wordsplit/wordsplit.c

/* wordsplit - a word splitter
   Copyright (C) 2009-2025 Sergey Poznyakoff

   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/>. */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <errno.h>
#include <ctype.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <pwd.h>
#include <glob.h>
#include <limits.h>

#if ENABLE_NLS
# include <gettext.h>
#else
# define gettext(msgid) msgid
#endif
#define _(msgid) gettext (msgid)
#define N_(msgid) msgid

#include <wordsplit.h>

#define ISWS(c) ((c)==' '||(c)=='\t'||(c)=='\n')
#define ISDELIM(ws,c) \
  (strchr ((ws)->ws_delim, (c)) != NULL)
#define ISPUNCT(c) (strchr("!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~",(c))!=NULL)
#define ISUPPER(c) ('A' <= ((unsigned) (c)) && ((unsigned) (c)) <= 'Z')
#define ISLOWER(c) ('a' <= ((unsigned) (c)) && ((unsigned) (c)) <= 'z')
#define ISALPHA(c) (ISUPPER(c) || ISLOWER(c))
#define ISDIGIT(c) ('0' <= ((unsigned) (c)) && ((unsigned) (c)) <= '9')
#define ISXDIGIT(c) (strchr("abcdefABCDEF", c)!=NULL)
#define ISALNUM(c) (ISALPHA(c) || ISDIGIT(c))
#define ISPRINT(c) (' ' <= ((unsigned) (c)) && ((unsigned) (c)) <= 127)

#define ISVARBEG(c) (ISALPHA(c) || c == '_')
static inline int
is_name_char (struct wordsplit *wsp, int c)
{
	return ISALNUM (c)
		|| c == '_'
		|| ((wsp->ws_options & WRDSO_NAMECHAR)
		    && strchr (wsp->ws_namechar, c));
}

#define WSP_RETURN_DELIMS(wsp) \
 ((wsp)->ws_flags & WRDSF_RETURN_DELIMS || ((wsp)->ws_options & WRDSO_MAXWORDS))

#define to_num(c) \
  (ISDIGIT(c) ? c - '0' : (ISXDIGIT(c) ? toupper(c) - 'A' + 10 : 255 ))

static int wsplt_unquote_char (const char *transtab, int c);

#define ALLOC_INIT 128
#define ALLOC_INCR 128

static void
_wsplt_alloc_die (struct wordsplit *wsp)
{
  wsp->ws_error ("%s", _("memory exhausted"));
  abort ();
}

static void _wsplt_error (const char *fmt, ...)
   __attribute__ ((format (printf, 1, 2)));

static void
_wsplt_error (const char *fmt, ...)
{
  va_list ap;

  va_start (ap, fmt);
  vfprintf (stderr, fmt, ap);
  va_end (ap);
  fputc ('\n', stderr);
}

static void wordsplit_free_nodes (struct wordsplit *);

static int
_wsplt_seterr (struct wordsplit *wsp, int ec)
{
  wsp->ws_errno = ec;
  if (wsp->ws_flags & WRDSF_SHOWERR)
    wordsplit_perror (wsp);
  if (ec == WRDSE_USAGE)
    errno = EINVAL;
  return ec;
}

static int
_wsplt_nomem (struct wordsplit *wsp)
{
  errno = ENOMEM;
  wsp->ws_errno = WRDSE_NOSPACE;
  if (wsp->ws_flags & WRDSF_ENOMEMABRT)
    wsp->ws_alloc_die (wsp);
  if (wsp->ws_flags & WRDSF_SHOWERR)
    wordsplit_perror (wsp);
  if (!(wsp->ws_flags & WRDSF_REUSE))
    wordsplit_free (wsp);
  wordsplit_free_nodes (wsp);
  return wsp->ws_errno;
}

static void
_wsplt_store_errctx (struct wordsplit *wsp, char const *str, size_t len)
{
  free (wsp->ws_errctx);
  wsp->ws_errctx = malloc (len + 1);
  if (!wsp->ws_errctx)
    {
      wsp->ws_error ("%s",
		     _("memory exhausted while trying to store error context"));
    }
  else
    {
      memcpy (wsp->ws_errctx, str, len);
      wsp->ws_errctx[len] = 0;
    }
}

static inline int
_wsplt_setctxerr (struct wordsplit *wsp, int ec, char const *str, size_t len)
{
  _wsplt_store_errctx (wsp, str, len);
  return _wsplt_seterr (wsp, ec);
}

static int wordsplit_run (const char *command, size_t length,
			  struct wordsplit *wsp,
			  int flags, int lvl);

static int wordsplit_init (struct wordsplit *wsp, const char *input, size_t len,
			   int flags);
static int wordsplit_process_list (struct wordsplit *wsp, size_t start);
static int wordsplit_finish (struct wordsplit *wsp);

static int
_wsplt_subsplit (struct wordsplit *wsp, struct wordsplit *wss,
		 char const *str, int len,
		 int flags, int finalize)
{
  int rc;

  wss->ws_delim = wsp->ws_delim;
  wss->ws_debug = wsp->ws_debug;
  wss->ws_error = wsp->ws_error;
  wss->ws_alloc_die = wsp->ws_alloc_die;

  if (!(flags & WRDSF_NOVAR))
    {
      wss->ws_env = wsp->ws_env;
      wss->ws_getvar = wsp->ws_getvar;
      flags |= wsp->ws_flags & (WRDSF_ENV | WRDSF_ENV_KV | WRDSF_GETVAR);
    }
  if (!(flags & WRDSF_NOCMD))
    {
      wss->ws_command = wsp->ws_command;
    }

  if ((flags & (WRDSF_NOVAR|WRDSF_NOCMD)) != (WRDSF_NOVAR|WRDSF_NOCMD))
    {
      wss->ws_closure = wsp->ws_closure;
      flags |= wsp->ws_flags & WRDSF_CLOSURE;
    }

  wss->ws_options = wsp->ws_options & ~WRDSO_MAXWORDS;
  wss->ws_namechar = wsp->ws_namechar;

  flags |= WRDSF_DELIM
	 | WRDSF_ALLOC_DIE
	 | WRDSF_ERROR
	 | WRDSF_DEBUG
	 | (wsp->ws_flags & (WRDSF_SHOWDBG | WRDSF_SHOWERR | WRDSF_OPTIONS));

  rc = wordsplit_init (wss, str, len, flags);
  if (rc)
    return rc;
  wss->ws_lvl = wsp->ws_lvl + 1;
  rc = wordsplit_process_list (wss, 0);
  if (rc)
    {
      wordsplit_free_nodes (wss);
      return rc;
    }
  if (finalize)
    {
      rc = wordsplit_finish (wss);
      wordsplit_free_nodes (wss);
    }
  return rc;
}

static void
_wsplt_seterr_sub (struct wordsplit *wsp, struct wordsplit *wss)
{
  /* Clear user-defined error */
  if (wsp->ws_errno == WRDSE_USERERR)
    free (wsp->ws_usererr);
  /* Copy error state */
  wsp->ws_errno = wss->ws_errno;
  if (wss->ws_errno == WRDSE_USERERR)
    {
      wsp->ws_usererr = wss->ws_usererr;
      wss->ws_errno = WRDSE_EOF;
      wss->ws_usererr = NULL;
    }
  /* Copy error context */
  free (wsp->ws_errctx);
  wsp->ws_errctx = wss->ws_errctx;
  wss->ws_errctx = NULL;
}

static void
wordsplit_init0 (struct wordsplit *wsp)
{
  if (wsp->ws_flags & WRDSF_REUSE)
    {
      if (!(wsp->ws_flags & WRDSF_APPEND))
	wordsplit_free_words (wsp);
      wordsplit_clearerr (wsp);
    }
  else
    {
      wsp->ws_wordv = NULL;
      wsp->ws_wordc = 0;
      wsp->ws_wordn = 0;
    }

  wsp->ws_errno = 0;
}

char const *wordsplit_escape[] = {
	/* C-style escapes, for quoted strings */
	[WS_ESC_C]     = "\\\\\"\"a\ab\bf\fn\nr\rt\tv\v",
	/* C-style escapes, outsize of quoted strings */
	[WS_ESC_C_WS]  = "\\\\\"\"a\ab\bf\fn\nr\rt\tv\v  \t\t",
	/* Escape double-quote and backslash. */
	[WS_ESC_DQ]    = "\\\\\"\"",
	/* Escape double-quote, backslash, and whitespace. */
	[WS_ESC_DQ_WS] = "\\\\\"\"  \t\t"
};

static int
wordsplit_init (struct wordsplit *wsp, const char *input, size_t len,
		int flags)
{
  wsp->ws_flags = flags;

  if (!(wsp->ws_flags & WRDSF_ALLOC_DIE))
    wsp->ws_alloc_die = _wsplt_alloc_die;
  if (!(wsp->ws_flags & WRDSF_ERROR))
    wsp->ws_error = _wsplt_error;

  if (!(wsp->ws_flags & WRDSF_NOVAR))
    {
      /* These will be initialized on first variable assignment */
      wsp->ws_envidx = wsp->ws_envsiz = 0;
      wsp->ws_envbuf = NULL;
    }

  if (!(wsp->ws_flags & WRDSF_NOCMD))
    {
      if (!wsp->ws_command)
	return _wsplt_seterr (wsp, WRDSE_USAGE);
    }

  if (wsp->ws_flags & WRDSF_SHOWDBG)
    {
      if (!(wsp->ws_flags & WRDSF_DEBUG))
	{
	  if (wsp->ws_flags & WRDSF_ERROR)
	    wsp->ws_debug = wsp->ws_error;
	  else if (wsp->ws_flags & WRDSF_SHOWERR)
	    wsp->ws_debug = _wsplt_error;
	  else
	    wsp->ws_flags &= ~WRDSF_SHOWDBG;
	}
    }

  wsp->ws_input = input;
  wsp->ws_len = len;

  if (!(wsp->ws_flags & WRDSF_DOOFFS))
    wsp->ws_offs = 0;

  if (!(wsp->ws_flags & WRDSF_DELIM))
    wsp->ws_delim = " \t\n";

  wsp->ws_sep[0] = wsp->ws_delim[0];
  wsp->ws_sep[1] = 0;

  if (!(wsp->ws_flags & WRDSF_COMMENT))
    wsp->ws_comment = NULL;

  if (!(wsp->ws_flags & WRDSF_CLOSURE))
    wsp->ws_closure = NULL;

  if (!(wsp->ws_flags & WRDSF_OPTIONS))
    wsp->ws_options = 0;

  if (wsp->ws_flags & WRDSF_ESCAPE)
    {
      if (!wsp->ws_escape[WRDSX_WORD])
	wsp->ws_escape[WRDSX_WORD] = "";
      if (!wsp->ws_escape[WRDSX_QUOTE])
	wsp->ws_escape[WRDSX_QUOTE] = "";
    }
  else if (wsp->ws_flags & WRDSF_CESCAPES)
    {
      wsp->ws_escape[WRDSX_WORD] = wordsplit_escape[WS_ESC_C_WS];
      wsp->ws_escape[WRDSX_QUOTE] = wordsplit_escape[WS_ESC_C];
      wsp->ws_options |= WRDSO_OESC_QUOTE | WRDSO_OESC_WORD
		      | WRDSO_XESC_QUOTE | WRDSO_XESC_WORD;
    }
  else
    {
      wsp->ws_escape[WRDSX_WORD] = "";
      wsp->ws_escape[WRDSX_QUOTE] = "";
    }

  if (!(wsp->ws_options & WRDSO_PARAMV))
    {
      wsp->ws_paramv = NULL;
      wsp->ws_paramc = 0;
    }
  wsp->ws_paramidx = wsp->ws_paramsiz = 0;
  wsp->ws_parambuf = NULL;

  if (wsp->ws_options & WRDSO_NAMECHAR)
    {
      if (wsp->ws_namechar[strcspn(wsp->ws_namechar, "${}*@-+?=")])
	return _wsplt_seterr (wsp, WRDSE_USAGE);
    }
  else
    wsp->ws_namechar = NULL;

  wsp->ws_endp = 0;
  wsp->ws_wordi = 0;

  if (wsp->ws_flags & WRDSF_REUSE)
    wordsplit_free_nodes (wsp);
  wsp->ws_head = wsp->ws_tail = NULL;

  wsp->ws_errctx = NULL;

  wordsplit_init0 (wsp);

  return 0;
}

static int
alloc_space (struct wordsplit *wsp, size_t count)
{
  size_t offs = (wsp->ws_flags & WRDSF_DOOFFS) ? wsp->ws_offs : 0;
  char **ptr;
  size_t newalloc;

  if (wsp->ws_wordv == NULL)
    {
      newalloc = offs + count > ALLOC_INIT ? count : ALLOC_INIT;
      ptr = calloc (newalloc, sizeof (ptr[0]));
    }
  else if (wsp->ws_wordn < offs + wsp->ws_wordc + count)
    {
      newalloc = offs + wsp->ws_wordc +
	(count > ALLOC_INCR ? count : ALLOC_INCR);
      ptr = realloc (wsp->ws_wordv, newalloc * sizeof (ptr[0]));
    }
  else
    return 0;

  if (ptr)
    {
      wsp->ws_wordn = newalloc;
      wsp->ws_wordv = ptr;
    }
  else
    return _wsplt_nomem (wsp);
  return 0;
}


/* Node state flags */
#define _WSNF_NULL     0x01	/* null node (a noop) */
#define _WSNF_WORD     0x02	/* node contains word in v.word */
#define _WSNF_QUOTE    0x04	/* text is quoted */
#define _WSNF_NOEXPAND 0x08	/* text is not subject to expansion */
#define _WSNF_JOIN     0x10	/* node must be joined with the next node */
#define _WSNF_SEXP     0x20	/* is a sed expression */
#define _WSNF_DELIM    0x40     /* node is a delimiter */
#define _WSNF_CONST    0x80     /* with _WSNF_WORD: v.word is constant */
#define _WSNF_EMPTYOK  0x0100	/* special flag indicating that
				   wordsplit_add_segm must add the
				   segment even if it is empty */

struct wordsplit_node
{
  struct wordsplit_node *prev;	/* Previous element */
  struct wordsplit_node *next;	/* Next element */
  int flags;			/* Node flags */
  union
  {
    struct
    {
      size_t beg;		/* Start of word in ws_input */
      size_t end;		/* End of word in ws_input */
    } segm;
    char *word;
  } v;
};

static const char *
wsnode_flagstr (int flags)
{
  static char retbuf[7];
  char *p = retbuf;

  if (flags & _WSNF_WORD)
    *p++ = 'w';
  else if (flags & _WSNF_NULL)
    *p++ = 'n';
  else
    *p++ = '-';
  if (flags & _WSNF_QUOTE)
    *p++ = 'q';
  else
    *p++ = '-';
  if (flags & _WSNF_NOEXPAND)
    *p++ = 'E';
  else
    *p++ = '-';
  if (flags & _WSNF_JOIN)
    *p++ = 'j';
  else
    *p++ = '-';
  if (flags & _WSNF_SEXP)
    *p++ = 's';
  else
    *p++ = '-';
  if (flags & _WSNF_DELIM)
    *p++ = 'd';
  else
    *p++ = '-';
  *p = 0;
  return retbuf;
}

static const char *
wsnode_ptr (struct wordsplit *wsp, struct wordsplit_node *p)
{
  if (p->flags & _WSNF_NULL)
    return "";
  else if (p->flags & _WSNF_WORD)
    return p->v.word;
  else
    return wsp->ws_input + p->v.segm.beg;
}

static size_t
wsnode_len (struct wordsplit_node *p)
{
  if (p->flags & _WSNF_NULL)
    return 0;
  else if (p->flags & _WSNF_WORD)
    return strlen (p->v.word);
  else
    return p->v.segm.end - p->v.segm.beg;
}

static int
wsnode_new (struct wordsplit *wsp, struct wordsplit_node **pnode)
{
  struct wordsplit_node *node = calloc (1, sizeof (*node));
  if (!node)
    return _wsplt_nomem (wsp);
  *pnode = node;
  return 0;
}

static void
wsnode_free (struct wordsplit_node *p)
{
  if ((p->flags & (_WSNF_WORD|_WSNF_CONST)) == _WSNF_WORD)
    free (p->v.word);
  free (p);
}

static void
wsnode_append (struct wordsplit *wsp, struct wordsplit_node *node)
{
  node->next = NULL;
  node->prev = wsp->ws_tail;
  if (wsp->ws_tail)
    wsp->ws_tail->next = node;
  else
    wsp->ws_head = node;
  wsp->ws_tail = node;
}

static void
wsnode_remove (struct wordsplit *wsp, struct wordsplit_node *node)
{
  struct wordsplit_node *p;

  p = node->prev;
  if (p)
    {
      p->next = node->next;
      if (!node->next)
	p->flags &= ~_WSNF_JOIN;
    }
  else
    wsp->ws_head = node->next;

  p = node->next;
  if (p)
    p->prev = node->prev;
  else
    wsp->ws_tail = node->prev;

  wsnode_free (node);
}

static struct wordsplit_node *
wsnode_tail (struct wordsplit_node *p)
{
  while (p && p->next)
    p = p->next;
  return p;
}

static void
wsnode_insert (struct wordsplit *wsp, struct wordsplit_node *node,
	       struct wordsplit_node *anchor, int before)
{
  if (!wsp->ws_head)
    {
      node->next = node->prev = NULL;
      wsp->ws_head = wsp->ws_tail = node;
    }
  else if (before)
    {
      if (anchor->prev)
	wsnode_insert (wsp, node, anchor->prev, 0);
      else
	{
	  struct wordsplit_node *tail = wsnode_tail (node);
	  node->prev = NULL;
	  tail->next = anchor;
	  anchor->prev = tail;
	  wsp->ws_head = node;
	}
    }
  else
    {
      struct wordsplit_node *p;
      struct wordsplit_node *tail = wsnode_tail (node);

      p = anchor->next;
      if (p)
	p->prev = tail;
      else
	wsp->ws_tail = tail;
      tail->next = p;
      node->prev = anchor;
      anchor->next = node;
    }
}

static int
wordsplit_add_segm (struct wordsplit *wsp, size_t beg, size_t end, int flg)
{
  struct wordsplit_node *node;
  int rc;

  if (end == beg && !(flg & _WSNF_EMPTYOK))
    return 0;
  rc = wsnode_new (wsp, &node);
  if (rc)
    return rc;
  node->flags = flg & ~(_WSNF_WORD | _WSNF_EMPTYOK);
  node->v.segm.beg = beg;
  node->v.segm.end = end;
  wsnode_append (wsp, node);
  return 0;
}

static void
wordsplit_free_nodes (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p;)
    {
      struct wordsplit_node *next = p->next;
      wsnode_free (p);
      p = next;
    }
  wsp->ws_head = wsp->ws_tail = NULL;
}

static void
wordsplit_dump_nodes (struct wordsplit *wsp)
{
  struct wordsplit_node *p;
  int n = 0;

  for (p = wsp->ws_head, n = 0; p; p = p->next, n++)
    {
      if (p->flags & _WSNF_WORD)
	wsp->ws_debug ("(%02d) %4d: %p: %#04x (%s):%s;",
		       wsp->ws_lvl,
		       n, p, p->flags, wsnode_flagstr (p->flags), p->v.word);
      else
	wsp->ws_debug ("(%02d) %4d: %p: %#04x (%s):%.*s;",
		       wsp->ws_lvl,
		       n, p, p->flags, wsnode_flagstr (p->flags),
		       (int) (p->v.segm.end - p->v.segm.beg),
		       wsp->ws_input + p->v.segm.beg);
    }
}

static int
coalesce_segment (struct wordsplit *wsp, struct wordsplit_node *node)
{
  struct wordsplit_node *p, *end;
  size_t len = 0;
  char *buf, *cur;
  int stop;

  if (!(node->flags & _WSNF_JOIN))
    return 0;

  for (p = node; p && (p->flags & _WSNF_JOIN); p = p->next)
    {
      len += wsnode_len (p);
    }
  if (p)
    len += wsnode_len (p);
  end = p;

  buf = malloc (len + 1);
  if (!buf)
    return _wsplt_nomem (wsp);
  cur = buf;

  p = node;
  for (stop = 0; !stop;)
    {
      struct wordsplit_node *next = p->next;
      const char *str = wsnode_ptr (wsp, p);
      size_t slen = wsnode_len (p);

      memcpy (cur, str, slen);
      cur += slen;
      if (p != node)
	{
	  node->flags |= p->flags & _WSNF_QUOTE;
	  stop = p == end;
	  wsnode_remove (wsp, p);
	}
      p = next;
    }

  *cur = 0;

  node->flags &= ~_WSNF_JOIN;

  if (node->flags & _WSNF_WORD)
    free (node->v.word);
  else
    node->flags |= _WSNF_WORD;
  node->v.word = buf;
  return 0;
}

static void wordsplit_string_unquote_copy (struct wordsplit *ws, int inquote,
					   char *dst, const char *src,
					   size_t n);

static int
wsnode_quoteremoval (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p; p = p->next)
    {
      const char *str = wsnode_ptr (wsp, p);
      size_t slen = wsnode_len (p);

      if (!(p->flags & _WSNF_NOEXPAND))
	{
	  if (!(p->flags & _WSNF_WORD))
	    {
	      char *newstr = malloc (slen + 1);
	      if (!newstr)
		return _wsplt_nomem (wsp);
	      memcpy (newstr, str, slen);
	      newstr[slen] = 0;
	      p->v.word = newstr;
	      p->flags |= _WSNF_WORD;
	    }

	  wordsplit_string_unquote_copy (wsp, p->flags & _WSNF_QUOTE,
					 p->v.word, str, slen);
	}
    }
  return 0;
}

static int
wsnode_coalesce (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p; p = p->next)
    {
      if (p->flags & _WSNF_JOIN)
	if (coalesce_segment (wsp, p))
	  return 1;
    }
  return 0;
}

static int
wsnode_tail_coalesce (struct wordsplit *wsp, struct wordsplit_node *p)
{
  if (p->next)
    {
      struct wordsplit_node *np = p;
      while (np && np->next)
	{
	  np->flags |= _WSNF_JOIN;
	  np = np->next;
	}
      if (coalesce_segment (wsp, p))
	return 1;
    }
  return 0;
}

static size_t skip_delim (struct wordsplit *wsp);

static int
wordsplit_finish (struct wordsplit *wsp)
{
  struct wordsplit_node *p;
  size_t n;

  /* Postprocess delimiters. It would be rather simple, if it weren't for
     the incremental operation.

     Nodes of type _WSNF_DELIM get inserted to the node list if either
     WRDSF_RETURN_DELIMS flag or WRDSO_MAXWORDS option is set.

     The following cases should be distinguished:

     1. If both WRDSF_SQUEEZE_DELIMS and WRDSF_RETURN_DELIMS are set, compress
	any runs of similar delimiter nodes to a single node. The nodes are
	'similar' if they point to the same delimiter character.

	If WRDSO_MAXWORDS option is set, stop compressing when
	ws_wordi + 1 == ws_maxwords, and coalesce the rest of nodes into
	a single last node.

     2. If WRDSO_MAXWORDS option is set, but WRDSF_RETURN_DELIMS is not,
	remove any delimiter nodes. Stop operation when
	ws_wordi + 1 == ws_maxwords, and coalesce the rest of nodes into
	a single last node.

     3. If incremental operation is in progress, restart the loop any time
	a delimiter node is about to be returned, unless WRDSF_RETURN_DELIMS
	is set.
  */
 again:
  n = 0;             /* Number of words processed so far */
  p = wsp->ws_head;  /* Current node */

  while (p)
    {
      struct wordsplit_node *next = p->next;
      if (p->flags & _WSNF_DELIM)
	{
	  if (wsp->ws_flags & WRDSF_SQUEEZE_DELIMS)
	    {
	      if (next)
		{
		  if ((next->flags & _WSNF_DELIM) &&
		      (wsnode_ptr (wsp, p))[0] == (wsnode_ptr (wsp, next))[0])
		    {
		      wsnode_remove (wsp, p);
		      p = next;
		      continue;
		    }
		}
	      else if (wsp->ws_flags & WRDSF_INCREMENTAL)
		goto restart;
	    }
	  else if ((next && (next->flags & _WSNF_DELIM)) &&
		   (!(wsp->ws_options & WRDSO_RETDELNOTEMPTY)))
	    {
	      int rc;
	      struct wordsplit_node *nulnode;
	      if ((rc = wsnode_new (wsp, &nulnode)) != 0)
		return rc;
	      nulnode->flags = _WSNF_NULL | _WSNF_NOEXPAND;
	      wsnode_insert (wsp, nulnode, p, 0);
	      next = nulnode;
	    }

	  if ((wsp->ws_options & WRDSO_MAXWORDS) &&
	      !(wsp->ws_flags & WRDSF_RETURN_DELIMS))
	    {
	      wsnode_remove (wsp, p);
	      p = next;
	      continue;
	    }
	}

      n++;

      if ((wsp->ws_options & WRDSO_MAXWORDS) &&
	  (wsp->ws_wordi + n == wsp->ws_maxwords))
	  break;

      if (wsp->ws_flags & WRDSF_INCREMENTAL)
	p = NULL; /* Break the loop */
      else
	p = next;
    }

  if (p)
    {
      /* We're here if WRDSO_MAXWORDS is in effect and wsp->ws_maxwords
	 words have already been collected. Reconstruct a single final
	 node from the remaining nodes. */
      if (wsnode_tail_coalesce (wsp, p))
	return wsp->ws_errno;
      n++;
    }

  if (n == 0)
    {
      /* The loop above have eliminated all nodes. */
      if (wsp->ws_flags & WRDSF_INCREMENTAL)
	{
	  /* Restart the processing, if there's any input left. */
	restart:
	  if (wsp->ws_endp < wsp->ws_len)
	    {
	      int rc;
	      if (wsp->ws_flags & WRDSF_SHOWDBG)
		wsp->ws_debug (_("Restarting"));
	      rc = wordsplit_process_list (wsp, skip_delim (wsp));
	      if (rc)
		return rc;
	    }
	  else
	    {
	      wsp->ws_errno = WRDSE_EOF;
	      return WRDSE_EOF;
	    }
	  goto again;
	}

      if (wsp->ws_flags & WRDSF_NOSPLIT)
	{
	  if (wordsplit_add_segm (wsp, 0, 0, _WSNF_EMPTYOK))
	    return wsp->ws_errno;
	  n = 1;
	}
    }

  if (alloc_space (wsp, n + 1))
    return wsp->ws_errno;

  while (wsp->ws_head)
    {
      const char *str = wsnode_ptr (wsp, wsp->ws_head);
      size_t slen = wsnode_len (wsp->ws_head);
      char *newstr = malloc (slen + 1);

      /* Assign newstr first, even if it is NULL.  This way
	 wordsplit_free will work even if we return
	 nomem later. */
      wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc] = newstr;
      if (!newstr)
	return _wsplt_nomem (wsp);
      memcpy (newstr, str, slen);
      newstr[slen] = 0;

      wsnode_remove (wsp, wsp->ws_head);

      wsp->ws_wordc++;
      wsp->ws_wordi++;

      if (wsp->ws_flags & WRDSF_INCREMENTAL)
	break;
    }
  wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc] = NULL;
  return 0;
}

int
wordsplit_append (wordsplit_t *wsp, int argc, char **argv)
{
  int rc;
  size_t i;

  rc = alloc_space (wsp, wsp->ws_wordc + argc + 1);
  if (rc)
    return rc;
  for (i = 0; i < argc; i++)
    {
      char *newstr = strdup (argv[i]);
      if (!newstr)
	{
	  while (i > 0)
	    {
	      free (wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc + i - 1]);
	      wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc + i - 1] = NULL;
	      i--;
	    }
	  return _wsplt_nomem (wsp);
	}
      wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc + i] = newstr;
    }
  wsp->ws_wordc += i;
  wsp->ws_wordv[wsp->ws_offs + wsp->ws_wordc] = NULL;
  return 0;
}

/* Variable expansion */
static int
node_split_prefix (struct wordsplit *wsp,
		   struct wordsplit_node **ptail,
		   struct wordsplit_node *node,
		   size_t beg, size_t len, int flg)
{
  struct wordsplit_node *newnode;

  if (len == 0)
    return 0;
  if (wsnode_new (wsp, &newnode))
    return 1;
  wsnode_insert (wsp, newnode, *ptail, 0);
  if (node->flags & _WSNF_WORD)
    {
      const char *str = wsnode_ptr (wsp, node);
      char *newstr = malloc (len + 1);
      if (!newstr)
	return _wsplt_nomem (wsp);
      memcpy (newstr, str + beg, len);
      newstr[len] = 0;
      newnode->flags = _WSNF_WORD;
      newnode->v.word = newstr;
    }
  else
    {
      newnode->v.segm.beg = node->v.segm.beg + beg;
      newnode->v.segm.end = newnode->v.segm.beg + len;
    }
  newnode->flags |= flg;
  *ptail = newnode;
  return 0;
}

static int
find_closing_paren (const char *str, size_t i, size_t len, size_t *poff,
		    char const *paren)
{
  enum { st_init, st_squote, st_dquote } state = st_init;
  size_t level = 1;

  for (; i < len; i++)
    {
      switch (state)
	{
	case st_init:
	  switch (str[i])
	    {
	    default:
	      if (str[i] == paren[0])
		{
		  level++;
		  break;
		}
	      else if (str[i] == paren[1])
		{
		  if (--level == 0)
		    {
		      *poff = i;
		      return 0;
		    }
		  break;
		}
	      break;

	    case '"':
	      state = st_dquote;
	      break;

	    case '\'':
	      state = st_squote;
	      break;
	    }
	  break;

	case st_squote:
	  if (str[i] == '\'')
	    state = st_init;
	  break;

	case st_dquote:
	  if (str[i] == '\\')
	    i++;
	  else if (str[i] == '"')
	    state = st_init;
	  break;
	}
    }
  return 1;
}

static char const *
wsplt_env_find (struct wordsplit *wsp, const char *name, size_t len)
{
  size_t i;

  if (!wsp->ws_env)
    return NULL;
  if (wsp->ws_flags & WRDSF_ENV_KV)
    {
      /* A key-value pair environment */
      for (i = 0; wsp->ws_env[i]; i++)
	{
	  size_t elen = strlen (wsp->ws_env[i]);
	  if (elen == len && memcmp (wsp->ws_env[i], name, elen) == 0)
	    return wsp->ws_env[i + 1];
	  /* Skip the value.  Break the loop if it is NULL. */
	  i++;
	  if (wsp->ws_env[i] == NULL)
	    break;
	}
    }
  else
    {
      /* Usual (A=B) environment. */
      for (i = 0; wsp->ws_env[i]; i++)
	{
	  size_t j;
	  const char *var = wsp->ws_env[i];

	  for (j = 0; j < len; j++)
	    if (name[j] != var[j])
	      break;
	  if (j == len && var[j] == '=')
	    return var + j + 1;
	}
    }
  return NULL;
}

static int
wsplt_env_lookup (struct wordsplit *wsp, const char *name, size_t len,
		  char **ret)
{
  if (wsp->ws_flags & WRDSF_ENV)
    {
      char const *val = wsplt_env_find (wsp, name, len);
      if (val)
	{
	  char *retval = strdup (val);
	  if (!retval)
	    return WRDSE_NOSPACE;
	  *ret = retval;
	  return WRDSE_OK;
	}
    }
  return WRDSE_UNDEF;
}

static int
wsplt_env_getvar (struct wordsplit *wsp, const char *name, size_t len,
		  char **ret)
{
  return wsp->ws_getvar (ret, name, len, wsp->ws_closure);
}

static int
wsplt_assign_var (struct wordsplit *wsp, const char *name, size_t namelen,
		  char const *value)
{
  int n = (wsp->ws_flags & WRDSF_ENV_KV) ? 2 : 1;
  char *v;

  if (wsp->ws_envidx + n >= wsp->ws_envsiz)
    {
      size_t sz;
      char **newenv;

      if (!wsp->ws_envbuf)
	{
	  if (wsp->ws_flags & WRDSF_ENV)
	    {
	      size_t i = 0, j;

	      if (wsp->ws_env)
		{
		  for (; wsp->ws_env[i]; i++)
		    ;
		}

	      sz = i + n + 1;

	      newenv = calloc (sz, sizeof(newenv[0]));
	      if (!newenv)
		return _wsplt_nomem (wsp);

	      for (j = 0; j < i; j++)
		{
		  newenv[j] = strdup (wsp->ws_env[j]);
		  if (!newenv[j])
		    {
		      for (; j > 1; j--)
			free (newenv[j-1]);
		      free (newenv);
		      return _wsplt_nomem (wsp);
		    }
		}
	      newenv[j] = NULL;

	      wsp->ws_envbuf = newenv;
	      wsp->ws_envidx = i;
	      wsp->ws_envsiz = sz;
	      wsp->ws_env = (const char**) wsp->ws_envbuf;
	    }
	  else
	    {
	      newenv = calloc (WORDSPLIT_ENV_INIT, sizeof(newenv[0]));
	      if (!newenv)
		return _wsplt_nomem (wsp);
	      wsp->ws_envbuf = newenv;
	      wsp->ws_envidx = 0;
	      wsp->ws_envsiz = WORDSPLIT_ENV_INIT;
	      wsp->ws_env = (const char**) wsp->ws_envbuf;
	      wsp->ws_flags |= WRDSF_ENV;
	    }
	}
      else
	{
	  size_t n = wsp->ws_envsiz;

	  if ((size_t) -1 / 3 * 2 / sizeof (wsp->ws_envbuf[0]) <= n)
	    return _wsplt_nomem (wsp);
	  n += (n + 1) / 2;
	  newenv = realloc (wsp->ws_envbuf, n * sizeof (wsp->ws_envbuf[0]));
	  if (!newenv)
	    return _wsplt_nomem (wsp);
	  wsp->ws_envbuf = newenv;
	  wsp->ws_envsiz = n;
	  wsp->ws_env = (const char**) wsp->ws_envbuf;
	}
    }

  if (wsp->ws_flags & WRDSF_ENV_KV)
    {
      /* A key-value pair environment */
      char *p = malloc (namelen + 1);
      if (!p)
	return _wsplt_nomem (wsp);
      memcpy (p, name, namelen);
      p[namelen] = 0;

      v = strdup (value);
      if (!v)
	{
	  free (p);
	  return _wsplt_nomem (wsp);
	}
      wsp->ws_env[wsp->ws_envidx++] = p;
      wsp->ws_env[wsp->ws_envidx++] = v;
    }
  else
    {
      v = malloc (namelen + strlen(value) + 2);
      if (!v)
	return _wsplt_nomem (wsp);
      memcpy (v, name, namelen);
      v[namelen++] = '=';
      strcpy(v + namelen, value);
      wsp->ws_env[wsp->ws_envidx++] = v;
    }
  wsp->ws_env[wsp->ws_envidx] = NULL;
  return WRDSE_OK;
}

static int
wsplt_assign_param (struct wordsplit *wsp, int param_idx, char *value)
{
  char *v;

  if (param_idx < 0)
    return _wsplt_seterr (wsp, WRDSE_BADPARAM);
  if (param_idx == wsp->ws_paramc)
    {
      char **parambuf;
      if (!wsp->ws_parambuf)
	{
	  size_t i;

	  parambuf = calloc ((size_t)param_idx + 1, sizeof (parambuf[0]));
	  if (!parambuf)
	    return _wsplt_nomem (wsp);

	  for (i = 0; i < wsp->ws_paramc; i++)
	    {
	      parambuf[i] = strdup (wsp->ws_paramv[i]);
	      if (!parambuf[i])
		{
		  for (; i > 1; i--)
		    free (parambuf[i-1]);
		  free (parambuf);
		  return _wsplt_nomem (wsp);
		}
	    }

	  wsp->ws_parambuf = parambuf;
	  wsp->ws_paramidx = param_idx;
	  wsp->ws_paramsiz = param_idx + 1;
	}
      else
	{
	  size_t n = wsp->ws_paramsiz;

	  if ((size_t) -1 / 3 * 2 / sizeof (wsp->ws_parambuf[0]) <= n)
	    return _wsplt_nomem (wsp);
	  n += (n + 1) / 2;
	  parambuf = realloc (wsp->ws_parambuf, n * sizeof (wsp->ws_parambuf[0]));
	  if (!parambuf)
	    return _wsplt_nomem (wsp);
	  wsp->ws_parambuf = parambuf;
	  wsp->ws_paramsiz = n;
	  wsp->ws_parambuf[param_idx] = NULL;
	}

      wsp->ws_paramv = (const char**) wsp->ws_parambuf;
      wsp->ws_paramc = param_idx + 1;
    }
  else if (param_idx > wsp->ws_paramc)
    return _wsplt_seterr (wsp, WRDSE_BADPARAM);

  v = strdup (value);
  if (!v)
    return _wsplt_nomem (wsp);

  free (wsp->ws_parambuf[param_idx]);
  wsp->ws_parambuf[param_idx] = v;
  return WRDSE_OK;
}

/* Recover from what looked like a variable reference, but turned out
   not to be one. STR points to first character after '$'. */
static int
expvar_recover (struct wordsplit *wsp, const char *str,
		struct wordsplit_node **ptail, const char **pend, int flg)
{
  struct wordsplit_node *newnode;

  if (wsnode_new (wsp, &newnode))
    return 1;
  wsnode_insert (wsp, newnode, *ptail, 0);
  *ptail = newnode;
  newnode->flags = _WSNF_WORD | flg;
  newnode->v.word = malloc (3);
  if (!newnode->v.word)
    return _wsplt_nomem (wsp);
  newnode->v.word[0] = '$';
  newnode->v.word[1] = str[0];
  newnode->v.word[2] = 0;
  *pend = str;
  return 0;
}

static int
expand_paramv (struct wordsplit *wsp, struct wordsplit_node **ptail, int flg,
	       int q)
{
  struct wordsplit ws;
  int wsflags = WRDSF_NOVAR | WRDSF_NOCMD | WRDSF_QUOTE
	      | (WSP_RETURN_DELIMS (wsp) ? WRDSF_RETURN_DELIMS : 0)
	      | (q ? WRDSF_NOSPLIT : 0);
  size_t i;
  struct wordsplit_node *tail = *ptail;

  for (i = 0; i < wsp->ws_paramc; i++)
    {
      struct wordsplit_node *np;
      int rc = _wsplt_subsplit (wsp, &ws,
				wsp->ws_paramv[i], strlen (wsp->ws_paramv[i]),
				wsflags, q);
      if (rc)
	{
	  _wsplt_seterr_sub (wsp, &ws);
	  wordsplit_free (&ws);
	  return 1;
	}

      if (q)
	{
	  if (wsnode_new (wsp, &np))
	    return 1;
	  wsnode_insert (wsp, np, *ptail, 0);
	  *ptail = np;
	  np->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
	  np->v.word = ws.ws_wordv[0];

	  ws.ws_wordv[0] = NULL;
	}
      else
	{
	  for (np = ws.ws_head; np; np = np->next)
	    np->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
	  wsnode_insert (wsp, ws.ws_head, *ptail, 0);
	  *ptail = ws.ws_tail;
	  ws.ws_head = ws.ws_tail = NULL;
	}

      wsflags |= WRDSF_REUSE;
    }
  if (wsflags & WRDSF_REUSE)
    wordsplit_free (&ws);

  if (flg & _WSNF_QUOTE)
    {
      tail = tail->next;
      /* Insert delimiters, mark nodes as joinable */
      while (tail != *ptail)
	{
	  struct wordsplit_node *next = tail->next;
	  struct wordsplit_node *newnode;

	  tail->flags |= _WSNF_JOIN;

	  if (wsnode_new (wsp, &newnode))
	    return 1;
	  newnode->flags = _WSNF_WORD | _WSNF_CONST | _WSNF_NOEXPAND | _WSNF_JOIN;
	  newnode->v.word = wsp->ws_sep;

	  wsnode_insert (wsp, newnode, tail, 0);
	  tail = next;
	}
    }

  return 0;
}

static int
expvar (struct wordsplit *wsp, const char *str, size_t len,
	struct wordsplit_node **ptail, const char **pend, int flg)
{
  size_t i = 0;
  const char *defstr = NULL;
  char *value;
  struct wordsplit_node *newnode;
  const char *start = str - 1;
  int rc;
  struct wordsplit ws;
  int is_param = 0;
  long param_idx = 0;

  if (ISVARBEG (str[0]))
    {
      for (i = 1; i < len; i++)
	if (!is_name_char (wsp, str[i]))
	  break;
      *pend = str + i - 1;
    }
  else if ((wsp->ws_options & WRDSO_PARAMV) && ISDIGIT (str[0]))
    {
      i = 1;
      *pend = str;
      is_param = 1;
      param_idx = to_num (str[0]);
    }
  else if ((wsp->ws_options & WRDSO_PARAMV) && str[0] == '#')
    {
      char b[16];
      snprintf (b, sizeof(b), "%d", (int) wsp->ws_paramc);
      value = strdup (b);
      if (!value)
	return _wsplt_nomem (wsp);
      if (wsnode_new (wsp, &newnode))
	return 1;
      wsnode_insert (wsp, newnode, *ptail, 0);
      *ptail = newnode;
      newnode->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
      newnode->v.word = value;
      return 0;
    }
  else if ((wsp->ws_options & WRDSO_PARAMV) && str[0] == '*')
    {
      return expand_paramv (wsp, ptail, flg, 0);
    }
  else if ((wsp->ws_options & WRDSO_PARAMV) && str[0] == '@')
    {
      return expand_paramv (wsp, ptail, flg, 1);
    }
  else if (str[0] == '{'
	   && (ISVARBEG (str[1])
	       || (is_param = (((wsp->ws_options & WRDSO_PARAMV)
				&& ISDIGIT (str[1]))
			       || ((wsp->ws_options & WRDSO_PARAM_NEGIDX)
				   && (str[1] == '-'
				       && ISDIGIT (str[2]))))) != 0))
    {
      int i0 = str[1] == '-' ? 1 : 0;
      str++;
      len--;
      for (i = i0; i < len; i++)
	{
	  if (str[i] == '}')
	    {
	      defstr = NULL;
	      *pend = str + i;
	      break;
	    }
	  else if (strchr ("-+?=", str[i]))
	    {
	      size_t j;

	      defstr = str + i;
	      if (find_closing_paren (str, i, len, &j, "{}"))
		return _wsplt_seterr (wsp, WRDSE_CBRACE);
	      if (i > i0 + 1 && str[i-1] == ':')
		i--;
	      *pend = str + j;
	      break;
	    }
	  else if (is_param)
	    {
	      if (ISDIGIT (str[i]))
		{
		  param_idx = param_idx * 10 + to_num (str[i]);
		  if ((str[0] == '-' && -param_idx < INT_MIN)
		      || param_idx > INT_MAX)
		    return expvar_recover (wsp, str - 1, ptail, pend, flg);
		}
	      else
		{
		  return expvar_recover (wsp, str - 1, ptail, pend, flg);
		}
	    }
	  else if (!is_name_char (wsp, str[i]))
	    {
	      if (str[i] == ':' && i + 1 < len && strchr ("-+?=", str[i+1]))
		continue;
	      return expvar_recover (wsp, str - 1, ptail, pend, flg);
	    }
	}

      if (is_param && str[0] == '-')
	param_idx = wsp->ws_paramc - param_idx;

      if (i == len)
	return _wsplt_seterr (wsp, WRDSE_CBRACE);
    }
  else
    {
      return expvar_recover (wsp, str, ptail, pend, flg);
    }

  /* Actually expand the variable */
  /* str - start of the variable name
     i   - its length
     defstr - default replacement str */

  if (is_param)
    {
      if (param_idx >= 0 && param_idx < wsp->ws_paramc)
	{
	  value = strdup (wsp->ws_paramv[param_idx]);
	  if (!value)
	    rc = WRDSE_NOSPACE;
	  else
	    rc = WRDSE_OK;
	}
      else
	rc = WRDSE_UNDEF;
    }
  else
    {
      if (wsp->ws_flags & WRDSF_GETVAR)
	{
	  if (wsp->ws_options & WRDSO_GETVARPREF)
	    {
	      rc = wsplt_env_getvar (wsp, str, i, &value);
	      if (rc == WRDSE_UNDEF)
		rc = wsplt_env_lookup (wsp, str, i, &value);
	    }
	  else
	    {
	      rc = wsplt_env_lookup (wsp, str, i, &value);
	      if (rc == WRDSE_UNDEF)
		rc = wsplt_env_getvar (wsp, str, i, &value);
	    }
	}
      else
	rc = wsplt_env_lookup (wsp, str, i, &value);
    }

  if (rc == WRDSE_OK
      && (!value || value[0] == 0)
      && defstr && defstr[-1] == ':')
    {
      free (value);
      rc = WRDSE_UNDEF;
    }

  switch (rc)
    {
    case WRDSE_OK:
      if (defstr && *defstr == '+')
	{
	  size_t size = *pend - ++defstr;

	  rc = _wsplt_subsplit (wsp, &ws, defstr, size,
				WRDSF_NOSPLIT | WRDSF_WS | WRDSF_QUOTE |
				(wsp->ws_flags &
				 (WRDSF_NOVAR | WRDSF_NOCMD)), 1);
	  if (rc)
	    return rc;
	  free (value);
	  value = ws.ws_wordv[0];
	  ws.ws_wordv[0] = NULL;
	  wordsplit_free (&ws);
	}
      break;

    case WRDSE_UNDEF:
      if (defstr)
	{
	  size_t size;
	  if (*defstr == '-' || *defstr == '=')
	    {
	      size = *pend - ++defstr;

	      rc = _wsplt_subsplit (wsp, &ws, defstr, size,
				    WRDSF_NOSPLIT | WRDSF_WS | WRDSF_QUOTE |
				    (wsp->ws_flags &
				     (WRDSF_NOVAR | WRDSF_NOCMD)),
				    1);
	      if (rc)
		return rc;

	      value = ws.ws_wordv[0];
	      ws.ws_wordv[0] = NULL;
	      wordsplit_free (&ws);

	      if (defstr[-1] == '=')
		{
		  if (is_param)
		    rc = wsplt_assign_param (wsp, param_idx, value);
		  else
		    rc = wsplt_assign_var (wsp, str, i, value);
		}
	      if (rc)
		{
		  free (value);
		  return rc;
		}
	    }
	  else
	    {
	      if (*defstr == '?')
		{
		  size = *pend - ++defstr;
		  if (size == 0)
		    wsp->ws_error (_("%.*s: variable null or not set"),
				   (int) i, str);
		  else
		    {
		      rc = _wsplt_subsplit (wsp, &ws, defstr, size,
					    WRDSF_NOSPLIT | WRDSF_WS |
					    WRDSF_QUOTE |
					    (wsp->ws_flags &
					     (WRDSF_NOVAR | WRDSF_NOCMD)),
					    1);
		      if (rc == 0)
			wsp->ws_error ("%.*s: %s",
				       (int) i, str, ws.ws_wordv[0]);
		      else
			wsp->ws_error ("%.*s: %.*s",
				       (int) i, str, (int) size, defstr);
		      wordsplit_free (&ws);
		    }
		}
	      value = NULL;
	    }
	}
      else if (wsp->ws_flags & WRDSF_UNDEF)
	{
	  _wsplt_setctxerr (wsp, WRDSE_UNDEF, str, i);
	  return 1;
	}
      else
	{
	  if (wsp->ws_flags & WRDSF_WARNUNDEF)
	    wsp->ws_error (_("warning: undefined variable `%.*s'"),
			   (int) i, str);
	  if (wsp->ws_flags & WRDSF_KEEPUNDEF)
	    value = NULL;
	  else
	    {
	      value = strdup ("");
	      if (!value)
		return _wsplt_nomem (wsp);
	    }
	}
      break;

    case WRDSE_NOSPACE:
      return _wsplt_nomem (wsp);

    case WRDSE_USERERR:
      if (wsp->ws_errno == WRDSE_USERERR)
	free (wsp->ws_usererr);
      wsp->ws_usererr = value;
      /* fall through */
    default:
      _wsplt_seterr (wsp, rc);
      return 1;
    }

  if (value)
    {
      if (flg & _WSNF_QUOTE)
	{
	  if (wsnode_new (wsp, &newnode))
	    return 1;
	  wsnode_insert (wsp, newnode, *ptail, 0);
	  *ptail = newnode;
	  newnode->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
	  newnode->v.word = value;
	}
      else if (*value == 0)
	{
	  free (value);
	  /* Empty string is a special case */
	  if (wsnode_new (wsp, &newnode))
	    return 1;
	  wsnode_insert (wsp, newnode, *ptail, 0);
	  *ptail = newnode;
	  newnode->flags = _WSNF_NULL | _WSNF_NOEXPAND;
	}
      else
	{
	  struct wordsplit ws;
	  int rc;

	  rc = _wsplt_subsplit (wsp, &ws, value, strlen (value),
				WRDSF_NOVAR | WRDSF_NOCMD |
				WRDSF_QUOTE
				| (WSP_RETURN_DELIMS (wsp) ? WRDSF_RETURN_DELIMS : 0) ,
				0);
	  free (value);
	  if (rc)
	    {
	      _wsplt_seterr_sub (wsp, &ws);
	      wordsplit_free (&ws);
	      return 1;
	    }
	  wsnode_insert (wsp, ws.ws_head, *ptail, 0);
	  *ptail = ws.ws_tail;
	  ws.ws_head = ws.ws_tail = NULL;
	  wordsplit_free (&ws);
	}
    }
  else if (wsp->ws_flags & WRDSF_KEEPUNDEF)
    {
      size_t size = *pend - start + 1;

      if (wsnode_new (wsp, &newnode))
	return 1;
      wsnode_insert (wsp, newnode, *ptail, 0);
      *ptail = newnode;
      newnode->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
      newnode->v.word = malloc (size + 1);
      if (!newnode->v.word)
	return _wsplt_nomem (wsp);
      memcpy (newnode->v.word, start, size);
      newnode->v.word[size] = 0;
    }
  else
    {
      if (wsnode_new (wsp, &newnode))
	return 1;
      wsnode_insert (wsp, newnode, *ptail, 0);
      *ptail = newnode;
      newnode->flags = _WSNF_NULL | _WSNF_NOEXPAND;
    }
  return 0;
}

static int
begin_var_p (int c)
{
  return memchr ("{#@*", c, 4) != NULL || ISVARBEG (c) || ISDIGIT (c);
}

static int
node_expand (struct wordsplit *wsp, struct wordsplit_node *node,
	     int (*beg_p) (int),
	     int (*ws_exp_fn) (struct wordsplit *wsp,
			       const char *str, size_t len,
			       struct wordsplit_node **ptail,
			       const char **pend,
			       int flg))
{
  const char *str = wsnode_ptr (wsp, node);
  size_t slen = wsnode_len (node);
  const char *end = str + slen;
  const char *p;
  size_t off = 0;
  struct wordsplit_node *tail = node;

  for (p = str; p < end; p++)
    {
      if (*p == '\\')
	{
	  p++;
	  continue;
	}
      if (*p == '$' && beg_p (p[1]))
	{
	  size_t n = p - str;

	  if (tail != node)
	    tail->flags |= _WSNF_JOIN;
	  if (node_split_prefix (wsp, &tail, node, off, n, _WSNF_JOIN))
	    return 1;
	  p++;
	  if (ws_exp_fn (wsp, p, slen - n, &tail, &p,
			 node->flags & (_WSNF_JOIN | _WSNF_QUOTE)))
	    return 1;
	  off += p - str + 1;
	  str = p + 1;
	}
    }
  if (p > str)
    {
      if (tail != node)
	tail->flags |= _WSNF_JOIN;
      if (node_split_prefix (wsp, &tail, node, off, p - str,
			     node->flags & (_WSNF_JOIN|_WSNF_QUOTE)))
	return 1;
    }
  if (tail != node)
    {
      wsnode_remove (wsp, node);
    }
  return 0;
}

/* Remove NULL nodes from the list */
static void
wsnode_nullelim (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p;)
    {
      struct wordsplit_node *next = p->next;
      if (p->flags & _WSNF_DELIM && p->prev)
	p->prev->flags &= ~_WSNF_JOIN;
      if (p->flags & _WSNF_NULL)
	{
	  wsnode_remove (wsp, p);
	}
      p = next;
    }
}

static int
wordsplit_varexp (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p;)
    {
      struct wordsplit_node *next = p->next;
      if (!(p->flags & (_WSNF_NOEXPAND|_WSNF_DELIM)))
	if (node_expand (wsp, p, begin_var_p, expvar))
	  return 1;
      p = next;
    }

  wsnode_nullelim (wsp);
  return 0;
}

static int
begin_cmd_p (int c)
{
  return c == '(';
}

static int
expcmd (struct wordsplit *wsp, const char *str, size_t len,
	struct wordsplit_node **ptail, const char **pend, int flg)
{
  int rc;
  size_t j;
  char *value;
  struct wordsplit_node *newnode;
  struct wordsplit ws;

  str++;
  len--;

  if (find_closing_paren (str, 0, len, &j, "()"))
    {
      _wsplt_seterr (wsp, WRDSE_PAREN);
      return 1;
    }

  *pend = str + j;
  rc = _wsplt_subsplit (wsp, &ws, str, j, WRDSF_WS | WRDSF_QUOTE, 1);
  if (rc)
    {
      _wsplt_seterr_sub (wsp, &ws);
      wordsplit_free (&ws);
      return 1;
    }
  rc = wsp->ws_command (&value, str, j, ws.ws_wordv, wsp->ws_closure);
  wordsplit_free (&ws);

  if (rc == WRDSE_NOSPACE)
    return _wsplt_nomem (wsp);
  else if (rc)
    {
      if (rc == WRDSE_USERERR)
	{
	  if (wsp->ws_errno == WRDSE_USERERR)
	    free (wsp->ws_usererr);
	  wsp->ws_usererr = value;
	}
      _wsplt_seterr (wsp, rc);
      return 1;
    }

  if (value)
    {
      if (flg & _WSNF_QUOTE)
	{
	  if (wsnode_new (wsp, &newnode))
	    return 1;
	  wsnode_insert (wsp, newnode, *ptail, 0);
	  *ptail = newnode;
	  newnode->flags = _WSNF_WORD | _WSNF_NOEXPAND | flg;
	  newnode->v.word = value;
	}
      else if (*value == 0)
	{
	  free (value);
	  /* Empty string is a special case */
	  if (wsnode_new (wsp, &newnode))
	    return 1;
	  wsnode_insert (wsp, newnode, *ptail, 0);
	  *ptail = newnode;
	  newnode->flags = _WSNF_NULL | _WSNF_NOEXPAND;
	}
      else
	{
	  struct wordsplit ws;
	  int rc;

	  rc = _wsplt_subsplit (wsp, &ws, value, strlen (value),
				WRDSF_NOVAR | WRDSF_NOCMD
				| WRDSF_WS | WRDSF_QUOTE
				| (WSP_RETURN_DELIMS (wsp) ? WRDSF_RETURN_DELIMS : 0),
				0);
	  free (value);
	  if (rc)
	    {
	      _wsplt_seterr_sub (wsp, &ws);
	      wordsplit_free (&ws);
	      return 1;
	    }
	  wsnode_insert (wsp, ws.ws_head, *ptail, 0);
	  *ptail = ws.ws_tail;
	  ws.ws_head = ws.ws_tail = NULL;
	  wordsplit_free (&ws);
	}
    }
  else
    {
      if (wsnode_new (wsp, &newnode))
	return 1;
      wsnode_insert (wsp, newnode, *ptail, 0);
      *ptail = newnode;
      newnode->flags = _WSNF_NULL | _WSNF_NOEXPAND;
    }
  return 0;
}

static int
wordsplit_cmdexp (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p;)
    {
      struct wordsplit_node *next = p->next;
      if (!(p->flags & _WSNF_NOEXPAND))
	if (node_expand (wsp, p, begin_cmd_p, expcmd))
	  return 1;
      p = next;
    }

  wsnode_nullelim (wsp);
  return 0;
}

/* Strip off any leading and trailing whitespace.  This function is called
   right after the initial scanning, therefore it assumes that every
   node in the list is a text reference node. */
static int
wordsplit_trimws (struct wordsplit *wsp)
{
  struct wordsplit_node *p;

  for (p = wsp->ws_head; p; p = p->next)
    {
      size_t n;

      if (!(p->flags & _WSNF_QUOTE))
	{
	  /* Skip leading whitespace: */
	  for (n = p->v.segm.beg; n < p->v.segm.end && ISWS (wsp->ws_input[n]);
	       n++)
	    ;
	  p->v.segm.beg = n;
	}

      while (p->next && (p->flags & _WSNF_JOIN))
	p = p->next;

      if (p->flags & _WSNF_QUOTE)
	continue;

      /* Trim trailing whitespace */
      for (n = p->v.segm.end;
	   n > p->v.segm.beg && ISWS (wsp->ws_input[n - 1]); n--);
      p->v.segm.end = n;
      if (p->v.segm.beg == p->v.segm.end)
	p->flags |= _WSNF_NULL | _WSNF_NOEXPAND;
    }

  wsnode_nullelim (wsp);
  return 0;
}

static int
wordsplit_tildexpand (struct wordsplit *wsp)
{
  struct wordsplit_node *p;
  char *uname = NULL;
  size_t usize = 0;

  for (p = wsp->ws_head; p; p = p->next)
    {
      const char *str;

      if (p->flags & _WSNF_QUOTE)
	continue;

      str = wsnode_ptr (wsp, p);
      if (str[0] == '~')
	{
	  size_t i, size, dlen;
	  size_t slen = wsnode_len (p);
	  struct passwd *pw;
	  char *newstr;

	  for (i = 1; i < slen && str[i] != '/'; i++)
	    ;
	  if (i == slen)
	    continue;
	  if (i > 1)
	    {
	      if (i > usize)
		{
		  char *p = realloc (uname, i);
		  if (!p)
		    {
		      free (uname);
		      return _wsplt_nomem (wsp);
		    }
		  uname = p;
		  usize = i;
		}
	      --i;
	      memcpy (uname, str + 1, i);
	      uname[i] = 0;
	      pw = getpwnam (uname);
	    }
	  else
	    pw = getpwuid (getuid ());

	  if (!pw)
	    continue;

	  dlen = strlen (pw->pw_dir);
	  size = slen - i + dlen;
	  newstr = malloc (size);
	  if (!newstr)
	    {
	      free (uname);
	      return _wsplt_nomem (wsp);
	    }
	  --size;

	  memcpy (newstr, pw->pw_dir, dlen);
	  memcpy (newstr + dlen, str + i + 1, slen - i - 1);
	  newstr[size] = 0;
	  if (p->flags & _WSNF_WORD)
	    free (p->v.word);
	  p->v.word = newstr;
	  p->flags |= _WSNF_WORD;
	}
    }
  free (uname);
  return 0;
}

static int
isglob (const char *s, int l)
{
  while (l--)
    {
      if (strchr ("*?[", *s++))
	return 1;
    }
  return 0;
}

static int
wordsplit_pathexpand (struct wordsplit *wsp)
{
  struct wordsplit_node *p, *next;
  char *pattern = NULL;
  size_t patsize = 0;
  size_t slen;
  int flags = 0;

#ifdef GLOB_PERIOD
  if (wsp->ws_options & WRDSO_DOTGLOB)
    flags = GLOB_PERIOD;
#endif

  for (p = wsp->ws_head; p; p = next)
    {
      const char *str;

      next = p->next;

      if (p->flags & _WSNF_QUOTE)
	continue;

      str = wsnode_ptr (wsp, p);
      slen = wsnode_len (p);

      if (isglob (str, slen))
	{
	  int i;
	  glob_t g;
	  struct wordsplit_node *prev;

	  if (slen + 1 > patsize)
	    {
	      char *p = realloc (pattern, slen + 1);
	      if (!p)
		return _wsplt_nomem (wsp);
	      pattern = p;
	      patsize = slen + 1;
	    }
	  memcpy (pattern, str, slen);
	  pattern[slen] = 0;

	  switch (glob (pattern, flags, NULL, &g))
	    {
	    case 0:
	      break;

	    case GLOB_NOSPACE:
	      free (pattern);
	      return _wsplt_nomem (wsp);

	    case GLOB_NOMATCH:
	      if (wsp->ws_options & WRDSO_NULLGLOB)
		{
		  wsnode_remove (wsp, p);
		}
	      else if (wsp->ws_options & WRDSO_FAILGLOB)
		{
		  char buf[128];
		  if (wsp->ws_errno == WRDSE_USERERR)
		    free (wsp->ws_usererr);
		  snprintf (buf, sizeof (buf), _("no files match pattern %s"),
			    pattern);
		  free (pattern);
		  wsp->ws_usererr = strdup (buf);
		  if (!wsp->ws_usererr)
		    return _wsplt_nomem (wsp);
		  else
		    return _wsplt_seterr (wsp, WRDSE_USERERR);
		}
	      continue;

	    default:
	      free (pattern);
	      return _wsplt_setctxerr (wsp, WRDSE_GLOBERR, str, slen);
	    }

	  prev = p;
	  for (i = 0; i < g.gl_pathc; i++)
	    {
	      struct wordsplit_node *newnode;
	      char *newstr;

	      if (wsnode_new (wsp, &newnode))
		return 1;
	      newstr = strdup (g.gl_pathv[i]);
	      if (!newstr)
		return _wsplt_nomem (wsp);
	      newnode->v.word = newstr;
	      newnode->flags |= _WSNF_WORD|_WSNF_QUOTE;
	      wsnode_insert (wsp, newnode, prev, 0);
	      prev = newnode;
	    }
	  globfree (&g);

	  wsnode_remove (wsp, p);
	}
    }
  free (pattern);
  return 0;
}

static int
skip_sed_expr (const char *command, size_t i, size_t len)
{
  int state;

  do
    {
      int delim;

      if (command[i] == ';')
	i++;
      if (!(command[i] == 's' && i + 3 < len && ISPUNCT (command[i + 1])))
	break;

      delim = command[++i];
      state = 1;
      for (i++; i < len; i++)
	{
	  if (state == 3)
	    {
	      if (command[i] == delim || !ISALNUM (command[i]))
		break;
	    }
	  else if (command[i] == '\\')
	    i++;
	  else if (command[i] == delim)
	    state++;
	}
    }
  while (state == 3 && i < len && command[i] == ';');
  return i;
}

/* wsp->ws_endp points to a delimiter character. If RETURN_DELIMS
   is true, return its value, otherwise return the index past it. */
static inline size_t
skip_delim_internal (struct wordsplit *wsp, int return_delims)
{
  return return_delims ? wsp->ws_endp : wsp->ws_endp + 1;
}

static inline size_t
skip_delim (struct wordsplit *wsp)
{
  return skip_delim_internal (wsp, WSP_RETURN_DELIMS (wsp));
}

static inline size_t
skip_delim_real (struct wordsplit *wsp)
{
  return skip_delim_internal (wsp, wsp->ws_flags & WRDSF_RETURN_DELIMS);
}

#define _WRDS_EOF   0
#define _WRDS_OK    1
#define _WRDS_ERR   2

static int
scan_qstring (struct wordsplit *wsp, size_t start, size_t *end)
{
  size_t j;
  const char *command = wsp->ws_input;
  size_t len = wsp->ws_len;
  char q = command[start];

  for (j = start + 1; j < len && command[j] != q; j++)
    if (q == '"' && command[j] == '\\')
      j++;
  if (j < len && command[j] == q)
    {
      int flags = _WSNF_QUOTE | _WSNF_EMPTYOK;
      if (q == '\'')
	flags |= _WSNF_NOEXPAND;
      if (wordsplit_add_segm (wsp, start + 1, j, flags))
	return _WRDS_ERR;
      *end = j;
    }
  else
    {
      wsp->ws_endp = start;
      _wsplt_seterr (wsp, WRDSE_QUOTE);
      return _WRDS_ERR;
    }
  return 0;
}

static int
scan_word (struct wordsplit *wsp, size_t start, int consume_all)
{
  size_t len = wsp->ws_len;
  const char *command = wsp->ws_input;
  const char *comment = wsp->ws_comment;
  int join = 0;
  int flags = 0;
  struct wordsplit_node *np = wsp->ws_tail;

  size_t i = start;

  if (i >= len)
    {
      wsp->ws_errno = WRDSE_EOF;
      return _WRDS_EOF;
    }

  start = i;

  if (wsp->ws_flags & WRDSF_SED_EXPR
      && command[i] == 's' && i + 3 < len && ISPUNCT (command[i + 1]))
    {
      flags = _WSNF_SEXP;
      i = skip_sed_expr (command, i, len);
    }
  else if (consume_all || !ISDELIM (wsp, command[i]))
    {
      while (i < len)
	{
	  if (comment && strchr (comment, command[i]) != NULL)
	    {
	      size_t j;
	      for (j = i + 1; j < len && command[j] != '\n'; j++)
		;
	      if (wordsplit_add_segm (wsp, start, i, 0))
		return _WRDS_ERR;
	      wsp->ws_endp = j;
	      return _WRDS_OK;
	    }

	  if (command[i] == '\\')
	    {
	      if (i + 1 == len)
		{
		  i++;
		  break;
		}
	      if (wsplt_unquote_char (wsp->ws_escape[WRDSX_WORD], command[i+1]))
		{
		  i += 2;
		  continue;
		}
	    }

	  if ((wsp->ws_flags & WRDSF_QUOTE) &&
	      (((wsp->ws_flags & WRDSF_SQUOTE) && command[i] == '\'') ||
	       ((wsp->ws_flags & WRDSF_DQUOTE) && command[i] == '"')))
	    {
	      if (join && wsp->ws_tail)
		wsp->ws_tail->flags |= _WSNF_JOIN;
	      if (wordsplit_add_segm (wsp, start, i, _WSNF_JOIN))
		return _WRDS_ERR;
	      if (scan_qstring (wsp, i, &i))
		return _WRDS_ERR;
	      start = i + 1;
	      join = 1;
	    }

	  if (command[i] == '$')
	    {
	      if ((!(wsp->ws_flags & WRDSF_NOVAR)
		   || (wsp->ws_options & WRDSO_NOVARSPLIT))
		  && command[i+1] == '{'
		  && find_closing_paren (command, i + 2, len, &i, "{}") == 0)
		continue;
	      if ((!(wsp->ws_flags & WRDSF_NOCMD)
		   || (wsp->ws_options & WRDSO_NOCMDSPLIT))
		  && command[i+1] == '('
		  && find_closing_paren (command, i + 2, len, &i, "()") == 0)
		continue;
	    }

	  if (!consume_all && ISDELIM (wsp, command[i]))
	    break;
	  else
	    i++;
	}
    }
  else if (WSP_RETURN_DELIMS (wsp))
    {
      i++;
      flags |= _WSNF_DELIM | _WSNF_NOEXPAND;
    }
  else if (!(wsp->ws_flags & WRDSF_SQUEEZE_DELIMS))
    flags |= _WSNF_EMPTYOK;

  if (join && i > start && wsp->ws_tail)
    wsp->ws_tail->flags |= _WSNF_JOIN;
  if (wordsplit_add_segm (wsp, start, i, flags))
    return _WRDS_ERR;
  wsp->ws_endp = i;
  if (wsp->ws_flags & WRDSF_INCREMENTAL)
    return _WRDS_EOF;

  if (consume_all)
    {
      if (!np)
	np = wsp->ws_head;
      while (np)
	{
	  np->flags |= _WSNF_QUOTE;
	  np = np->next;
	}
    }

  return _WRDS_OK;
}

static int
xtonum (int *pval, const char *src, int base, int cnt)
{
  int i, val;

  for (i = 0, val = 0; i < cnt; i++, src++)
    {
      int n = *(unsigned char *) src;
      if (n > 127 || (n = to_num (n)) >= base)
	break;
      val = val * base + n;
    }
  *pval = val;
  return i;
}

size_t
wordsplit_c_quoted_length (const char *str, int quote_hex, int *quote)
{
  size_t len = 0;

  *quote = 0;
  for (; *str; str++)
    {
      if (strchr (" \"", *str))
	*quote = 1;

      if (*str == ' ')
	len++;
      else if (*str == '"')
	len += 2;
      else if (*str != '\t' && *str != '\\' && ISPRINT (*str))
	len++;
      else if (quote_hex)
	len += 3;
      else
	{
	  if (wordsplit_c_quote_char (*str))
	    len += 2;
	  else
	    len += 4;
	}
    }
  return len;
}

static int
wsplt_unquote_char (const char *transtab, int c)
{
  while (*transtab && transtab[1])
    {
      if (*transtab++ == c)
	return *transtab;
      ++transtab;
    }
  return 0;
}

static int
wsplt_quote_char (const char *transtab, int c)
{
  for (; *transtab && transtab[1]; transtab += 2)
    {
      if (transtab[1] == c)
	return *transtab;
    }
  return 0;
}

int
wordsplit_c_unquote_char (int c)
{
  return wsplt_unquote_char (wordsplit_escape[WS_ESC_C], c);
}

int
wordsplit_c_quote_char (int c)
{
  return wsplt_quote_char (wordsplit_escape[WS_ESC_C], c);
}

void
wordsplit_string_unquote_copy (struct wordsplit *ws, int inquote,
			       char *dst, const char *src, size_t n)
{
  int i = 0;
  int c;

  inquote = !!inquote;
  while (i < n)
    {
      if (src[i] == '\\')
	{
	  ++i;
	  if (WRDSO_ESC_TEST (ws, inquote, WRDSO_XESC)
	      && (src[i] == 'x' || src[i] == 'X'))
	    {
	      if (n - i < 2)
		{
		  *dst++ = '\\';
		  *dst++ = src[i++];
		}
	      else
		{
		  int off = xtonum (&c, src + i + 1,
				    16, 2);
		  if (off == 0)
		    {
		      *dst++ = '\\';
		      *dst++ = src[i++];
		    }
		  else
		    {
		      *dst++ = c;
		      i += off + 1;
		    }
		}
	    }
	  else if (WRDSO_ESC_TEST (ws, inquote, WRDSO_OESC)
		   && (unsigned char) src[i] < 128 && ISDIGIT (src[i]))
	    {
	      if (n - i < 1)
		{
		  *dst++ = '\\';
		  *dst++ = src[i++];
		}
	      else
		{
		  int off = xtonum (&c, src + i, 8, 3);
		  if (off == 0)
		    {
		      *dst++ = '\\';
		      *dst++ = src[i++];
		    }
		  else
		    {
		      *dst++ = c;
		      i += off;
		    }
		}
	    }
	  else if ((c = wsplt_unquote_char (ws->ws_escape[inquote], src[i])))
	    {
	      *dst++ = c;
	      ++i;
	    }
	  else
	    {
	      if (WRDSO_ESC_TEST (ws, inquote, WRDSO_BSKEEP))
		*dst++ = '\\';
	      *dst++ = src[i++];
	    }
	}
      else
	*dst++ = src[i++];
    }
  *dst = 0;
}

void
wordsplit_c_quote_copy (char *dst, const char *src, int quote_hex)
{
  for (; *src; src++)
    {
      if (*src == '"')
	{
	  *dst++ = '\\';
	  *dst++ = *src;
	}
      else if (*src != '\t' && *src != '\\' && ISPRINT (*src))
	*dst++ = *src;
      else
	{
	  char tmp[4];

	  if (quote_hex)
	    {
	      snprintf (tmp, sizeof tmp, "%%%02X", *(unsigned char *) src);
	      memcpy (dst, tmp, 3);
	      dst += 3;
	    }
	  else
	    {
	      int c = wordsplit_c_quote_char (*src);
	      *dst++ = '\\';
	      if (c)
		*dst++ = c;
	      else
		{
		  snprintf (tmp, sizeof tmp, "%03o", *(unsigned char *) src);
		  memcpy (dst, tmp, 3);
		  dst += 3;
		}
	    }
	}
    }
}


/* This structure describes a single expansion phase */
struct exptab
{
  char const *descr; /* Textual description (for debugging) */
  int flag;          /* WRDSF_ bit that controls this phase */
  int opt;           /* Entry-specific options (see EXPOPT_ flags below */
  int (*expansion) (struct wordsplit *wsp); /* expansion function */
};

/* The following options control expansions: */
/* Normally the exptab entry is run if its flag bit is set in struct
   wordsplit.  The EXPOPT_NEG option negates this test so that expansion
   is performed if its associated flag bit is not set in struct wordsplit. */
#define EXPOPT_NEG      0x01
/* All bits in flag must be set in order for entry to match */
#define EXPORT_ALLOF    0x02
/* Coalesce the input list before running the expansion. */
#define EXPOPT_COALESCE 0x04

static struct exptab exptab[] = {
  { N_("WS trimming"),          WRDSF_WS,         0,
    wordsplit_trimws },
  { N_("command substitution"), WRDSF_NOCMD,      EXPOPT_NEG|EXPOPT_COALESCE,
    wordsplit_cmdexp },
  { N_("coalesce list"),        0,                EXPOPT_NEG|EXPOPT_COALESCE,
    NULL },
  { N_("tilde expansion"),      WRDSF_PATHEXPAND, 0,
    wordsplit_tildexpand },
  { N_("variable expansion"),   WRDSF_NOVAR,      EXPOPT_NEG,
    wordsplit_varexp },
  { N_("quote removal"),        0,                EXPOPT_NEG,
    wsnode_quoteremoval },
  { N_("coalesce list"),        0,                EXPOPT_NEG|EXPOPT_COALESCE,
    NULL },
  { N_("path expansion"),       WRDSF_PATHEXPAND, 0,
    wordsplit_pathexpand },
  { NULL }
};

static inline int
exptab_matches(struct exptab *p, struct wordsplit *wsp)
{
  int result;

  result = (wsp->ws_flags & p->flag);
  if (p->opt & EXPORT_ALLOF)
    result = result == p->flag;
  if (p->opt & EXPOPT_NEG)
    result = !result;

  return result;
}

static int
wordsplit_process_list (struct wordsplit *wsp, size_t start)
{
  struct exptab *p;

  if (wsp->ws_flags & WRDSF_SHOWDBG)
    wsp->ws_debug (_("(%02d) Input:%.*s;"),
		   wsp->ws_lvl, (int) wsp->ws_len, wsp->ws_input);

  if ((wsp->ws_flags & WRDSF_NOSPLIT)
      || ((wsp->ws_options & WRDSO_MAXWORDS)
	  && wsp->ws_wordi + 1 == wsp->ws_maxwords))
    {
      /* Treat entire input as a single word */
      if (scan_word (wsp, start, 1) == _WRDS_ERR)
	return wsp->ws_errno;
    }
  else
    {
      int rc;

      while ((rc = scan_word (wsp, start, 0)) == _WRDS_OK)
	start = skip_delim (wsp);
      /* Make sure tail element is not joinable */
      if (wsp->ws_tail)
	wsp->ws_tail->flags &= ~_WSNF_JOIN;
      if (rc == _WRDS_ERR)
	return wsp->ws_errno;
    }

  if (wsp->ws_flags & WRDSF_SHOWDBG)
    {
      wsp->ws_debug ("(%02d) %s", wsp->ws_lvl, _("Initial list:"));
      wordsplit_dump_nodes (wsp);
    }

  for (p = exptab; p->descr; p++)
    {
      if (exptab_matches(p, wsp))
	{
	  if (p->opt & EXPOPT_COALESCE)
	    {
	      if (wsnode_coalesce (wsp))
		break;
	      if (wsp->ws_flags & WRDSF_SHOWDBG)
		{
		  wsp->ws_debug ("(%02d) %s", wsp->ws_lvl,
				 _("Coalesced list:"));
		  wordsplit_dump_nodes (wsp);
		}
	    }
	  if (p->expansion)
	    {
	      if (p->expansion (wsp))
		break;
	      if (wsp->ws_flags & WRDSF_SHOWDBG)
		{
		  wsp->ws_debug ("(%02d) %s", wsp->ws_lvl, _(p->descr));
		  wordsplit_dump_nodes (wsp);
		}
	    }
	}
    }

  return wsp->ws_errno;
}

static int
wordsplit_run (const char *command, size_t length, struct wordsplit *wsp,
	       int flags, int lvl)
{
  int rc;
  size_t start;

  /* Initialize error context early */
  wsp->ws_errctx = NULL;
  if (!command)
    {
      if (!(flags & WRDSF_INCREMENTAL))
	{
	  /* Make sure _wsplt_seterr gets correct flags. */
	  wsp->ws_flags = flags;
	  return _wsplt_seterr (wsp, WRDSE_USAGE);
	}

      if (wsp->ws_head)
	return wordsplit_finish (wsp);

      start = skip_delim_real (wsp);
      if (wsp->ws_endp == wsp->ws_len)
	return _wsplt_seterr (wsp, WRDSE_NOINPUT);

      wsp->ws_flags |= WRDSF_REUSE;
      wordsplit_init0 (wsp);
    }
  else
    {
      start = 0;
      rc = wordsplit_init (wsp, command, length, flags);
      if (rc)
	return rc;
      wsp->ws_lvl = lvl;
    }

  rc = wordsplit_process_list (wsp, start);
  if (rc)
    return rc;
  return wordsplit_finish (wsp);
}

int
wordsplit_len (const char *command, size_t length, struct wordsplit *wsp,
	       int flags)
{
  return wordsplit_run (command, length, wsp, flags, 0);
}

int
wordsplit (const char *command, struct wordsplit *ws, int flags)
{
  return wordsplit_len (command, command ? strlen (command) : 0, ws, flags);
}

void
wordsplit_free_words (struct wordsplit *ws)
{
  size_t i;

  for (i = 0; i < ws->ws_wordc; i++)
    {
      char *p = ws->ws_wordv[ws->ws_offs + i];
      if (p)
	{
	  free (p);
	  ws->ws_wordv[ws->ws_offs + i] = NULL;
	}
    }
  ws->ws_wordc = 0;
}

void
wordsplit_free_envbuf (struct wordsplit *ws)
{
  if (!(ws->ws_flags & WRDSF_ENV))
    return;
  if (ws->ws_envbuf)
    {
      size_t i;

      for (i = 0; ws->ws_envbuf[i]; i++)
	free (ws->ws_envbuf[i]);
      free (ws->ws_envbuf);
      ws->ws_envidx = ws->ws_envsiz = 0;
      ws->ws_envbuf = NULL;
    }
}

void
wordsplit_free_parambuf (struct wordsplit *ws)
{
  if (!(ws->ws_options & WRDSO_PARAMV))
    return;
  if (ws->ws_parambuf)
    {
      size_t i;

      for (i = 0; ws->ws_parambuf[i]; i++)
	free (ws->ws_parambuf[i]);
      free (ws->ws_parambuf);
      ws->ws_paramidx = ws->ws_paramsiz = 0;
      ws->ws_parambuf = NULL;
    }
}

void
wordsplit_clearerr (struct wordsplit *ws)
{
  if (ws->ws_errno == WRDSE_USERERR)
    free (ws->ws_usererr);
  ws->ws_usererr = NULL;

  free (ws->ws_errctx);
  ws->ws_errctx = NULL;

  ws->ws_errno = WRDSE_OK;
}

void
wordsplit_free (struct wordsplit *ws)
{
  if (ws->ws_errno == WRDSE_USAGE)
    /* Usage error: the structure is not properly initialized and there's
       nothing to free. */
    return;
  wordsplit_clearerr (ws);
  wordsplit_free_nodes (ws);
  wordsplit_free_words (ws);
  free (ws->ws_wordv);
  ws->ws_wordv = NULL;
  wordsplit_free_envbuf (ws);
  wordsplit_free_parambuf (ws);
}

int
wordsplit_get_words (struct wordsplit *ws, size_t *wordc, char ***wordv)
{
  char **p = realloc (ws->ws_wordv,
		      (ws->ws_wordc + 1) * sizeof (ws->ws_wordv[0]));
  if (!p)
    return -1;
  *wordv = p;
  *wordc = ws->ws_wordc;

  ws->ws_wordv = NULL;
  ws->ws_wordc = 0;
  ws->ws_wordn = 0;

  return 0;
}

const char *_wordsplit_errstr[] = {
  N_("no error"),
  N_("missing closing quote"),
  N_("memory exhausted"),
  N_("invalid wordsplit usage"),
  N_("unbalanced curly brace"),
  N_("undefined variable"),
  N_("input exhausted"),
  N_("unbalanced parenthesis"),
  N_("globbing error"),
  N_("user-defined error"),
  N_("invalid parameter number in assignment")
};
int _wordsplit_nerrs =
  sizeof (_wordsplit_errstr) / sizeof (_wordsplit_errstr[0]);

const char *
wordsplit_strerror (struct wordsplit *ws)
{
  if (ws->ws_errno == WRDSE_USERERR)
    return ws->ws_usererr;
  if (ws->ws_errno < _wordsplit_nerrs)
    return _wordsplit_errstr[ws->ws_errno];
  return N_("unknown error");
}

void
wordsplit_perror (struct wordsplit *wsp)
{
  switch (wsp->ws_errno)
    {
    case WRDSE_QUOTE:
      wsp->ws_error (_("missing closing %c (start near #%lu)"),
		     wsp->ws_input[wsp->ws_endp],
		     (unsigned long) wsp->ws_endp);
      break;

    default:
      if (wsp->ws_errctx)
	wsp->ws_error ("%s: %s", wordsplit_strerror (wsp), wsp->ws_errctx);
      else
	wsp->ws_error ("%s", wordsplit_strerror (wsp));
    }
}