Initial import of the CDE 2.1.30 sources from the Open Group.

cde/programs/dtinfo/DtMmdb/utility/atomic_lock.C

@@ -0,0 +1,76 @@
+/*
+ * $XConsortium: atomic_lock.C /main/4 1996/11/01 10:19:09 drk $
+ *
+ * Copyright (c) 1993 HAL Computer Systems International, Ltd.
+ * All rights reserved.  Unpublished -- rights reserved under
+ * the Copyright Laws of the United States.  USE OF A COPYRIGHT
+ * NOTICE IS PRECAUTIONARY ONLY AND DOES NOT IMPLY PUBLICATION
+ * OR DISCLOSURE.
+ * 
+ * THIS SOFTWARE CONTAINS CONFIDENTIAL INFORMATION AND TRADE
+ * SECRETS OF HAL COMPUTER SYSTEMS INTERNATIONAL, LTD.  USE,
+ * DISCLOSURE, OR REPRODUCTION IS PROHIBITED WITHOUT THE
+ * PRIOR EXPRESS WRITTEN PERMISSION OF HAL COMPUTER SYSTEMS
+ * INTERNATIONAL, LTD.
+ * 
+ *                         RESTRICTED RIGHTS LEGEND
+ * Use, duplication, or disclosure by the Government is subject
+ * to the restrictions as set forth in subparagraph (c)(l)(ii)
+ * of the Rights in Technical Data and Computer Software clause
+ * at DFARS 252.227-7013.
+ *
+ *          HAL COMPUTER SYSTEMS INTERNATIONAL, LTD.
+ *                  1315 Dell Avenue
+ *                  Campbell, CA  95008
+ * 
+ */
+
+
+#include "atomic_lock.h"
+
+#include <X11/Xosdefs.h>
+#include <errno.h>
+#ifdef X_NOT_STDC_ENV
+extern int errno;
+#endif
+
+atomic_lock::atomic_lock(const char* p)
+{
+   strcpy(v_path, p);
+}
+
+atomic_lock::~atomic_lock()
+{
+}
+
+/////////////////////////////////////////
+// from Rochkind's Adv. UNIX programming
+/////////////////////////////////////////
+Boolean atomic_lock::lock()
+{
+   int fd, tries;
+
+   tries = 0;
+
+   while ( (fd = creat(v_path, 0)) == -1 && errno == EACCES ) {
+      if ( ++tries >= MAXTRIES )
+         break;
+      sleep (NAPTIME);
+   }
+   if ( fd == -1 || close(fd) == -1 ) {
+      perror("lock");
+      return false;
+   } else
+      return true;
+}
+
+Boolean atomic_lock::unlock()
+{
+   if ( unlink(v_path) == -1 ) {
+      MESSAGE(cerr, "unlock(): unlink() failed");
+      throw(systemException(errno));
+   }
+
+   return true;
+}
+