X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/5892fd39c789b9207fe799e91080dbef773d30cb..17119f584e90f494da54aa9e2d1d10227213d96b:/fdflags.c

diff --git a/fdflags.c b/fdflags.c
index ae9cf6a..6f401e4 100644
--- a/fdflags.c
+++ b/fdflags.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: fdflags.c,v 1.2 2004/04/08 01:36:11 mdw Exp $
+ * $Id$
  *
  * Manipulates flags on file descriptors
  *
@@ -54,13 +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);
 }