/*

 * Unix SMB/CIFS implementation.

 *  Samba system utilities

 * Copyright (C) Jeremy Allison  2000

 *

 * 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.

 */

#include "replace.h"

#include "system/wait.h"

#include "system/filesys.h"

#include <talloc.h>

#include "lib/util/sys_popen.h"

#include "lib/util/debug.h"

/**************************************************************************

 Wrapper for popen. Safer as it doesn't search a path.

 Modified from the glibc sources.

 modified by tridge to return a file descriptor. We must kick our FILE* habit

****************************************************************************/

typedef struct _popen_list

{

  int fd;

  pid_t child_pid;

  struct _popen_list *next;

} popen_list;

static popen_list *popen_chain;

int sys_popenv(char * const argl[])

{

  int parent_end, child_end;

  int pipe_fds[2];

  popen_list *entry = NULL;

  const char *command = NULL;

  int ret;

  if (argl == NULL) {

    errno = EINVAL;

    return -1;

  }

  command = argl[0];

  if (!*command) {

    errno = EINVAL;

    return -1;

  }

  ret = pipe(pipe_fds);

  if (ret < 0) {

    DBG_ERR("error opening pipe: %s\n",

        strerror(errno));

    return -1;

  }

  parent_end = pipe_fds[0];

  child_end = pipe_fds[1];

  entry = talloc_zero(NULL, popen_list);

  if (entry == NULL) {

    DBG_ERR("talloc failed\n");

    goto err_exit;

  }

  entry->child_pid = fork();

  if (entry->child_pid == -1) {

    DBG_ERR("fork failed: %s\n", strerror(errno));

    goto err_exit;

  }

  if (entry->child_pid == 0) {

    /*

     * Child !

     */

    int child_std_end = STDOUT_FILENO;

    popen_list *p;

    close(parent_end);

    if (child_end != child_std_end) {

      dup2 (child_end, child_std_end);

      close (child_end);

    }

    /*

     * POSIX.2:  "popen() shall ensure that any streams from previous

     * popen() calls that remain open in the parent process are closed

     * in the new child process."

     */

    for (p = popen_chain; p; p = p->next)

      close(p->fd);

    ret = execv(argl[0], argl);

    if (ret == -1) {

      DBG_ERR("ERROR executing command "

        "'%s': %s\n", command, strerror(errno));

    }

    _exit (127);

  }

  /*

   * Parent.

   */

  close (child_end);

  /* Link into popen_chain. */

  entry->next = popen_chain;

  popen_chain = entry;

  entry->fd = parent_end;

  return entry->fd;

err_exit:

  TALLOC_FREE(entry);

  close(pipe_fds[0]);

  close(pipe_fds[1]);

  return -1;

}

/**************************************************************************

 Wrapper for pclose. Modified from the glibc sources.

****************************************************************************/

int sys_pclose(int fd)

{

  int wstatus;

  popen_list **ptr = &popen_chain;

  popen_list *entry = NULL;

  pid_t wait_pid;

  int status = -1;

  /* Unlink from popen_chain. */

  for ( ; *ptr != NULL; ptr = &(*ptr)->next) {

    if ((*ptr)->fd == fd) {

      entry = *ptr;

      *ptr = (*ptr)->next;

      status = 0;

      break;

    }

  }

  if (status < 0 || close(entry->fd) < 0)

    return -1;

  /*

   * As Samba is catching and eating child process

   * exits we don't really care about the child exit

   * code, a -1 with errno = ECHILD will do fine for us.

   */

  do {

    wait_pid = waitpid (entry->child_pid, &wstatus, 0);

  } while (wait_pid == -1 && errno == EINTR);

  TALLOC_FREE(entry);

  if (wait_pid == -1)

    return -1;

  return wstatus;

}