Logo Search packages:      
Sourcecode: glibc version File versions

wordexp.c

/* POSIX.2 wordexp implementation.
   Copyright (C) 1997,1998,1999,2000,2001,2002 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <fnmatch.h>
#include <glob.h>
#include <libintl.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#ifdef USE_IN_LIBIO
# include <wchar.h>
#endif
#include <wordexp.h>

#include <stdio-common/_itoa.h>

/* Undefine the following line for the production version.  */
/* #define NDEBUG 1 */
#include <assert.h>

/* Get some device information.  */
#include <device-nrs.h>

/*
 * This is a recursive-descent-style word expansion routine.
 */

/* These variables are defined and initialized in the startup code.  */
extern int __libc_argc attribute_hidden;
extern char **__libc_argv attribute_hidden;

/* 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)
     internal_function;
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)
     internal_function;
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)
     internal_function;
static int eval_expr (char *expr, long int *result) internal_function;

/* 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 *
internal_function
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 *
internal_function
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
internal_function
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
internal_function
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
internal_function
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
internal_function
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 = strndupa (&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
internal_function
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;
  unsigned 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
internal_function
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 */
  size_t 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
internal_function
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
internal_function
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
internal_function
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
internal_function
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
internal_function
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
internal_function
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)
    {
      struct stat64 st;
      int fd;
      __close (2);
      fd = __open (_PATH_DEVNULL, O_WRONLY);
      if (fd >= 0 && fd != 2)
      {
        __dup2 (fd, 2);
        __close (fd);
      }
      /* Be paranoid.  Check that we actually opened the /dev/null
         device.  */
      if (__builtin_expect (__fxstat64 (_STAT_VER, 2, &st), 0) != 0
        || __builtin_expect (S_ISCHR (st.st_mode), 1) == 0
#if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
        || st.st_rdev != makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
#endif
        )
      /* It's not the /dev/null device.  Stop right here.  The
           problem is: how do we stop?  We use _exit() with an
           hopefully unusual exit code.  */
      _exit (90);
    }

  /* 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
internal_function
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
internal_function
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;
          }

        /* This is just part of the script */
        break;

      case '(':
        if (!quoted)
          ++paren_depth;
      }

      comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
      if (comm == NULL)
      return WRDE_NOSPACE;
    }

  /* Premature end */
  if (comm)
    free (comm);

  return WRDE_SYNTAX;
}

static int
internal_function
parse_param (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)
{
  /* We are poised just after "$" */
  enum action
  {
    ACT_NONE,
    ACT_RP_SHORT_LEFT = '#',
    ACT_RP_LONG_LEFT = 'L',
    ACT_RP_SHORT_RIGHT = '%',
    ACT_RP_LONG_RIGHT = 'R',
    ACT_NULL_ERROR = '?',
    ACT_NULL_SUBST = '-',
    ACT_NONNULL_SUBST = '+',
    ACT_NULL_ASSIGN = '='
  };
  size_t env_length;
  size_t env_maxlen;
  size_t pat_length;
  size_t pat_maxlen;
  size_t start = *offset;
  char *env;
  char *pattern;
  char *value = NULL;
  enum action action = ACT_NONE;
  int depth = 0;
  int colon_seen = 0;
  int seen_hash = 0;
  int free_value = 0;
  int pattern_is_quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
  int error;
  int special = 0;
  char buffer[21];
  int brace = words[*offset] == '{';

  env = w_newword (&env_length, &env_maxlen);
  pattern = w_newword (&pat_length, &pat_maxlen);

  if (brace)
    ++*offset;

  /* First collect the parameter name. */

  if (words[*offset] == '#')
    {
      seen_hash = 1;
      if (!brace)
      goto envsubst;
      ++*offset;
    }

  if (isalpha (words[*offset]) || words[*offset] == '_')
    {
      /* Normal parameter name. */
      do
      {
        env = w_addchar (env, &env_length, &env_maxlen,
                     words[*offset]);
        if (env == NULL)
          goto no_space;
      }
      while (isalnum (words[++*offset]) || words[*offset] == '_');
    }
  else if (isdigit (words[*offset]))
    {
      /* Numeric parameter name. */
      special = 1;
      do
      {
        env = w_addchar (env, &env_length, &env_maxlen,
                     words[*offset]);
        if (env == NULL)
          goto no_space;
        if (!brace)
          goto envsubst;
      }
      while (isdigit(words[++*offset]));
    }
  else if (strchr ("*@$", words[*offset]) != NULL)
    {
      /* Special parameter. */
      special = 1;
      env = w_addchar (env, &env_length, &env_maxlen,
                   words[*offset]);
      if (env == NULL)
      goto no_space;
      ++*offset;
    }
  else
    {
      if (brace)
      goto syntax;
    }

  if (brace)
    {
      /* Check for special action to be applied to the value. */
      switch (words[*offset])
      {
      case '}':
        /* Evaluate. */
        goto envsubst;

      case '#':
        action = ACT_RP_SHORT_LEFT;
        if (words[1 + *offset] == '#')
          {
            ++*offset;
            action = ACT_RP_LONG_LEFT;
          }
        break;

      case '%':
        action = ACT_RP_SHORT_RIGHT;
        if (words[1 + *offset] == '%')
          {
            ++*offset;
            action = ACT_RP_LONG_RIGHT;
          }
        break;

      case ':':
        if (strchr ("-=?+", words[1 + *offset]) == NULL)
          goto syntax;

        colon_seen = 1;
        action = words[++*offset];
        break;

      case '-':
      case '=':
      case '?':
      case '+':
        action = words[*offset];
        break;

      default:
        goto syntax;
      }

      /* Now collect the pattern, but don't expand it yet. */
      ++*offset;
      for (; words[*offset]; ++(*offset))
      {
        switch (words[*offset])
          {
          case '{':
            if (!pattern_is_quoted)
            ++depth;
            break;

          case '}':
            if (!pattern_is_quoted)
            {
              if (depth == 0)
                goto envsubst;
              --depth;
            }
            break;

          case '\\':
            if (pattern_is_quoted)
            /* Quoted; treat as normal character. */
            break;

            /* Otherwise, it's an escape: next character is literal. */
            if (words[++*offset] == '\0')
            goto syntax;

            pattern = w_addchar (pattern, &pat_length, &pat_maxlen, '\\');
            if (pattern == NULL)
            goto no_space;

            break;

          case '\'':
            if (pattern_is_quoted == 0)
            pattern_is_quoted = 1;
            else if (pattern_is_quoted == 1)
            pattern_is_quoted = 0;

            break;

          case '"':
            if (pattern_is_quoted == 0)
            pattern_is_quoted = 2;
            else if (pattern_is_quoted == 2)
            pattern_is_quoted = 0;

            break;
          }

        pattern = w_addchar (pattern, &pat_length, &pat_maxlen,
                         words[*offset]);
        if (pattern == NULL)
          goto no_space;
      }
    }

  /* End of input string -- remember to reparse the character that we
   * stopped at.  */
  --(*offset);

envsubst:
  if (words[start] == '{' && words[*offset] != '}')
    goto syntax;

  if (env == NULL)
    {
      if (seen_hash)
      {
        /* $# expands to the number of positional parameters */
        buffer[20] = '\0';
        value = _itoa_word (__libc_argc - 1, &buffer[20], 10, 0);
        seen_hash = 0;
      }
      else
      {
        /* Just $ on its own */
        *offset = start - 1;
        *word = w_addchar (*word, word_length, max_length, '$');
        return *word ? 0 : WRDE_NOSPACE;
      }
    }
  /* Is it a numeric parameter? */
  else if (isdigit (env[0]))
    {
      int n = atoi (env);

      if (n >= __libc_argc)
      /* Substitute NULL. */
      value = NULL;
      else
      /* Replace with appropriate positional parameter. */
      value = __libc_argv[n];
    }
  /* Is it a special parameter? */
  else if (special)
    {
      /* Is it `$$'? */
      if (*env == '$')
      {
        buffer[20] = '\0';
        value = _itoa_word (__getpid (), &buffer[20], 10, 0);
      }
      /* Is it `${#*}' or `${#@}'? */
      else if ((*env == '*' || *env == '@') && seen_hash)
      {
        buffer[20] = '\0';
        value = _itoa_word (__libc_argc > 0 ? __libc_argc - 1 : 0,
                        &buffer[20], 10, 0);
        *word = w_addstr (*word, word_length, max_length, value);
        free (env);
        if (pattern)
          free (pattern);
        return *word ? 0 : WRDE_NOSPACE;
      }
      /* Is it `$*' or `$@' (unquoted) ? */
      else if (*env == '*' || (*env == '@' && !quoted))
      {
        size_t plist_len = 0;
        int p;
        char *end;

        /* Build up value parameter by parameter (copy them) */
        for (p = 1; __libc_argv[p]; ++p)
          plist_len += strlen (__libc_argv[p]) + 1; /* for space */
        value = malloc (plist_len);
        if (value == NULL)
          goto no_space;
        end = value;
        *end = 0;
        for (p = 1; __libc_argv[p]; ++p)
          {
            if (p > 1)
            *end++ = ' ';
            end = __stpcpy (end, __libc_argv[p]);
          }

        free_value = 1;
      }
      else
      {
        /* Must be a quoted `$@' */
        assert (*env == '@' && quoted);

        /* Each parameter is a separate word ("$@") */
        if (__libc_argc == 2)
          value = __libc_argv[1];
        else if (__libc_argc > 2)
          {
            int p;

            /* Append first parameter to current word. */
            value = w_addstr (*word, word_length, max_length,
                        __libc_argv[1]);
            if (value == NULL || w_addword (pwordexp, value))
            goto no_space;

            for (p = 2; __libc_argv[p + 1]; p++)
            {
              char *newword = __strdup (__libc_argv[p]);
              if (newword == NULL || w_addword (pwordexp, newword))
                goto no_space;
            }

            /* Start a new word with the last parameter. */
            *word = w_newword (word_length, max_length);
            value = __libc_argv[p];
          }
        else
          {
            free (env);
            free (pattern);
            return 0;
          }
      }
    }
  else
    value = getenv (env);

  if (value == NULL && (flags & WRDE_UNDEF))
    {
      /* Variable not defined. */
      error = WRDE_BADVAL;
      goto do_error;
    }

  if (action != ACT_NONE)
    {
      int expand_pattern = 0;

      /* First, find out if we need to expand pattern (i.e. if we will
       * use it). */
      switch (action)
      {
      case ACT_RP_SHORT_LEFT:
      case ACT_RP_LONG_LEFT:
      case ACT_RP_SHORT_RIGHT:
      case ACT_RP_LONG_RIGHT:
        /* Always expand for these. */
        expand_pattern = 1;
        break;

      case ACT_NULL_ERROR:
      case ACT_NULL_SUBST:
      case ACT_NULL_ASSIGN:
        if (!value || (!*value && colon_seen))
          /* If param is unset, or set but null and a colon has been seen,
             the expansion of the pattern will be needed. */
          expand_pattern = 1;

        break;

      case ACT_NONNULL_SUBST:
        /* Expansion of word will be needed if parameter is set and not null,
           or set null but no colon has been seen. */
        if (value && (*value || !colon_seen))
          expand_pattern = 1;

        break;

      default:
        assert (! "Unrecognised action!");
      }

      if (expand_pattern)
      {
        /* We need to perform tilde expansion, parameter expansion,
             command substitution, and arithmetic expansion.  We also
           have to be a bit careful with wildcard characters, as
           pattern might be given to fnmatch soon.  To do this, we
           convert quotes to escapes. */

        char *expanded;
        size_t exp_len;
        size_t exp_maxl;
        char *p;
        int quoted = 0; /* 1: single quotes; 2: double */

        expanded = w_newword (&exp_len, &exp_maxl);
        for (p = pattern; p && *p; p++)
          {
            size_t offset;

            switch (*p)
            {
            case '"':
              if (quoted == 2)
                quoted = 0;
              else if (quoted == 0)
                quoted = 2;
              else break;

              continue;

            case '\'':
              if (quoted == 1)
                quoted = 0;
              else if (quoted == 0)
                quoted = 1;
              else break;

              continue;

            case '*':
            case '?':
              if (quoted)
                {
                  /* Convert quoted wildchar to escaped wildchar. */
                  expanded = w_addchar (expanded, &exp_len,
                                  &exp_maxl, '\\');

                  if (expanded == NULL)
                  goto no_space;
                }
              break;

            case '$':
              offset = 0;
              error = parse_dollars (&expanded, &exp_len, &exp_maxl, p,
                               &offset, flags, NULL, NULL, NULL, 1);
              if (error)
                {
                  if (free_value)
                  free (value);

                  if (expanded)
                  free (expanded);

                  goto do_error;
                }

              p += offset;
              continue;

            case '~':
              if (quoted || exp_len)
                break;

              offset = 0;
              error = parse_tilde (&expanded, &exp_len, &exp_maxl, p,
                               &offset, 0);
              if (error)
                {
                  if (free_value)
                  free (value);

                  if (expanded)
                  free (expanded);

                  goto do_error;
                }

              p += offset;
              continue;

            case '\\':
              expanded = w_addchar (expanded, &exp_len, &exp_maxl, '\\');
              ++p;
              assert (*p); /* checked when extracted initially */
              if (expanded == NULL)
                goto no_space;
            }

            expanded = w_addchar (expanded, &exp_len, &exp_maxl, *p);

            if (expanded == NULL)
            goto no_space;
          }

        if (pattern)
              free (pattern);

        pattern = expanded;
      }

      switch (action)
      {
      case ACT_RP_SHORT_LEFT:
      case ACT_RP_LONG_LEFT:
      case ACT_RP_SHORT_RIGHT:
      case ACT_RP_LONG_RIGHT:
        {
          char *p;
          char c;
          char *end;

          if (value == NULL || pattern == NULL || *pattern == '\0')
            break;

          end = value + strlen (value);

          switch (action)
            {
            case ACT_RP_SHORT_LEFT:
            for (p = value; p <= end; ++p)
              {
                c = *p;
                *p = '\0';
                if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
                  {
                  *p = c;
                  if (free_value)
                    {
                      char *newval = __strdup (p);
                      if (newval == NULL)
                        {
                        free (value);
                        goto no_space;
                        }
                      free (value);
                      value = newval;
                    }
                  else
                    value = p;
                  break;
                  }
                *p = c;
              }

            break;

            case ACT_RP_LONG_LEFT:
            for (p = end; p >= value; --p)
              {
                c = *p;
                *p = '\0';
                if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
                  {
                  *p = c;
                  if (free_value)
                    {
                      char *newval = __strdup (p);
                      if (newval == NULL)
                        {
                        free (value);
                        goto no_space;
                        }
                      free (value);
                      value = newval;
                    }
                  else
                    value = p;
                  break;
                  }
                *p = c;
              }

            break;

            case ACT_RP_SHORT_RIGHT:
            for (p = end; p >= value; --p)
              {
                if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
                  {
                  char *newval;
                  newval = malloc (p - value + 1);

                  if (newval == NULL)
                    {
                      if (free_value)
                        free (value);
                      goto no_space;
                    }

                  *(char *) __mempcpy (newval, value, p - value) = '\0';
                  if (free_value)
                    free (value);
                  value = newval;
                  free_value = 1;
                  break;
                  }
              }

            break;

            case ACT_RP_LONG_RIGHT:
            for (p = value; p <= end; ++p)
              {
                if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
                  {
                  char *newval;
                  newval = malloc (p - value + 1);

                  if (newval == NULL)
                    {
                      if (free_value)
                        free (value);
                      goto no_space;
                    }

                  *(char *) __mempcpy (newval, value, p - value) = '\0';
                  if (free_value)
                    free (value);
                  value = newval;
                  free_value = 1;
                  break;
                  }
              }

            break;

            default:
            break;
            }

          break;
        }

      case ACT_NULL_ERROR:
        if (value && *value)
          /* Substitute parameter */
          break;

        error = 0;
        if (!colon_seen && value)
          /* Substitute NULL */
          ;
        else
          {
            const char *str = pattern;

            if (str[0] == '\0')
            str = _("parameter null or not set");

#ifdef USE_IN_LIBIO
            if (_IO_fwide (stderr, 0) > 0)
            __fwprintf (stderr, L"%s: %s\n", env, str);
            else
#endif
            fprintf (stderr, "%s: %s\n", env, str);
          }

        if (free_value)
          free (value);
        goto do_error;

      case ACT_NULL_SUBST:
        if (value && *value)
          /* Substitute parameter */
          break;

        if (free_value && value)
          free (value);

        if (!colon_seen && value)
          /* Substitute NULL */
          goto success;

        value = pattern ? __strdup (pattern) : pattern;
        free_value = 1;

        if (pattern && !value)
          goto no_space;

        break;

      case ACT_NONNULL_SUBST:
        if (value && (*value || !colon_seen))
          {
            if (free_value && value)
            free (value);

            value = pattern ? __strdup (pattern) : pattern;
            free_value = 1;

            if (pattern && !value)
            goto no_space;

            break;
          }

        /* Substitute NULL */
        if (free_value)
          free (value);
        goto success;

      case ACT_NULL_ASSIGN:
        if (value && *value)
          /* Substitute parameter */
          break;

        if (!colon_seen && value)
          {
            /* Substitute NULL */
            if (free_value)
            free (value);
            goto success;
          }

        if (free_value && value)
          free (value);

        value = pattern ? __strdup (pattern) : pattern;
        free_value = 1;

        if (pattern && !value)
          goto no_space;

        __setenv (env, value, 1);
        break;

      default:
        assert (! "Unrecognised action!");
      }
    }

  free (env); env = NULL;
  free (pattern); pattern = NULL;

  if (seen_hash)
    {
      char param_length[21];
      param_length[20] = '\0';
      *word = w_addstr (*word, word_length, max_length,
                  _itoa_word (value ? strlen (value) : 0,
                            &param_length[20], 10, 0));
      if (free_value)
      {
        assert (value != NULL);
        free (value);
      }

      return *word ? 0 : WRDE_NOSPACE;
    }

  if (value == NULL)
    return 0;

  if (quoted || !pwordexp)
    {
      /* Quoted - no field split */
      *word = w_addstr (*word, word_length, max_length, value);
      if (free_value)
      free (value);

      return *word ? 0 : WRDE_NOSPACE;
    }
  else
    {
      /* Need to field-split */
      char *value_copy = __strdup (value); /* Don't modify value */
      char *field_begin = value_copy;
      int seen_nonws_ifs = 0;

      if (free_value)
      free (value);

      if (value_copy == NULL)
      goto no_space;

      do
      {
        char *field_end = field_begin;
        char *next_field;

        /* If this isn't the first field, start a new word */
        if (field_begin != value_copy)
          {
            if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
            {
              free (value_copy);
              goto no_space;
            }

            *word = w_newword (word_length, max_length);
          }

        /* Skip IFS whitespace before the field */
        field_begin += strspn (field_begin, ifs_white);

        if (!seen_nonws_ifs && *field_begin == 0)
          /* Nothing but whitespace */
          break;

        /* Search for the end of the field */
        field_end = field_begin + strcspn (field_begin, ifs);

        /* Set up pointer to the character after end of field and
             skip whitespace IFS after it. */
        next_field = field_end + strspn (field_end, ifs_white);

        /* Skip at most one non-whitespace IFS character after the field */
        seen_nonws_ifs = 0;
        if (*next_field && strchr (ifs, *next_field))
          {
            seen_nonws_ifs = 1;
            next_field++;
          }

        /* Null-terminate it */
        *field_end = 0;

        /* Tag a copy onto the current word */
        *word = w_addstr (*word, word_length, max_length, field_begin);

        if (*word == NULL && *field_begin != '\0')
          {
            free (value_copy);
            goto no_space;
          }

        field_begin = next_field;
      }
      while (seen_nonws_ifs || *field_begin);

      free (value_copy);
    }

  return 0;

success:
  error = 0;
  goto do_error;

no_space:
  error = WRDE_NOSPACE;
  goto do_error;

syntax:
  error = WRDE_SYNTAX;

do_error:
  if (env)
    free (env);

  if (pattern)
    free (pattern);

  return error;
}

static int
internal_function
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)
{
  /* We are poised _at_ "$" */
  switch (words[1 + *offset])
    {
    case '"':
    case '\'':
    case 0:
      *word = w_addchar (*word, word_length, max_length, '$');
      return *word ? 0 : WRDE_NOSPACE;

    case '(':
      if (words[2 + *offset] == '(')
      {
        /* Differentiate between $((1+3)) and $((echo);(ls)) */
        int i = 3 + *offset;
        int depth = 0;
        while (words[i] && !(depth == 0 && words[i] == ')'))
          {
            if (words[i] == '(')
            ++depth;
            else if (words[i] == ')')
            --depth;

            ++i;
          }

        if (words[i] == ')' && words[i + 1] == ')')
          {
            (*offset) += 3;
            /* Call parse_arith -- 0 is for "no brackets" */
            return parse_arith (word, word_length, max_length, words, offset,
                          flags, 0);
          }
      }

      if (flags & WRDE_NOCMD)
      return WRDE_CMDSUB;

      (*offset) += 2;
      return parse_comm (word, word_length, max_length, words, offset, flags,
                   quoted? NULL : pwordexp, ifs, ifs_white);

    case '[':
      (*offset) += 2;
      /* Call parse_arith -- 1 is for "brackets" */
      return parse_arith (word, word_length, max_length, words, offset, flags,
                    1);

    case '{':
    default:
      ++(*offset);      /* parse_param needs to know if "{" is there */
      return parse_param (word, word_length, max_length, words, offset, flags,
                     pwordexp, ifs, ifs_white, quoted);
    }
}

static int
internal_function
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)
{
  /* We are poised just after "`" */
  int error;
  int squoting = 0;
  size_t comm_length;
  size_t comm_maxlen;
  char *comm = w_newword (&comm_length, &comm_maxlen);

  for (; words[*offset]; ++(*offset))
    {
      switch (words[*offset])
      {
      case '`':
        /* Go -- give the script to the shell */
        error = exec_comm (comm, word, word_length, max_length, flags,
                       pwordexp, ifs, ifs_white);
        free (comm);
        return error;

      case '\\':
        if (squoting)
          {
            error = parse_qtd_backslash (&comm, &comm_length, &comm_maxlen,
                                 words, offset);

            if (error)
            {
              free (comm);
              return error;
            }

            break;
          }

        ++(*offset);
        error = parse_backslash (&comm, &comm_length, &comm_maxlen, words,
                           offset);

        if (error)
          {
            free (comm);
            return error;
          }

        break;

      case '\'':
        squoting = 1 - squoting;
      default:
        comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
        if (comm == NULL)
          return WRDE_NOSPACE;
      }
    }

  /* Premature end */
  free (comm);
  return WRDE_SYNTAX;
}

static int
internal_function
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)
{
  /* We are poised just after a double-quote */
  int error;

  for (; words[*offset]; ++(*offset))
    {
      switch (words[*offset])
      {
      case '"':
        return 0;

      case '$':
        error = parse_dollars (word, word_length, max_length, words, offset,
                         flags, pwordexp, ifs, ifs_white, 1);
        /* The ``1'' here is to tell parse_dollars not to
         * split the fields.  It may need to, however ("$@").
         */
        if (error)
          return error;

        break;

      case '`':
        if (flags & WRDE_NOCMD)
          return WRDE_CMDSUB;

        ++(*offset);
        error = parse_backtick (word, word_length, max_length, words,
                          offset, flags, NULL, NULL, NULL);
        /* The first NULL here is to tell parse_backtick not to
         * split the fields.
         */
        if (error)
          return error;

        break;

      case '\\':
        error = parse_qtd_backslash (word, word_length, max_length, words,
                               offset);

        if (error)
          return error;

        break;

      default:
        *word = w_addchar (*word, word_length, max_length, words[*offset]);
        if (*word == NULL)
          return WRDE_NOSPACE;
      }
    }

  /* Unterminated string */
  return WRDE_SYNTAX;
}

/*
 * wordfree() is to be called after pwordexp is finished with.
 */

void
wordfree (wordexp_t *pwordexp)
{

  /* wordexp can set pwordexp to NULL */
  if (pwordexp && pwordexp->we_wordv)
    {
      char **wordv = pwordexp->we_wordv;

      for (wordv += pwordexp->we_offs; *wordv; ++wordv)
      free (*wordv);

      free (pwordexp->we_wordv);
      pwordexp->we_wordv = NULL;
    }
}
libc_hidden_def (wordfree)

/*
 * wordexp()
 */

int
wordexp (const char *words, wordexp_t *pwordexp, int flags)
{
  size_t words_offset;
  size_t word_length;
  size_t max_length;
  char *word = w_newword (&word_length, &max_length);
  int error;
  char *ifs;
  char ifs_white[4];
  wordexp_t old_word = *pwordexp;

  if (flags & WRDE_REUSE)
    {
      /* Minimal implementation of WRDE_REUSE for now */
      wordfree (pwordexp);
      old_word.we_wordv = NULL;
    }

  if ((flags & WRDE_APPEND) == 0)
    {
      pwordexp->we_wordc = 0;

      if (flags & WRDE_DOOFFS)
      {
        pwordexp->we_wordv = calloc (1 + pwordexp->we_offs, sizeof (char *));
        if (pwordexp->we_wordv == NULL)
          {
            error = WRDE_NOSPACE;
            goto do_error;
          }
      }
      else
      {
        pwordexp->we_wordv = calloc (1, sizeof (char *));
        if (pwordexp->we_wordv == NULL)
          {
            error = WRDE_NOSPACE;
            goto do_error;
          }

        pwordexp->we_offs = 0;
      }
    }

  /* Find out what the field separators are.
   * There are two types: whitespace and non-whitespace.
   */
  ifs = getenv ("IFS");

  if (!ifs)
    /* IFS unset - use <space><tab><newline>. */
    ifs = strcpy (ifs_white, " \t\n");
  else
    {
      char *ifsch = ifs;
      char *whch = ifs_white;

      /* Start off with no whitespace IFS characters */
      ifs_white[0] = '\0';

      while (*ifsch != '\0')
      {
        if ((*ifsch == ' ') || (*ifsch == '\t') || (*ifsch == '\n'))
          {
            /* Whitespace IFS.  See first whether it is already in our
             collection.  */
            char *runp = ifs_white;

            while (runp < whch && *runp != '\0' && *runp != *ifsch)
            ++runp;

            if (runp == whch)
            *whch++ = *ifsch;
          }

        ++ifsch;
      }
      *whch = '\0';
    }

  for (words_offset = 0 ; words[words_offset] ; ++words_offset)
    switch (words[words_offset])
      {
      case '\\':
      error = parse_backslash (&word, &word_length, &max_length, words,
                         &words_offset);

      if (error)
        goto do_error;

      break;

      case '$':
      error = parse_dollars (&word, &word_length, &max_length, words,
                         &words_offset, flags, pwordexp, ifs, ifs_white,
                         0);

      if (error)
        goto do_error;

      break;

      case '`':
      if (flags & WRDE_NOCMD)
        {
          error = WRDE_CMDSUB;
          goto do_error;
        }

      ++words_offset;
      error = parse_backtick (&word, &word_length, &max_length, words,
                        &words_offset, flags, pwordexp, ifs,
                        ifs_white);

      if (error)
        goto do_error;

      break;

      case '"':
      ++words_offset;
      error = parse_dquote (&word, &word_length, &max_length, words,
                        &words_offset, flags, pwordexp, ifs, ifs_white);

      if (error)
        goto do_error;

      if (!word_length)
        {
          error = w_addword (pwordexp, NULL);

          if (error)
            return error;
        }

      break;

      case '\'':
      ++words_offset;
      error = parse_squote (&word, &word_length, &max_length, words,
                        &words_offset);

      if (error)
        goto do_error;

      if (!word_length)
        {
          error = w_addword (pwordexp, NULL);

          if (error)
            return error;
        }

      break;

      case '~':
      error = parse_tilde (&word, &word_length, &max_length, words,
                       &words_offset, pwordexp->we_wordc);

      if (error)
        goto do_error;

      break;

      case '*':
      case '[':
      case '?':
      error = parse_glob (&word, &word_length, &max_length, words,
                      &words_offset, flags, pwordexp, ifs, ifs_white);

      if (error)
        goto do_error;

      break;

      default:
      /* Is it a word separator? */
      if (strchr (" \t", words[words_offset]) == NULL)
        {
          char ch = words[words_offset];

          /* Not a word separator -- but is it a valid word char? */
          if (strchr ("\n|&;<>(){}", ch))
            {
            /* Fail */
            error = WRDE_BADCHAR;
            goto do_error;
            }

          /* "Ordinary" character -- add it to word */
          word = w_addchar (word, &word_length, &max_length,
                        ch);
          if (word == NULL)
            {
            error = WRDE_NOSPACE;
            goto do_error;
            }

          break;
        }

      /* If a word has been delimited, add it to the list. */
      if (word != NULL)
        {
          error = w_addword (pwordexp, word);
          if (error)
            goto do_error;
        }

      word = w_newword (&word_length, &max_length);
      }

  /* End of string */

  /* There was a word separator at the end */
  if (word == NULL) /* i.e. w_newword */
    return 0;

  /* There was no field separator at the end */
  return w_addword (pwordexp, word);

do_error:
  /* Error:
   *  free memory used (unless error is WRDE_NOSPACE), and
   *  set pwordexp members back to what they were.
   */

  if (word != NULL)
    free (word);

  if (error == WRDE_NOSPACE)
    return WRDE_NOSPACE;

  if ((flags & WRDE_APPEND) == 0)
    wordfree (pwordexp);

  *pwordexp = old_word;
  return error;
}

Generated by  Doxygen 1.6.0   Back to index