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.

configure.ac

@@ -2349,7 +2349,7 @@ CURL_CHECK_FUNC_LOCALTIME_R
 CURL_CHECK_FUNC_MEMRCHR
 CURL_CHECK_FUNC_POLL
 CURL_CHECK_FUNC_SETSOCKOPT
-CURL_CHECK_FUNC_SETXATTR
+CURL_CHECK_FUNC_FSETXATTR
 CURL_CHECK_FUNC_SIGACTION
 CURL_CHECK_FUNC_SIGINTERRUPT
 CURL_CHECK_FUNC_SIGNAL

m4/curl-functions.m4

@@ -5924,86 +5924,86 @@ AC_DEFUN([CURL_CHECK_FUNC_WRITEV], [
   fi
 ])
 
-dnl CURL_CHECK_FUNC_SETXATTR
+dnl CURL_CHECK_FUNC_FSETXATTR
 dnl -------------------------------------------------
-dnl Verify if setxattr is available, prototyped, and
+dnl Verify if fsetxattr is available, prototyped, and
 dnl can be compiled. If all of these are true, and
 dnl usage has not been previously disallowed with
-dnl shell variable curl_disallow_setxattr, then
-dnl HAVE_SETXATTR will be defined.
+dnl shell variable curl_disallow_fsetxattr, then
+dnl HAVE_FSETXATTR will be defined.
 
-AC_DEFUN([CURL_CHECK_FUNC_SETXATTR], [
+AC_DEFUN([CURL_CHECK_FUNC_FSETXATTR], [
   AC_REQUIRE([CURL_INCLUDES_SYS_XATTR])dnl
   #
-  tst_links_setxattr="unknown"
-  tst_proto_setxattr="unknown"
-  tst_compi_setxattr="unknown"
-  tst_allow_setxattr="unknown"
+  tst_links_fsetxattr="unknown"
+  tst_proto_fsetxattr="unknown"
+  tst_compi_fsetxattr="unknown"
+  tst_allow_fsetxattr="unknown"
   #
-  AC_MSG_CHECKING([if setxattr can be linked])
+  AC_MSG_CHECKING([if fsetxattr can be linked])
   AC_LINK_IFELSE([
-    AC_LANG_FUNC_LINK_TRY([setxattr])
+    AC_LANG_FUNC_LINK_TRY([fsetxattr])
   ],[
     AC_MSG_RESULT([yes])
-    tst_links_setxattr="yes"
+    tst_links_fsetxattr="yes"
   ],[
     AC_MSG_RESULT([no])
-    tst_links_setxattr="no"
+    tst_links_fsetxattr="no"
   ])
   #
-  if test "$tst_links_setxattr" = "yes"; then
-    AC_MSG_CHECKING([if setxattr is prototyped])
-    AC_EGREP_CPP([setxattr],[
+  if test "$tst_links_fsetxattr" = "yes"; then
+    AC_MSG_CHECKING([if fsetxattr is prototyped])
+    AC_EGREP_CPP([fsetxattr],[
       $curl_includes_sys_xattr
     ],[
       AC_MSG_RESULT([yes])
-      tst_proto_setxattr="yes"
+      tst_proto_fsetxattr="yes"
     ],[
       AC_MSG_RESULT([no])
-      tst_proto_setxattr="no"
+      tst_proto_fsetxattr="no"
     ])
   fi
   #
-  if test "$tst_proto_setxattr" = "yes"; then
-    AC_MSG_CHECKING([if setxattr is compilable])
+  if test "$tst_proto_fsetxattr" = "yes"; then
+    AC_MSG_CHECKING([if fsetxattr is compilable])
     AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([[
         $curl_includes_sys_xattr
       ]],[[
-        if(0 != setxattr(0, 0, 0, 0, 0))
+        if(0 != fsetxattr("", "", "", 0, 0))
           return 1;
       ]])
     ],[
       AC_MSG_RESULT([yes])
-      tst_compi_setxattr="yes"
+      tst_compi_fsetxattr="yes"
     ],[
       AC_MSG_RESULT([no])
-      tst_compi_setxattr="no"
+      tst_compi_fsetxattr="no"
     ])
   fi
   #
-  if test "$tst_compi_setxattr" = "yes"; then
-    AC_MSG_CHECKING([if setxattr usage allowed])
-    if test "x$curl_disallow_setxattr" != "xyes"; then
+  if test "$tst_compi_fsetxattr" = "yes"; then
+    AC_MSG_CHECKING([if fsetxattr usage allowed])
+    if test "x$curl_disallow_fsetxattr" != "xyes"; then
       AC_MSG_RESULT([yes])
-      tst_allow_setxattr="yes"
+      tst_allow_fsetxattr="yes"
     else
       AC_MSG_RESULT([no])
-      tst_allow_setxattr="no"
+      tst_allow_fsetxattr="no"
     fi
   fi
   #
-  AC_MSG_CHECKING([if setxattr might be used])
-  if test "$tst_links_setxattr" = "yes" &&
-     test "$tst_proto_setxattr" = "yes" &&
-     test "$tst_compi_setxattr" = "yes" &&
-     test "$tst_allow_setxattr" = "yes"; then
+  AC_MSG_CHECKING([if fsetxattr might be used])
+  if test "$tst_links_fsetxattr" = "yes" &&
+     test "$tst_proto_fsetxattr" = "yes" &&
+     test "$tst_compi_fsetxattr" = "yes" &&
+     test "$tst_allow_fsetxattr" = "yes"; then
     AC_MSG_RESULT([yes])
-    AC_DEFINE_UNQUOTED(HAVE_SETXATTR, 1,
-      [Define to 1 if you have the setxattr function.])
-    ac_cv_func_setxattr="yes"
+    AC_DEFINE_UNQUOTED(HAVE_FSETXATTR, 1,
+      [Define to 1 if you have the fsetxattr function.])
+    ac_cv_func_fsetxattr="yes"
   else
     AC_MSG_RESULT([no])
-    ac_cv_func_setxattr="no"
+    ac_cv_func_fsetxattr="no"
   fi
 ])

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