arrayfunc.cc

// arrayfunc.cc -- High-level array functions used by other parts of the shell.

/* Copyright (C) 2001-2020 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/>.
*/

#include "config.h"

#if defined(ARRAY_VARS)

#include "shell.hh"

#if defined(HAVE_MBSTR_H) && defined(HAVE_MBSCHR)
#include <mbstr.h> /* mbschr */
#endif

#include "builtins/common.hh"

#ifndef LBRACK
#define LBRACK '['
#define RBRACK ']'
#endif

namespace bash
{

#if 0
/* This variable means to not expand associative array subscripts more than
   once, when performing variable expansion. */
char assoc_expand_once = 0;

/* Ditto for indexed array subscripts -- currently unused */
char array_expand_once = 0;

static SHELL_VAR *bind_array_var_internal (SHELL_VAR *, arrayind_t, char *,
                                           const char *, int);
static SHELL_VAR *assign_array_element_internal (SHELL_VAR *, const char *,
                                                 char *, char *, int,
                                                 const char *, int);

static void assign_assoc_from_kvlist (SHELL_VAR *, WORD_LIST *, HASH_TABLE *,
                                      int);

static char *quote_assign (const char *);
static void quote_array_assignment_chars (WORD_LIST *);
static char *quote_compound_array_word (char *, int);
static char *array_value_internal (const char *, int, int, int *,
                                   arrayind_t *);
#endif

// Standard error message to use when encountering an invalid array subscript
const char *bash_badsub_errmsg = N_ ("bad array subscript");

/* **************************************************************** */
/*								    */
/*  Functions to manipulate array variables and perform assignments */
/*								    */
/* **************************************************************** */

/* Convert a shell variable to an array variable.  The original value is
   saved as array[0]. */
SHELL_VAR *
Shell::convert_var_to_array (SHELL_VAR *var)
{
  std::string *oldval = var->str_value ();

  ARRAY *array = new ARRAY ();
  if (oldval)
    array->insert (0, *oldval);

  delete oldval;
  var->set_array_value (array);

  /* these aren't valid anymore */
  var->dynamic_value = nullptr;
  var->assign_func = nullptr;

  var->exportstr.clear ();
  if (var->exported ())
    array_needs_making = true;

  var->set_attr (att_array);
  if (oldval)
    var->unset_attr (att_invisible);

  /* Make sure it's not marked as an associative array any more */
  var->unset_attr (att_assoc);

  /* Since namerefs can't be array variables, turn off nameref attribute */
  var->unset_attr (att_nameref);

  return var;
}

/* Convert a shell variable to an associative array. The original value is
   saved as array[0]. */
SHELL_VAR *
Shell::convert_var_to_assoc (SHELL_VAR *var)
{
  std::string *oldval = var->str_value ();

  hash = assoc_create (0);
  if (oldval)
    assoc_insert (hash, savestring ("0"), oldval);

  FREE (value_cell (var));
  var_setassoc (var, hash);

  /* these aren't valid anymore */
  var->dynamic_value = nullptr;
  var->assign_func = nullptr;

  var->exportstr.clear ();

  if (var->exported ())
    array_needs_making = true;

  var->set_attr (att_assoc);
  if (oldval)
    var->unset_attr (att_invisible);

  /* Make sure it's not marked as an indexed array any more */
  var->unset_attr (att_array);

  /* Since namerefs can't be assoc arrays, turn off nameref attribute */
  var->unset_attr (att_nameref);

  return var;
}

char *
make_array_variable_value (SHELL_VAR *entry, arrayind_t ind, const char *key,
                           const char *value, assign_flags flags)
{
  SHELL_VAR *dentry;
  char *newval;

  /* If we're appending, we need the old value of the array reference, so
     fake out make_variable_value with a dummy SHELL_VAR */
  if (flags & ASS_APPEND)
    {
      dentry = (SHELL_VAR *)xmalloc (sizeof (SHELL_VAR));
      dentry->name = savestring (entry->name);
      if (assoc_p (entry))
        newval = assoc_reference (assoc_cell (entry), key);
      else
        newval = array_reference (array_cell (entry), ind);
      if (newval)
        dentry->value.s = savestring (newval);
      else
        {
          dentry->value.s = (char *)xmalloc (1);
          dentry->value.s[0] = '\0';
        }
      dentry->exportstr = 0;
      dentry->attributes
          = entry->attributes & ~(att_array | att_assoc | att_exported);
      /* Leave the rest of the members uninitialized; the code doesn't look
         at them. */
      newval = make_variable_value (dentry, value, flags);
      dispose_variable (dentry);
    }
  else
    newval = make_variable_value (entry, value, flags);

  return newval;
}

/* Assign HASH[KEY]=VALUE according to FLAGS. ENTRY is an associative array
   variable; HASH is the hash table to assign into. HASH may or may not be
   the hash table associated with ENTRY; if it's not, the caller takes care
   of it.
   XXX - make sure that any dynamic associative array variables recreate the
   hash table on each assignment. BASH_CMDS and BASH_ALIASES already do this */
static SHELL_VAR *
bind_assoc_var_internal (SHELL_VAR *entry, HASH_TABLE *hash, const char *key,
                         const char *value, int flags)
{
  char *newval;

  /* Use the existing array contents to expand the value */
  newval = make_array_variable_value (entry, 0, key, value, flags);

  if (entry->assign_func)
    (*entry->assign_func) (entry, newval, 0, key);
  else
    assoc_insert (hash, key, newval);

  FREE (newval);

  VUNSETATTR (entry, att_invisible); /* no longer invisible */

  /* check mark_modified_variables if we ever want to export array vars */
  return entry;
}

/* Perform ENTRY[IND]=VALUE or ENTRY[KEY]=VALUE. This is not called for every
   assignment to an associative array; see assign_compound_array_list below. */
static SHELL_VAR *
bind_array_var_internal (SHELL_VAR *entry, arrayind_t ind, char *key,
                         const char *value, int flags)
{
  char *newval;

  newval = make_array_variable_value (entry, ind, key, value, flags);

  if (entry->assign_func)
    (*entry->assign_func) (entry, newval, ind, key);
  else if (assoc_p (entry))
    assoc_insert (assoc_cell (entry), key, newval);
  else
    array_insert (array_cell (entry), ind, newval);
  FREE (newval);

  VUNSETATTR (entry, att_invisible); /* no longer invisible */

  /* check mark_modified_variables if we ever want to export array vars */
  return entry;
}

/* Perform an array assignment name[ind]=value.  If NAME already exists and
   is not an array, and IND is 0, perform name=value instead.  If NAME exists
   and is not an array, and IND is not 0, convert it into an array with the
   existing value as name[0].

   If NAME does not exist, just create an array variable, no matter what
   IND's value may be. */
SHELL_VAR *
bind_array_variable (const char *name, arrayind_t ind, const char *value,
                     int flags)
{
  SHELL_VAR *entry;

  entry = find_shell_variable (name);

  if (entry == (SHELL_VAR *)0)
    {
      /* Is NAME a nameref variable that points to an unset variable? */
      entry = find_variable_nameref_for_create (name, 0);
      if (entry == INVALID_NAMEREF_VALUE)
        return (SHELL_VAR *)0;
      if (entry && nameref_p (entry))
        entry = make_new_array_variable (nameref_cell (entry));
    }
  if (entry == (SHELL_VAR *)0)
    entry = make_new_array_variable (name);
  else if ((readonly_p (entry) && (flags & ASS_FORCE) == 0)
           || noassign_p (entry))
    {
      if (readonly_p (entry))
        err_readonly (name);
      return entry;
    }
  else if (array_p (entry) == 0)
    entry = convert_var_to_array (entry);

  /* ENTRY is an array variable, and ARRAY points to the value. */
  return bind_array_var_internal (entry, ind, 0, value, flags);
}

SHELL_VAR *
bind_array_element (SHELL_VAR *entry, arrayind_t ind, const char *value,
                    int flags)
{
  return bind_array_var_internal (entry, ind, 0, value, flags);
}

SHELL_VAR *
bind_assoc_variable (SHELL_VAR *entry, const char *name, char *key,
                     const char *value, int flags)
{
  if ((readonly_p (entry) && (flags & ASS_FORCE) == 0) || noassign_p (entry))
    {
      if (readonly_p (entry))
        err_readonly (name);
      return entry;
    }

  return bind_assoc_var_internal (entry, assoc_cell (entry), key, value,
                                  flags);
}

/* Parse NAME, a lhs of an assignment statement of the form v[s], and
   assign VALUE to that array element by calling bind_array_variable().
   Flags are ASS_ assignment flags */
SHELL_VAR *
assign_array_element (const char *name, const char *value, int flags)
{
  char *sub;
  int sublen;

  char *vname
      = array_variable_name (name, (flags & ASS_NOEXPAND) != 0, &sub, &sublen);

  if (vname == 0)
    return (SHELL_VAR *)NULL;

  SHELL_VAR *entry = find_variable (vname);
  bool isassoc = entry && assoc_p (entry);

  if (((!(isassoc) || (flags & ASS_NOEXPAND) == 0)
       && (ALL_ELEMENT_SUB (sub[0]) && sub[1] == ']'))
      || (sublen <= 1))
    {
      free (vname);
      err_badarraysub (name);
      return (SHELL_VAR *)NULL;
    }

  entry = assign_array_element_internal (entry, name, vname, sub, sublen,
                                         value, flags);

  free (vname);
  return entry;
}

static SHELL_VAR *
assign_array_element_internal (
    SHELL_VAR *entry, const char *name, /* only used for error messages */
    char *vname, char *sub, int sublen, const char *value, int flags)
{
  if (entry && assoc_p (entry))
    {
      sub[sublen - 1] = '\0';
      char *akey;
      if ((flags & ASS_NOEXPAND) == 0)
        akey = expand_assignment_string_to_string (sub, 0);
      else
        akey = savestring (sub);
      sub[sublen - 1] = ']';
      if (akey == 0 || *akey == 0)
        {
          err_badarraysub (name);
          FREE (akey);
          return (SHELL_VAR *)NULL;
        }
      entry = bind_assoc_variable (entry, vname, akey, value, flags);
    }
  else
    {
      arrayind_t ind = array_expand_index (entry, sub, sublen, 0);
      /* negative subscripts to indexed arrays count back from end */
      if (entry && ind < 0)
        ind = (array_p (entry) ? array_max_index (array_cell (entry)) : 0) + 1
              + ind;
      if (ind < 0)
        {
          err_badarraysub (name);
          return (SHELL_VAR *)NULL;
        }
      entry = bind_array_variable (vname, ind, value, flags);
    }

  return entry;
}

/* Find the array variable corresponding to NAME.  If there is no variable,
   create a new array variable.  If the variable exists but is not an array,
   convert it to an indexed array.  If FLAGS&1 is non-zero, an existing
   variable is checked for the readonly or noassign attribute in preparation
   for assignment (e.g., by the `read' builtin).  If FLAGS&2 is non-zero, we
   create an associative array. */
SHELL_VAR *
find_or_make_array_variable (const char *name, int flags)
{
  SHELL_VAR *var;

  var = find_variable (name);
  if (var == 0)
    {
      /* See if we have a nameref pointing to a variable that hasn't been
         created yet. */
      var = find_variable_last_nameref (name, 1);
      if (var && nameref_p (var) && invisible_p (var))
        {
          internal_warning (_ ("%s: removing nameref attribute"), name);
          var->unset_attr (att_nameref);
        }
      if (var && nameref_p (var))
        {
          if (valid_nameref_value (nameref_cell (var), 2) == 0)
            {
              sh_invalidid (nameref_cell (var));
              return (SHELL_VAR *)NULL;
            }
          var = (flags & 2) ? make_new_assoc_variable (nameref_cell (var))
                            : make_new_array_variable (nameref_cell (var));
        }
    }

  if (var == 0)
    var = (flags & 2) ? make_new_assoc_variable (name)
                      : make_new_array_variable (name);
  else if ((flags & 1) && (readonly_p (var) || noassign_p (var)))
    {
      if (readonly_p (var))
        err_readonly (name);
      return (SHELL_VAR *)NULL;
    }
  else if ((flags & 2) && array_p (var))
    {
      set_exit_status (EXECUTION_FAILURE);
      report_error (_ ("%s: cannot convert indexed to associative array"),
                    name);
      return (SHELL_VAR *)NULL;
    }
  else if (array_p (var) == 0 && assoc_p (var) == 0)
    var = convert_var_to_array (var);

  return var;
}

/* Perform a compound assignment statement for array NAME, where VALUE is
   the text between the parens:  NAME=( VALUE ) */
SHELL_VAR *
assign_array_from_string (const char *name, const char *value, int flags)
{
  SHELL_VAR *var;
  int vflags;

  vflags = 1;
  if (flags & ASS_MKASSOC)
    vflags |= 2;

  var = find_or_make_array_variable (name, vflags);
  if (var == 0)
    return (SHELL_VAR *)NULL;

  return assign_array_var_from_string (var, value, flags);
}

/* Sequentially assign the indices of indexed array variable VAR from the
   words in LIST. */
SHELL_VAR *
assign_array_var_from_word_list (SHELL_VAR *var, WORD_LIST *list, int flags)
{
  ARRAY *a = array_cell (var);
  arrayind_t i = (flags & ASS_APPEND) ? array_max_index (a) + 1 : 0;

  for (WORD_LIST *l = list; l; l = (WORD_LIST *)l->next, i++)
    bind_array_var_internal (var, i, 0, l->word->word, flags & ~ASS_APPEND);

  var->unset_attr (att_invisible); /* no longer invisible */

  return var;
}

WORD_LIST *
expand_compound_array_assignment (SHELL_VAR *var, const char *value, int flags)
{
  char *val;

  /* This condition is true when invoked from the declare builtin with a
     command like
        declare -a d='([1]="" [2]="bdef" [5]="hello world" "test")' */
  if (*value == '(')
    {
      int ni = 1;
      val = extract_array_assignment_list (value, &ni);
      if (val == 0)
        return (WORD_LIST *)NULL;
    }
  else
    val = (char *)value;

  /* Expand the value string into a list of words, performing all the
     shell expansions including pathname generation and word splitting. */
  /* First we split the string on whitespace, using the shell parser
     (ksh93 seems to do this). */
  WORD_LIST *list = parse_string_to_word_list (val, 1, "array assign");

  /* Note that we defer expansion of the assignment statements for associative
     arrays here, so we don't have to scan the subscript and find the ending
     bracket twice. See the caller below. */
  if (var && assoc_p (var))
    {
      if (val != value)
        free (val);
      return list;
    }

  /* If we're using [subscript]=value, we need to quote each [ and ] to
     prevent unwanted filename expansion.  This doesn't need to be done
     for associative array expansion, since that uses a different expansion
     function (see assign_compound_array_list below). */
  if (list)
    quote_array_assignment_chars (list);

  /* Now that we've split it, perform the shell expansions on each
     word in the list. */
  WORD_LIST *nlist = list ? expand_words_no_vars (list) : (WORD_LIST *)NULL;

  dispose_words (list);

  if (val != value)
    free (val);

  return nlist;
}

#if ASSOC_KVPAIR_ASSIGNMENT
static void
assign_assoc_from_kvlist (SHELL_VAR *var, WORD_LIST *nlist, HASH_TABLE *h,
                          int flags)
{
  for (WORD_LIST *list = nlist; list; list = (WORD_LIST *)list->next)
    {
      char *k = list->word->word;
      char *v = list->next ? ((WORD_LIST *)list->next)->word->word : 0;

      if (list->next)
        list = (WORD_LIST *)list->next;

      char *akey = expand_assignment_string_to_string (k, 0);
      if (akey == 0 || *akey == 0)
        {
          err_badarraysub (k);
          FREE (akey);
          continue;
        }

      char *aval = expand_assignment_string_to_string (v, 0);
      if (aval == 0)
        {
          aval = (char *)xmalloc (1);
          aval[0] = '\0'; /* like do_assignment_internal */
        }

      bind_assoc_var_internal (var, h, akey, aval, flags);
      free (aval);
    }
}

/* Return non-zero if L appears to be a key-value pair associative array
   compound assignment. */
bool
kvpair_assignment_p (WORD_LIST *l)
{
  return l && (l->word->flags & W_ASSIGNMENT) == 0 && l->word->word[0] != '[';
}

char *
expand_and_quote_kvpair_word (const char *w)
{
  char *t, *r;

  t = w ? expand_assignment_string_to_string (w, 0) : 0;
  r = sh_single_quote (t ? t : "");
  free (t);
  return r;
}
#endif

/* Callers ensure that VAR is not NULL. Associative array assignments have not
   been expanded when this is called, or have been expanded once and single-
   quoted, so we don't have to scan through an unquoted expanded subscript to
   find the ending bracket; indexed array assignments have been expanded and
   possibly single-quoted to prevent further expansion.

   If this is an associative array, we perform the assignments into NHASH and
   set NHASH to be the value of VAR after processing the assignments in NLIST
 */
void
assign_compound_array_list (SHELL_VAR *var, WORD_LIST *nlist, int flags)
{
  ARRAY *a;
  HASH_TABLE *h, *nhash;

  a = (var && array_p (var)) ? array_cell (var) : (ARRAY *)0;
  nhash = h = (var && assoc_p (var)) ? assoc_cell (var) : (HASH_TABLE *)0;

  /* Now that we are ready to assign values to the array, kill the existing
     value. */
  if ((flags & ASS_APPEND) == 0)
    {
      if (a && array_p (var))
        array_flush (a);
      else if (h && assoc_p (var))
        nhash = assoc_create (h->nbuckets);
    }

  arrayind_t last_ind
      = (a && (flags & ASS_APPEND)) ? array_max_index (a) + 1 : 0;

#if ASSOC_KVPAIR_ASSIGNMENT
  if (assoc_p (var) && kvpair_assignment_p (nlist))
    {
      int iflags = flags & ~ASS_APPEND;
      assign_assoc_from_kvlist (var, nlist, nhash, iflags);
      if (nhash && nhash != h)
        {
          h = assoc_cell (var);
          var_setassoc (var, nhash);
          assoc_dispose (h);
        }
      return;
    }
#endif

  char *akey = 0;
  char *val = 0;
  arrayind_t ind = 0;

  for (WORD_LIST *list = nlist; list; list = (WORD_LIST *)list->next)
    {
      /* Don't allow var+=(values) to make assignments in VALUES append to
         existing values by default. */
      int iflags = flags & ~ASS_APPEND;
      char *w = list->word->word;

      /* We have a word of the form [ind]=value */
      if ((list->word->flags & W_ASSIGNMENT) && w[0] == '[')
        {
          /* Don't have to handle embedded quotes specially any more, since
             associative array subscripts have not been expanded yet (see
             above). */
          int len = skipsubscript (w, 0, 0);

          /* XXX - changes for `+=' */
          if (w[len] != ']'
              || (w[len + 1] != '='
                  && (w[len + 1] != '+' || w[len + 2] != '=')))
            {
              if (assoc_p (var))
                {
                  err_badarraysub (w);
                  continue;
                }
              char *nval = make_variable_value (var, w, flags);
              if (var->assign_func)
                (*var->assign_func) (var, nval, last_ind, 0);
              else
                array_insert (a, last_ind, nval);
              FREE (nval);
              last_ind++;
              continue;
            }

          if (len == 1)
            {
              err_badarraysub (w);
              continue;
            }

          if (ALL_ELEMENT_SUB (w[1]) && len == 2)
            {
              set_exit_status (EXECUTION_FAILURE);
              if (assoc_p (var))
                report_error (_ ("%s: invalid associative array key"), w);
              else
                report_error (_ ("%s: cannot assign to non-numeric index"), w);
              continue;
            }

          if (array_p (var))
            {
              ind = array_expand_index (var, w + 1, len, 0);
              /* negative subscripts to indexed arrays count back from end */
              if (ind < 0)
                ind = array_max_index (array_cell (var)) + 1 + ind;
              if (ind < 0)
                {
                  err_badarraysub (w);
                  continue;
                }

              last_ind = ind;
            }
          else if (assoc_p (var))
            {
              /* This is not performed above, see
               * expand_compound_array_assignment */
              w[len] = '\0';
              akey = expand_assignment_string_to_string (w + 1, 0);
              w[len] = ']';
              /* And we need to expand the value also, see below */
              if (akey == 0 || *akey == 0)
                {
                  err_badarraysub (w);
                  FREE (akey);
                  continue;
                }
            }

          /* XXX - changes for `+=' -- just accept the syntax.  ksh93 doesn't
           * do this */
          if (w[len + 1] == '+' && w[len + 2] == '=')
            {
              iflags |= ASS_APPEND;
              val = w + len + 3;
            }
          else
            val = w + len + 2;
        }
      else if (assoc_p (var))
        {
          set_exit_status (EXECUTION_FAILURE);
          report_error (_ ("%s: %s: must use subscript when assigning "
                           "associative array"),
                        var->name, w);
          continue;
        }
      else /* No [ind]=value, just a stray `=' */
        {
          ind = last_ind;
          val = w;
        }

      bool free_val = false;
      /* See above; we need to expand the value here */
      if (assoc_p (var))
        {
          val = expand_assignment_string_to_string (val, 0);
          if (val == 0)
            {
              val = (char *)xmalloc (1);
              val[0] = '\0'; /* like do_assignment_internal */
            }
          free_val = true;
        }

      const char *savecmd = this_command_name;
      if (integer_p (var))
        this_command_name = nullptr; /* no command name for errors */
      if (assoc_p (var))
        bind_assoc_var_internal (var, nhash, akey, val, iflags);
      else
        bind_array_var_internal (var, ind, akey, val, iflags);
      last_ind++;
      this_command_name = savecmd;

      if (free_val)
        free (val);
    }

  if (assoc_p (var) && nhash && nhash != h)
    {
      h = assoc_cell (var);
      var_setassoc (var, nhash);
      assoc_dispose (h);
    }
}

/* Perform a compound array assignment:  VAR->name=( VALUE ).  The
   VALUE has already had the parentheses stripped. */
SHELL_VAR *
assign_array_var_from_string (SHELL_VAR *var, const char *value, int flags)
{
  WORD_LIST *nlist;

  if (value == 0)
    return var;

  nlist = expand_compound_array_assignment (var, value, flags);
  assign_compound_array_list (var, nlist, flags);

  if (nlist)
    dispose_words (nlist);

  if (var)
    var->unset_attr (att_invisible); /* no longer invisible */

  return var;
}

/* Quote globbing chars and characters in $IFS before the `=' in an assignment
   statement (usually a compound array assignment) to protect them from
   unwanted filename expansion or word splitting. */
static char *
quote_assign (const char *string)
{
  DECLARE_MBSTATE;

  size_t slen = strlen (string);
  const char *send = string + slen;

  char *temp = (char *)xmalloc (slen * 2 + 1);
  char *t = temp;
  bool saw_eq = false;

  for (const char *s = string; *s;)
    {
      if (*s == '=')
        saw_eq = true;

      if (!saw_eq && *s == '[') /* looks like a subscript */
        {
          int ss = s - string;
          int se = skipsubscript (string, ss, 0);
          char *subs = substring (s, ss, se);
          *t++ = '\\';
          strcpy (t, subs);
          t += se - ss;
          *t++ = '\\';
          *t++ = ']';
          s += se + 1;
          free (subs);
          continue;
        }

      if (!saw_eq && (glob_char_p (s) || isifs (*s)))
        *t++ = '\\';

      COPY_CHAR_P (t, s, send);
    }
  *t = '\0';
  return temp;
}

/* Take a word W of the form [IND]=VALUE and transform it to ['IND']='VALUE'
   to prevent further expansion. This is called for compound assignments to
   indexed arrays. W has already undergone word expansions. If W has no [IND]=,
   just single-quote and return it. */
static char *
quote_compound_array_word (char *w, int type)
{
  char *nword, *sub, *value, *t;
  int ind, wlen, i;

  if (w[0] != LBRACK)
    return sh_single_quote (w);
  ind = skipsubscript (w, 0, 0);
  if (w[ind] != RBRACK)
    return sh_single_quote (w);

  wlen = strlen (w);
  w[ind] = '\0';
  sub = sh_single_quote (w + 1);
  w[ind] = RBRACK;

  nword = (char *)xmalloc (wlen * 4
                           + 5); /* wlen*4 is max single quoted length */
  nword[0] = LBRACK;
  i = STRLEN (sub);
  memcpy (nword + 1, sub, i);
  free (sub);

  i++;                   /* accommodate the opening LBRACK */
  nword[i++] = w[ind++]; /* RBRACK */
  if (w[ind] == '+')
    nword[i++] = w[ind++];
  nword[i++] = w[ind++];
  value = sh_single_quote (w + ind);
  strcpy (nword + i, value);
  free (value); /* fix leak */

  return nword;
}

/* Expand the key and value in W, which is of the form [KEY]=VALUE, and
   reconstruct W with the expanded and single-quoted version:
   ['expanded-key']='expanded-value'. If there is no [KEY]=, single-quote the
   word and return it. Very similar to previous function, but does not assume
   W has already been expanded, and expands the KEY and VALUE separately.
   Used for compound assignments to associative arrays that are arguments to
   declaration builtins (declare -A a=( list )). */
char *
expand_and_quote_assoc_word (const char *w, int type)
{
  if (w[0] != LBRACK)
    return sh_single_quote (w);
  int ind = skipsubscript (w, 0, 0);
  if (w[ind] != RBRACK)
    return sh_single_quote (w);

  ((char *)w)[ind] = '\0';
  char *t = expand_assignment_string_to_string (w + 1, 0);
  ((char *)w)[ind] = RBRACK;
  char *key = sh_single_quote (t ? t : "");
  free (t);

  int wlen = STRLEN (key);
  char *nword = (char *)xmalloc (wlen + 5);
  nword[0] = LBRACK;
  memcpy (nword + 1, key, wlen);
  int i = wlen + 1; /* accommodate the opening LBRACK */

  nword[i++] = w[ind++]; /* RBRACK */
  if (w[ind] == '+')
    nword[i++] = w[ind++];
  nword[i++] = w[ind++];

  t = expand_assignment_string_to_string (w + ind, 0);
  char *value = sh_single_quote (t ? t : "");
  free (t);
  nword = (char *)xrealloc (nword, wlen + 5 + STRLEN (value));
  strcpy (nword + i, value);

  free (key);
  free (value);

  return nword;
}

/* For each word in a compound array assignment, if the word looks like
   [ind]=value, single-quote ind and value, but leave the brackets and
   the = sign (and any `+') alone. If it's not an assignment, just single-
   quote the word. This is used for indexed arrays. */
void
quote_compound_array_list (WORD_LIST *list, int type)
{
  for (WORD_LIST *l = list; l; l = (WORD_LIST *)l->next)
    {
      if (l->word == 0 || l->word->word == 0)
        continue; /* should not happen, but just in case... */

      char *t;
      if ((l->word->flags & W_ASSIGNMENT) == 0)
        t = sh_single_quote (l->word->word);
      else
        t = quote_compound_array_word (l->word->word, type);
      free (l->word->word);
      l->word->word = t;
    }
}

/* For each word in a compound array assignment, if the word looks like
   [ind]=value, quote globbing chars and characters in $IFS before the `='. */
static void
quote_array_assignment_chars (WORD_LIST *list)
{
  for (WORD_LIST *l = list; l; l = (WORD_LIST *)l->next)
    {
      if (l->word == 0 || l->word->word == 0 || l->word->word[0] == '\0')
        continue; /* should not happen, but just in case... */
      /* Don't bother if it hasn't been recognized as an assignment or
         doesn't look like [ind]=value */
      if ((l->word->flags & W_ASSIGNMENT) == 0)
        continue;
      if (l->word->word[0] != '[' || mbschr (l->word->word, '=') == 0)
        continue;

      char *nword = quote_assign (l->word->word);
      free (l->word->word);
      l->word->word = nword;
      l->word->flags |= W_NOGLOB; /* XXX - W_NOSPLIT also? */
    }
}

/* skipsubscript moved to subst.c to use private functions. 2009/02/24. */

/* This function is called with SUB pointing to just after the beginning
   `[' of an array subscript and removes the array element to which SUB
   expands from array VAR.  A subscript of `*' or `@' unsets the array. */
/* If FLAGS&1 we don't expand the subscript; we just use it as-is. */
int
unbind_array_element (SHELL_VAR *var, char *sub, int flags)
{
  int len = skipsubscript (sub, 0,
                           (flags & 1) || (var && assoc_p (var))); /* XXX */
  if (sub[len] != ']' || len == 0)
    {
      builtin_error ("%s[%s: %s", var->name, sub, _ (bash_badsub_errmsg));
      return -1;
    }
  sub[len] = '\0';

  if (ALL_ELEMENT_SUB (sub[0]) && sub[1] == 0)
    {
      if (array_p (var) || assoc_p (var))
        {
          unbind_variable (var->name); /* XXX -- {array,assoc}_flush ? */
          return 0;
        }
      else
        return -2; /* don't allow this to unset scalar variables */
    }

  if (assoc_p (var))
    {
      char *akey
          = (flags & 1) ? sub : expand_assignment_string_to_string (sub, 0);
      if (akey == 0 || *akey == 0)
        {
          builtin_error ("[%s]: %s", sub, _ (bash_badsub_errmsg));
          FREE (akey);
          return -1;
        }
      assoc_remove (assoc_cell (var), akey);
      if (akey != sub)
        free (akey);
    }
  else if (array_p (var))
    {
      arrayind_t ind = array_expand_index (var, sub, len + 1, 0);
      /* negative subscripts to indexed arrays count back from end */
      if (ind < 0)
        ind = array_max_index (array_cell (var)) + 1 + ind;
      if (ind < 0)
        {
          builtin_error ("[%s]: %s", sub, _ (bash_badsub_errmsg));
          return -1;
        }
      ARRAY_ELEMENT *ae = array_remove (array_cell (var), ind);
      if (ae)
        array_dispose_element (ae);
    }
  else /* array_p (var) == 0 && assoc_p (var) == 0 */
    {
      const char *akey = this_command_name;
      arrayind_t ind = array_expand_index (var, sub, len + 1, 0);
      this_command_name = akey;
      if (ind == 0)
        {
          unbind_variable (var->name);
          return 0;
        }
      else
        return -2; /* any subscript other than 0 is invalid with scalar
                      variables */
    }

  return 0;
}

/* Format and output an array assignment in compound form VAR=(VALUES),
   suitable for re-use as input. */
void
print_array_assignment (SHELL_VAR *var, int quoted)
{
  char *vstr;

  vstr = array_to_assign (array_cell (var), quoted);

  if (vstr == 0)
    printf ("%s=%s\n", var->name, quoted ? "'()'" : "()");
  else
    {
      printf ("%s=%s\n", var->name, vstr);
      free (vstr);
    }
}

/* Format and output an associative array assignment in compound form
   VAR=(VALUES), suitable for re-use as input. */
void
print_assoc_assignment (SHELL_VAR *var, int quoted)
{
  char *vstr;

  vstr = assoc_to_assign (assoc_cell (var), quoted);

  if (vstr == 0)
    printf ("%s=%s\n", var->name, quoted ? "'()'" : "()");
  else
    {
      printf ("%s=%s\n", var->name, vstr);
      free (vstr);
    }
}

/***********************************************************************/
/*								       */
/* Utility functions to manage arrays and their contents for expansion */
/*								       */
/***********************************************************************/

/* Return 1 if NAME is a properly-formed array reference v[sub]. */

/* We need to reserve 1 for FLAGS, which we pass to skipsubscript. */
bool
Shell::valid_array_reference (const char *name, valid_array_flags flags)
{
  char *t = mbschr (name, '[');
  bool isassoc = false;
  if (t)
    {
      *t = '\0';
      int r = legal_identifier (name);
      SHELL_VAR *entry;
      if (flags & VA_NOEXPAND) /* Don't waste a lookup if we don't need one */
        isassoc = (entry = find_variable (name)) && assoc_p (entry);
      *t = '[';
      if (r == 0)
        return false;

      int len;
      if (isassoc
          && ((flags & (VA_NOEXPAND | VA_ONEWORD))
              == (VA_NOEXPAND | VA_ONEWORD)))
        len = strlen (t) - 1;
      else if (isassoc)
        len = skipsubscript (t, 0,
                             flags & VA_NOEXPAND); /* VA_NOEXPAND must be 1 */
      else
        /* Check for a properly-terminated non-null subscript. */
        len = skipsubscript (t, 0, 0); /* arithmetic expression */

      if (t[len] != ']' || len == 1 || t[len + 1] != '\0')
        return false;

#if 0
      /* Could check and allow subscripts consisting only of whitespace for
	 existing associative arrays, using isassoc */
      for (int r = 1; r < len; r++)
	if (!whitespace (t[r]))
	  return true;
      return false;
#else
      /* This allows blank subscripts */
      return true;
#endif
    }
  return false;
}

/* Expand the array index beginning at S and extending LEN characters. */
arrayind_t
array_expand_index (SHELL_VAR *var, const char *s, int len, int flags)
{
  char *exp = (char *)xmalloc (len);
  strncpy (exp, s, len - 1);
  exp[len - 1] = '\0';
#if 0 /* TAG: maybe bash-5.2 */
  if ((flags & AV_NOEXPAND) == 0)
    t = expand_arith_string (exp, Q_DOUBLE_QUOTES|Q_ARITH|Q_ARRAYSUB);	/* XXX - Q_ARRAYSUB for future use */
  else
    t = exp;
#endif
  char *t = expand_arith_string (
      exp, Q_DOUBLE_QUOTES | Q_ARITH
               | Q_ARRAYSUB); /* XXX - Q_ARRAYSUB for future use */
  const char *savecmd = this_command_name;
  this_command_name = nullptr;

  bool expok;
  arrayind_t val = evalexp (
      t, EXP_EXPANDED, &expok); /* XXX - was 0 but we expanded exp already */
  this_command_name = savecmd;
  if (t != exp)
    free (t);
  free (exp);
  if (expok == 0)
    {
      set_exit_status (EXECUTION_FAILURE);

      if (no_longjmp_on_fatal_error)
        return 0;
      top_level_cleanup ();
      jump_to_top_level (DISCARD);
    }
  return val;
}

/* Return the name of the variable specified by S without any subscript.
   If SUBP is non-null, return a pointer to the start of the subscript
   in *SUBP. If LENP is non-null, the length of the subscript is returned
   in *LENP.  This returns newly-allocated memory. */
char *
array_variable_name (const char *s, int flags, char **subp, int *lenp)
{
  char *t, *ret;
  int ind, ni;

  t = mbschr (s, '[');
  if (t == 0)
    {
      if (subp)
        *subp = t;
      if (lenp)
        *lenp = 0;
      return nullptr;
    }
  ind = t - s;
  ni = skipsubscript (s, ind, flags); /* XXX - was 0 not flags */
  if (ni <= ind + 1 || s[ni] != ']')
    {
      err_badarraysub (s);
      if (subp)
        *subp = t;
      if (lenp)
        *lenp = 0;
      return nullptr;
    }

  *t = '\0';
  ret = savestring (s);
  *t++ = '[';

  if (subp)
    *subp = t;
  if (lenp)
    *lenp = ni - ind;

  return ret;
}

/* Return the variable specified by S without any subscript.  If SUBP is
   non-null, return a pointer to the start of the subscript in *SUBP.
   If LENP is non-null, the length of the subscript is returned in *LENP. */
SHELL_VAR *
array_variable_part (const char *s, int flags, char **subp, int *lenp)
{
  char *t;
  SHELL_VAR *var;

  t = array_variable_name (s, flags, subp, lenp);
  if (t == 0)
    return (SHELL_VAR *)NULL;
  var = find_variable (t); /* XXX - handle namerefs here? */

  free (t);
  return var; /* now return invisible variables; caller must handle */
}

#define INDEX_ERROR()                                                         \
  do                                                                          \
    {                                                                         \
      if (var)                                                                \
        err_badarraysub (var->name);                                          \
      else                                                                    \
        {                                                                     \
          t[-1] = '\0';                                                       \
          err_badarraysub (s);                                                \
          t[-1] = '[';                                                        \
        }                                                                     \
      return nullptr;                                                         \
    }                                                                         \
  while (0)

/* Return a string containing the elements in the array and subscript
   described by S.  If the subscript is * or @, obeys quoting rules akin
   to the expansion of $* and $@ including double quoting.  If RTYPE
   is non-null it gets 1 if the array reference is name[*], 2 if the
   reference is name[@], and 0 otherwise. */
static char *
array_value_internal (const char *s, int quoted, int flags, int *rtype,
                      arrayind_t *indp)
{
  int len;
  arrayind_t ind;
  char *akey;
  char *retval, *t, *temp;
  WORD_LIST *l;
  SHELL_VAR *var;

  var = array_variable_part (s, (flags & AV_NOEXPAND) ? 1 : 0, &t,
                             &len); /* XXX */

  /* Expand the index, even if the variable doesn't exist, in case side
     effects are needed, like ${w[i++]} where w is unset. */
#if 0
  if (var == 0)
    return nullptr;
#endif

  if (len == 0)
    return nullptr; /* error message already printed */

  akey = 0;
  if (ALL_ELEMENT_SUB (t[0]) && t[1] == ']')
    {
      if (rtype)
        *rtype = (t[0] == '*') ? 1 : 2;
      if ((flags & AV_ALLOWALL) == 0)
        {
          err_badarraysub (s);
          return nullptr;
        }
      else if (var == 0
               || value_cell (var)
                      == 0) /* XXX - check for invisible_p(var) ? */
        return nullptr;
      else if (invisible_p (var))
        return nullptr;
      else if (array_p (var) == 0 && assoc_p (var) == 0)
        l = add_string_to_list (value_cell (var), (WORD_LIST *)NULL);
      else if (assoc_p (var))
        {
          l = assoc_to_word_list (assoc_cell (var));
          if (l == (WORD_LIST *)NULL)
            return nullptr;
        }
      else
        {
          l = array_to_word_list (array_cell (var));
          if (l == (WORD_LIST *)NULL)
            return nullptr;
        }

      /* Caller of array_value takes care of inspecting rtype and duplicating
         retval if rtype == 0, so this is not a memory leak */
      if (t[0] == '*' && (quoted & (Q_HERE_DOCUMENT | Q_DOUBLE_QUOTES)))
        {
          temp = string_list_dollar_star (
              l, quoted, (flags & AV_ASSIGNRHS) ? PF_ASSIGNRHS : 0);
          retval = quote_string (temp);
          free (temp);
        }
      else /* ${name[@]} or unquoted ${name[*]} */
        retval = string_list_dollar_at (
            l, quoted, (flags & AV_ASSIGNRHS) ? PF_ASSIGNRHS : 0);

      dispose_words (l);
    }
  else
    {
      if (rtype)
        *rtype = 0;
      if (var == 0 || array_p (var) || assoc_p (var) == 0)
        {
          if ((flags & AV_USEIND) == 0 || indp == 0)
            {
              ind = array_expand_index (var, t, len, flags);
              if (ind < 0)
                {
                  /* negative subscripts to indexed arrays count back from end
                   */
                  if (var && array_p (var))
                    ind = array_max_index (array_cell (var)) + 1 + ind;
                  if (ind < 0)
                    INDEX_ERROR ();
                }
              if (indp)
                *indp = ind;
            }
          else if (indp)
            ind = *indp;
        }
      else if (assoc_p (var))
        {
          t[len - 1] = '\0';
          if ((flags & AV_NOEXPAND) == 0)
            akey = expand_assignment_string_to_string (t, 0);
          else
            akey = savestring (t);
          t[len - 1] = ']';
          if (akey == 0 || *akey == 0)
            {
              FREE (akey);
              INDEX_ERROR ();
            }
        }

      if (var == 0
          || value_cell (var) == 0) /* XXX - check invisible_p(var) ? */
        {
          FREE (akey);
          return nullptr;
        }
      else if (invisible_p (var))
        {
          FREE (akey);
          return nullptr;
        }
      if (array_p (var) == 0 && assoc_p (var) == 0)
        return ind == 0 ? value_cell (var) : nullptr;
      else if (assoc_p (var))
        {
          retval = assoc_reference (assoc_cell (var), akey);
          free (akey);
        }
      else
        retval = array_reference (array_cell (var), ind);
    }

  return retval;
}

/* Return a string containing the elements described by the array and
   subscript contained in S, obeying quoting for subscripts * and @. */
char *
array_value (const char *s, int quoted, int flags, int *rtype,
             arrayind_t *indp)
{
  return array_value_internal (s, quoted, flags | AV_ALLOWALL, rtype, indp);
}

/* Return the value of the array indexing expression S as a single string.
   If (FLAGS & AV_ALLOWALL) is 0, do not allow `@' and `*' subscripts.  This
   is used by other parts of the shell such as the arithmetic expression
   evaluator in expr.c. */
char *
get_array_value (const char *s, int flags, int *rtype, arrayind_t *indp)
{
  return array_value_internal (s, 0, flags, rtype, indp);
}

char *
array_keys (const char *s, int quoted, int pflags)
{
  int len;
  char *t;

  SHELL_VAR *var = array_variable_part (s, 0, &t, &len);

  if (var == 0 || ALL_ELEMENT_SUB (t[0]) == 0 || t[1] != ']')
    return nullptr;

  if (var_isset (var) == 0 || invisible_p (var))
    return nullptr;

  WORD_LIST *l;
  if (array_p (var) == 0 && assoc_p (var) == 0)
    l = add_string_to_list ("0", (WORD_LIST *)NULL);
  else if (assoc_p (var))
    l = assoc_keys_to_word_list (assoc_cell (var));
  else
    l = array_keys_to_word_list (array_cell (var));
  if (l == (WORD_LIST *)NULL)
    return nullptr;

  char *retval = string_list_pos_params (t[0], l, quoted, pflags);

  dispose_words (l);
  return retval;
}

} // namespace bash

#endif /* ARRAY_VARS */