dotlock - setgid program to dot lock a file, modelled on mutt_dotlock.

+dotlock
+Makefile
+Makefile.in
+.gdbinit
+.deps
+.libs
+_*

+AUTOMAKE_OPTIONS = ../lib/ansi2knr
+INCLUDES =-I$(srcdir) -I$(top_srcdir)/lib -I$(top_srcdir)/include -I$(top_srcdir)/libmu_scm @ARGPINCS@
+
+bin_PROGRAMS = dotlock
+#dotlock_SOURCES = dotlock.c
+
+dotlock_LDADD = ../mailbox/libmailbox.la @ARGPLIBS@ ../lib/libmailutils.la
+
+install-exec-hook:
+	for i in $(bin_PROGRAMS); do\
+		chown root:mail $(DESTDIR)$(bindir)/$$i;\
+		chmod 2755 $(DESTDIR)$(bindir)/$$i;\
+	done

+/* GNU mailutils - a suite of utilities for electronic mail
+   Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
+
+   This program 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 2, or (at your option)
+   any later version.
+
+   This program 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, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdlib.h>
+
+#include <argp.h>
+
+#include <mailutils/errno.h>
+#include <mailutils/locker.h>
+
+#define MU_DL_EX_OK      0
+#define MU_DL_EX_ERROR   1
+#define MU_DL_EX_EXIST   3
+
+const char *argp_program_version = "GNU dotlock (" PACKAGE ") " VERSION;
+const char *argp_program_bug_address = "<bug-mailutils@gnu.org>";
+static char doc[] =
+  "GNU dotlock -- lock mail spool files"
+  "\v"
+  "Returns 0 on success, 3 if the locking the file fails because"
+  " it's already locked, and 1 if some other kind of error occurred."
+  ;
+static char args_doc[] = "FILE";
+error_t argp_err_exit_status = MU_DL_EX_ERROR;
+
+static struct argp_option options[] = {
+  {"unlock", 'u', NULL, 0,
+   "Unlock", 0},
+
+  {"force", 'f', "MINUTES", OPTION_ARG_OPTIONAL,
+   "Forcibly break an existing lock older than a certain time", 0},
+
+  {"retry", 'r', "RETRIES", OPTION_ARG_OPTIONAL,
+   "Retry the lock a few times", 0},
+
+  {"debug", 'd', NULL, 0,
+   "Print details of failure reasons to stderr", 0},
+
+  {NULL, 0, NULL, 0, NULL, 0}
+};
+
+static error_t parse_opt (int key, char *arg, struct argp_state *state);
+
+static struct argp argp = {
+  options,
+  parse_opt,
+  args_doc,
+  doc,
+};
+
+static const char *file;
+static int unlock;
+static int flags;
+static int retries;
+static int force;
+static int debug;
+
+static error_t
+parse_opt (int key, char *arg, struct argp_state *state)
+{
+  switch (key)
+    {
+    case 'd':
+      debug = 1;
+      break;
+
+    case 'u':
+      unlock = 1;
+      break;
+
+    case 'r':
+      if (arg)
+	{
+	  retries = atoi (arg);
+	  if (retries == 0)
+	    argp_error (state, "RETRIES must be greater than 0");
+	}
+      flags |= MU_LOCKER_RETRY;
+      break;
+
+    case 'f':
+      if (arg)
+	{
+	  force = atoi (arg);
+	  if (force == 0)
+	    argp_error (state, "MINUTES must be greater than 0");
+	  force *= 60;
+	}
+      flags |= MU_LOCKER_TIME;
+      break;
+
+    case ARGP_KEY_ARG:
+      if (file)
+	argp_error (state, "only one FILE can be specified");
+      file = arg;
+      break;
+
+    case ARGP_KEY_NO_ARGS:
+      argp_error (state, "FILE must be specified");
+
+    default:
+      return ARGP_ERR_UNKNOWN;
+    }
+  return 0;
+}
+
+int
+main (int argc, char *argv[])
+{
+  locker_t locker = 0;
+  int err = 0;
+
+  argp_parse (&argp, argc, argv, 0, NULL, NULL);
+
+  if ((err = locker_create (&locker, file, flags)))
+    {
+      if (debug)
+	fprintf (stderr, "locker create failed: %s\n", mu_errstring (err));
+      return MU_DL_EX_ERROR;
+    }
+
+  locker_set_flags (locker, flags);
+
+  if (force != 0)
+    locker_set_expire_time (locker, force);
+
+  if (retries != 0)
+    locker_set_retries (locker, retries);
+
+  if (unlock)
+    err = locker_remove_lock (locker);
+  else
+    err = locker_lock (locker);
+
+  locker_destroy (&locker);
+
+  if (debug && err)
+    fprintf (stderr, "%slocking %s failed: %s\n",
+	     unlock ? "un" : "", file, mu_errstring (err));
+
+  switch (err)
+    {
+    case 0:
+      err = MU_DL_EX_OK;
+      break;
+    case MU_ERR_LOCK_CONFLICT:
+      err = MU_DL_EX_EXIST;
+      break;
+    default:
+      err = MU_DL_EX_ERROR;
+      break;
+    }
+
+  return err;
+}