/* unknown.c -- implement the unknown dynamically loadable builtin
   Copyright (C) 2000 Gary V. Vaughan
  
   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.
*/

/** @start 1 */
#if HAVE_CONFIG_H
#  include <config.h>
#endif

#include <sys/types.h>
#include <sys/wait.h>
#include <sic/module.h>

#define builtin_table   unknown_LTX_builtin_table

static char *path_find  (const char *command);
static int path_execute (Sic *sic, const char *path, char *const argv[]);

/* Generate prototype. */
SIC_BUILTIN (builtin_unknown);

Builtin builtin_table[] = {
  { "unknown", builtin_unknown, 0, -1 },
  { 0, 0, -1, -1 }
};

BUILTIN_DECLARATION(unknown)
{
  char *path = path_find (argv[0]);
  int status = SIC_ERROR;

  if (!path)
    sic_result_append (sic, "command \"", argv[0], "\" not found",
                       NULL);
  else if (path_execute (sic, path, argv) != SIC_OKAY)
    sic_result_append (sic, "command \"", argv[0],"\" failed: ",
                       strerror (errno), NULL);
  else
    status = SIC_OKAY;

  return status;
}
/** @end 1 */

static char *
path_find (const char *command)
{
  char *path = xstrdup (command);
  
  if (*command == '/')
    {
      if (access (command, X_OK) < 0)
        goto notfound;
    }
  else
    {
      char *PATH = getenv ("PATH");
      char *pbeg, *pend;
      size_t len;

      for (pbeg = PATH; *pbeg != '\0'; pbeg = pend)
        {
          pbeg += strspn (pbeg, ":");
          len = strcspn (pbeg, ":");
          pend = pbeg + len;
          path = XREALLOC (char, path, 2 + len + strlen(command));
          *path = '\0';
          strncat (path, pbeg, len);
          if (path[len -1] != '/') strcat (path, "/");
          strcat (path, command);
          
          if (access (path, X_OK) == 0)
              break;
        }

      if (*pbeg == '\0')
          goto notfound;
    }

  return path;

 notfound:
  XFREE (path);
  return NULL;
}  

static int
path_execute (Sic *sic, const char *path, char *const argv[])
{
  int status = SIC_OKAY;        /* assume successful for now */
  pid_t pid;

  pid = fork ();
  switch (pid)
    {
    case -1:                    /* fork failed */
      status = SIC_ERROR;
      break;

    case 0:
      execv (path, argv);
      _exit (1);                /* execv in child failed */
      break;

    default:                    /* wait for child to exit */
      {
        int stat;
        if (waitpid (pid, &stat, 0) == pid)
          {
            if (WIFSIGNALED (stat)
                || (WIFEXITED (stat) && (WEXITSTATUS (stat) != 0)))
              status = SIC_ERROR;
          }
        else
          status = SIC_ERROR;
      }
      break;
    }
  
  return status;
}