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/*
     This file is part of GNUnet.
     Copyright (C) 2012 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file util/gnunet-uri.c
 * @brief tool to dispatch URIs to the appropriate GNUnet helper process
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"

/**
 * Handler exit code
 */
static long unsigned int exit_code = 1;

/**
 * Helper process we started.
 */
static struct GNUNET_OS_Process *p;

/**
 * Pipe used to communicate shutdown via signal.
 */
static struct GNUNET_DISK_PipeHandle *sigpipe;


/**
 * Task triggered whenever we receive a SIGCHLD (child
 * process died) or when user presses CTRL-C.
 *
 * @param cls closure, NULL
 */
static void
maint_child_death (void *cls)
{
  enum GNUNET_OS_ProcessStatusType type;

  (void) cls;
  if ((GNUNET_OK != GNUNET_OS_process_status (p, &type, &exit_code)) ||
      (type != GNUNET_OS_PROCESS_EXITED))
    GNUNET_break (0 == GNUNET_OS_process_kill (p, GNUNET_TERM_SIG));
  GNUNET_OS_process_destroy (p);
}


/**
 * Main function that will be run by the scheduler.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param cfg configuration
 */
static void
run (void *cls,
     char *const *args,
     const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  const char *uri;
  const char *slash;
  char *subsystem;
  char *program;
  struct GNUNET_SCHEDULER_Task *rt;

  (void) cls;
  (void) cfgfile;
  if (NULL == (uri = args[0]))
  {
    fprintf (stderr, _ ("No URI specified on command line\n"));
    return;
  }
  if (0 != strncasecmp ("gnunet://", uri, strlen ("gnunet://")))
  {
    fprintf (stderr,
             _ ("Invalid URI: does not start with `%s'\n"),
             "gnunet://");
    return;
  }
  uri += strlen ("gnunet://");
  if (NULL == (slash = strchr (uri, '/')))
  {
    fprintf (stderr, _ ("Invalid URI: fails to specify subsystem\n"));
    return;
  }
  subsystem = GNUNET_strndup (uri, slash - uri);
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_string (cfg, "uri", subsystem, &program))
  {
    fprintf (stderr, _ ("No handler known for subsystem `%s'\n"), subsystem);
    GNUNET_free (subsystem);
    return;
  }
  GNUNET_free (subsystem);
  rt = GNUNET_SCHEDULER_add_read_file (
    GNUNET_TIME_UNIT_FOREVER_REL,
    GNUNET_DISK_pipe_handle (sigpipe, GNUNET_DISK_PIPE_END_READ),
    &maint_child_death,
    NULL);
  p = GNUNET_OS_start_process (GNUNET_NO,
                               0,
                               NULL,
                               NULL,
                               NULL,
                               program,
                               program,
                               args[0],
                               NULL);
  GNUNET_free (program);
  if (NULL == p)
    GNUNET_SCHEDULER_cancel (rt);
}


/**
 * Signal handler called for SIGCHLD.  Triggers the
 * respective handler by writing to the trigger pipe.
 */
static void
sighandler_child_death ()
{
  static char c;
  int old_errno = errno; /* back-up errno */

  GNUNET_break (
    1 ==
    GNUNET_DISK_file_write (GNUNET_DISK_pipe_handle (sigpipe,
                                                     GNUNET_DISK_PIPE_END_WRITE),
                            &c,
                            sizeof(c)));
  errno = old_errno; /* restore errno */
}


/**
 * The main function to handle gnunet://-URIs.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_OPTION_END
  };
  struct GNUNET_SIGNAL_Context *shc_chld;
  int ret;

  if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
    return 2;
  sigpipe = GNUNET_DISK_pipe (GNUNET_NO, GNUNET_NO, GNUNET_NO, GNUNET_NO);
  GNUNET_assert (sigpipe != NULL);
  shc_chld =
    GNUNET_SIGNAL_handler_install (GNUNET_SIGCHLD, &sighandler_child_death);
  ret = GNUNET_PROGRAM_run (argc,
                            argv,
                            "gnunet-uri URI",
                            gettext_noop (
                              "Perform default-actions for GNUnet URIs"),
                            options,
                            &run,
                            NULL);
  GNUNET_SIGNAL_handler_uninstall (shc_chld);
  shc_chld = NULL;
  GNUNET_DISK_pipe_close (sigpipe);
  sigpipe = NULL;
  GNUNET_free ((void *) argv);
  return ((GNUNET_OK == ret) && (0 == exit_code)) ? 0 : 1;
}


/* end of gnunet-uri.c */