Add in wordexp support (mostly stubbed out for now) since the busybox

shell, lash, is about to start using wordexp.
 -Erik

5 files changed, 2735 insertions, 1 deletions

diff --git a/include/string.h b/include/string.h
index 58614b291..6dff15b2d 100644
--- a/include/string.h
+++ b/include/string.h
@@ -118,4 +118,29 @@ int bcmp(const void *s1, const void *s2, size_t n);
 /* Linux silly hour */
 char *strfry __P ((char *));
 
+/* Find the length of STRING, but scan at most MAXLEN characters.
+   If no '\0' terminator is found in that many characters, return MAXLEN.  */
+extern size_t strnlen __P ((__const char *__string, size_t __maxlen));
+
+/* Duplicate S, returning an identical alloca'd string.  */
+# define strdupa(s)							      \
+  (__extension__							      \
+    ({									      \
+      __const char *__old = (s);					      \
+      size_t __len = strlen (__old) + 1;				      \
+      char *__new = __builtin_alloca (__len);				      \
+      (char *) memcpy (__new, __old, __len);				      \
+    }))
+
+/* Return an alloca'd copy of at most N bytes of string.  */
+# define strndupa(s, n)							      \
+  (__extension__							      \
+    ({									      \
+      __const char *__old = (s);					      \
+      size_t __len = strnlen (__old, (n));				      \
+      char *__new = __builtin_alloca (__len + 1);			      \
+      __new[__len] = '\0';						      \
+      (char *) memcpy (__new, __old, __len);				      \
+    }))
+
 #endif
diff --git a/libc/misc/Makefile b/libc/misc/Makefile
index ae61b13a7..6334bcf15 100644
--- a/libc/misc/Makefile
+++ b/libc/misc/Makefile
@@ -25,7 +25,8 @@ include $(TOPDIR)Rules.mak
 LIBC=$(TOPDIR)libc.a
 
 
-DIRS = assert crypt ctype fnmatch glob internals lsearch mntent syslog shm time utmp tsearch
+DIRS = assert crypt ctype fnmatch glob internals lsearch mntent syslog shm \
+	time utmp tsearch #wordexp
 
 # regex bombs out with an internal compiler error using m68k-pic-coff-gcc.
 ifneq ($(TARGET_ARCH),m68k)
diff --git a/libc/misc/wordexp/Makefile b/libc/misc/wordexp/Makefile
new file mode 100644
index 000000000..731dc919b
--- /dev/null
+++ b/libc/misc/wordexp/Makefile
@@ -0,0 +1,45 @@
+# Makefile for uClibc
+#
+# Copyright (C) 2000 by Lineo, inc.
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU Library General Public License as published by the Free
+# Software Foundation; either version 2 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 Library General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Library General Public License
+# along with this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+#
+# Derived in part from the Linux-8086 C library, the GNU C Library, and several
+# other sundry sources.  Files within this library are copyright by their
+# respective copyright holders.
+
+TOPDIR=../../
+include $(TOPDIR)Rules.mak
+LIBC=$(TOPDIR)libc.a
+
+#CSRC=wordexp.c
+CSRC=wordexp_stub.c
+COBJS=$(patsubst %.c,%.o, $(CSRC))
+OBJS=$(COBJS)
+
+all: $(OBJS) $(LIBC)
+
+$(LIBC): ar-target
+
+ar-target: $(OBJS)
+	$(AR) $(ARFLAGS) $(LIBC) $(OBJS)
+
+$(COBJS): %.o : %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+	$(STRIPTOOL) -x -R .note -R .comment $*.o
+
+clean:
+	rm -f *.[oa] *~ core
+
diff --git a/libc/misc/wordexp/wordexp.c b/libc/misc/wordexp/wordexp.c
new file mode 100644
index 000000000..9e468d6a5
--- /dev/null
+++ b/libc/misc/wordexp/wordexp.c
@@ -0,0 +1,2411 @@
+/* POSIX.2 wordexp implementation.
+   Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Tim Waugh <tim@cyberelk.demon.co.uk>.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <wordexp.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <pwd.h>
+#include <sys/types.h>
+#include <string.h>
+#include <glob.h>
+#include <ctype.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <paths.h>
+#include <errno.h>
+#include <sys/param.h>
+#include <stdio.h>
+#include <fnmatch.h>
+
+/* Undefine the following line for the production version.  */
+/* #define NDEBUG 1 */
+#include <assert.h>
+
+/*
+ * This is a recursive-descent-style word expansion routine.
+ */
+
+/* These variables are defined and initialized in the startup code.  */
+extern int __libc_argc;
+extern char **__libc_argv;
+
+/* Some forward declarations */
+static int parse_dollars (char **word, size_t *word_length, size_t *max_length,
+			  const char *words, size_t *offset, int flags,
+			  wordexp_t *pwordexp, const char *ifs,
+			  const char *ifs_white, int quoted);
+static int parse_backtick (char **word, size_t *word_length,
+			   size_t *max_length, const char *words,
+			   size_t *offset, int flags, wordexp_t *pwordexp,
+			   const char *ifs, const char *ifs_white);
+static int parse_dquote (char **word, size_t *word_length, size_t *max_length,
+			 const char *words, size_t *offset, int flags,
+			 wordexp_t *pwordexp, const char *ifs,
+			 const char *ifs_white);
+static int eval_expr (char *expr, long int *result);
+
+/* The w_*() functions manipulate word lists. */
+
+#define W_CHUNK	(100)
+
+/* Result of w_newword will be ignored if it's the last word. */
+static inline char *
+w_newword (size_t *actlen, size_t *maxlen)
+{
+  *actlen = *maxlen = 0;
+  return NULL;
+}
+
+static inline char *
+w_addchar (char *buffer, size_t *actlen, size_t *maxlen, char ch)
+     /* (lengths exclude trailing zero) */
+{
+  /* Add a character to the buffer, allocating room for it if needed.
+   */
+
+  if (*actlen == *maxlen)
+    {
+      char *old_buffer = buffer;
+      assert (buffer == NULL || *maxlen != 0);
+      *maxlen += W_CHUNK;
+      buffer = realloc (buffer, 1 + *maxlen);
+
+      if (buffer == NULL)
+	free (old_buffer);
+    }
+
+  if (buffer != NULL)
+    {
+      buffer[*actlen] = ch;
+      buffer[++(*actlen)] = '\0';
+    }
+
+  return buffer;
+}
+
+static char *
+w_addmem (char *buffer, size_t *actlen, size_t *maxlen, const char *str,
+	  size_t len)
+{
+  /* Add a string to the buffer, allocating room for it if needed.
+   */
+  if (*actlen + len > *maxlen)
+    {
+      char *old_buffer = buffer;
+      assert (buffer == NULL || *maxlen != 0);
+      *maxlen += MAX (2 * len, W_CHUNK);
+      buffer = realloc (old_buffer, 1 + *maxlen);
+
+      if (buffer == NULL)
+	free (old_buffer);
+    }
+
+  if (buffer != NULL)
+    {
+      *((char *) mempcpy (&buffer[*actlen], str, len)) = '\0';
+      *actlen += len;
+    }
+
+  return buffer;
+}
+
+static char *
+w_addstr (char *buffer, size_t *actlen, size_t *maxlen, const char *str)
+     /* (lengths exclude trailing zero) */
+{
+  /* Add a string to the buffer, allocating room for it if needed.
+   */
+  size_t len;
+
+  assert (str != NULL); /* w_addstr only called from this file */
+  len = strlen (str);
+
+  return w_addmem (buffer, actlen, maxlen, str, len);
+}
+
+static int
+w_addword (wordexp_t *pwordexp, char *word)
+{
+  /* Add a word to the wordlist */
+  size_t num_p;
+  char **new_wordv;
+
+  /* Internally, NULL acts like "".  Convert NULLs to "" before
+   * the caller sees them.
+   */
+  if (word == NULL)
+    {
+      word = strdup ("");
+      if (word == NULL)
+	goto no_space;
+    }
+
+  num_p = 2 + pwordexp->we_wordc + pwordexp->we_offs;
+  new_wordv = realloc (pwordexp->we_wordv, sizeof (char *) * num_p);
+  if (new_wordv != NULL)
+    {
+      pwordexp->we_wordv = new_wordv;
+      pwordexp->we_wordv[pwordexp->we_offs + pwordexp->we_wordc++] = word;
+      pwordexp->we_wordv[pwordexp->we_offs + pwordexp->we_wordc] = NULL;
+      return 0;
+    }
+
+no_space:
+  return WRDE_NOSPACE;
+}
+
+/* The parse_*() functions should leave *offset being the offset in 'words'
+ * to the last character processed.
+ */
+
+static int
+parse_backslash (char **word, size_t *word_length, size_t *max_length,
+		 const char *words, size_t *offset)
+{
+  /* We are poised _at_ a backslash, not in quotes */
+
+  switch (words[1 + *offset])
+    {
+    case 0:
+      /* Backslash is last character of input words */
+      return WRDE_SYNTAX;
+
+    case '\n':
+      ++(*offset);
+      break;
+
+    default:
+      *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
+      if (*word == NULL)
+	return WRDE_NOSPACE;
+
+      ++(*offset);
+      break;
+    }
+
+  return 0;
+}
+
+static int
+parse_qtd_backslash (char **word, size_t *word_length, size_t *max_length,
+		     const char *words, size_t *offset)
+{
+  /* We are poised _at_ a backslash, inside quotes */
+
+  switch (words[1 + *offset])
+    {
+    case 0:
+      /* Backslash is last character of input words */
+      return WRDE_SYNTAX;
+
+    case '\n':
+      ++(*offset);
+      break;
+
+    case '$':
+    case '`':
+    case '"':
+    case '\\':
+      *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
+      if (*word == NULL)
+	return WRDE_NOSPACE;
+
+      ++(*offset);
+      break;
+
+    default:
+      *word = w_addchar (*word, word_length, max_length, words[*offset]);
+      if (*word != NULL)
+	*word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
+
+      if (*word == NULL)
+	return WRDE_NOSPACE;
+
+      ++(*offset);
+      break;
+    }
+
+  return 0;
+}
+
+static int
+parse_tilde (char **word, size_t *word_length, size_t *max_length,
+	     const char *words, size_t *offset, size_t wordc)
+{
+  /* We are poised _at_ a tilde */
+  size_t i;
+
+  if (*word_length != 0)
+    {
+      if (!((*word)[*word_length - 1] == '=' && wordc == 0))
+	{
+	  if (!((*word)[*word_length - 1] == ':'
+		&& strchr (*word, '=') && wordc == 0))
+	    {
+	      *word = w_addchar (*word, word_length, max_length, '~');
+	      return *word ? 0 : WRDE_NOSPACE;
+	    }
+	}
+    }
+
+  for (i = 1 + *offset; words[i]; i++)
+    {
+      if (words[i] == ':' || words[i] == '/' || words[i] == ' ' ||
+	  words[i] == '\t' || words[i] == 0 )
+	break;
+
+      if (words[i] == '\\')
+	{
+	  *word = w_addchar (*word, word_length, max_length, '~');
+	  return *word ? 0 : WRDE_NOSPACE;
+	}
+    }
+
+  if (i == 1 + *offset)
+    {
+      /* Tilde appears on its own */
+      uid_t uid;
+      struct passwd pwd, *tpwd;
+      int buflen = 1000;
+      char* home;
+      char* buffer;
+      int result;
+
+      /* POSIX.2 says ~ expands to $HOME and if HOME is unset the
+	 results are unspecified.  We do a lookup on the uid if
+	 HOME is unset. */
+
+      home = getenv ("HOME");
+      if (home != NULL)
+	{
+	  *word = w_addstr (*word, word_length, max_length, home);
+	  if (*word == NULL)
+	    return WRDE_NOSPACE;
+	}
+      else
+	{
+	  uid = getuid ();
+	  buffer = alloca (buflen);
+
+	  while ((result = getpwuid_r (uid, &pwd, buffer, buflen, &tpwd)) != 0
+		 && errno == ERANGE)
+	    {
+	      buflen += 1000;
+	      buffer = alloca (buflen);
+	    }
+
+	  if (result == 0 && tpwd != NULL && pwd.pw_dir != NULL)
+	    {
+	      *word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
+	      if (*word == NULL)
+		return WRDE_NOSPACE;
+	    }
+	  else
+	    {
+	      *word = w_addchar (*word, word_length, max_length, '~');
+	      if (*word == NULL)
+		return WRDE_NOSPACE;
+	    }
+	}
+    }
+  else
+    {
+      /* Look up user name in database to get home directory */
+      char *user = strndup (&words[1 + *offset], i - (1 + *offset));
+      struct passwd pwd, *tpwd;
+      int buflen = 1000;
+      char* buffer = alloca (buflen);
+      int result;
+
+      while ((result = getpwnam_r (user, &pwd, buffer, buflen, &tpwd)) != 0
+	     && errno == ERANGE)
+	{
+	  buflen += 1000;
+	  buffer = alloca (buflen);
+	}
+
+      if (result == 0 && tpwd != NULL && pwd.pw_dir)
+	*word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
+      else
+	{
+	  /* (invalid login name) */
+	  *word = w_addchar (*word, word_length, max_length, '~');
+	  if (*word != NULL)
+	    *word = w_addstr (*word, word_length, max_length, user);
+	}
+
+      *offset = i - 1;
+    }
+  return *word ? 0 : WRDE_NOSPACE;
+}
+
+
+static int
+do_parse_glob (const char *glob_word, char **word, size_t *word_length,
+	       size_t *max_length, wordexp_t *pwordexp, const char *ifs,
+	       const char *ifs_white)
+{
+  int error;
+  int match;
+  glob_t globbuf;
+
+  error = glob (glob_word, GLOB_NOCHECK, NULL, &globbuf);
+
+  if (error != 0)
+    {
+      /* We can only run into memory problems.  */
+      assert (error == GLOB_NOSPACE);
+      return WRDE_NOSPACE;
+    }
+
+  if (ifs && !*ifs)
+    {
+      /* No field splitting allowed. */
+      assert (globbuf.gl_pathv[0] != NULL);
+      *word = w_addstr (*word, word_length, max_length, globbuf.gl_pathv[0]);
+      for (match = 1; match < globbuf.gl_pathc && *word != NULL; ++match)
+	{
+	  *word = w_addchar (*word, word_length, max_length, ' ');
+	  if (*word != NULL)
+	    *word = w_addstr (*word, word_length, max_length,
+			      globbuf.gl_pathv[match]);
+	}
+
+      globfree (&globbuf);
+      return *word ? 0 : WRDE_NOSPACE;
+    }
+
+  assert (ifs == NULL || *ifs != '\0');
+  if (*word != NULL)
+    {
+      free (*word);
+      *word = w_newword (word_length, max_length);
+    }
+
+  for (match = 0; match < globbuf.gl_pathc; ++match)
+    {
+      char *matching_word = strdup (globbuf.gl_pathv[match]);
+      if (matching_word == NULL || w_addword (pwordexp, matching_word))
+	{
+	  globfree (&globbuf);
+	  return WRDE_NOSPACE;
+	}
+    }
+
+  globfree (&globbuf);
+  return 0;
+}
+
+static int
+parse_glob (char **word, size_t *word_length, size_t *max_length,
+	    const char *words, size_t *offset, int flags,
+	    wordexp_t *pwordexp, const char *ifs, const char *ifs_white)
+{
+  /* We are poised just after a '*', a '[' or a '?'. */
+  int error = WRDE_NOSPACE;
+  int quoted = 0; /* 1 if singly-quoted, 2 if doubly */
+  int i;
+  wordexp_t glob_list; /* List of words to glob */
+
+  glob_list.we_wordc = 0;
+  glob_list.we_wordv = NULL;
+  glob_list.we_offs = 0;
+  for (; words[*offset] != '\0'; ++*offset)
+    {
+      if ((ifs && strchr (ifs, words[*offset])) ||
+	  (!ifs && strchr (" \t\n", words[*offset])))
+	/* Reached IFS */
+	break;
+
+      /* Sort out quoting */
+      if (words[*offset] == '\'')
+	{
+	  if (quoted == 0)
+	    {
+	      quoted = 1;
+	      continue;
+	    }
+	  else if (quoted == 1)
+	    {
+	      quoted = 0;
+	      continue;
+	    }
+	}
+      else if (words[*offset] == '"')
+	{
+	  if (quoted == 0)
+	    {
+	      quoted = 2;
+	      continue;
+	    }
+	  else if (quoted == 2)
+	    {
+	      quoted = 0;
+	      continue;
+	    }
+	}
+
+      /* Sort out other special characters */
+      if (quoted != 1 && words[*offset] == '$')
+	{
+	  error = parse_dollars (word, word_length, max_length, words,
+				 offset, flags, &glob_list, ifs, ifs_white,
+				 quoted == 2);
+	  if (error)
+	    goto tidy_up;
+
+	  continue;
+	}
+      else if (words[*offset] == '\\')
+	{
+	  if (quoted)
+	    error = parse_qtd_backslash (word, word_length, max_length,
+					 words, offset);
+	  else
+	    error = parse_backslash (word, word_length, max_length,
+				     words, offset);
+
+	  if (error)
+	    goto tidy_up;
+
+	  continue;
+	}
+
+      *word = w_addchar (*word, word_length, max_length, words[*offset]);
+      if (*word == NULL)
+	goto tidy_up;
+    }
+
+  /* Don't forget to re-parse the character we stopped at. */
+  --*offset;
+
+  /* Glob the words */
+  error = w_addword (&glob_list, *word);
+  *word = w_newword (word_length, max_length);
+  for (i = 0; error == 0 && i < glob_list.we_wordc; i++)
+    error = do_parse_glob (glob_list.we_wordv[i], word, word_length,
+			   max_length, pwordexp, ifs, ifs_white);
+
+  /* Now tidy up */
+tidy_up:
+  wordfree (&glob_list);
+  return error;
+}
+
+static int
+parse_squote (char **word, size_t *word_length, size_t *max_length,
+	      const char *words, size_t *offset)
+{
+  /* We are poised just after a single quote */
+  for (; words[*offset]; ++(*offset))
+    {
+      if (words[*offset] != '\'')
+	{
+	  *word = w_addchar (*word, word_length, max_length, words[*offset]);
+	  if (*word == NULL)
+	    return WRDE_NOSPACE;
+	}
+      else return 0;
+    }
+
+  /* Unterminated string */
+  return WRDE_SYNTAX;
+}
+
+/* Functions to evaluate an arithmetic expression */
+static int
+eval_expr_val (char **expr, long int *result)
+{
+  int sgn = +1;
+  char *digit;
+
+  /* Skip white space */
+  for (digit = *expr; digit && *digit && isspace (*digit); ++digit);
+
+  switch (*digit)
+    {
+    case '(':
+
+      /* Scan for closing paren */
+      for (++digit; **expr && **expr != ')'; ++(*expr));
+
+      /* Is there one? */
+      if (!**expr)
+	return WRDE_SYNTAX;
+
+      *(*expr)++ = 0;
+
+      if (eval_expr (digit, result))
+	return WRDE_SYNTAX;
+
+      return 0;
+
+    case '+':	/* Positive value */
+      ++digit;
+      break;
+
+    case '-':	/* Negative value */
+      ++digit;
+      sgn = -1;
+      break;
+
+    default:
+      if (!isdigit (*digit))
+	return WRDE_SYNTAX;
+    }
+
+  *result = 0;
+  for (; *digit && isdigit (*digit); ++digit)
+    *result = (*result * 10) + (*digit - '0');
+
+  *expr = digit;
+  *result *= sgn;
+  return 0;
+}
+
+static int
+eval_expr_multdiv (char **expr, long int *result)
+{
+  long int arg;
+
+  /* Read a Value */
+  if (eval_expr_val (expr, result) != 0)
+    return WRDE_SYNTAX;
+
+  while (**expr)
+    {
+      /* Skip white space */
+      for (; *expr && **expr && isspace (**expr); ++(*expr));
+
+      if (**expr == '*')
+	{
+	  ++(*expr);
+	  if (eval_expr_val (expr, &arg) != 0)
+	    return WRDE_SYNTAX;
+
+	  *result *= arg;
+	}
+      else if (**expr == '/')
+	{
+	  ++(*expr);
+	  if (eval_expr_val (expr, &arg) != 0)
+	    return WRDE_SYNTAX;
+
+	  *result /= arg;
+	}
+      else break;
+    }
+
+  return 0;
+}
+
+static int
+eval_expr (char *expr, long int *result)
+{
+  long int arg;
+
+  /* Read a Multdiv */
+  if (eval_expr_multdiv (&expr, result) != 0)
+    return WRDE_SYNTAX;
+
+  while (*expr)
+    {
+      /* Skip white space */
+      for (; expr && *expr && isspace (*expr); ++expr);
+
+      if (*expr == '+')
+	{
+	  ++expr;
+	  if (eval_expr_multdiv (&expr, &arg) != 0)
+	    return WRDE_SYNTAX;
+
+	  *result += arg;
+	}
+      else if (*expr == '-')
+	{
+	  ++expr;
+	  if (eval_expr_multdiv (&expr, &arg) != 0)
+	    return WRDE_SYNTAX;
+
+	  *result -= arg;
+	}
+      else break;
+    }
+
+  return 0;
+}
+
+static int
+parse_arith (char **word, size_t *word_length, size_t *max_length,
+	     const char *words, size_t *offset, int flags, int bracket)
+{
+  /* We are poised just after "$((" or "$[" */
+  int error;
+  int paren_depth = 1;
+  size_t expr_length;
+  size_t expr_maxlen;
+  char *expr;
+
+  expr = w_newword (&expr_length, &expr_maxlen);
+  for (; words[*offset]; ++(*offset))
+    {
+      switch (words[*offset])
+	{
+	case '$':
+	  error = parse_dollars (&expr, &expr_length, &expr_maxlen,
+				 words, offset, flags, NULL, NULL, NULL, 1);
+	  /* The ``1'' here is to tell parse_dollars not to
+	   * split the fields.
+	   */
+	  if (error)
+	    {
+	      free (expr);
+	      return error;
+	    }
+	  break;
+
+	case '`':
+	  (*offset)++;
+	  error = parse_backtick (&expr, &expr_length, &expr_maxlen,
+				  words, offset, flags, NULL, NULL, NULL);
+	  /* The first NULL here is to tell parse_backtick not to
+	   * split the fields.
+	   */
+	  if (error)
+	    {
+	      free (expr);
+	      return error;
+	    }
+	  break;
+
+	case '\\':
+	  error = parse_qtd_backslash (&expr, &expr_length, &expr_maxlen,
+				       words, offset);
+	  if (error)
+	    {
+	      free (expr);
+	      return error;
+	    }
+	  /* I think that a backslash within an
+	   * arithmetic expansion is bound to
+	   * cause an error sooner or later anyway though.
+	   */
+	  break;
+
+	case ')':
+	  if (--paren_depth == 0)
+	    {
+	      char result[21];	/* 21 = ceil(log10(2^64)) + 1 */
+	      long int numresult = 0;
+	      long long int convertme;
+
+	      if (bracket || words[1 + *offset] != ')')
+		{
+		  free (expr);
+		  return WRDE_SYNTAX;
+		}
+
+	      ++(*offset);
+
+	      /* Go - evaluate. */
+	      if (*expr && eval_expr (expr, &numresult) != 0)
+		{
+		  free (expr);
+		  return WRDE_SYNTAX;
+		}
+
+	      if (numresult < 0)
+		{
+		  convertme = -numresult;
+		  *word = w_addchar (*word, word_length, max_length, '-');
+		  if (!*word)
+		    {
+		      free (expr);
+		      return WRDE_NOSPACE;
+		    }
+		}
+	      else
+		convertme = numresult;
+
+	      result[20] = '\0';
+	      *word = w_addstr (*word, word_length, max_length,
+				itoa (convertme, &result[20], 10, 0));
+	      free (expr);
+	      return *word ? 0 : WRDE_NOSPACE;
+	    }
+	  expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
+	  if (expr == NULL)
+	    return WRDE_NOSPACE;
+
+	  break;
+
+	case ']':
+	  if (bracket && paren_depth == 1)
+	    {
+	      char result[21];	/* 21 = ceil(log10(2^64)) + 1 */
+	      long int numresult = 0;
+
+	      /* Go - evaluate. */
+	      if (*expr && eval_expr (expr, &numresult) != 0)
+		{
+		  free (expr);
+		  return WRDE_SYNTAX;
+		}
+
+	      result[20] = '\0';
+	      *word = w_addstr (*word, word_length, max_length,
+				itoa_word (numresult, &result[20], 10, 0));
+	      free (expr);
+	      return *word ? 0 : WRDE_NOSPACE;
+	    }
+
+	  free (expr);
+	  return WRDE_SYNTAX;
+
+	case '\n':
+	case ';':
+	case '{':
+	case '}':
+	  free (expr);
+	  return WRDE_BADCHAR;
+
+	case '(':
+	  ++paren_depth;
+	default:
+	  expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
+	  if (expr == NULL)
+	    return WRDE_NOSPACE;
+	}
+    }
+
+  /* Premature end */
+  free (expr);
+  return WRDE_SYNTAX;
+}
+
+/* Function called by child process in exec_comm() */
+static void
+exec_comm_child (char *comm, int *fildes, int showerr, int noexec)
+{
+  const char *args[4] = { _PATH_BSHELL, "-c", comm, NULL };
+
+  /* Execute the command, or just check syntax? */
+  if (noexec)
+    args[1] = "-nc";
+
+  /* Redirect output.  */
+  dup2 (fildes[1], 1);
+  close (fildes[1]);
+
+  /* Redirect stderr to /dev/null if we have to.  */
+  if (showerr == 0)
+    {
+      int fd;
+      close (2);
+      fd = open (_PATH_DEVNULL, O_WRONLY);
+      if (fd >= 0 && fd != 2)
+	{
+	  dup2 (fd, 2);
+	  close (fd);
+	}
+    }
+
+  /* Make sure the subshell doesn't field-split on our behalf. */
+  unsetenv ("IFS");
+
+  close (fildes[0]);
+  execve (_PATH_BSHELL, (char *const *) args, __environ);
+
+  /* Bad.  What now?  */
+  abort ();
+}
+
+/* Function to execute a command and retrieve the results */
+/* pwordexp contains NULL if field-splitting is forbidden */
+static int
+exec_comm (char *comm, char **word, size_t *word_length, size_t *max_length,
+	   int flags, wordexp_t *pwordexp, const char *ifs,
+	   const char *ifs_white)
+{
+  int fildes[2];
+  int bufsize = 128;
+  int buflen;
+  int i;
+  int status = 0;
+  size_t maxnewlines = 0;
+  char *buffer;
+  pid_t pid;
+
+  /* Don't fork() unless necessary */
+  if (!comm || !*comm)
+    return 0;
+
+  if (pipe (fildes))
+    /* Bad */
+    return WRDE_NOSPACE;
+
+  if ((pid = fork ()) < 0)
+    {
+      /* Bad */
+      close (fildes[0]);
+      close (fildes[1]);
+      return WRDE_NOSPACE;
+    }
+
+  if (pid == 0)
+    exec_comm_child(comm, fildes, (flags & WRDE_SHOWERR), 0);
+
+  /* Parent */
+
+  close (fildes[1]);
+  buffer = alloca (bufsize);
+
+  if (!pwordexp)
+    /* Quoted - no field splitting */
+    {
+      while (1)
+	{
+	  if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
+	    {
+	      if (waitpid (pid, &status, WNOHANG) == 0)
+		continue;
+	      if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
+		break;
+	    }
+
+	  maxnewlines += buflen;
+
+	  *word = w_addmem (*word, word_length, max_length, buffer, buflen);
+	  if (*word == NULL)
+	    goto no_space;
+	}
+    }
+  else
+    /* Not quoted - split fields */
+    {
+      int copying = 0;
+      /* 'copying' is:
+       *  0 when searching for first character in a field not IFS white space
+       *  1 when copying the text of a field
+       *  2 when searching for possible non-whitespace IFS
+       *  3 when searching for non-newline after copying field
+       */
+
+      while (1)
+	{
+	  if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
+	    {
+	      if (waitpid (pid, &status, WNOHANG) == 0)
+		continue;
+	      if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
+		break;
+	    }
+
+	  for (i = 0; i < buflen; ++i)
+	    {
+	      if (strchr (ifs, buffer[i]) != NULL)
+		{
+		  /* Current character is IFS */
+		  if (strchr (ifs_white, buffer[i]) == NULL)
+		    {
+		      /* Current character is IFS but not whitespace */
+		      if (copying == 2)
+			{
+			  /*            current character
+			   *                   |
+			   *                   V
+			   * eg: text<space><comma><space>moretext
+			   *
+			   * So, strip whitespace IFS (like at the start)
+			   */
+			  copying = 0;
+			  continue;
+			}
+
+		      copying = 0;
+		      /* fall through and delimit field.. */
+		    }
+		  else
+		    {
+		      if (buffer[i] == '\n')
+			{
+			  /* Current character is (IFS) newline */
+
+			  /* If copying a field, this is the end of it,
+			     but maybe all that's left is trailing newlines.
+			     So start searching for a non-newline. */
+			  if (copying == 1)
+			    copying = 3;
+
+			  continue;
+			}
+		      else
+			{
+			  /* Current character is IFS white space, but
+			     not a newline */
+
+			  /* If not either copying a field or searching
+			     for non-newline after a field, ignore it */
+			  if (copying != 1 && copying != 3)
+			    continue;
+
+			  /* End of field (search for non-ws IFS afterwards) */
+			  copying = 2;
+			}
+		    }
+
+		  /* First IFS white space (non-newline), or IFS non-whitespace.
+		   * Delimit the field.  Nulls are converted by w_addword. */
+		  if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
+		    goto no_space;
+
+		  *word = w_newword (word_length, max_length);
+
+		  maxnewlines = 0;
+		  /* fall back round the loop.. */
+		}
+	      else
+		{
+		  /* Not IFS character */
+
+		  if (copying == 3)
+		    {
+		      /* Nothing but (IFS) newlines since the last field,
+		         so delimit it here before starting new word */
+		      if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
+			goto no_space;
+
+		      *word = w_newword (word_length, max_length);
+		    }
+
+		  copying = 1;
+
+		  if (buffer[i] == '\n') /* happens if newline not in IFS */
+		    maxnewlines++;
+		  else
+		    maxnewlines = 0;
+
+		  *word = w_addchar (*word, word_length, max_length,
+				     buffer[i]);
+		  if (*word == NULL)
+		    goto no_space;
+		}
+	    }
+	}
+    }
+
+  /* Chop off trailing newlines (required by POSIX.2)  */
+  /* Ensure we don't go back further than the beginning of the
+     substitution (i.e. remove maxnewlines bytes at most) */
+  while (maxnewlines-- != 0 &&
+         *word_length > 0 && (*word)[*word_length - 1] == '\n')
+    {
+      (*word)[--*word_length] = '\0';
+
+      /* If the last word was entirely newlines, turn it into a new word
+       * which can be ignored if there's nothing following it. */
+      if (*word_length == 0)
+	{
+	  free (*word);
+	  *word = w_newword (word_length, max_length);
+	  break;
+	}
+    }
+
+  close (fildes[0]);
+
+  /* Check for syntax error (re-execute but with "-n" flag) */
+  if (buflen < 1 && status != 0)
+    {
+      if ((pid = fork ()) < 0)
+	{
+	  /* Bad */
+	  return WRDE_NOSPACE;
+	}
+
+      if (pid == 0)
+	{
+          fildes[0] = fildes[1] = -1;
+	  exec_comm_child(comm, fildes, 0, 1);
+	}
+      
+      if (waitpid (pid, &status, 0) == pid && status != 0)
+	return WRDE_SYNTAX;
+    }
+
+  return 0;
+
+no_space:
+  kill (pid, SIGKILL);
+  waitpid (pid, NULL, 0);
+  close (fildes[0]);
+  return WRDE_NOSPACE;
+}
+
+static int
+parse_comm (char **word, size_t *word_length, size_t *max_length,
+	    const char *words, size_t *offset, int flags, wordexp_t *pwordexp,
+	    const char *ifs, const char *ifs_white)
+{
+  /* We are poised just after "$(" */
+  int paren_depth = 1;
+  int error = 0;
+  int quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
+  size_t comm_length;
+  size_t comm_maxlen;
+  char *comm = w_newword (&comm_length, &comm_maxlen);
+
+  for (; words[*offset]; ++(*offset))
+    {
+      switch (words[*offset])
+	{
+	case '\'':
+	  if (quoted == 0)
+	    quoted = 1;
+	  else if (quoted == 1)
+	    quoted = 0;
+
+	  break;
+
+	case '"':
+	  if (quoted == 0)
+	    quoted = 2;
+	  else if (quoted == 2)
+	    quoted = 0;
+
+	  break;
+
+	case ')':
+	  if (!quoted && --paren_depth == 0)
+	    {
+	      /* Go -- give script to the shell */
+	      if (comm)
+		{
+		  error = exec_comm (comm, word, word_length, max_length,
+				     flags, pwordexp, ifs, ifs_white);
+		  free (comm);
+		}
+
+	      return error;