input.c

android-w.song.android.widget

/* input.c -- functions to perform buffered input with synchronization. */

/* Copyright (C) 1992-2009 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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.

   Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "config.h"

#include "bashtypes.h"
#if !defined (_MINIX) && defined (HAVE_SYS_FILE_H)
#  include <sys/file.h>
#endif
#include "filecntl.h"
#include "posixstat.h"
#include <stdio.h>
#include <errno.h>

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

#include "bashansi.h"
#include "bashintl.h"

#include "command.h"
#include "general.h"
#include "input.h"
#include "error.h"
#include "externs.h"
#include "quit.h"

#if !defined (errno)
extern int errno;
#endif /* !errno */

#if defined (EAGAIN)
#  define X_EAGAIN EAGAIN
#else
#  define X_EAGAIN -99
#endif

#if defined (EWOULDBLOCK)
#  define X_EWOULDBLOCK EWOULDBLOCK
#else
#  define X_EWOULDBLOCK -99
#endif

extern void termsig_handler __P((int));

/* Functions to handle reading input on systems that don't restart read(2)
   if a signal is received. */

static char localbuf[128];
static int local_index = 0, local_bufused = 0;

/* Posix and USG systems do not guarantee to restart read () if it is
   interrupted by a signal.  We do the read ourselves, and restart it
   if it returns EINTR. */
int
getc_with_restart (stream)
     FILE *stream;
{
  unsigned char uc;

  CHECK_TERMSIG;

  /* Try local buffering to reduce the number of read(2) calls. */
  if (local_index == local_bufused || local_bufused == 0)
    {
      while (1)
	{
	  CHECK_TERMSIG;
	  local_bufused = read (fileno (stream), localbuf, sizeof(localbuf));
	  if (local_bufused > 0)
	    break;
	  else if (errno == X_EAGAIN || errno == X_EWOULDBLOCK)
	    {
	      if (sh_unset_nodelay_mode (fileno (stream)) < 0)
		{
		  sys_error (_("cannot reset nodelay mode for fd %d"), fileno (stream));
		  return EOF;
		}
	      continue;
	    }
	  else if (local_bufused == 0 || errno != EINTR)
	    {
	      local_index = 0;
	      return EOF;
	    }
	}
      local_index = 0;
    }
  uc = localbuf[local_index++];
  return uc;
}

int
ungetc_with_restart (c, stream)
     int c;
     FILE *stream;
{
  if (local_index == 0 || c == EOF)
    return EOF;
  localbuf[--local_index] = c;
  return c;
}

#if defined (BUFFERED_INPUT)

/* A facility similar to stdio, but input-only. */

#if defined (USING_BASH_MALLOC)
#  define MAX_INPUT_BUFFER_SIZE	8176
#else
#  define MAX_INPUT_BUFFER_SIZE	8192
#endif

#if !defined (SEEK_CUR)
#  define SEEK_CUR 1
#endif /* !SEEK_CUR */

#ifdef max
#  undef max
#endif
#define max(a, b)	(((a) > (b)) ? (a) : (b))
#ifdef min
#  undef min
#endif
#define min(a, b)	((a) > (b) ? (b) : (a))

extern int interactive_shell;

int bash_input_fd_changed;

/* This provides a way to map from a file descriptor to the buffer
   associated with that file descriptor, rather than just the other
   way around.  This is needed so that buffers are managed properly
   in constructs like 3<&4.  buffers[x]->b_fd == x -- that is how the
   correspondence is maintained. */
static BUFFERED_STREAM **buffers = (BUFFERED_STREAM **)NULL;
static int nbuffers;

#define ALLOCATE_BUFFERS(n) \
	do { if ((n) >= nbuffers) allocate_buffers (n); } while (0)

/* Make sure `buffers' has at least N elements. */
static void
allocate_buffers (n)
     int n;
{
  register int i, orig_nbuffers;

  orig_nbuffers = nbuffers;
  nbuffers = n + 20;
  buffers = (BUFFERED_STREAM **)xrealloc
    (buffers, nbuffers * sizeof (BUFFERED_STREAM *));

  /* Zero out the new buffers. */
  for (i = orig_nbuffers; i < nbuffers; i++)
    buffers[i] = (BUFFERED_STREAM *)NULL;
}

/* Construct and return a BUFFERED_STREAM corresponding to file descriptor
   FD, using BUFFER. */
static BUFFERED_STREAM *
make_buffered_stream (fd, buffer, bufsize)
     int fd;
     char *buffer;
     size_t bufsize;
{
  BUFFERED_STREAM *bp;

  bp = (BUFFERED_STREAM *)xmalloc (sizeof (BUFFERED_STREAM));
  ALLOCATE_BUFFERS (fd);
  buffers[fd] = bp;
  bp->b_fd = fd;
  bp->b_buffer = buffer;
  bp->b_size = bufsize;
  bp->b_used = bp->b_inputp = bp->b_flag = 0;
  if (bufsize == 1)
    bp->b_flag |= B_UNBUFF;
  if (O_TEXT && (fcntl (fd, F_GETFL) & O_TEXT) != 0)
    bp->b_flag |= O_TEXT;
  return (bp);
}

/* Allocate a new BUFFERED_STREAM, copy BP to it, and return the new copy. */
static BUFFERED_STREAM *
copy_buffered_stream (bp)
     BUFFERED_STREAM *bp;
{
  BUFFERED_STREAM *nbp;

  if (!bp)
    return ((BUFFERED_STREAM *)NULL);

  nbp = (BUFFERED_STREAM *)xmalloc (sizeof (BUFFERED_STREAM));
  xbcopy ((char *)bp, (char *)nbp, sizeof (BUFFERED_STREAM));
  return (nbp);
}

int
set_bash_input_fd (fd)
     int fd;
{
  if (bash_input.type == st_bstream)
    bash_input.location.buffered_fd = fd;
  else if (interactive_shell == 0)
    default_buffered_input = fd;
  return 0;
}

int
fd_is_bash_input (fd)
     int fd;
{
  if (bash_input.type == st_bstream && bash_input.location.buffered_fd == fd)
    return 1;
  else if (interactive_shell == 0 && default_buffered_input == fd)
    return 1;
  return 0;
}

/* Save the buffered stream corresponding to file descriptor FD (which bash
   is using to read input) to a buffered stream associated with NEW_FD.  If
   NEW_FD is -1, a new file descriptor is allocated with fcntl.  The new
   file descriptor is returned on success, -1 on error. */
int
save_bash_input (fd, new_fd)
     int fd, new_fd;
{
  int nfd;

  /* Sync the stream so we can re-read from the new file descriptor.  We
     might be able to avoid this by copying the buffered stream verbatim
     to the new file descriptor. */
  if (buffers[fd])
    sync_buffered_stream (fd);

  /* Now take care of duplicating the file descriptor that bash is
     using for input, so we can reinitialize it later. */
  nfd = (new_fd == -1) ? fcntl (fd, F_DUPFD, 10) : new_fd;
  if (nfd == -1)
    {
      if (fcntl (fd, F_GETFD, 0) == 0)
	sys_error (_("cannot allocate new file descriptor for bash input from fd %d"), fd);
      return -1;
    }

  if (buffers[nfd])
    {
      /* What's this?  A stray buffer without an associated open file
	 descriptor?  Free up the buffer and report the error. */
      internal_error (_("save_bash_input: buffer already exists for new fd %d"), nfd);
      free_buffered_stream (buffers[nfd]);
    }

  /* Reinitialize bash_input.location. */
  if (bash_input.type == st_bstream)
    {
      bash_input.location.buffered_fd = nfd;
      fd_to_buffered_stream (nfd);
      close_buffered_fd (fd);	/* XXX */
    }
  else
    /* If the current input type is not a buffered stream, but the shell
       is not interactive and therefore using a buffered stream to read
       input (e.g. with an `eval exec 3>output' inside a script), note
       that the input fd has been changed.  pop_stream() looks at this
       value and adjusts the input fd to the new value of
       default_buffered_input accordingly. */
    bash_input_fd_changed++;

  if (default_buffered_input == fd)
    default_buffered_input = nfd;

  SET_CLOSE_ON_EXEC (nfd);
  return nfd;
}

/* Check that file descriptor FD is not the one that bash is currently
   using to read input from a script.  FD is about to be duplicated onto,
   which means that the kernel will close it for us.  If FD is the bash
   input file descriptor, we need to seek backwards in the script (if
   possible and necessary -- scripts read from stdin are still unbuffered),
   allocate a new file descriptor to use for bash input, and re-initialize
   the buffered stream.  Make sure the file descriptor used to save bash
   input is set close-on-exec. Returns 0 on success, -1 on failure.  This
   works only if fd is > 0 -- if fd == 0 and bash is reading input from
   fd 0, save_bash_input is used instead, to cooperate with input
   redirection (look at redir.c:add_undo_redirect()). */
int
check_bash_input (fd)
     int fd;
{
  if (fd_is_bash_input (fd))
    {
      if (fd > 0)
	return ((save_bash_input (fd, -1) == -1) ? -1 : 0);
      else if (fd == 0)
        return ((sync_buffered_stream (fd) == -1) ? -1 : 0);
    }
  return 0;
}
      
/* This is the buffered stream analogue of dup2(fd1, fd2).  The
   BUFFERED_STREAM corresponding to fd2 is deallocated, if one exists.
   BUFFERS[fd1] is copied to BUFFERS[fd2].  This is called by the
   redirect code for constructs like 4<&0 and 3</etc/rc.local. */
int
duplicate_buffered_stream (fd1, fd2)
     int fd1, fd2;
{
  int is_bash_input, m;