This file is setattr.def, from which is created setattr.c.
It implements the builtins "export" and "readonly", in Bash.

Copyright (C) 1987-2015 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/>.

$PRODUCES setattr.c

#include <config.h>

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

#include <stdio.h>
#include "../bashansi.h"
#include "../bashintl.h"

#include "../shell.h"
#include "../execute_cmd.h"
#include "../flags.h"
#include "common.h"
#include "bashgetopt.h"

extern sh_builtin_func_t *this_shell_builtin;

#ifdef ARRAY_VARS
extern int declare_builtin __P((WORD_LIST *));
#endif

#define READONLY_OR_EXPORT \
  (this_shell_builtin == readonly_builtin || this_shell_builtin == export_builtin)

$BUILTIN export
$FUNCTION export_builtin
$SHORT_DOC export [-fn] [name[=value] ...] or export -p
Set export attribute for shell variables.

Marks each NAME for automatic export to the environment of subsequently
executed commands.  If VALUE is supplied, assign VALUE before exporting.

Options:
  -f	refer to shell functions
  -n	remove the export property from each NAME
  -p	display a list of all exported variables and functions

An argument of `--' disables further option processing.

Exit Status:
Returns success unless an invalid option is given or NAME is invalid.
$END

/* For each variable name in LIST, make that variable appear in the
   environment passed to simple commands.  If there is no LIST, then
   print all such variables.  An argument of `-n' says to remove the
   exported attribute from variables named in LIST.  An argument of
  -f indicates that the names present in LIST refer to functions. */
int
export_builtin (list)
     register WORD_LIST *list;
{
  return (set_or_show_attributes (list, att_exported, 0));
}

$BUILTIN readonly
$FUNCTION readonly_builtin
$SHORT_DOC readonly [-aAf] [name[=value] ...] or readonly -p
Mark shell variables as unchangeable.

Mark each NAME as read-only; the values of these NAMEs may not be
changed by subsequent assignment.  If VALUE is supplied, assign VALUE
before marking as read-only.

Options:
  -a	refer to indexed array variables
  -A	refer to associative array variables
  -f	refer to shell functions
  -p	display a list of all readonly variables or functions,
		depending on whether or not the -f option is given

An argument of `--' disables further option processing.

Exit Status:
Returns success unless an invalid option is given or NAME is invalid.
$END

/* For each variable name in LIST, make that variable readonly.  Given an
   empty LIST, print out all existing readonly variables. */
int
readonly_builtin (list)
     register WORD_LIST *list;
{
  return (set_or_show_attributes (list, att_readonly, 0));
}

#if defined (ARRAY_VARS)
#  define ATTROPTS	"aAfnp"
#else
#  define ATTROPTS	"fnp"
#endif

/* For each variable name in LIST, make that variable have the specified
   ATTRIBUTE.  An arg of `-n' says to remove the attribute from the the
   remaining names in LIST (doesn't work for readonly). */
int
set_or_show_attributes (list, attribute, nodefs)
     register WORD_LIST *list;
     int attribute, nodefs;
{
  register SHELL_VAR *var;
  int assign, undo, any_failed, assign_error, opt;
  int functions_only, arrays_only, assoc_only;
  int aflags;
  char *name;
#if defined (ARRAY_VARS)
  WORD_LIST *nlist, *tlist;
  WORD_DESC *w;
  char optw[8];
  int opti;
#endif

  functions_only = arrays_only = assoc_only = 0;
  undo = any_failed = assign_error = 0;
  /* Read arguments from the front of the list. */
  reset_internal_getopt ();
  while ((opt = internal_getopt (list, ATTROPTS)) != -1)
    {
      switch (opt)
	{
	  case 'n':
	    undo = 1;
	    break;
	  case 'f':
	    functions_only = 1;
	    break;
#if defined (ARRAY_VARS)
	  case 'a':
	    arrays_only = 1;
	    break;
	  case 'A':
	    assoc_only = 1;
	    break;
#endif
	  case 'p':
	    break;
	  CASE_HELPOPT;
	  default:
	    builtin_usage ();
	    return (EX_USAGE);
	}
    }
  list = loptend;

  if (list)
    {
      if (attribute & att_exported)
	array_needs_making = 1;

      /* Cannot undo readonly status, silently disallowed. */
      if (undo && (attribute & att_readonly))
	attribute &= ~att_readonly;

      while (list)
	{
	  name = list->word->word;

	  if (functions_only)		/* xxx -f name */
	    {
	      var = find_function (name);
	      if (var == 0)
		{
		  builtin_error (_("%s: not a function"), name);
		  any_failed++;
		}
	      else if ((attribute & att_exported) && undo == 0 && exportable_function_name (name) == 0)
		{
		  builtin_error (_("%s: cannot export"), name);
		  any_failed++;
		}
	      else
		SETVARATTR (var, attribute, undo);

	      list = list->next;
	      continue;
	    }

	  /* xxx [-np] name[=value] */
	  assign = assignment (name, 0);

	  aflags = 0;
	  if (assign)
	    {
	      name[assign] = '\0';
	      if (name[assign - 1] == '+')
		{
		  aflags |= ASS_APPEND;
		  name[assign - 1] = '\0';
		}
	    }

	  if (legal_identifier (name) == 0)
	    {
	      sh_invalidid (name);
	      if (assign)
		assign_error++;
	      else
		any_failed++;
	      list = list->next;
	      continue;
	    }

	  if (assign)	/* xxx [-np] name=value */
	    {
	      name[assign] = '=';
	      if (aflags & ASS_APPEND)
		name[assign - 1] = '+';
#if defined (ARRAY_VARS)
	      /* Let's try something here.  Turn readonly -a xxx=yyy into
		 declare -ra xxx=yyy and see what that gets us. */
	      if (arrays_only || assoc_only)
		{
		  tlist = list->next;
		  list->next = (WORD_LIST *)NULL;
		  /* Add -g to avoid readonly/export creating local variables:
		     only local/declare/typeset create local variables */
		  opti = 0;
		  optw[opti++] = '-';
		  optw[opti++] = 'g';
		  if (attribute & att_readonly)
		    optw[opti++] = 'r';
		  if (attribute & att_exported)
		    optw[opti++] = 'x';
		  if (arrays_only)
		    optw[opti++] = 'a';
		  else
		    optw[opti++] = 'A';
		  optw[opti] = '\0';

		  w = make_word (optw);
		  nlist = make_word_list (w, list);

		  opt = declare_builtin (nlist);
		  if (opt != EXECUTION_SUCCESS)
		    assign_error++;
		  list->next = tlist;
		  dispose_word (w);
		  free (nlist);
		}
	      else
#endif
	      /* This word has already been expanded once with command
		 and parameter expansion.  Call do_assignment_no_expand (),
		 which does not do command or parameter substitution.  If
		 the assignment is not performed correctly, flag an error. */
	      if (do_assignment_no_expand (name) == 0)
		assign_error++;
	      name[assign] = '\0';
	      if (aflags & ASS_APPEND)
		name[assign - 1] = '\0';
	    }

	  set_var_attribute (name, attribute, undo);
	  if (assign)		/* restore word */
	    {
	      name[assign] = '=';
	      if (aflags & ASS_APPEND)
		name[assign-1] = '+';
	    }
	  list = list->next;
	}
    }
  else
    {
      SHELL_VAR **variable_list;
      register int i;

      if ((attribute & att_function) || functions_only)
	{
	  variable_list = all_shell_functions ();
	  if (attribute != att_function)
	    attribute &= ~att_function;	/* so declare -xf works, for example */
	}
      else
	variable_list = all_shell_variables ();

#if defined (ARRAY_VARS)
      if (attribute & att_array)
	{
	  arrays_only++;
	  if (attribute != att_array)
	    attribute &= ~att_array;
	}
      else if (attribute & att_assoc)
	{
	  assoc_only++;
	  if (attribute != att_assoc)
	    attribute &= ~att_assoc;
	}
#endif

      if (variable_list)
	{
	  for (i = 0; var = variable_list[i]; i++)
	    {
#if defined (ARRAY_VARS)
	      if (arrays_only && array_p (var) == 0)
		continue;
	      else if (assoc_only && assoc_p (var) == 0)
		continue;
#endif

	      /* If we imported a variable that's not a valid identifier, don't
		 show it in any lists. */
	      if ((var->attributes & (att_invisible|att_imported)) == (att_invisible|att_imported))
		continue;

	      if ((var->attributes & attribute))
		{
		  show_var_attributes (var, READONLY_OR_EXPORT, nodefs);
		  if (any_failed = sh_chkwrite (any_failed))
		    break;
		}
	    }
	  free (variable_list);
	}
    }

  return (assign_error ? EX_BADASSIGN
		       : ((any_failed == 0) ? EXECUTION_SUCCESS
  					    : EXECUTION_FAILURE));
}

/* Show all variable variables (v == 1) or functions (v == 0) with
   attributes. */
int
show_all_var_attributes (v, nodefs)
     int v, nodefs;
{
  SHELL_VAR **variable_list, *var;
  int any_failed;
  register int i;

  variable_list = v ? all_shell_variables () : all_shell_functions ();
  if (variable_list == 0)  
    return (EXECUTION_SUCCESS);

  for (i = any_failed = 0; var = variable_list[i]; i++)
    {
      show_var_attributes (var, READONLY_OR_EXPORT, nodefs);
      if (any_failed = sh_chkwrite (any_failed))
        break;
    }
  free (variable_list);
  return (any_failed == 0 ? EXECUTION_SUCCESS : EXECUTION_FAILURE);
}

int
var_attribute_string (var, pattr, flags)
     SHELL_VAR *var;
     int pattr;
     char *flags;	/* filled in with attributes */
{
  int i;

  i = 0;

  /* pattr == 0 means we are called from `declare'. */
  if (pattr == 0 || posixly_correct == 0)
    {
#if defined (ARRAY_VARS)
      if (array_p (var))
	flags[i++] = 'a';

      if (assoc_p (var))
	flags[i++] = 'A';
#endif

      if (function_p (var))
	flags[i++] = 'f';

      if (integer_p (var))
	flags[i++] = 'i';

      if (nameref_p (var))
	flags[i++] = 'n';

      if (readonly_p (var))
	flags[i++] = 'r';

      if (trace_p (var))
	flags[i++] = 't';

      if (exported_p (var))
	flags[i++] = 'x';

      if (capcase_p (var))
	flags[i++] = 'c';

      if (lowercase_p (var))
	flags[i++] = 'l';

      if (uppercase_p (var))
	flags[i++] = 'u';
    }
  else
    {
#if defined (ARRAY_VARS)
      if (array_p (var))
	flags[i++] = 'a';

      if (assoc_p (var))
	flags[i++] = 'A';
#endif

      if (function_p (var))
	flags[i++] = 'f';
    }

  flags[i] = '\0';
  return i;
}

/* Show the attributes for shell variable VAR.  If NODEFS is non-zero,
   don't show function definitions along with the name.  If PATTR is
   non-zero, it indicates we're being called from `export' or `readonly'.
   In POSIX mode, this prints the name of the calling builtin (`export'
   or `readonly') instead of `declare', and doesn't print function defs
   when called by `export' or `readonly'. */
int
show_var_attributes (var, pattr, nodefs)
     SHELL_VAR *var;
     int pattr, nodefs;
{
  char flags[MAX_ATTRIBUTES], *x;
  int i;

  i = var_attribute_string (var, pattr, flags);

  /* If we're printing functions with definitions, print the function def
     first, then the attributes, instead of printing output that can't be
     reused as input to recreate the current state. */
  if (function_p (var) && nodefs == 0 && (pattr == 0 || posixly_correct == 0))
    {
      printf ("%s\n", named_function_string (var->name, function_cell (var), FUNC_MULTILINE|FUNC_EXTERNAL));
      nodefs++;
      if (pattr == 0 && i == 1 && flags[0] == 'f')
	return 0;		/* don't print `declare -f name' */
    }

  if (pattr == 0 || posixly_correct == 0)
    printf ("declare -%s ", i ? flags : "-");
  else if (i)
    printf ("%s -%s ", this_command_name, flags);
  else
    printf ("%s ", this_command_name);

#if defined (ARRAY_VARS)
  if (invisible_p (var) && (array_p (var) || assoc_p (var)))
    printf ("%s\n", var->name);
  else if (array_p (var))
    print_array_assignment (var, 0);
  else if (assoc_p (var))
    print_assoc_assignment (var, 0);
  else
#endif
  /* force `readonly' and `export' to not print out function definitions
     when in POSIX mode. */
  if (nodefs || (function_p (var) && pattr != 0 && posixly_correct))
    printf ("%s\n", var->name);
  else if (function_p (var))
    printf ("%s\n", named_function_string (var->name, function_cell (var), FUNC_MULTILINE|FUNC_EXTERNAL));
  else if (invisible_p (var) || var_isset (var) == 0)
    printf ("%s\n", var->name);
  else
    {
      x = sh_double_quote (value_cell (var));
      printf ("%s=%s\n", var->name, x);
      free (x);
    }
  return (0);
}

int
show_name_attributes (name, nodefs)
     char *name;
     int nodefs;
{
  SHELL_VAR *var;

#if 0
  var = find_variable_tempenv (name);
#else
  var = find_variable_noref (name);
#endif

  if (var /* && invisible_p (var) == 0 */)
    {
      show_var_attributes (var, READONLY_OR_EXPORT, nodefs);
      return (0);
    }
  else
    return (1);
}

int
show_func_attributes (name, nodefs)
     char *name;
     int nodefs;
{
  SHELL_VAR *var;

  var = find_function (name);

  if (var)
    {
      show_var_attributes (var, READONLY_OR_EXPORT, nodefs);
      return (0);
    }
  else
    return (1);
}

void
set_var_attribute (name, attribute, undo)
     char *name;
     int attribute, undo;
{
  SHELL_VAR *var, *tv, *v, *refvar;
  char *tvalue;

  if (undo)
    var = find_variable (name);
  else
    {
      tv = find_tempenv_variable (name);
      /* XXX -- need to handle case where tv is a temp variable in a
	 function-scope context, since function_env has been merged into
	 the local variables table. */
      if (tv && tempvar_p (tv))
	{
	  tvalue = var_isset (tv) ? savestring (value_cell (tv)) : savestring ("");

	  var = bind_variable (tv->name, tvalue, 0);
	  if (var == 0)
	    {
	      free (tvalue);
	      return;		/* XXX - no error message here */
	    }
	  var->attributes |= tv->attributes & ~att_tempvar;
	  /* This avoids an error message when propagating a read-only var
	     later on. */
	  if (posixly_correct || shell_compatibility_level <= 44)
	    {
	      if (var->context == 0 && (attribute & att_readonly))
		{
		  /* Don't bother to set the `propagate to the global variables
		     table' flag if we've just bound the variable in that
		     table */
		  v = find_global_variable (tv->name);
		  if (v != var)
		    VSETATTR (tv, att_propagate);
		}
	      else
		VSETATTR (tv, att_propagate);
	      if (var->context != 0)
		VSETATTR (var, att_propagate);
	    }

	  SETVARATTR (tv, attribute, undo);	/* XXX */

	  stupidly_hack_special_variables (tv->name);

	  free (tvalue);
	}
      else
	{
	  var = find_variable_notempenv (name);
	  if (var == 0)
	    {
	      /* We might have a nameref pointing to something that we can't
		 resolve to a shell variable.  If we do, skip it.  We do a little
		 checking just so we can print an error message. */
	      refvar = find_variable_nameref_for_create (name, 0);
	      if (refvar == INVALID_NAMEREF_VALUE)
		return;
	      /* Otherwise we probably have a nameref pointing to a variable
		 that hasn't been created yet. bind_variable will take care
		 of that. */
	    }
	  if (var == 0)
	    {
	      var = bind_variable (name, (char *)NULL, 0);
	      if (var && no_invisible_vars == 0)
		VSETATTR (var, att_invisible);
	    }
	  else if (var->context != 0)
	    VSETATTR (var, att_propagate);
	}
    }

  if (var)
    SETVARATTR (var, attribute, undo);

  if (var && (exported_p (var) || (attribute & att_exported)))
    array_needs_making++;	/* XXX */
}