Improved the dotlock module.

- It is now more portable and may be used outside of GnuPG
- vfat file systems are now supported.
- The use of link(2) is more robust.
- Wrote extensive documentation.

common/t-dotlock.c

@@ -0,0 +1,145 @@
+/* t-dotlock.c - Module test for dotlock.c
+ * Copyright (C) 2011 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Note: This is a standalone test program which does not rely on any
+   GnuPG helper files.  However, it may also be build as part of the
+   GnuPG build system.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Some quick replacements for stuff we usually expect to be defined
+   in config.h.  Define HAVE_POSIX_SYSTEM for better readability. */
+#if !defined (HAVE_DOSISH_SYSTEM) && defined(_WIN32)
+# define HAVE_DOSISH_SYSTEM 1
+#endif
+#if !defined (HAVE_DOSISH_SYSTEM) && !defined (HAVE_POSIX_SYSTEM)
+# define HAVE_POSIX_SYSTEM 1
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include "dotlock.h"
+
+#define PGM "t-dotlock"
+
+
+static volatile int ctrl_c_pending;
+
+static void
+control_c_handler (int signo)
+{
+  (void)signo;
+  ctrl_c_pending = 1;
+}
+
+
+
+static void
+die (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  va_start (arg_ptr, format);
+  fprintf (stderr, PGM "[%lu]: ", (unsigned long)getpid ());
+  vfprintf (stderr, format, arg_ptr);
+  putc ('\n', stderr);
+  va_end (arg_ptr);
+  exit (1);
+}
+
+
+static void
+inf (const char *format, ...)
+{
+  va_list arg_ptr;
+
+  va_start (arg_ptr, format);
+  fprintf (stderr, PGM "[%lu]: ", (unsigned long)getpid ());
+  vfprintf (stderr, format, arg_ptr);
+  putc ('\n', stderr);
+  va_end (arg_ptr);
+}
+
+
+static void
+lock_and_unlock (const char *fname)
+{
+  dotlock_t h;
+
+  h = dotlock_create (fname);
+  if (!h)
+    die ("error creating lock file for `%s': %s", fname, strerror (errno));
+  inf ("lock created");
+
+  while (!ctrl_c_pending)
+    {
+      if (dotlock_take (h, -1))
+        die ("error taking lock");
+      inf ("lock taken");
+      sleep (1);
+      if (dotlock_release (h))
+        die ("error releasing lock");
+      inf ("lock released");
+      sleep (1);
+    }
+  dotlock_destroy (h);
+  inf ("lock destroyed");
+}
+
+
+int
+main (int argc, char **argv)
+{
+  const char *fname;
+
+  if (argc > 1)
+    fname = argv[1];
+  else
+    fname = "t-dotlock.tmp";
+
+  {
+    struct sigaction nact;
+
+    nact.sa_handler = control_c_handler;
+    nact.sa_flags = 0;
+    sigaction (SIGINT, &nact, NULL);
+  }
+
+  dotlock_create (NULL);  /* Initialize (optional).  */
+
+  lock_and_unlock (fname);
+
+
+  return 0;
+}
+
+
+/*
+Local Variables:
+compile-command: "cc -Wall -O2 -D_FILE_OFFSET_BITS=64 -o t-dotlock t-dotlock.c dotlock.c"
+End:
+*/