braces.c

/* braces.c -- code for doing word expansion in curly braces. */

/* Copyright (C) 1987-2020,2022-2025 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/>.
*/

/* Stuff in curly braces gets expanded before all other shell expansions. */

#include "config.h"

#if defined (BRACE_EXPANSION)

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include <errno.h>
#include <stdckdint.h>

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

#if defined (SHELL)
#  include "shell.h"
#  include "parser.h"		/* FUNSUB_CHAR */
#else
#  if defined (TEST)
typedef char *WORD_DESC;
typedef char **WORD_LIST;
#define _(X)	X
#  endif /* TEST */
#endif /* SHELL */

#include "typemax.h"		/* INTMAX_MIN, INTMAX_MAX */
#include "general.h"
#include "shmbutil.h"
#include "chartypes.h"

#ifndef errno
extern int errno;
#endif

#define brace_whitespace(c) (!(c) || (c) == ' ' || (c) == '\t' || (c) == '\n')

#define BRACE_SEQ_SPECIFIER	".."

/* What kind of brace expansion do we think we have? brace_gobbler() decides. */
#define BRACE_COMMA	0x01
#define BRACE_SEQ	0x02
#define BRACE_NONE	0x04

extern int asprintf (char **, const char *, ...) __attribute__((__format__ (printf, 2, 3)));

/* Basic idea:

   Segregate the text into 3 sections: preamble (stuff before an open brace),
   postamble (stuff after the matching close brace) and amble (stuff after
   preamble, and before postamble).  Expand amble, and then tack on the
   expansions to preamble.  Expand postamble, and tack on the expansions to
   the result so far.
 */

/* The character which is used to separate arguments. */
static const int brace_arg_separator = ',';

static int brace_gobbler (char *, size_t, int *, int *, int);
static char **expand_amble (char *, size_t, int);
static char **expand_seqterm (char *, size_t);
static int valid_seqterm (char *, size_t);
static char **mkseq (intmax_t, intmax_t, intmax_t, int, size_t);
static char **array_concat (char **, char **);

#if 0
static void
dump_result (a)
     char **a;
{
  int i;

  for (i = 0; a[i]; i++)
    printf ("dump_result: a[%d] = -%s-\n", i, a[i]);
}
#endif

/* Return an array of strings; the brace expansion of TEXT. */
char **
brace_expand (char *text)
{
  int start;
  size_t tlen;
  char *preamble, *postamble, *amble;
  size_t alen;
  char **tack, **result;
  int i, j, c, c1, etype;

  DECLARE_MBSTATE;

  /* Find the text of the preamble. */
  tlen = strlen (text);
  i = 0;
#if defined (CSH_BRACE_COMPAT)
  c = brace_gobbler (text, tlen, &i, (int *)NULL, '{');	/* } */
#else
  /* Make sure that when we exit this loop, c == 0 or text[i] begins a
     valid brace expansion sequence. */
  do
    {
      c = brace_gobbler (text, tlen, &i, (int *)NULL, '{');	/* } */
      if (i >= tlen)
	break;
      c1 = c;
      /* Verify that c begins a valid brace expansion word.  If it doesn't, we
	 go on.  Loop stops when there are no more open braces in the word. */
      if (c)
	{
	  start = j = i + 1;	/* { */
	  c = brace_gobbler (text, tlen, &j, &etype, '}');
#if 1
	  /* One alternative is to perform validity checking on the sequence
	     terms here. If the sequence expression is invalid, we just skip
	     over the open brace and go on, leaving other brace expressions in
	     the candidate sequence expression to be expanded. */
	  if (etype == BRACE_SEQ && valid_seqterm (text + start, j - start) == 0)
	    c = 0;
#endif

	  if (c == 0)		/* it's not */
	    {
	      i++;
	      c = c1;
	      continue;
	    }
	  else			/* it is */
	    {
	      c = c1;
	      break;
	    }
	}
      else
	break;
    }
  while (c);
#endif /* !CSH_BRACE_COMPAT */

  preamble = (char *)xmalloc (i + 1);
  if (i > 0)
    strncpy (preamble, text, i);
  preamble[i] = '\0';

  result = (char **)xmalloc (2 * sizeof (char *));
  result[0] = preamble;
  result[1] = (char *)NULL;

  /* Special case.  If we never found an exciting character, then
     the preamble is all of the text, so just return that. */
  if (c != '{')
    return (result);

  /* Find the amble.  This is the stuff inside this set of braces. */
  start = ++i;
  c = brace_gobbler (text, tlen, &i, &etype, '}');

  /* What if there isn't a matching close brace? */
  if (c == 0)
    {
#if defined (NOTDEF)
      /* Well, if we found an unquoted BRACE_ARG_SEPARATOR between START
	 and I, then this should be an error.  Otherwise, it isn't. */
      j = start;
      while (j < i)
	{
	  if (text[j] == '\\')
	    {
	      j++;
	      ADVANCE_CHAR (text, tlen, j);
	      continue;
	    }

	  if (text[j] == brace_arg_separator)
	    {	/* { */
	      strvec_dispose (result);
	      set_exit_status (EXECUTION_FAILURE);
	      report_error ("no closing `%c' in %s", '}', text);
	      throw_to_top_level ();
	    }
	  ADVANCE_CHAR (text, tlen, j);
	}
#endif
      free (preamble);		/* Same as result[0]; see initialization. */
      result[0] = savestring (text);
      return (result);
    }

#if defined (SHELL)
  amble = substring (text, start, i);
  alen = i - start;
#else
  amble = (char *)xmalloc (1 + (i - start));
  strncpy (amble, &text[start], (i - start));
  alen = i - start;
  amble[alen] = '\0';
#endif

#if defined (SHELL)
  INITIALIZE_MBSTATE;

  /* If the amble does not contain an unquoted BRACE_ARG_SEPARATOR, and we
     think we have a BRACE_COMMA-separated sequence, then do no expansion. */
  j = 0;
  while (amble[j])
    {
      if (amble[j] == '\\')
	{
	  j++;
	  ADVANCE_CHAR (amble, alen, j);
	  continue;
	}

      if (amble[j] == brace_arg_separator && etype == BRACE_COMMA)
	break;

      ADVANCE_CHAR (amble, alen, j);
    }

  /* If we think we have a sequence expression, try to expand it. */
  if (amble[j] == 0 && etype == BRACE_SEQ)
    {
      /* The other alternative (see call to valid_seqterm() above) is to
	 perform the validity checking in expand_seqterm(). If we do this,
	 and the sequence isn't valid, we just treat the entire candidate
	 sequence expansion as a single unexpanded string. */
      tack = expand_seqterm (amble, alen);
      if (tack)
	goto add_tack;
      else if (i < tlen && text[i + 1])
	{
	  /* If the sequence expansion fails (e.g., because the integers
	     overflow), but there is more in the string, try and process
	     the rest of the string, which may contain additional brace
	     expansions.  Treat the unexpanded sequence term as a simple
	     string (including the braces). */
	  tack = strvec_create (2);
	  tack[0] = savestring (text+start-1);
	  tack[0][i-start+2] = '\0';
	  tack[1] = (char *)0;
	  goto add_tack;
	}
      else
	{
	  free (amble);
	  free (preamble);
	  result[0] = savestring (text);
	  return (result);
	}
    }
#endif /* SHELL */

  tack = expand_amble (amble, alen, 0);
add_tack:
  result = array_concat (result, tack);
  free (amble);
  if (tack != result)
    strvec_dispose (tack);

  postamble = text + i + 1;

  if (postamble && *postamble)
    {
      tack = brace_expand (postamble);
      result = array_concat (result, tack);
      if (tack != result)
	strvec_dispose (tack);
    }

  return (result);
}

/* Expand the text found inside of braces.  We simply try to split the
   text at BRACE_ARG_SEPARATORs into separate strings.  We then brace
   expand each slot which needs it, until there are no more slots which
   need it. */
static char **
expand_amble (char *text, size_t tlen, int flags)
{
  char **result, **partial, **tresult;
  char *tem;
  int start, i, c;

#if defined (SHELL)
  DECLARE_MBSTATE;
#endif

  result = (char **)NULL;

  start = i = 0;
  c = 1;
  while (c)
    {
      c = brace_gobbler (text, tlen, &i, (int *)NULL, brace_arg_separator);
#if defined (SHELL)
      tem = substring (text, start, i);
#else
      tem = (char *)xmalloc (1 + (i - start));
      strncpy (tem, &text[start], (i - start));
      tem[i - start] = '\0';
#endif

      partial = brace_expand (tem);

      if (!result)
	result = partial;
      else
	{
	  size_t lr, lp;
	  int j;

	  lr = strvec_len (result);
	  lp = strvec_len (partial);

	  tresult = strvec_mresize (result, lp + lr + 1);
	  if (tresult == 0)
	    {
	      internal_error (_("brace expansion: cannot allocate memory for %s"), tem);
	      free (tem);
	      strvec_dispose (partial);
	      strvec_dispose (result);
	      result = (char **)NULL;
	      return result;
	    }
	  else
	    result = tresult;

	  for (j = 0; j < lp; j++)
	    result[lr + j] = partial[j];

	  result[lr + j] = (char *)NULL;
	  free (partial);
	}
      free (tem);
#if defined (SHELL)
      ADVANCE_CHAR (text, tlen, i);
#else
      i++;
#endif
      start = i;
    }
  return (result);
}

#define ST_BAD	0
#define ST_INT	1
#define ST_CHAR	2
#define ST_ZINT	3

static char **
mkseq (intmax_t start, intmax_t end, intmax_t incr, int type, size_t width)
{
  intmax_t prevn, n, abs_incr;
  size_t nelem, i;
  char **result, *t;
  char lbuf[INT_BUFSIZE_BOUND (uintmax_t)];

  if (incr == 0)
    incr = 1;

  abs_incr = incr;
  if (incr < 0 && ckd_sub (&abs_incr, 0, incr))
    return ((char **)NULL);

  /* Make sure incr agrees with start and end */
  if ((start < end) == (incr < 0) && ckd_sub (&incr, 0, incr))
    return ((char **)NULL);

  /* prevn = sh_imaxabs (end - start); */
  if (start < end ? ckd_sub (&prevn, end, start) : ckd_sub (&prevn, start, end))
    return ((char **)NULL);

  /* nelem = floor (abs ((end - start) / incr)) plus 1 for first element plus
     trailing null. Account for trailing null up here for overflow check */
  if (ckd_add (&nelem, prevn / abs_incr, 2))
    return ((char **)NULL);

  result = strvec_mcreate (nelem);
  if (result == 0)
    {
      internal_error (_("brace expansion: failed to allocate memory for %s elements"), uinttostr (nelem - 1, lbuf, sizeof (lbuf)));
      return ((char **)NULL);
    }

  /* Make sure we go through the loop at least once, so {3..3} prints `3' */
  i = 0;
  n = start;
  do
    {
#if defined (SHELL)
      if (ISINTERRUPT)
        {
          result[i] = (char *)NULL;
          strvec_dispose (result);
          result = (char **)NULL;
        }
      QUIT;
#endif
      if (type == ST_INT)
	t = itos (n);
      else if (type == ST_ZINT)
	{
	  size_t tlen;

	  t = itos (n);
	  tlen = strlen (t);
	  if (tlen < width)	/* zero-pad the result directly to avoid sprintf */
	    {
	      char *t0;
	      t0 = t;
	      t = realloc (t, width + 1);
	      if (t == 0)
		free (t0);
	      else
		{
		  memmove (t + (width - tlen), t, tlen + 1);
		  memset (t + (n < 0), '0', width - tlen);
		}
	    }
	}
      else
	{
	  if (t = (char *)malloc (2))
	    {
	      t[0] = n;
	      t[1] = '\0';
	    }
	}

      result[i++] = t;

      /* We failed to allocate memory for this number, so we bail. */
      if (t == 0)
	{
	  char *p;

	  /* Easier to do this than mess around with various intmax_t printf
	     formats (%ld? %lld? %jd?) and PRIdMAX. */
	  p = uinttostr (n, lbuf, sizeof (lbuf));
	  internal_error (_("brace expansion: failed to allocate memory for `%s'"), p);
	  strvec_dispose (result);
	  return ((char **)NULL);
	}

      if (i >= nelem - 1)
	break;

      n += incr;
    }
  while (1);

  result[i] = (char *)0;
  return (result);
}

/* For now. */
static int
valid_seqterm (char *text, size_t tlen)
{
  char *t, *lhs, *rhs;
  int lhs_t, rhs_t;
  int c;

  c = text[tlen];	/* XXX - text[tlen] == RBRACE */
  text[tlen] = '\0';	/* don't be tricked by something later in the string */
  t = strstr (text, BRACE_SEQ_SPECIFIER);
  text[tlen] = c;
    
  if (t == 0)
    return 0;		/* invalid */
  
  lhs = text;
  rhs = t + sizeof(BRACE_SEQ_SPECIFIER) - 1;

  /*{*/
  if (lhs[0] == BRACE_SEQ_SPECIFIER[0] || rhs[0] == '}')
    return 0;		/* invalid */

  /* Now figure out whether LHS and RHS are integers or letters.  Both
     sides have to match. Minimal checking here, just enough to throw out the
     obvious invalid candidates. */
  lhs_t = (ISDIGIT (lhs[0]) || ((lhs[0] == '+' || lhs[0] == '-') && ISDIGIT (lhs[1]))) ? ST_INT :
	    (ISALPHA (lhs[0]) && lhs[1] == '.') ?  ST_CHAR : ST_BAD;

  rhs_t = (ISDIGIT (rhs[0]) || ((rhs[0] == '+' || rhs[0] == '-') && ISDIGIT (rhs[1]))) ? ST_INT :
/*{*/	    (ISALPHA (rhs[0]) && (rhs[1] == '}' || rhs[1] == '.')) ? ST_CHAR : ST_BAD;

  if (lhs_t != rhs_t || lhs_t == ST_BAD || rhs_t == ST_BAD)
    return 0;		/* invalid */

  return 1;
}

static char **
expand_seqterm (char *text, size_t tlen)
{
  char *t, *lhs, *rhs;
  int lhs_t, rhs_t;
  size_t lhs_l, rhs_l, width;
  intmax_t lhs_v, rhs_v, incr;
  intmax_t tl, tr;
  char **result, *ep, *oep;

  t = strstr (text, BRACE_SEQ_SPECIFIER);
  if (t == 0)
    return ((char **)NULL);

  lhs_l = t - text;		/* index of start of BRACE_SEQ_SPECIFIER */
  lhs = substring (text, 0, lhs_l);
  rhs = substring (text, lhs_l + sizeof(BRACE_SEQ_SPECIFIER) - 1, tlen);

  if (lhs[0] == 0 || rhs[0] == 0)
    {
      free (lhs);
      free (rhs);
      return ((char **)NULL);
    }

  /* Now figure out whether LHS and RHS are integers or letters.  Both
     sides have to match. */
  lhs_t = (valid_number (lhs, &tl)) ? ST_INT :
  		((ISALPHA (lhs[0]) && lhs[1] == 0) ?  ST_CHAR : ST_BAD);

  /* Decide on rhs and whether or not it looks like the user specified
     an increment */
  ep = 0;
  if (ISDIGIT (rhs[0]) || ((rhs[0] == '+' || rhs[0] == '-') && ISDIGIT (rhs[1])))
    {
      rhs_t = ST_INT;
      errno = 0;
      tr = strtoimax (rhs, &ep, 10);
      if (errno == ERANGE || (ep && *ep != 0 && *ep != '.'))
	rhs_t = ST_BAD;			/* invalid */
    }
  else if (ISALPHA (rhs[0]) && (rhs[1] == 0 || rhs[1] == '.'))
    {
      rhs_t = ST_CHAR;
      ep = rhs + 1;
    }
  else
    {
      rhs_t = ST_BAD;
      ep = 0;
    }

  incr = 1;
  if (rhs_t != ST_BAD)
    {
      oep = ep;
      errno = 0;
      if (ep && *ep == '.' && ep[1] == '.' && ep[2])
	incr = strtoimax (ep + 2, &ep, 10);
      if (*ep != 0 || errno == ERANGE)
	rhs_t = ST_BAD;			/* invalid incr or overflow */
      tlen -= ep - oep;
    }

  if (lhs_t != rhs_t || lhs_t == ST_BAD || rhs_t == ST_BAD)
    {
      free (lhs);
      free (rhs);
      return ((char **)NULL);
    }

  /* OK, we have something.  It's either a sequence of integers, ascending
     or descending, or a sequence or letters, ditto.  Generate the sequence,
     put it into a string vector, and return it. */
  
  if (lhs_t == ST_CHAR)
    {
      lhs_v = (unsigned char)lhs[0];
      rhs_v = (unsigned char)rhs[0];
      width = 1;
    }
  else
    {
      lhs_v = tl;		/* integer truncation */
      rhs_v = tr;

      /* Decide whether or not the terms need zero-padding */
      rhs_l = tlen - lhs_l - sizeof (BRACE_SEQ_SPECIFIER) + 1;
      width = 0;
      if (lhs_l > 1 && lhs[0] == '0')
	width = lhs_l, lhs_t = ST_ZINT;
      if (lhs_l > 2 && lhs[0] == '-' && lhs[1] == '0')
	width = lhs_l, lhs_t = ST_ZINT;
      if (rhs_l > 1 && rhs[0] == '0' && width < rhs_l)
	width = rhs_l, lhs_t = ST_ZINT;
      if (rhs_l > 2 && rhs[0] == '-' && rhs[1] == '0' && width < rhs_l)
	width = rhs_l, lhs_t = ST_ZINT;

      if (width < lhs_l && lhs_t == ST_ZINT)
        width = lhs_l;
      if (width < rhs_l && lhs_t == ST_ZINT)
        width = rhs_l;
    }

  result = mkseq (lhs_v, rhs_v, incr, lhs_t, width);

  free (lhs);
  free (rhs);

  return (result);
}

/* Start at INDEX, and skip characters in TEXT. Set INDEX to the
   index of the character matching SATISFY.  This understands about
   quoting.  Return the character that caused us to stop searching;
   this is either the same as SATISFY, or 0. */
/* If SATISFY is `}', we are looking for a brace expression, so we
   should enforce the rules that govern valid brace expansions:
	1) to count as an arg separator, a comma or `..' has to be outside
	   an inner set of braces.	 
*/
static int
brace_gobbler (char *text, size_t tlen, int *indx, int *typep, int satisfy)
{
  int i, c, quoted, level, commas, pass_next, btype;
#if defined (SHELL)
  size_t si;
  char *t;
#endif
  DECLARE_MBSTATE;

  level = quoted = pass_next = 0;
  btype = BRACE_NONE;
#if defined (CSH_BRACE_COMPAT)
  commas = 1;
#else
  commas = (satisfy == '}') ? 0 : 1;
#endif

  i = *indx;
  while (c = text[i])
    {
      if (pass_next)
	{
	  pass_next = 0;
#if defined (SHELL)
	  ADVANCE_CHAR (text, tlen, i);
#else
	  i++;
#endif
	  continue;
	}

      /* A backslash escapes the next character.  This allows backslash to
	 escape the quote character in a double-quoted string. */
      if (c == '\\' && (quoted == 0 || quoted == '"' || quoted == '`'))
	{
	  pass_next = 1;
	  i++;
	  continue;
	}

#if defined (SHELL)
      /* If compiling for the shell, treat ${...} like \{...} */
      if (c == '$' && i < tlen && text[i+1] == '{' && quoted != '\'')		/* } */
	{
#if 1
	  /* nofork command substitution */
	  if (i < tlen - 1 && FUNSUB_CHAR (text[i+2]))
	    {
	      int o, f;
funsub:
	      o = no_longjmp_on_fatal_error;
	      no_longjmp_on_fatal_error = 1;
	      f = (quoted == '"') ? Q_DOUBLE_QUOTES : 0;
	      si = i + 2;
	      t = extract_function_subst (text, &si, f, SX_NOALLOC|SX_NOLONGJMP|SX_NOERROR);
	      i = si + 1;
	      no_longjmp_on_fatal_error = o;
	      if (i > tlen)
		{
	          i = tlen;
	          c = 0;
	          break;
		}
	      continue;
	    }
#endif
	  pass_next = 1;
	  i++;
	  if (quoted == 0)
	    level++;
	  continue;
	}
#endif

      if (quoted)
	{
	  if (c == quoted)
	    quoted = 0;
#if defined (SHELL)
	  /* The shell allows quoted command substitutions */
	  if (quoted == '"' && c == '$' && i < tlen && text[i+1] == '(')	/*)*/
	    goto comsub;
#endif
#if defined (SHELL)
	  ADVANCE_CHAR (text, tlen, i);
#else
	  i++;
#endif
	  continue;
	}

      if (c == '"' || c == '\'' || c == '`')
	{
	  quoted = c;
	  i++;
	  continue;
	}

#if defined (SHELL)
      /* Pass new-style command and process substitutions through unchanged. */
      if ((c == '$' || c == '<' || c == '>') && i < tlen && text[i+1] == '(')	/* ) */
	{
	  int o;

comsub:
	  o = no_longjmp_on_fatal_error;
	  no_longjmp_on_fatal_error = 1;
	  si = i + 2;
	  t = extract_command_subst (text, &si, SX_NOALLOC|SX_NOLONGJMP|SX_NOERROR);
	  i = si + 1;
	  no_longjmp_on_fatal_error = o;
	  if (i > tlen)
	    {
	      i = tlen;
	      c = 0;
	      break;
	    }
	  continue;
	}
#endif

      if (c == satisfy && level == 0 && quoted == 0 && commas > 0)
	{
	  /* We ignore an open brace surrounded by whitespace, and also
	     an open brace followed immediately by a close brace preceded
	     by whitespace.  */
	  if (c == '{' &&
	      ((!i || brace_whitespace (text[i - 1])) &&
	       (brace_whitespace (text[i + 1]) || text[i + 1] == '}')))
	    {
	      i++;
	      continue;
	    }

	    break;
	}

      if (c == '{')
	level++;
      else if (c == '}' && level)
	level--;
#if !defined (CSH_BRACE_COMPAT)
      else if (satisfy == '}' && c == brace_arg_separator && level == 0)
	{
	  btype = BRACE_COMMA;
	  commas++;
	}
      else if (satisfy == '}' && STREQN (text+i, BRACE_SEQ_SPECIFIER, 2) &&
      		text[i+2] != satisfy && level == 0 && btype == BRACE_NONE)
	{
	  /* The check against BRACE_NONE gives the comma higher precedence */
	  btype = BRACE_SEQ;
	  commas++;
	}
#endif

#if defined (SHELL)
      ADVANCE_CHAR (text, tlen, i);
#else
      i++;
#endif
    }

  *indx = i;
  if (typep)
    *typep = btype;
  return (c);
}

/* Return a new array of strings which is the result of appending each
   string in ARR2 to each string in ARR1.  The resultant array is
   len (arr1) * len (arr2) long.  For convenience, ARR1 (and its contents)
   are free ()'ed.  ARR1 can be NULL, in that case, a new version of ARR2
   is returned. */
static char **
array_concat (char **arr1, char **arr2)
{
  int i, j, len;
  size_t len1, len2;
  char **result;

  if (arr1 == 0)
    return (arr2);		/* XXX - see if we can get away without copying? */

  if (arr2 == 0)
    return (arr1);		/* XXX - caller expects us to free arr1 */

  /* We can only short-circuit if the array consists of a single null element;
     otherwise we need to replicate the contents of the other array and
     prefix (or append, below) an empty element to each one. */
  if (arr1[0] && arr1[0][0] == 0 && arr1[1] == 0)
    {
      strvec_dispose (arr1);
      return (arr2);		/* XXX - use flags to see if we can avoid copying here */
    }

  if (arr2[0] && arr2[0][0] == 0 && arr2[1] == 0)
    return (arr1);		/* XXX - rather than copying and freeing it */

  len1 = strvec_len (arr1);
  len2 = strvec_len (arr2);

  result = (char **)malloc ((1 + (len1 * len2)) * sizeof (char *));
  if (result == 0)
    return (result);

  len = 0;
  for (i = 0; i < len1; i++)
    {
      int strlen_1 = strlen (arr1[i]);

      for (j = 0; j < len2; j++)
	{
#if defined (SHELL)
	  if (ISINTERRUPT)
	    {
	      result[len] = (char *)NULL;
	      strvec_dispose (result);
	      result = (char **)NULL;
	      strvec_dispose (arr1);	/* caller expects us to free arr1 */
	    }
	  QUIT;
#endif
	
	  result[len] = (char *)xmalloc (1 + strlen_1 + strlen (arr2[j]));
	  strcpy (result[len], arr1[i]);
	  strcpy (result[len] + strlen_1, arr2[j]);
	  len++;
	}
      free (arr1[i]);
    }
  free (arr1);

  result[len] = (char *)NULL;
  return (result);
}

#if defined (TEST)
#include <stdio.h>

void *
xmalloc(size_t n)
{
  return (malloc (n));
}

void *
xrealloc(void *p, size_t n)
{
  return (realloc (p, n));
}

int
internal_error (char *format, char *arg1, char *arg2)
{
  fprintf (stderr, format, arg1, arg2);
  fprintf (stderr, "\n");
}
      
main (int c, char **v)
{
  char example[256];

  for (;;)
    {
      char **result;
      int i;

      fprintf (stderr, "brace_expand> ");

      if ((!fgets (example, 256, stdin)) ||
	  (strncmp (example, "quit", 4) == 0))
	break;

      if (strlen (example))
	example[strlen (example) - 1] = '\0';

      result = brace_expand (example);

      for (i = 0; result[i]; i++)
	printf ("%s\n", result[i]);

      strvec_dispose (result);
    }
}

/*
 * Local variables:
 * compile-command: "gcc -g -Bstatic -DTEST -o brace_expand braces.c general.o"
 * end:
 */

#endif /* TEST */
#endif /* BRACE_EXPANSION */