy_getinfo(curl, mappings[i].info, &value);
     if ( rc == CURLE_OK && value ) {
-      err = setxattr( filename, mappings[i].attr, value, strlen(value), 0 );
+      err = fsetxattr( fd, mappings[i].attr, value, strlen(value), 0 );
     }
     i++;
   }
   return err;
 }
 #else
-int write_xattr(CURL *curl, const char *filename)
+int fwrite_xattr(CURL *curl, int fd)
 {
   (void)curl;
-  (void)filename;
+  (void)fd;
   return 0;
 }
 #endif

src/xattr.h

@@ -21,6 +21,6 @@
  * KIND, either express or implied.
  *
  ***************************************************************************/
-int write_xattr( CURL *curl, const char *filename );
+int fwrite_xattr(CURL *curl, int fd);
 
 #endif