bash/builtins/read.def

This file is read.def, from which is created read.c.
It implements the builtin "read" in Bash.

Copyright (C) 1987-2024 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/>.

$PRODUCES read.c

$BUILTIN read
$FUNCTION read_builtin
$SHORT_DOC read [-Eers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
Read a line from the standard input and split it into fields.

Reads a single line from the standard input, or from file descriptor FD
if the -u option is supplied.  The line is split into fields as with word
splitting, and the first word is assigned to the first NAME, the second
word to the second NAME, and so on, with any leftover words assigned to
the last NAME.  Only the characters found in $IFS are recognized as word
delimiters. By default, the backslash character escapes delimiter characters
and newline.

If no NAMEs are supplied, the line read is stored in the REPLY variable.

Options:
  -a array	assign the words read to sequential indices of the array
		variable ARRAY, starting at zero
  -d delim	continue until the first character of DELIM is read, rather
		than newline
  -e	use Readline to obtain the line
  -E	use Readline to obtain the line and use the bash default
		completion instead of Readline's default completion
  -i text	use TEXT as the initial text for Readline
  -n nchars	return after reading NCHARS characters rather than waiting
		for a newline, but honor a delimiter if fewer than
		NCHARS characters are read before the delimiter
  -N nchars	return only after reading exactly NCHARS characters, unless
		EOF is encountered or read times out, ignoring any
		delimiter
  -p prompt	output the string PROMPT without a trailing newline before
		attempting to read
  -r	do not allow backslashes to escape any characters
  -s	do not echo input coming from a terminal
  -t timeout	time out and return failure if a complete line of
		input is not read within TIMEOUT seconds.  The value of the
		TMOUT variable is the default timeout.  TIMEOUT may be a
		fractional number.  If TIMEOUT is 0, read returns
		immediately, without trying to read any data, returning
		success only if input is available on the specified
		file descriptor.  The exit status is greater than 128
		if the timeout is exceeded
  -u fd	read from file descriptor FD instead of the standard input

Exit Status:
The return code is zero, unless end-of-file is encountered, read times out
(in which case it's greater than 128), a variable assignment error occurs,
or an invalid file descriptor is supplied as the argument to -u.
$END

#include <config.h>

#include "bashtypes.h"
#include "posixstat.h"

#include <stdio.h>

#include "bashansi.h"

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

#include <signal.h>
#include <errno.h>

#ifdef __CYGWIN__
#  include <fcntl.h>
#endif

#include "../bashintl.h"

#include "../shell.h"
#include "common.h"
#include "bashgetopt.h"
#include "trap.h"

#include <shtty.h>

#if defined (READLINE)
#include "../bashline.h"
#include <readline/readline.h>
#endif

#include "input.h"

#include "shmbutil.h"
#include "timer.h"

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

struct ttsave
{
  int fd;
  TTYSTRUCT attrs;
};

#if defined (READLINE)
static void uw_reset_attempted_completion_function (void *);
static int set_itext (void);
static char *edit_line (char *, char *, int, int);
static void set_eol_delim (int);
static void reset_eol_delim (void *);
static void set_readline_timeout (sh_timer *t, time_t, long);
static void uw_bashline_reset_event_hook (void *);
#endif
static SHELL_VAR *bind_read_variable (char *, char *, int);
#if defined (HANDLE_MULTIBYTE)
static int read_mbchar (int, char *, int, int, int, int);
#endif
static void ttyrestore (struct ttsave *);
static void uw_ttyrestore (void *);

static sighandler sigalrm (int);
static void reset_timeout (void);
static void uw_reset_timeout (void *);

/* Try this to see what the rest of the shell can do with the information. */
sh_timer *read_timeout;

static int reading, tty_modified;

static struct ttsave termsave;

/* In all cases, SIGALRM just sets a flag that we check periodically.  This
   avoids problems with the semi-tricky stuff we do with the xfree of
   input_string at the top of the unwind-protect list (see below). */

/* Set a flag that check_read_timeout can check.  This relies on zread or
   read_builtin calling trap.c:check_signals() (which calls check_read_timeout()) */
static sighandler
sigalrm (int s)
{
  /* Display warning if this is called without read_timeout set? */
  if (read_timeout)
    read_timeout->alrmflag = 1;
}

static void
reset_timeout (void)
{
  /* Cancel alarm before restoring signal handler. */
  if (read_timeout)
    shtimer_clear (read_timeout);
#if defined (READLINE)
  rl_clear_timeout ();
#endif
  read_timeout = 0;
}

static void
uw_reset_timeout (void *ignore)
{
  reset_timeout ();
}

void
check_read_timeout (void)
{
  if (read_timeout && shtimer_chktimeout (read_timeout))
    sh_longjmp (read_timeout->jmpenv, 1);
}

int
read_builtin_timeout (int fd)
{
  if ((read_timeout == 0) ||
      (read_timeout->fd != fd) ||
      (read_timeout->tmout.tv_sec == 0 && read_timeout->tmout.tv_usec == 0))
    return 0;

#if defined (HAVE_SELECT)
  return ((read_timeout->flags & SHTIMER_ALARM) ? shtimer_alrm (read_timeout)
  						: shtimer_select (read_timeout));
#else
  return (shtimer_alrm (read_timeout));
#endif
}

#if defined (READLINE)
void
reset_rl_instream (FILE *save_instream)
{
  fclose (rl_instream);
  rl_instream = save_instream;
}

void
uw_reset_rl_instream (void *fp)
{
  reset_rl_instream (fp);
}
#endif

/* Read the value of the shell variables whose names follow.
   The reading is done from the current input stream, whatever
   that may be.  Successive words of the input line are assigned
   to the variables mentioned in LIST.  The last variable in LIST
   gets the remainder of the words on the line.  If no variables
   are mentioned in LIST, then the default variable is $REPLY. */
int
read_builtin (WORD_LIST *list)
{
  char *varname;
  int nr, pass_next, saw_escape, eof, opt, retval, code, print_ps2, nflag;
  size_t size;
  volatile int i;
  int input_is_tty, input_is_pipe, unbuffered_read, skip_ctlesc, skip_ctlnul;
  int edit, use_bash_completion;
  int raw, nchars, silent, have_timeout, ignore_delim, fd;
  int free_ifs;
  int lastsig, t_errno;
  int mb_cur_max;
  unsigned int tmsec, tmusec;
  long ival, uval;
  intmax_t intval;
  char c;
  int delim;
  char *input_string, *orig_input_string, *ifs_chars, *prompt, *arrayname;
  char *e, *t, *t1, *ps2, *tofree;
  struct stat tsb;
  SHELL_VAR *var;
  TTYSTRUCT ttattrs, ttset;
  sigset_t chldset, prevset;
#if defined (ARRAY_VARS)
  WORD_LIST *alist;
  int vflags;
#endif
  int bindflags;
#if defined (READLINE)
  char *rlbuf, *itext;
  int rlind;
  FILE *save_instream;
#endif

  USE_VAR(size);
  USE_VAR(i);
  USE_VAR(pass_next);
  USE_VAR(print_ps2);
  USE_VAR(saw_escape);
  USE_VAR(input_is_pipe);
/*  USE_VAR(raw); */
  USE_VAR(edit);
  USE_VAR(use_bash_completion);
  USE_VAR(delim);
  USE_VAR(tmsec);
  USE_VAR(tmusec);
  USE_VAR(nchars);
  USE_VAR(silent);
  USE_VAR(ifs_chars);
  USE_VAR(prompt);
  USE_VAR(arrayname);
#if defined (READLINE)
  USE_VAR(rlbuf);
  USE_VAR(rlind);
  USE_VAR(itext);
#endif
  USE_VAR(list);
  USE_VAR(ps2);
  USE_VAR(lastsig);

  reading = tty_modified = 0;
  read_timeout = 0;

  i = 0;		/* Index into the string that we are reading. */
  raw = edit = 0;	/* Not reading raw input by default. */
  use_bash_completion = 0;
  silent = 0;
  arrayname = prompt = (char *)NULL;
  fd = 0;		/* file descriptor to read from */

#if defined (READLINE)
  rlbuf = itext = (char *)0;
  rlind = 0;
#endif

  mb_cur_max = MB_CUR_MAX;
  tmsec = tmusec = 0;		/* no timeout */
  nr = nchars = input_is_tty = input_is_pipe = unbuffered_read = have_timeout = 0;
  delim = '\n';		/* read until newline */
  ignore_delim = nflag = 0;

  reset_internal_getopt ();
  while ((opt = internal_getopt (list, "Eersa:d:i:n:p:t:u:N:")) != -1)
    {
      switch (opt)
	{
	case 'r':
	  raw = 1;
	  break;
	case 'p':
	  prompt = list_optarg;
	  break;
	case 's':
	  silent = 1;
	  break;
	case 'e':
#if defined (READLINE)
	  edit = 1;
#endif
	  break;
	case 'E':
#if defined (READLINE)
	  edit = use_bash_completion = 1;
#endif
	  break;

	case 'i':
#if defined (READLINE)
	  itext = list_optarg;
#endif
	  break;
#if defined (ARRAY_VARS)
	case 'a':
	  arrayname = list_optarg;
	  break;
#endif
	case 't':
	  code = uconvert (list_optarg, &ival, &uval, (char **)NULL);
	  if (code == 0 || ival < 0 || uval < 0)
	    {
	      builtin_error (_("%s: invalid timeout specification"), list_optarg);
	      return (EXECUTION_FAILURE);
	    }
	  else
	    {
	      have_timeout = 1;
	      tmsec = ival;
	      tmusec = uval;
	    }
	  break;
	case 'N':
	  ignore_delim = 1;
	case 'n':
	  nflag = 1;
	  code = valid_number (list_optarg, &intval);
	  if (code == 0 || intval < 0 || intval != (int)intval)
	    {
	      sh_invalidnum (list_optarg);
	      return (EXECUTION_FAILURE);
	    }
	  else
	    nchars = intval;
	  break;
	case 'u':
	  code = valid_number (list_optarg, &intval);
	  if (code == 0 || intval < 0 || intval != (int)intval)
	    {
	      builtin_error (_("%s: invalid file descriptor specification"), list_optarg);
	      return (EXECUTION_FAILURE);
	    }
	  else
	    fd = intval;
	  if (sh_validfd (fd) == 0)
	    {
	      builtin_error ("%d: %s: %s", fd, _("invalid file descriptor"), strerror (errno));
	      return (EXECUTION_FAILURE);
	    }
	  break;
	case 'd':
	  delim = (unsigned char)*list_optarg;
	  break;
	CASE_HELPOPT;
	default:
	  builtin_usage ();
	  return (EX_USAGE);
	}
    }
  list = loptend;

  /* `read -t 0 var' tests whether input is available with select/FIONREAD,
     and fails if those are unavailable */
  if (have_timeout && tmsec == 0 && tmusec == 0)
    return (input_avail (fd) ? EXECUTION_SUCCESS : EXECUTION_FAILURE);

  /* Convenience: check early whether or not the first of possibly several
     variable names is a valid identifier, and bail early if so. */
#if defined (ARRAY_VARS)
  if (list)
    SET_VFLAGS (list->word->flags, vflags, bindflags);
  if (list && valid_identifier (list->word->word) == 0 && valid_array_reference (list->word->word, vflags) == 0)
#else
  bindflags = 0;
  if (list && valid_identifier (list->word->word) == 0)
#endif
    {
      sh_invalidid (list->word->word);
      return (EXECUTION_FAILURE);
    }

  /* If we're asked to ignore the delimiter, make sure we do. */
  if (ignore_delim)
    delim = -1;

  /* IF IFS is unset, we use the default of " \t\n". */
  free_ifs = 0;
  /* If we want to read exactly NCHARS chars, don't split on IFS */
  if (ignore_delim)
    ifs_chars = "";
  else
    {
      ifs_chars = getifs ();
      if (ifs_chars == 0)		/* XXX - shouldn't happen */
	ifs_chars = "";
      else
	free_ifs = 1;
    }
  for (skip_ctlesc = skip_ctlnul = 0, e = ifs_chars; *e; e++)
    skip_ctlesc |= *e == CTLESC, skip_ctlnul |= *e == CTLNUL;

  input_string = (char *)xmalloc (size = 112);	/* XXX was 128 */
  input_string[0] = '\0';

  pass_next = 0;	/* Non-zero signifies last char was backslash. */
  saw_escape = 0;	/* Non-zero is count of escape chars we added */

  /* More input and options validation */
  if (nflag == 1 && nchars == 0)
    {
      retval = read (fd, &c, 0);
      retval = (retval >= 0) ? EXECUTION_SUCCESS : EXECUTION_FAILURE;
      goto assign_vars;		/* bail early if asked to read 0 chars */
    }

  /* $TMOUT, if set, is the default timeout for read. */
  if (have_timeout == 0 && (e = get_string_value ("TMOUT")))
    {
      code = uconvert (e, &ival, &uval, (char **)NULL);
      if (code == 0 || ival < 0 || uval < 0)
	tmsec = tmusec = 0;
      else
	{
	  tmsec = ival;
	  tmusec = uval;
	}
    }

#if defined (SIGCHLD)
  sigemptyset (&chldset);
  sigprocmask (SIG_BLOCK, (sigset_t *)0, &chldset);
  sigaddset (&chldset, SIGCHLD);
  sigemptyset (&prevset);
  sigprocmask (SIG_SETMASK, (sigset_t *)0, &prevset);
#endif

  begin_unwind_frame ("read_builtin");

  if (interactive == 0 && default_buffered_input >= 0 && fd_is_bash_input (fd))
    sync_buffered_stream (default_buffered_input);

#if 1
  input_is_tty = isatty (fd);
#else
  input_is_tty = 1;
#endif
  if (input_is_tty == 0)
#ifndef __CYGWIN__
    input_is_pipe = fd_ispipe (fd);
#else
    input_is_pipe = 1;
#endif

  /* If the -p, -e or -s flags were given, but input is not coming from the
     terminal, turn them off. */
  if ((prompt || edit || silent) && input_is_tty == 0)
    {
      prompt = (char *)NULL;
#if defined (READLINE)
      itext = (char *)NULL;
#endif
      edit = silent = 0;
    }

#if defined (READLINE)
  if (edit)
    add_unwind_protect (xfree, rlbuf);
#endif

  if (tmsec > 0 || tmusec > 0)
    {
      /* Turn off the timeout if stdin is a regular file (e.g. from
	 input redirection). */
      if ((fstat (fd, &tsb) < 0) || S_ISREG (tsb.st_mode))
	tmsec = tmusec = 0;
    }

  if (tmsec > 0 || tmusec > 0)
    {
      read_timeout = shtimer_alloc ();
      read_timeout->flags = SHTIMER_LONGJMP;

#if defined (HAVE_SELECT) || defined (HAVE_PSELECT)
      read_timeout->flags |= (edit || posixly_correct) ? SHTIMER_ALARM : SHTIMER_SELECT;
#else
      read_timeout->flags |= SHTIMER_ALARM;
#endif
      read_timeout->fd = fd;

      read_timeout->alrm_handler = sigalrm;
    }

  if (tmsec > 0 || tmusec > 0)
    {
      code = setjmp_nosigs (read_timeout->jmpenv);
      if (code)
	{
	  reset_timeout ();
#if defined (SIGCHLD)
	  sigprocmask (SIG_SETMASK, &prevset, (sigset_t *)0);
#endif

	  /* Tricky.  The top of the unwind-protect stack is the free of
	     input_string.  We want to run all the rest and use input_string,
	     so we have to save input_string temporarily, run the unwind-
	     protects, then restore input_string so we can use it later */
	  orig_input_string = 0;
	  input_string[i] = '\0';	/* make sure it's terminated */
	  if (i == 0)
	    {
	      t = (char *)xmalloc (1);
	      t[0] = 0;
	    }
	  else
	    t = savestring (input_string);

	  run_unwind_frame ("read_builtin");
	  input_string = t;
	  retval = 128+SIGALRM;
	  goto assign_vars;
	}
      if (interactive_shell == 0)
	initialize_terminating_signals ();
      add_unwind_protect (uw_reset_timeout, NULL);
#if defined (READLINE)
      if (edit)
	set_readline_timeout (read_timeout, tmsec, tmusec);
      else
#endif
      shtimer_set (read_timeout, tmsec, tmusec);
    }

  /* If we've been asked to read only NCHARS chars, or we're using some
     character other than newline to terminate the line, do the right
     thing to readline or the tty. */
  if (nchars > 0 || delim != '\n')
    {
#if defined (READLINE)
      if (edit)
	{
	  if (nchars > 0)
	    {
	      unwind_protect_int (rl_num_chars_to_read);
	      rl_num_chars_to_read = nchars;
	    }
	  if (delim != '\n')
	    {
	      set_eol_delim (delim);
	      add_unwind_protect (reset_eol_delim, NULL);
	    }
	}
      else
#endif
      if (input_is_tty)
	{
	  /* ttsave() */
	  termsave.fd = fd;
	  ttgetattr (fd, &ttattrs);
	  termsave.attrs = ttattrs;

	  ttset = ttattrs;	  
	  i = silent ? ttfd_cbreak (fd, &ttset) : ttfd_onechar (fd, &ttset);
	  if (i < 0)
	    sh_ttyerror (1);
	  tty_modified = 1;
	  add_unwind_protect (uw_ttyrestore, &termsave);
	  if (interactive_shell == 0)
	    initialize_terminating_signals ();
	}
    }
  else if (silent)	/* turn off echo but leave term in canonical mode */
    {
      /* ttsave (); */
      termsave.fd = fd;
      ttgetattr (fd, &ttattrs);
      termsave.attrs = ttattrs;

      ttset = ttattrs;
      i = ttfd_noecho (fd, &ttset);			/* ttnoecho (); */
      if (i < 0)
	sh_ttyerror (1);

      tty_modified = 1;
      add_unwind_protect (uw_ttyrestore, &termsave);
      if (interactive_shell == 0)
	initialize_terminating_signals ();
    }

#if defined (READLINE)
  save_instream = 0;
  if (edit && fd != 0)
    {
      int fd2;
      FILE *fp2;

      if ((fd2 = dup (fd)) < 0 || (fp2 = fdopen (fd2, "r")) == 0)
	{
	  builtin_error ("%d: %s", fd, strerror (errno));
	  if (fd2 >= 0)
	    close (fd2);
	  run_unwind_frame ("read_builtin");
	  if (free_ifs)
	    free (ifs_chars);
	  return (EXECUTION_FAILURE);
	}

      if (bash_readline_initialized == 0)
	initialize_readline ();

      save_instream = rl_instream;
      rl_instream = fp2;
      add_unwind_protect (uw_reset_rl_instream, save_instream);

      fd = fd2;
    }

  if (edit)
    {
      add_unwind_protect (uw_reset_attempted_completion_function, NULL);
      add_unwind_protect (uw_bashline_reset_event_hook, NULL);
    }
#endif

  /* This *must* be the top unwind-protect on the stack, so the manipulation
     of the unwind-protect stack after the realloc() works right. */
  add_unwind_protect (xfree, input_string);

  check_read_timeout ();
  /* These only matter if edit == 0 */
  if ((nchars > 0) && (input_is_tty == 0) && ignore_delim)	/* read -N */
    unbuffered_read = 2;
#if 0
  else if ((nchars > 0) || (delim != '\n') || input_is_pipe)
#else
  else if (((nchars > 0 || delim != '\n') && input_is_tty) || input_is_pipe)
    unbuffered_read = 1;
#endif
  if (prompt && edit == 0)
    {
      fprintf (stderr, "%s", prompt);
      fflush (stderr);
    }

  ps2 = 0;
  for (print_ps2 = eof = retval = 0;;)
    {
      check_read_timeout ();

#if defined (READLINE)
      if (edit)
	{
	  /* If we have a null delimiter, don't treat NULL as ending the line */
	  if (rlbuf && rlbuf[rlind] == '\0' && delim != '\0')
	    {
	      free (rlbuf);
	      rlbuf = (char *)0;
	    }
#if defined (SIGCHLD)
	  if (tmsec > 0 || tmusec > 0)
	    sigprocmask (SIG_SETMASK, &chldset, &prevset);
#endif
	  if (rlbuf == 0)
	    {
	      reading = 1;
	      rlbuf = edit_line (prompt ? prompt : "", itext, delim, use_bash_completion);
	      reading = 0;
	      rlind = 0;
	    }
#if defined (SIGCHLD)
	  if (tmsec > 0 || tmusec > 0)
	    sigprocmask (SIG_SETMASK, &prevset, (sigset_t *)0);
#endif
	  if (rlbuf == 0)
	    {
	      eof = 1;
	      break;
	    }
	  c = rlbuf[rlind++];
	}
      else
	{
#endif

      if (print_ps2)
	{
	  if (ps2 == 0)
	    ps2 = get_string_value ("PS2");
	  fprintf (stderr, "%s", ps2 ? ps2 : "");
	  fflush (stderr);
	  print_ps2 = 0;
	}

      reading = 1;
      check_read_timeout ();
      errno = 0;

#if defined (SIGCHLD)
      if (tmsec > 0 || tmusec > 0)
	sigprocmask (SIG_SETMASK, &chldset, &prevset);
#endif
      if (unbuffered_read == 2)
	retval = posixly_correct ? zreadintr (fd, &c, 1) : zreadn (fd, &c, nchars - nr);
      else if (unbuffered_read)
	retval = posixly_correct ? zreadintr (fd, &c, 1) : zread (fd, &c, 1);
      else
	retval = posixly_correct ? zreadcintr (fd, &c) : zreadc (fd, &c);
#if defined (SIGCHLD)
      if (tmsec > 0 || tmusec > 0)
	sigprocmask (SIG_SETMASK, &prevset, (sigset_t *)0);
#endif

      reading = 0;

      if (retval <= 0)
	{
	  int x;

	  x = errno;
	  if (retval < 0 && errno == EINTR)
	    {
	      ZRESET ();
	      check_signals ();		/* in case we didn't call zread via zreadc */
	      lastsig = LASTSIG();
	      if (lastsig == 0)
		lastsig = trapped_signal_received;
#if 0
	      run_pending_traps ();	/* because interrupt_immediately is not set */
#endif
	    }
	  else
	    lastsig = 0;
	  if (terminating_signal && tty_modified)
	    ttyrestore (&termsave);	/* fix terminal before exiting */
	  CHECK_TERMSIG;
	  eof = 1;
	  errno = x;	/* preserve it for the error message below */
	  break;
	}

      /* Even if read returns a partial buffer, if we got an interrupt we're
	 going to throw it away. */
      ZRESET();

      QUIT;		/* in case we didn't call check_signals() */
#if defined (READLINE)
	}
#endif

      if (retval <= 0)			/* XXX shouldn't happen */
	check_read_timeout ();

      /* XXX -- use i + mb_cur_max (at least 4) for multibyte/read_mbchar */
      if (i + (mb_cur_max > 4 ? mb_cur_max : 4) >= size)
	{
	  char *x;
	  x = (char *)xrealloc (input_string, size += 128);

	  /* Only need to change unwind-protect if input_string changes */
	  if (x != input_string)
	    {
	      input_string = x;
	      remove_unwind_protect ();
	      add_unwind_protect (xfree, input_string);
	    }
	}

      /* If the next character is to be accepted verbatim, a backslash
	 newline pair still disappears from the input. */
      if (pass_next)
	{
	  pass_next = 0;
	  if (c == '\n' || c == '\0')
	    {
	      if (skip_ctlesc == 0 && i > 0)
		{
		  i--;			/* back up over the CTLESC */
		  saw_escape--;		/* one fewer CTLESC in the input */
		}
	      if (interactive && input_is_tty && raw == 0 && c == '\n')
		print_ps2 = 1;
	    }
	  else
	    goto add_char;
	  continue;
	}

      /* This may cause problems if IFS contains CTLESC */
      if (c == '\\' && raw == 0)
	{
	  pass_next++;
	  if (skip_ctlesc == 0)
	    {
	      saw_escape++;
	      input_string[i++] = CTLESC;
	    }
	  continue;
	}

      if ((unsigned char)c == delim)
	break;

      if (c == '\0' && delim != '\0')
	continue;		/* skip NUL bytes in input */

      if ((skip_ctlesc == 0 && c == CTLESC) || (skip_ctlnul == 0 && c == CTLNUL))
	{
	  saw_escape++;
	  input_string[i++] = CTLESC;
	}

add_char:
      input_string[i++] = c;

#if defined (HANDLE_MULTIBYTE)
      /* XXX - what if C == 127? Can DEL introduce a multibyte sequence? */
      if (mb_cur_max > 1 && is_basic (c) == 0)
	{
	  input_string[i] = '\0';	/* for simplicity and debugging */
	  /* If we got input from readline, grab the next multibyte char from
	     rlbuf. */
#  if defined (READLINE)
	  if (edit)
	    {
	      size_t clen;
	      clen = mbrlen (rlbuf + rlind - 1, mb_cur_max, (mbstate_t *)NULL);
	      /* We only deal with valid multibyte sequences longer than one
		 byte. If we get anything else, we leave the one character
		 copied and move on to the next. */
	      if ((int)clen > 1)
		{
		  memcpy (input_string+i, rlbuf+rlind, clen-1);
		  i += clen - 1;
		  rlind += clen - 1;
		}
	    }
	  else
#  endif
	  if (locale_utf8locale == 0 || ((c & 0x80) != 0))
	    i += read_mbchar (fd, input_string, i, c, delim, unbuffered_read);
	}
#endif

      nr++;

      if (nchars > 0 && nr >= nchars)
	break;

      check_read_timeout ();
    }
  /* Back up over trailing CTLESC if the input ends with an unescaped
     backslash */
  if (pass_next && skip_ctlesc == 0)
    {
      i--;
      saw_escape--;		/* that CTLESC is no longer in the input */
    }
  /* I don't think this clause ever tests true. */
  if (skip_ctlnul && saw_escape && i == 1 && input_string[0] == CTLNUL)
    saw_escape = 0;		/* Avoid dequoting bare CTLNUL */

  input_string[i] = '\0';
  /* Don't check the timeout unless we didn't read anything and zread returned
     EOF or error. */
  if (i == 0 && retval <= 0)
    check_read_timeout ();

#if defined (READLINE)
  if (edit)
    free (rlbuf);
#endif

  if (retval < 0)
    {
      t_errno = errno;
      if (errno != EINTR)
	builtin_error ("%d: %s: %s", fd, _("read error"), strerror (errno));
      run_unwind_frame ("read_builtin");
      if (free_ifs)
	free (ifs_chars);
      return ((t_errno != EINTR) ? EXECUTION_FAILURE : 128+lastsig);
    }

  if (tmsec > 0 || tmusec > 0)
    reset_timeout ();

  if (nchars > 0 || delim != '\n')
    {
#if defined (READLINE)
      if (edit)
	{
	  if (nchars > 0)
	    rl_num_chars_to_read = 0;
	  if (delim != '\n')
	    reset_eol_delim (NULL);
	}
      else
#endif
      if (input_is_tty)
	ttyrestore (&termsave);
    }
  else if (silent)
    ttyrestore (&termsave);

  if (unbuffered_read == 0)
    zsyncfd (fd);

#if defined (READLINE)
  if (save_instream)
    reset_rl_instream (save_instream);
#endif

  discard_unwind_frame ("read_builtin");

  retval = eof ? EXECUTION_FAILURE : EXECUTION_SUCCESS;

assign_vars:

#if defined (ARRAY_VARS)
  /* If -a was given, take the string read, break it into a list of words,
     an assign them to `arrayname' in turn. */
  if (arrayname)
    {
      /* pass 1 for flags arg to clear the existing array + 2 to check for a
	 valid identifier. */
      var = builtin_find_indexed_array (arrayname, 3);
      if (var == 0)
	{
	  free (input_string);
	  if (free_ifs)
	    free (ifs_chars);
	  return EXECUTION_FAILURE;	/* readonly or noassign */
	}

      alist = list_string (input_string, ifs_chars, 0);
      if (alist)
	{
	  if (saw_escape)
	    dequote_list (alist);
	  else
	    word_list_remove_quoted_nulls (alist);
	  assign_array_var_from_word_list (var, alist, 0);
	  dispose_words (alist);
	}
      free (input_string);
      if (free_ifs)
	free (ifs_chars);
      return (retval);
    }
#endif /* ARRAY_VARS */ 

  /* If there are no variables, save the text of the line read to the
     variable $REPLY.  ksh93 strips leading and trailing IFS whitespace,
     so that `read x ; echo "$x"' and `read ; echo "$REPLY"' behave the
     same way, but I believe that the difference in behaviors is useful
     enough to not do it.  Without the bash behavior, there is no way
     to read a line completely without interpretation or modification
     unless you mess with $IFS (e.g., setting it to the empty string).
     If you disagree, change the occurrences of `#if 0' to `#if 1' below. */
  if (list == 0)
    {
#if 0
      orig_input_string = input_string;
      for (t = input_string; ifs_chars && *ifs_chars && spctabnl(*t) && isifs(*t); t++)
	;
      input_string = t;
      input_string = strip_trailing_ifs_whitespace (input_string, ifs_chars, saw_escape);
#endif

      if (saw_escape)
	{
	  t = dequote_string (input_string);
	  var = bind_variable ("REPLY", t, 0);
	  free (t);
	}
      else
	var = bind_variable ("REPLY", input_string, 0);
      if (var == 0 || ASSIGN_DISALLOWED (var, 0))
	retval = EX_MISCERROR;
      else
	VUNSETATTR (var, att_invisible);

      free (input_string);
      if (free_ifs)
	free (ifs_chars);
      return (retval);
    }

  /* This code implements the Posix.2 spec for splitting the words
     read and assigning them to variables. */
  orig_input_string = input_string;

  /* Remove IFS white space at the beginning of the input string.  If
     $IFS is null, no field splitting is performed. */
  for (t = input_string; ifs_chars && *ifs_chars && spctabnl(*t) && isifs(*t); t++)
    ;
  input_string = t;
  for (; list->next; list = list->next)
    {
      varname = list->word->word;
#if defined (ARRAY_VARS)
      SET_VFLAGS (list->word->flags, vflags, bindflags);
      if (valid_identifier (varname) == 0 && valid_array_reference (varname, vflags) == 0)
#else
      if (valid_identifier (varname) == 0)
#endif
	{
	  sh_invalidid (varname);
	  free (orig_input_string);
	  if (free_ifs)
	    free (ifs_chars);
	  return (EXECUTION_FAILURE);
	}

      /* If there are more variables than words read from the input,
	 the remaining variables are set to the empty string. */
      if (*input_string)
	{
	  /* This call updates INPUT_STRING. */
	  t = get_word_from_string (&input_string, ifs_chars, &e);
	  if (t)
	    *e = '\0';
	  /* Don't bother to remove the CTLESC unless we added one
	     somewhere while reading the string. */
	  if (t && saw_escape)
	    {
	      t1 = dequote_string (t);
	      var = bind_read_variable (varname, t1, bindflags);
	      free (t1);
	    }
	  else
	    var = bind_read_variable (varname, t ? t : "", bindflags);
	}
      else
	{
	  t = (char *)0;
	  var = bind_read_variable (varname, "", bindflags);
	}

      FREE (t);
      if (var == 0)
	{
	  free (orig_input_string);
	  if (free_ifs)
	    free (ifs_chars);
	  return (EX_MISCERROR);
	}

      stupidly_hack_special_variables (varname);
      VUNSETATTR (var, att_invisible);
    }

  /* Now assign the rest of the line to the last variable argument. */
#if defined (ARRAY_VARS)
  SET_VFLAGS (list->word->flags, vflags, bindflags);
  if (valid_identifier (list->word->word) == 0 && valid_array_reference (list->word->word, vflags) == 0)
#else
  if (valid_identifier (list->word->word) == 0)
#endif
    {
      sh_invalidid (list->word->word);
      free (orig_input_string);
      if (free_ifs)
	free (ifs_chars);
      return (EXECUTION_FAILURE);
    }

#if 0
  /* This has to be done this way rather than using string_list
     and list_string because Posix.2 says that the last variable gets the
     remaining words and their intervening separators. */
  input_string = strip_trailing_ifs_whitespace (input_string, ifs_chars, saw_escape);
#else
  /* Check whether or not the number of fields is exactly the same as the
     number of variables. */
  tofree = NULL;
  if (*input_string)
    {
      t1 = input_string;
      t = get_word_from_string (&input_string, ifs_chars, &e);
      if (*input_string == 0)
	tofree = input_string = t;
      else
	{
	  input_string = strip_trailing_ifs_whitespace (t1, ifs_chars, saw_escape);
	  tofree = t;
	}
    }
#endif

  if (saw_escape && input_string && *input_string)
    {
      t = dequote_string (input_string);
      var = bind_read_variable (list->word->word, t, bindflags);
      free (t);
    }
  else
    var = bind_read_variable (list->word->word, input_string ? input_string : "", bindflags);

  if (var)
    {
      stupidly_hack_special_variables (list->word->word);
      VUNSETATTR (var, att_invisible);
    }
  else
    retval = EXECUTION_FAILURE;

  if (free_ifs)
    free (ifs_chars);
  FREE (tofree);
  free (orig_input_string);

  return (retval);
}

static SHELL_VAR *
bind_read_variable (char *name, char *value, int flags)
{
  SHELL_VAR *v;

  v = builtin_bind_variable (name, value, flags);
  return ((v == 0 || ASSIGN_DISALLOWED (v, 0)) ? (SHELL_VAR *)NULL : v);
}

#if defined (HANDLE_MULTIBYTE)
static int
read_mbchar (int fd, char *string, int ind, int ch, int delim, int unbuffered)
{
  char mbchar[MB_LEN_MAX + 1];
  int i, n, r, delim_ind;
  char c;
  size_t ret;
  mbstate_t ps, ps_back;
  wchar_t wc;

  memset (&ps, '\0', sizeof (mbstate_t));
  memset (&ps_back, '\0', sizeof (mbstate_t));

  delim_ind = 0;
  mbchar[0] = ch;
  i = 1;
  for (n = 0; n <= MB_LEN_MAX; n++)
    {
      ps_back = ps;
      ret = mbrtowc (&wc, mbchar, i, &ps);
      if (ret == (size_t)-2)
	{
	  ps = ps_back;

	  /* We don't want to be interrupted during a multibyte char read */
	  if (unbuffered == 2)
	    r = zreadn (fd, &c, 1);
	  else if (unbuffered)
	    r = zread (fd, &c, 1);
	  else
	    r = zreadc (fd, &c);
	  if (r <= 0)
	    goto mbchar_return;
	  if ((unsigned char)c == delim)
	    delim_ind = i;
	  mbchar[i++] = c;	
	  continue;
	}
      else if (ret == (size_t)-1)
	{
	  /* If we read (i > 1) a delimiter character (delim_ind >= 1)
	     that is a part of this invalid multibyte character, we can't
	     just add it to the input string and treat it as a byte.
	     We need to push it and everything we read after it back so a
	     subsequent zread will pick it up. */
	  if (i > 1 && delim_ind >= 1)
	    {
	      size_t j;
	      for (j = delim_ind; j < i; j++)
		zungetc ((unsigned char)mbchar[j]);
	      i = delim_ind;
	    }
	  break;		/* invalid multibyte character */
	}
      else if (ret == (size_t)0 || ret > (size_t)0)
	break;		/* valid multibyte character */
    }

mbchar_return:
  if (i > 1)	/* read a multibyte char */
    /* mbchar[0] is already string[ind-1] */
    for (r = 1; r < i; r++)
      string[ind+r-1] = mbchar[r];
  return i - 1;
}
#endif


static void
ttyrestore (struct ttsave *ttp)
{
  ttsetattr (ttp->fd, &(ttp->attrs));
  tty_modified = 0;
}

static void
uw_ttyrestore (void *ttp)
{
  ttyrestore (ttp);
}

void
read_tty_cleanup (void)
{
  if (tty_modified)
    ttyrestore (&termsave);
}

int
read_tty_modified (void)
{
  return (tty_modified);
}

#if defined (READLINE)
static rl_completion_func_t *old_attempted_completion_function = 0;
static rl_hook_func_t *old_startup_hook;
static char *deftext;

static void
uw_reset_attempted_completion_function (void *cp)
{
  if (rl_attempted_completion_function == 0 && old_attempted_completion_function)
    rl_attempted_completion_function = old_attempted_completion_function;
}

static void
uw_bashline_reset_event_hook (void *ignore)
{
  bashline_reset_event_hook ();
}

static int
set_itext (void)
{
  int r1, r2;

  r1 = r2 = 0;
  if (old_startup_hook)
    r1 = (*old_startup_hook) ();
  if (deftext)
    {
      r2 = rl_insert_text (deftext);
      deftext = (char *)NULL;
      rl_startup_hook = old_startup_hook;
      old_startup_hook = (rl_hook_func_t *)NULL;
    }
  return (r1 || r2);
}

static char *
edit_line (char *p, char *itext, int delim, int keep_completion_func)
{
  char *ret;
  size_t len;

  if (bash_readline_initialized == 0)
    initialize_readline ();

  old_attempted_completion_function = rl_attempted_completion_function;
  /* If we don't indicate that we want to keep the attempted completion
     function, reset it so we use the default readline word completion. */
  if (keep_completion_func == 0)
    rl_attempted_completion_function = (rl_completion_func_t *)NULL;
  bashline_set_event_hook ();
  if (itext)
    {
      old_startup_hook = rl_startup_hook;
      rl_startup_hook = set_itext;
      deftext = itext;
    }

  ret = readline (p);

  if (keep_completion_func == 0)
    rl_attempted_completion_function = old_attempted_completion_function;
  old_attempted_completion_function = (rl_completion_func_t *)NULL;
  bashline_reset_event_hook ();

  if (ret == 0)
    {
      if (RL_ISSTATE (RL_STATE_TIMEOUT))
	{
	  sigalrm (SIGALRM);		/* simulate receiving SIGALRM */
	  check_read_timeout ();
	}
      return ret;
    }

  len = strlen (ret);
  ret = (char *)xrealloc (ret, len + 2);
  if (delim > 0)
    ret[len++] = delim;
  ret[len] = '\0';
  return ret;
}

static void
set_readline_timeout (sh_timer *t, time_t sec, long usec)
{
  t->tmout.tv_sec = sec;
  t->tmout.tv_usec = usec;
  rl_set_timeout (sec, usec);
}

static int old_delim_ctype;
static rl_command_func_t *old_delim_func;
static int old_newline_ctype;
static rl_command_func_t *old_newline_func;

static int delim_char;

static void
set_eol_delim (int c)
{
  Keymap cmap;

  if (bash_readline_initialized == 0)
    initialize_readline ();
  cmap = rl_get_keymap ();

  /* Save the old newline binding and change it to self-insert */
  old_newline_ctype = cmap[RETURN].type;
  old_newline_func =  cmap[RETURN].function;
  cmap[RETURN].type = ISFUNC;
  cmap[RETURN].function = rl_insert;

  /* Save any binding to the delimiter and bind the delimiter to accept-line */
  if (c >= 0)
    {
      old_delim_ctype = cmap[c].type;
      old_delim_func = cmap[c].function;

      cmap[c].type = ISFUNC;
      cmap[c].function = rl_newline;
    }

  delim_char = c;
}

static void
reset_eol_delim (void *ignore)
{
  Keymap cmap;

  cmap = rl_get_keymap ();

  cmap[RETURN].type = old_newline_ctype;
  cmap[RETURN].function = old_newline_func;

  if (delim_char >= 0)
    {
      cmap[delim_char].type = old_delim_ctype;
      cmap[delim_char].function = old_delim_func;
    }
}
#endif