* flock.cc: Renamed from flock.c.

1 files changed, 89 insertions, 0 deletions

diff --git a/winsup/cygwin/flock.cc b/winsup/cygwin/flock.cc
new file mode 100644
index 0000000..09ea2b6
--- /dev/null
+++ b/winsup/cygwin/flock.cc
@@ -0,0 +1,89 @@
+/* One of many ways to emulate flock() on top of real (good) POSIX locks.
+ *
+ * This flock() emulation is based upon source taken from the Red Hat
+ * implementation used in their imap-2002d SRPM.
+ *
+ * $RH: flock.c,v 1.2 2000/08/23 17:07:00 nalin Exp $
+ */
+/* flock.c
+
+   Copyright 2003 Red Hat, Inc.
+
+   This file is part of Cygwin.
+
+   This software is a copyrighted work licensed under the terms of the
+   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+   details. */
+
+#include <sys/file.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int
+flock (int fd, int operation)
+{
+  int i, cmd;
+  struct flock l = { 0, 0, 0, 0, 0 };
+  if (operation & LOCK_NB)
+    {
+      cmd = F_SETLK;
+    }
+  else
+    {
+      cmd = F_SETLKW;
+    }
+  l.l_whence = SEEK_SET;
+  switch (operation & (~LOCK_NB))
+    {
+    case LOCK_EX:
+      l.l_type = F_WRLCK;
+      i = fcntl (fd, cmd, &l);
+      if (i == -1)
+	{
+	  if ((errno == EAGAIN) || (errno == EACCES))
+	    {
+	      errno = EWOULDBLOCK;
+	    }
+	}
+      break;
+    case LOCK_SH:
+      l.l_type = F_RDLCK;
+      i = fcntl (fd, cmd, &l);
+      if (i == -1)
+	{
+	  if ((errno == EAGAIN) || (errno == EACCES))
+	    {
+	      errno = EWOULDBLOCK;
+	    }
+	}
+      break;
+    case LOCK_UN:
+      l.l_type = F_UNLCK;
+      i = fcntl (fd, cmd, &l);
+      if (i == -1)
+	{
+	  if ((errno == EAGAIN) || (errno == EACCES))
+	    {
+	      errno = EWOULDBLOCK;
+	    }
+	}
+      break;
+    default:
+      i = -1;
+      errno = EINVAL;
+      break;
+    }
+  return i;
+}
+
+#ifdef FLOCK_EMULATE_IS_MAIN
+int
+main (int argc, char **argv)
+{
+  int fd = open (argv[1], O_WRONLY);
+  flock (fd, LOCK_EX);
+  return 0;
+}
+#endif