X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/aab9ab9fdd05119855383b33b67b27dcec5f3902..3bc429127d05ea3c84e3c151d53ad3546bea5e9b:/fdflags.c

diff --git a/fdflags.c b/fdflags.c
index 85ef67c..6f401e4 100644
--- a/fdflags.c
+++ b/fdflags.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: fdflags.c,v 1.1 1999/07/26 23:16:59 mdw Exp $
+ * $Id$
  *
  * Manipulates flags on file descriptors
  *
@@ -27,14 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: fdflags.c,v $
- * Revision 1.1  1999/07/26 23:16:59  mdw
- * Manipulate file descriptor flags.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <stdio.h>
@@ -62,13 +54,22 @@
 int fdflags(int fd, unsigned fbic, unsigned fxor,
 	    unsigned fdbic, unsigned fdxor)
 {
-  int f;
+  int f, ff;
 
-  if ((f = fcntl(fd, F_GETFL)) == -1 ||
-      fcntl(fd, F_SETFL, (f & ~fbic) ^ fxor) == -1 ||
-      (f = fcntl(fd, F_GETFD)) == -1 ||
-      fcntl(fd, F_SETFD, (f & ~fdbic) ^ fdxor) == -1)
-    return (-1);
+  if (fbic || fxor) {
+    if ((f = fcntl(fd, F_GETFL)) == -1)
+      return (-1);
+    ff = (f & fbic) ^ fxor;
+    if (f != ff && fcntl(fd, F_SETFL, ff) == -1)
+      return (-1);
+  }
+  if (fdbic || fdxor) {
+    if ((f = fcntl(fd, F_GETFD)) == -1)
+      return (-1);
+    ff = (f & fdbic) ^ fdxor;
+    if (f != ff && fcntl(fd, F_SETFD, ff) == -1)
+      return (-1);
+  }
   return (0);
 }