glibc/libio/iopopen.c

/* Copyright (C) 1993, 1997 Free Software Foundation, Inc.
   This file is part of the GNU IO Library.
   Written by Per Bothner <bothner@cygnus.com>.

   This library 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 library 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 library; see the file COPYING.  If not, write to
   the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA.

   As a special exception, if you link this library with files
   compiled with a GNU compiler to produce an executable, this does
   not cause the resulting executable to be covered by the GNU General
   Public License.  This exception does not however invalidate any
   other reasons why the executable file might be covered by the GNU
   General Public License.  */

#ifndef _POSIX_SOURCE
# define _POSIX_SOURCE
#endif
#include "libioP.h"
#if _IO_HAVE_SYS_WAIT
#include <signal.h>
#include <unistd.h>
#ifdef __STDC__
#include <stdlib.h>
#endif
#ifdef _LIBC
# include <unistd.h>
#endif
#include <sys/types.h>
#include <sys/wait.h>

#ifndef _IO_fork
#define _IO_fork vfork /* defined in libiberty, if needed */
extern _IO_pid_t _IO_fork __P ((void));
#endif

#endif /* _IO_HAVE_SYS_WAIT */

#ifndef _IO_pipe
#define _IO_pipe pipe
extern int _IO_pipe __P ((int des[2]));
#endif

#ifndef _IO_dup2
#define _IO_dup2 dup2
extern int _IO_dup2 __P ((int fd, int fd2));
#endif

#ifndef _IO_waitpid
#define _IO_waitpid waitpid
#endif

#ifndef _IO_execl
#define _IO_execl execl
#endif
#ifndef _IO__exit
#define _IO__exit _exit
#endif

struct _IO_proc_file
{
  struct _IO_FILE_plus file;
  /* Following fields must match those in class procbuf (procbuf.h) */
  _IO_pid_t pid;
  struct _IO_proc_file *next;
};
typedef struct _IO_proc_file _IO_proc_file;

static struct _IO_proc_file *proc_file_chain = NULL;

_IO_FILE *
_IO_proc_open (fp, command, mode)
     _IO_FILE *fp;
     const char *command;
     const char *mode;
{
#if _IO_HAVE_SYS_WAIT
  volatile int read_or_write;
  volatile int parent_end, child_end;
  int pipe_fds[2];
  _IO_pid_t child_pid;
  if (_IO_file_is_open (fp))
    return NULL;
  if (_IO_pipe (pipe_fds) < 0)
    return NULL;
  if (mode[0] == 'r')
    {
      parent_end = pipe_fds[0];
      child_end = pipe_fds[1];
      read_or_write = _IO_NO_WRITES;
    }
  else
    {
      parent_end = pipe_fds[1];
      child_end = pipe_fds[0];
      read_or_write = _IO_NO_READS;
    }
  ((_IO_proc_file *) fp)->pid = child_pid = _IO_fork ();
  if (child_pid == 0)
    {
      int child_std_end = mode[0] == 'r' ? 1 : 0;
      _IO_close (parent_end);
      if (child_end != child_std_end)
	{
	  _IO_dup2 (child_end, child_std_end);
	  _IO_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." */
      while (proc_file_chain)
	{
	  _IO_close (_IO_fileno ((_IO_FILE *) proc_file_chain));
	  proc_file_chain = proc_file_chain->next;
	}

      _IO_execl ("/bin/sh", "sh", "-c", command, (char *) 0);
      _IO__exit (127);
    }
  _IO_close (child_end);
  if (child_pid < 0)
    {
      _IO_close (parent_end);
      return NULL;
    }
  _IO_fileno (fp) = parent_end;

  /* Link into proc_file_chain. */
  ((_IO_proc_file *) fp)->next = proc_file_chain;
  proc_file_chain = (_IO_proc_file *) fp;

  _IO_mask_flags (fp, read_or_write, _IO_NO_READS|_IO_NO_WRITES);
  return fp;
#else /* !_IO_HAVE_SYS_WAIT */
  return NULL;
#endif
}

_IO_FILE *
_IO_popen (command, mode)
     const char *command;
     const char *mode;
{
  struct locked_FILE
  {
    struct _IO_proc_file fpx;
#ifdef _IO_MTSAFE_IO
    _IO_lock_t lock;
#endif
  } *new_f;
  _IO_FILE *fp;

  new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
  if (new_f == NULL)
    return NULL;
#ifdef _IO_MTSAFE_IO
  new_f->fpx.file.file._lock = &new_f->lock;
#endif
  fp = (_IO_FILE*)&new_f->fpx;
  _IO_init (fp, 0);
  _IO_JUMPS (fp) = &_IO_proc_jumps;
  _IO_file_init (fp);
#if  !_IO_UNIFIED_JUMPTABLES
  ((struct _IO_FILE_plus *) fp)->vtable = NULL;
#endif
  if (_IO_proc_open (fp, command, mode) != NULL)
    return fp;
  free (new_f);
  return NULL;
}

#ifdef strong_alias
strong_alias (_IO_popen, popen);
#endif

int
_IO_proc_close (fp)
     _IO_FILE *fp;
{
  /* This is not name-space clean. FIXME! */
#if _IO_HAVE_SYS_WAIT
  int wstatus;
  _IO_proc_file **ptr = &proc_file_chain;
  _IO_pid_t wait_pid;
  int status = -1;

  /* Unlink from proc_file_chain. */
  for ( ; *ptr != NULL; ptr = &(*ptr)->next)
    {
      if (*ptr == (_IO_proc_file *) fp)
	{
	  *ptr = (*ptr)->next;
	  status = 0;
	  break;
	}
    }

  if (status < 0 || _IO_close (_IO_fileno(fp)) < 0)
    return -1;
  /* POSIX.2 Rationale:  "Some historical implementations either block
     or ignore the signals SIGINT, SIGQUIT, and SIGHUP while waiting
     for the child process to terminate.  Since this behavior is not
     described in POSIX.2, such implementations are not conforming." */
  do
    {
      wait_pid = _IO_waitpid (((_IO_proc_file *) fp)->pid, &wstatus, 0);
    }
  while (wait_pid == -1 && errno == EINTR);
  if (wait_pid == -1)
    return -1;
  return wstatus;
#else /* !_IO_HAVE_SYS_WAIT */
  return -1;
#endif
}

struct _IO_jump_t _IO_proc_jumps = {
  JUMP_INIT_DUMMY,
  JUMP_INIT(finish, _IO_file_finish),
  JUMP_INIT(overflow, _IO_file_overflow),
  JUMP_INIT(underflow, _IO_file_underflow),
  JUMP_INIT(uflow, _IO_default_uflow),
  JUMP_INIT(pbackfail, _IO_default_pbackfail),
  JUMP_INIT(xsputn, _IO_file_xsputn),
  JUMP_INIT(xsgetn, _IO_default_xsgetn),
  JUMP_INIT(seekoff, _IO_file_seekoff),
  JUMP_INIT(seekpos, _IO_default_seekpos),
  JUMP_INIT(setbuf, _IO_file_setbuf),
  JUMP_INIT(sync, _IO_file_sync),
  JUMP_INIT(doallocate, _IO_file_doallocate),
  JUMP_INIT(read, _IO_file_read),
  JUMP_INIT(write, _IO_file_write),
  JUMP_INIT(seek, _IO_file_seek),
  JUMP_INIT(close, _IO_proc_close),
  JUMP_INIT(stat, _IO_file_stat)
};