inetutils/ftpd/popen.c

/*
  Copyright (C) 1994-2025 Free Software Foundation, Inc.

  This file is part of GNU Inetutils.

  GNU Inetutils 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.

  GNU Inetutils 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/'. */

/*
 * Copyright (c) 1988, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* This code is derived from software written by Ken Arnold and
   published in UNIX Review, Vol. 6, No. 8.  */

#include <config.h>

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

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* Include glob.h last, because it may define "const" which breaks
   system headers on some platforms. */
#include <glob.h>

#include "extern.h"

/*
 * Special version of popen which avoids call to shell.  This ensures no one
 * may create a pipe to a hidden program as a side effect of a list or dir
 * command.
 */

#define MAX_ARGC 100
#define MAX_GARGC 1000

struct file_pid
{
  FILE *file;
  pid_t pid;
  struct file_pid *next;
};

/* A linked list associating ftpd_popen'd FILEs with pids.  */
struct file_pid *file_pids = 0;

#ifdef WITH_LIBLS
extern int ls_main (int argc, char *argv[]);
#endif

FILE *
ftpd_popen (char *program, const char *type)
{
  char *cp;
  FILE *iop;
  struct file_pid *fpid;
  int argc, gargc, pdes[2], pid;
  char **pop, *argv[MAX_ARGC], *gargv[MAX_GARGC];

  if (((*type != 'r') && (*type != 'w')) || type[1])
    return (NULL);

  if (pipe (pdes) < 0)
    return (NULL);

  /* break up string into pieces */
  for (argc = 0, cp = program; argc < MAX_ARGC - 1; cp = NULL, argc++)
    if (!(argv[argc] = strtok (cp, " \t\n")))
      break;
  argv[MAX_ARGC - 1] = NULL;

  /* glob each piece */
  gargv[0] = argv[0];
  for (gargc = argc = 1; argv[argc]; argc++)
    {
      glob_t gl;
      int flags = GLOB_NOCHECK;

#ifdef GLOB_BRACE
      flags |= GLOB_BRACE;
#endif
#ifdef GLOB_QUOTE
      flags |= GLOB_QUOTE;
#endif
#ifdef GLOB_TILDE
      flags |= GLOB_TILDE;
#endif

      memset (&gl, 0, sizeof (gl));
      if (glob (argv[argc], flags, NULL, &gl))
	gargv[gargc++] = strdup (argv[argc]);
      else if (gl.gl_pathc > 0)
	for (pop = gl.gl_pathv; *pop && (gargc < MAX_GARGC - 1); pop++)
	  gargv[gargc++] = strdup (*pop);
      globfree (&gl);
    }
  gargv[gargc] = NULL;

  iop = NULL;

#ifdef WITH_LIBLS
  /* Do not use vfork() for internal ls.  */
  pid = (strcmp (gargv[0], "/bin/ls") == 0) ? fork () : vfork ();
  switch (pid)
#else
  switch (pid = vfork ())
#endif
    {
    case -1:			/* error */
      close (pdes[0]);
      close (pdes[1]);
      goto pfree;
    case 0:			/* child */
      if (*type == 'r')
	{
	  if (pdes[1] != STDOUT_FILENO)
	    {
	      dup2 (pdes[1], STDOUT_FILENO);
	      close (pdes[1]);
	    }
	  dup2 (STDOUT_FILENO, STDERR_FILENO);	/* stderr too! */
	  close (pdes[0]);
	}
      else
	{
	  if (pdes[0] != STDIN_FILENO)
	    {
	      dup2 (pdes[0], STDIN_FILENO);
	      close (pdes[0]);
	    }
	  close (pdes[1]);
	}

#ifdef WITH_LIBLS
      /* mvo: should this be a config-option? */
      if (strcmp (gargv[0], "/bin/ls") == 0)
	{
	  optind = 0;
	  exit (ls_main (gargc, gargv));
	}
#endif

      execv (gargv[0], gargv);
      _exit (EXIT_FAILURE);
    }
  /* parent; assume fdopen can't fail...  */
  if (*type == 'r')
    {
      iop = fdopen (pdes[0], type);
      close (pdes[1]);
    }
  else
    {
      iop = fdopen (pdes[1], type);
      close (pdes[0]);
    }

  fpid = (struct file_pid *) malloc (sizeof (struct file_pid));
  if (fpid)
    {
      fpid->file = iop;
      fpid->pid = pid;
      fpid->next = file_pids;
      file_pids = fpid;
    }

pfree:for (argc = 1; gargv[argc] != NULL; argc++)
    free (gargv[argc]);

  return (iop);
}

int
ftpd_pclose (FILE *iop)
{
  struct file_pid *fpid = file_pids, *prev_fpid = 0;
  int status;
#ifdef HAVE_SIGACTION
  sigset_t sigs, osigs;
#else
  int omask;
#endif
  pid_t pid;

  /*
   * pclose returns -1 if stream is not associated with a
   * `popened' command, or, if already `pclosed'.
   */
  while (fpid && fpid->file != iop)
    {
      prev_fpid = fpid;
      fpid = fpid->next;
    }
  if (!fpid)
    return -1;

  if (prev_fpid)
    prev_fpid->next = fpid->next;
  else
    file_pids = fpid->next;

  fclose (iop);
#ifdef HAVE_SIGACTION
  sigemptyset (&sigs);
  sigaddset (&sigs, SIGINT);
  sigaddset (&sigs, SIGQUIT);
  sigaddset (&sigs, SIGHUP);
  sigprocmask (SIG_BLOCK, &sigs, &osigs);
#else
  omask = sigblock (sigmask (SIGINT) | sigmask (SIGQUIT) | sigmask (SIGHUP));
#endif
  while ((pid = waitpid (fpid->pid, &status, 0)) < 0 && errno == EINTR)
    continue;

  free (fpid);

#ifdef HAVE_SIGACTION
  sigprocmask (SIG_SETMASK, &osigs, 0);
#else
  sigsetmask (omask);
#endif
  if (pid < 0)
    return (pid);
  if (WIFEXITED (status))
    return (WEXITSTATUS (status));
  return (1);
}