/*
   * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
   * Released under the terms of the GNU GPL v2.0.
   */
  
  #include <ctype.h>
  #include <stdlib.h>
  #include <string.h>
  #include <regex.h>
  #include <sys/utsname.h>
  
  #include "lkc.h"
  
  struct symbol symbol_yes = {
  	.name = "y",
  	.curr = { "y", yes },
  	.flags = SYMBOL_CONST|SYMBOL_VALID,
  }, symbol_mod = {
  	.name = "m",
  	.curr = { "m", mod },
  	.flags = SYMBOL_CONST|SYMBOL_VALID,
  }, symbol_no = {
  	.name = "n",
  	.curr = { "n", no },
  	.flags = SYMBOL_CONST|SYMBOL_VALID,
  }, symbol_empty = {
  	.name = "",
  	.curr = { "", no },
  	.flags = SYMBOL_VALID,
  };
  
  struct symbol *sym_defconfig_list;
  struct symbol *modules_sym;
  tristate modules_val;
  
  struct expr *sym_env_list;
  
  static void sym_add_default(struct symbol *sym, const char *def)
  {
  	struct property *prop = prop_alloc(P_DEFAULT, sym);
  
  	prop->expr = expr_alloc_symbol(sym_lookup(def, SYMBOL_CONST));
  }
  
  void sym_init(void)
  {
  	struct symbol *sym;
  	struct utsname uts;
  	static bool inited = false;
  
  	if (inited)
  		return;
  	inited = true;
  
  	uname(&uts);
  
  	sym = sym_lookup("UNAME_RELEASE", 0);
  	sym->type = S_STRING;
  	sym->flags |= SYMBOL_AUTO;
  	sym_add_default(sym, uts.release);
  }
  
  enum symbol_type sym_get_type(struct symbol *sym)
  {
  	enum symbol_type type = sym->type;
  
  	if (type == S_TRISTATE) {
  		if (sym_is_choice_value(sym) && sym->visible == yes)
  			type = S_BOOLEAN;
  		else if (modules_val == no)
  			type = S_BOOLEAN;
  	}
  	return type;
  }
  
  const char *sym_type_name(enum symbol_type type)
  {
  	switch (type) {
  	case S_BOOLEAN:
  		return "boolean";
  	case S_TRISTATE:
  		return "tristate";
  	case S_INT:
  		return "integer";
  	case S_HEX:
  		return "hex";
  	case S_STRING:
  		return "string";
  	case S_UNKNOWN:
  		return "unknown";
  	case S_OTHER:
  		break;
  	}
  	return "???";
  }
  
  struct property *sym_get_choice_prop(struct symbol *sym)
  {
  	struct property *prop;
  
  	for_all_choices(sym, prop)
  		return prop;
  	return NULL;
  }
  
  struct property *sym_get_env_prop(struct symbol *sym)
  {
  	struct property *prop;
  
  	for_all_properties(sym, prop, P_ENV)
  		return prop;
  	return NULL;
  }
  
  struct property *sym_get_default_prop(struct symbol *sym)
  {
  	struct property *prop;
  
  	for_all_defaults(sym, prop) {
  		prop->visible.tri = expr_calc_value(prop->visible.expr);
  		if (prop->visible.tri != no)
  			return prop;
  	}
  	return NULL;
  }
  
  static struct property *sym_get_range_prop(struct symbol *sym)
  {
  	struct property *prop;
  
  	for_all_properties(sym, prop, P_RANGE) {
  		prop->visible.tri = expr_calc_value(prop->visible.expr);
  		if (prop->visible.tri != no)
  			return prop;
  	}
  	return NULL;
  }
  
  static long long sym_get_range_val(struct symbol *sym, int base)
  {
  	sym_calc_value(sym);
  	switch (sym->type) {
  	case S_INT:
  		base = 10;
  		break;
  	case S_HEX:
  		base = 16;
  		break;
  	default:
  		break;
  	}
  	return strtoll(sym->curr.val, NULL, base);
  }
  
  static void sym_validate_range(struct symbol *sym)
  {
  	struct property *prop;
  	int base;
  	long long val, val2;
  	char str[64];
  
  	switch (sym->type) {
  	case S_INT:
  		base = 10;
  		break;
  	case S_HEX:
  		base = 16;
  		break;
  	default:
  		return;
  	}
  	prop = sym_get_range_prop(sym);
  	if (!prop)
  		return;
  	val = strtoll(sym->curr.val, NULL, base);
  	val2 = sym_get_range_val(prop->expr->left.sym, base);
  	if (val >= val2) {
  		val2 = sym_get_range_val(prop->expr->right.sym, base);
  		if (val <= val2)
  			return;
  	}
  	if (sym->type == S_INT)
  		sprintf(str, "%lld", val2);
  	else
  		sprintf(str, "0x%llx", val2);
  	sym->curr.val = strdup(str);
  }
  
  static void sym_calc_visibility(struct symbol *sym)
  {
  	struct property *prop;
  	tristate tri;
  
  	/* any prompt visible? */
  	tri = no;
  	for_all_prompts(sym, prop) {
  		prop->visible.tri = expr_calc_value(prop->visible.expr);
  		tri = EXPR_OR(tri, prop->visible.tri);
  	}
  	if (tri == mod && (sym->type != S_TRISTATE || modules_val == no))
  		tri = yes;
  	if (sym->visible != tri) {
  		sym->visible = tri;
  		sym_set_changed(sym);
  	}
  	if (sym_is_choice_value(sym))
  		return;
  	/* defaulting to "yes" if no explicit "depends on" are given */
  	tri = yes;
  	if (sym->dir_dep.expr)
  		tri = expr_calc_value(sym->dir_dep.expr);
  	if (tri == mod)
  		tri = yes;
  	if (sym->dir_dep.tri != tri) {
  		sym->dir_dep.tri = tri;
  		sym_set_changed(sym);
  	}
  	tri = no;
  	if (sym->rev_dep.expr)
  		tri = expr_calc_value(sym->rev_dep.expr);
  	if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
  		tri = yes;
  	if (sym->rev_dep.tri != tri) {
  		sym->rev_dep.tri = tri;
  		sym_set_changed(sym);
  	}
  }
  
  /*
   * Find the default symbol for a choice.
   * First try the default values for the choice symbol
   * Next locate the first visible choice value
   * Return NULL if none was found
   */
  struct symbol *sym_choice_default(struct symbol *sym)
  {
  	struct symbol *def_sym;
  	struct property *prop;
  	struct expr *e;
  
  	/* any of the defaults visible? */
  	for_all_defaults(sym, prop) {
  		prop->visible.tri = expr_calc_value(prop->visible.expr);
  		if (prop->visible.tri == no)
  			continue;
  		def_sym = prop_get_symbol(prop);
  		if (def_sym->visible != no)
  			return def_sym;
  	}
  
  	/* just get the first visible value */
  	prop = sym_get_choice_prop(sym);
  	expr_list_for_each_sym(prop->expr, e, def_sym)
  		if (def_sym->visible != no)
  			return def_sym;
  
  	/* failed to locate any defaults */
  	return NULL;
  }
  
  static struct symbol *sym_calc_choice(struct symbol *sym)
  {
  	struct symbol *def_sym;
  	struct property *prop;
  	struct expr *e;
  	int flags;
  
  	/* first calculate all choice values' visibilities */
  	flags = sym->flags;
  	prop = sym_get_choice_prop(sym);
  	expr_list_for_each_sym(prop->expr, e, def_sym) {
  		sym_calc_visibility(def_sym);
  		if (def_sym->visible != no)
  			flags &= def_sym->flags;
  	}
  
  	sym->flags &= flags | ~SYMBOL_DEF_USER;
  
  	/* is the user choice visible? */
  	def_sym = sym->def[S_DEF_USER].val;
  	if (def_sym && def_sym->visible != no)
  		return def_sym;
  
  	def_sym = sym_choice_default(sym);
  
  	if (def_sym == NULL)
  		/* no choice? reset tristate value */
  		sym->curr.tri = no;
  
  	return def_sym;
  }
  
  void sym_calc_value(struct symbol *sym)
  {
  	struct symbol_value newval, oldval;
  	struct property *prop;
  	struct expr *e;
  
  	if (!sym)
  		return;
  
  	if (sym->flags & SYMBOL_VALID)
  		return;
  
  	if (sym_is_choice_value(sym) &&
  	    sym->flags & SYMBOL_NEED_SET_CHOICE_VALUES) {
  		sym->flags &= ~SYMBOL_NEED_SET_CHOICE_VALUES;
  		prop = sym_get_choice_prop(sym);
  		sym_calc_value(prop_get_symbol(prop));
  	}
  
  	sym->flags |= SYMBOL_VALID;
  
  	oldval = sym->curr;
  
  	switch (sym->type) {
  	case S_INT:
  	case S_HEX:
  	case S_STRING:
  		newval = symbol_empty.curr;
  		break;
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		newval = symbol_no.curr;
  		break;
  	default:
  		sym->curr.val = sym->name;
  		sym->curr.tri = no;
  		return;
  	}
  	if (!sym_is_choice_value(sym))
  		sym->flags &= ~SYMBOL_WRITE;
  
  	sym_calc_visibility(sym);
  
  	/* set default if recursively called */
  	sym->curr = newval;
  
  	switch (sym_get_type(sym)) {
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		if (sym_is_choice_value(sym) && sym->visible == yes) {
  			prop = sym_get_choice_prop(sym);
  			newval.tri = (prop_get_symbol(prop)->curr.val == sym) ? yes : no;
  		} else {
  			if (sym->visible != no) {
  				/* if the symbol is visible use the user value
  				 * if available, otherwise try the default value
  				 */
  				sym->flags |= SYMBOL_WRITE;
  				if (sym_has_value(sym)) {
  					newval.tri = EXPR_AND(sym->def[S_DEF_USER].tri,
  							      sym->visible);
  					goto calc_newval;
  				}
  			}
  			if (sym->rev_dep.tri != no)
  				sym->flags |= SYMBOL_WRITE;
  			if (!sym_is_choice(sym)) {
  				prop = sym_get_default_prop(sym);
  				if (prop) {
  					sym->flags |= SYMBOL_WRITE;
  					newval.tri = EXPR_AND(expr_calc_value(prop->expr),
  							      prop->visible.tri);
  				}
  			}
  		calc_newval:
  			if (sym->dir_dep.tri == no && sym->rev_dep.tri != no) {
  				struct expr *e;
  				e = expr_simplify_unmet_dep(sym->rev_dep.expr,
  				    sym->dir_dep.expr);
  				fprintf(stderr, "warning: (");
  				expr_fprint(e, stderr);
  				fprintf(stderr, ") selects %s which has unmet direct dependencies (",
  					sym->name);
  				expr_fprint(sym->dir_dep.expr, stderr);
  				fprintf(stderr, ")
  ");
  				expr_free(e);
  			}
  			newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
  		}
  		if (newval.tri == mod && sym_get_type(sym) == S_BOOLEAN)
  			newval.tri = yes;
  		break;
  	case S_STRING:
  	case S_HEX:
  	case S_INT:
  		if (sym->visible != no) {
  			sym->flags |= SYMBOL_WRITE;
  			if (sym_has_value(sym)) {
  				newval.val = sym->def[S_DEF_USER].val;
  				break;
  			}
  		}
  		prop = sym_get_default_prop(sym);
  		if (prop) {
  			struct symbol *ds = prop_get_symbol(prop);
  			if (ds) {
  				sym->flags |= SYMBOL_WRITE;
  				sym_calc_value(ds);
  				newval.val = ds->curr.val;
  			}
  		}
  		break;
  	default:
  		;
  	}
  
  	sym->curr = newval;
  	if (sym_is_choice(sym) && newval.tri == yes)
  		sym->curr.val = sym_calc_choice(sym);
  	sym_validate_range(sym);
  
  	if (memcmp(&oldval, &sym->curr, sizeof(oldval))) {
  		sym_set_changed(sym);
  		if (modules_sym == sym) {
  			sym_set_all_changed();
  			modules_val = modules_sym->curr.tri;
  		}
  	}
  
  	if (sym_is_choice(sym)) {
  		struct symbol *choice_sym;
  
  		prop = sym_get_choice_prop(sym);
  		expr_list_for_each_sym(prop->expr, e, choice_sym) {
  			if ((sym->flags & SYMBOL_WRITE) &&
  			    choice_sym->visible != no)
  				choice_sym->flags |= SYMBOL_WRITE;
  			if (sym->flags & SYMBOL_CHANGED)
  				sym_set_changed(choice_sym);
  		}
  	}
  
  	if (sym->flags & SYMBOL_AUTO)
  		sym->flags &= ~SYMBOL_WRITE;
  
  	if (sym->flags & SYMBOL_NEED_SET_CHOICE_VALUES)
  		set_all_choice_values(sym);
  }
  
  void sym_clear_all_valid(void)
  {
  	struct symbol *sym;
  	int i;
  
  	for_all_symbols(i, sym)
  		sym->flags &= ~SYMBOL_VALID;
  	sym_add_change_count(1);
  	if (modules_sym)
  		sym_calc_value(modules_sym);
  }
  
  void sym_set_changed(struct symbol *sym)
  {
  	struct property *prop;
  
  	sym->flags |= SYMBOL_CHANGED;
  	for (prop = sym->prop; prop; prop = prop->next) {
  		if (prop->menu)
  			prop->menu->flags |= MENU_CHANGED;
  	}
  }
  
  void sym_set_all_changed(void)
  {
  	struct symbol *sym;
  	int i;
  
  	for_all_symbols(i, sym)
  		sym_set_changed(sym);
  }
  
  bool sym_tristate_within_range(struct symbol *sym, tristate val)
  {
  	int type = sym_get_type(sym);
  
  	if (sym->visible == no)
  		return false;
  
  	if (type != S_BOOLEAN && type != S_TRISTATE)
  		return false;
  
  	if (type == S_BOOLEAN && val == mod)
  		return false;
  	if (sym->visible <= sym->rev_dep.tri)
  		return false;
  	if (sym_is_choice_value(sym) && sym->visible == yes)
  		return val == yes;
  	return val >= sym->rev_dep.tri && val <= sym->visible;
  }
  
  bool sym_set_tristate_value(struct symbol *sym, tristate val)
  {
  	tristate oldval = sym_get_tristate_value(sym);
  
  	if (oldval != val && !sym_tristate_within_range(sym, val))
  		return false;
  
  	if (!(sym->flags & SYMBOL_DEF_USER)) {
  		sym->flags |= SYMBOL_DEF_USER;
  		sym_set_changed(sym);
  	}
  	/*
  	 * setting a choice value also resets the new flag of the choice
  	 * symbol and all other choice values.
  	 */
  	if (sym_is_choice_value(sym) && val == yes) {
  		struct symbol *cs = prop_get_symbol(sym_get_choice_prop(sym));
  		struct property *prop;
  		struct expr *e;
  
  		cs->def[S_DEF_USER].val = sym;
  		cs->flags |= SYMBOL_DEF_USER;
  		prop = sym_get_choice_prop(cs);
  		for (e = prop->expr; e; e = e->left.expr) {
  			if (e->right.sym->visible != no)
  				e->right.sym->flags |= SYMBOL_DEF_USER;
  		}
  	}
  
  	sym->def[S_DEF_USER].tri = val;
  	if (oldval != val)
  		sym_clear_all_valid();
  
  	return true;
  }
  
  tristate sym_toggle_tristate_value(struct symbol *sym)
  {
  	tristate oldval, newval;
  
  	oldval = newval = sym_get_tristate_value(sym);
  	do {
  		switch (newval) {
  		case no:
  			newval = mod;
  			break;
  		case mod:
  			newval = yes;
  			break;
  		case yes:
  			newval = no;
  			break;
  		}
  		if (sym_set_tristate_value(sym, newval))
  			break;
  	} while (oldval != newval);
  	return newval;
  }
  
  bool sym_string_valid(struct symbol *sym, const char *str)
  {
  	signed char ch;
  
  	switch (sym->type) {
  	case S_STRING:
  		return true;
  	case S_INT:
  		ch = *str++;
  		if (ch == '-')
  			ch = *str++;
  		if (!isdigit(ch))
  			return false;
  		if (ch == '0' && *str != 0)
  			return false;
  		while ((ch = *str++)) {
  			if (!isdigit(ch))
  				return false;
  		}
  		return true;
  	case S_HEX:
  		if (str[0] == '0' && (str[1] == 'x' || str[1] == 'X'))
  			str += 2;
  		ch = *str++;
  		do {
  			if (!isxdigit(ch))
  				return false;
  		} while ((ch = *str++));
  		return true;
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		switch (str[0]) {
  		case 'y': case 'Y':
  		case 'm': case 'M':
  		case 'n': case 'N':
  			return true;
  		}
  		return false;
  	default:
  		return false;
  	}
  }
  
  bool sym_string_within_range(struct symbol *sym, const char *str)
  {
  	struct property *prop;
  	long long val;
  
  	switch (sym->type) {
  	case S_STRING:
  		return sym_string_valid(sym, str);
  	case S_INT:
  		if (!sym_string_valid(sym, str))
  			return false;
  		prop = sym_get_range_prop(sym);
  		if (!prop)
  			return true;
  		val = strtoll(str, NULL, 10);
  		return val >= sym_get_range_val(prop->expr->left.sym, 10) &&
  		       val <= sym_get_range_val(prop->expr->right.sym, 10);
  	case S_HEX:
  		if (!sym_string_valid(sym, str))
  			return false;
  		prop = sym_get_range_prop(sym);
  		if (!prop)
  			return true;
  		val = strtoll(str, NULL, 16);
  		return val >= sym_get_range_val(prop->expr->left.sym, 16) &&
  		       val <= sym_get_range_val(prop->expr->right.sym, 16);
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		switch (str[0]) {
  		case 'y': case 'Y':
  			return sym_tristate_within_range(sym, yes);
  		case 'm': case 'M':
  			return sym_tristate_within_range(sym, mod);
  		case 'n': case 'N':
  			return sym_tristate_within_range(sym, no);
  		}
  		return false;
  	default:
  		return false;
  	}
  }
  
  bool sym_set_string_value(struct symbol *sym, const char *newval)
  {
  	const char *oldval;
  	char *val;
  	int size;
  
  	switch (sym->type) {
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		switch (newval[0]) {
  		case 'y': case 'Y':
  			return sym_set_tristate_value(sym, yes);
  		case 'm': case 'M':
  			return sym_set_tristate_value(sym, mod);
  		case 'n': case 'N':
  			return sym_set_tristate_value(sym, no);
  		}
  		return false;
  	default:
  		;
  	}
  
  	if (!sym_string_within_range(sym, newval))
  		return false;
  
  	if (!(sym->flags & SYMBOL_DEF_USER)) {
  		sym->flags |= SYMBOL_DEF_USER;
  		sym_set_changed(sym);
  	}
  
  	oldval = sym->def[S_DEF_USER].val;
  	size = strlen(newval) + 1;
  	if (sym->type == S_HEX && (newval[0] != '0' || (newval[1] != 'x' && newval[1] != 'X'))) {
  		size += 2;
  		sym->def[S_DEF_USER].val = val = xmalloc(size);
  		*val++ = '0';
  		*val++ = 'x';
  	} else if (!oldval || strcmp(oldval, newval))
  		sym->def[S_DEF_USER].val = val = xmalloc(size);
  	else
  		return true;
  
  	strcpy(val, newval);
  	free((void *)oldval);
  	sym_clear_all_valid();
  
  	return true;
  }
  
  /*
   * Find the default value associated to a symbol.
   * For tristate symbol handle the modules=n case
   * in which case "m" becomes "y".
   * If the symbol does not have any default then fallback
   * to the fixed default values.
   */
  const char *sym_get_string_default(struct symbol *sym)
  {
  	struct property *prop;
  	struct symbol *ds;
  	const char *str;
  	tristate val;
  
  	sym_calc_visibility(sym);
  	sym_calc_value(modules_sym);
  	val = symbol_no.curr.tri;
  	str = symbol_empty.curr.val;
  
  	/* If symbol has a default value look it up */
  	prop = sym_get_default_prop(sym);
  	if (prop != NULL) {
  		switch (sym->type) {
  		case S_BOOLEAN:
  		case S_TRISTATE:
  			/* The visibility may limit the value from yes => mod */
  			val = EXPR_AND(expr_calc_value(prop->expr), prop->visible.tri);
  			break;
  		default:
  			/*
  			 * The following fails to handle the situation
  			 * where a default value is further limited by
  			 * the valid range.
  			 */
  			ds = prop_get_symbol(prop);
  			if (ds != NULL) {
  				sym_calc_value(ds);
  				str = (const char *)ds->curr.val;
  			}
  		}
  	}
  
  	/* Handle select statements */
  	val = EXPR_OR(val, sym->rev_dep.tri);
  
  	/* transpose mod to yes if modules are not enabled */
  	if (val == mod)
  		if (!sym_is_choice_value(sym) && modules_sym->curr.tri == no)
  			val = yes;
  
  	/* transpose mod to yes if type is bool */
  	if (sym->type == S_BOOLEAN && val == mod)
  		val = yes;
  
  	switch (sym->type) {
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		switch (val) {
  		case no: return "n";
  		case mod: return "m";
  		case yes: return "y";
  		}
  	case S_INT:
  	case S_HEX:
  		return str;
  	case S_STRING:
  		return str;
  	case S_OTHER:
  	case S_UNKNOWN:
  		break;
  	}
  	return "";
  }
  
  const char *sym_get_string_value(struct symbol *sym)
  {
  	tristate val;
  
  	switch (sym->type) {
  	case S_BOOLEAN:
  	case S_TRISTATE:
  		val = sym_get_tristate_value(sym);
  		switch (val) {
  		case no:
  			return "n";
  		case mod:
  			sym_calc_value(modules_sym);
  			return (modules_sym->curr.tri == no) ? "n" : "m";
  		case yes:
  			return "y";
  		}
  		break;
  	default:
  		;
  	}
  	return (const char *)sym->curr.val;
  }
  
  bool sym_is_changable(struct symbol *sym)
  {
  	return sym->visible > sym->rev_dep.tri;
  }
  
  static unsigned strhash(const char *s)
  {
  	/* fnv32 hash */
  	unsigned hash = 2166136261U;
  	for (; *s; s++)
  		hash = (hash ^ *s) * 0x01000193;
  	return hash;
  }
  
  struct symbol *sym_lookup(const char *name, int flags)
  {
  	struct symbol *symbol;
  	char *new_name;
  	int hash;
  
  	if (name) {
  		if (name[0] && !name[1]) {
  			switch (name[0]) {
  			case 'y': return &symbol_yes;
  			case 'm': return &symbol_mod;
  			case 'n': return &symbol_no;
  			}
  		}
  		hash = strhash(name) % SYMBOL_HASHSIZE;
  
  		for (symbol = symbol_hash[hash]; symbol; symbol = symbol->next) {
  			if (symbol->name &&
  			    !strcmp(symbol->name, name) &&
  			    (flags ? symbol->flags & flags
  				   : !(symbol->flags & (SYMBOL_CONST|SYMBOL_CHOICE))))
  				return symbol;
  		}
  		new_name = strdup(name);
  	} else {
  		new_name = NULL;
  		hash = 0;
  	}
  
  	symbol = xmalloc(sizeof(*symbol));
  	memset(symbol, 0, sizeof(*symbol));
  	symbol->name = new_name;
  	symbol->type = S_UNKNOWN;
  	symbol->flags |= flags;
  
  	symbol->next = symbol_hash[hash];
  	symbol_hash[hash] = symbol;
  
  	return symbol;
  }
  
  struct symbol *sym_find(const char *name)
  {
  	struct symbol *symbol = NULL;
  	int hash = 0;
  
  	if (!name)
  		return NULL;
  
  	if (name[0] && !name[1]) {
  		switch (name[0]) {
  		case 'y': return &symbol_yes;
  		case 'm': return &symbol_mod;
  		case 'n': return &symbol_no;
  		}
  	}
  	hash = strhash(name) % SYMBOL_HASHSIZE;
  
  	for (symbol = symbol_hash[hash]; symbol; symbol = symbol->next) {
  		if (symbol->name &&
  		    !strcmp(symbol->name, name) &&
  		    !(symbol->flags & SYMBOL_CONST))
  				break;
  	}
  
  	return symbol;
  }
  
  /*
   * Expand symbol's names embedded in the string given in argument. Symbols'
   * name to be expanded shall be prefixed by a '$'. Unknown symbol expands to
   * the empty string.
   */
  const char *sym_expand_string_value(const char *in)
  {
  	const char *src;
  	char *res;
  	size_t reslen;
  
  	reslen = strlen(in) + 1;
  	res = xmalloc(reslen);
  	res[0] = '\0';
  
  	while ((src = strchr(in, '$'))) {
  		char *p, name[SYMBOL_MAXLENGTH];
  		const char *symval = "";
  		struct symbol *sym;
  		size_t newlen;
  
  		strncat(res, in, src - in);
  		src++;
  
  		p = name;
  		while (isalnum(*src) || *src == '_')
  			*p++ = *src++;
  		*p = '\0';
  
  		sym = sym_find(name);
  		if (sym != NULL) {
  			sym_calc_value(sym);
  			symval = sym_get_string_value(sym);
  		}
  
  		newlen = strlen(res) + strlen(symval) + strlen(src) + 1;
  		if (newlen > reslen) {
  			reslen = newlen;
  			res = realloc(res, reslen);
  		}
  
  		strcat(res, symval);
  		in = src;
  	}
  	strcat(res, in);
  
  	return res;
  }
  
  const char *sym_escape_string_value(const char *in)
  {
  	const char *p;
  	size_t reslen;
  	char *res;
  	size_t l;
  
  	reslen = strlen(in) + strlen("\"\"") + 1;
  
  	p = in;
  	for (;;) {
  		l = strcspn(p, "\"\\");
  		p += l;
  
  		if (p[0] == '\0')
  			break;
  
  		reslen++;
  		p++;
  	}
  
  	res = xmalloc(reslen);
  	res[0] = '\0';
  
  	strcat(res, "\"");
  
  	p = in;
  	for (;;) {
  		l = strcspn(p, "\"\\");
  		strncat(res, p, l);
  		p += l;
  
  		if (p[0] == '\0')
  			break;
  
  		strcat(res, "\\");
  		strncat(res, p++, 1);
  	}
  
  	strcat(res, "\"");
  	return res;
  }
  
  struct sym_match {
  	struct symbol	*sym;
  	off_t		so, eo;
  };
  
  /* Compare matched symbols as thus:
   * - first, symbols that match exactly
   * - then, alphabetical sort
   */
  static int sym_rel_comp(const void *sym1, const void *sym2)
  {
  	const struct sym_match *s1 = sym1;
  	const struct sym_match *s2 = sym2;
  	int exact1, exact2;
  
  	/* Exact match:
  	 * - if matched length on symbol s1 is the length of that symbol,
  	 *   then this symbol should come first;
  	 * - if matched length on symbol s2 is the length of that symbol,
  	 *   then this symbol should come first.
  	 * Note: since the search can be a regexp, both symbols may match
  	 * exactly; if this is the case, we can't decide which comes first,
  	 * and we fallback to sorting alphabetically.
  	 */
  	exact1 = (s1->eo - s1->so) == strlen(s1->sym->name);
  	exact2 = (s2->eo - s2->so) == strlen(s2->sym->name);
  	if (exact1 && !exact2)
  		return -1;
  	if (!exact1 && exact2)
  		return 1;
  
  	/* As a fallback, sort symbols alphabetically */
  	return strcmp(s1->sym->name, s2->sym->name);
  }
  
  struct symbol **sym_re_search(const char *pattern)
  {
  	struct symbol *sym, **sym_arr = NULL;
  	struct sym_match *sym_match_arr = NULL;
  	int i, cnt, size;
  	regex_t re;
  	regmatch_t match[1];
  
  	cnt = size = 0;
  	/* Skip if empty */
  	if (strlen(pattern) == 0)
  		return NULL;
  	if (regcomp(&re, pattern, REG_EXTENDED|REG_ICASE))
  		return NULL;
  
  	for_all_symbols(i, sym) {
  		if (sym->flags & SYMBOL_CONST || !sym->name)
  			continue;
  		if (regexec(&re, sym->name, 1, match, 0))
  			continue;
  		if (cnt >= size) {
  			void *tmp;
  			size += 16;
  			tmp = realloc(sym_match_arr, size * sizeof(struct sym_match));
  			if (!tmp)
  				goto sym_re_search_free;
  			sym_match_arr = tmp;
  		}
  		sym_calc_value(sym);
  		/* As regexec returned 0, we know we have a match, so
  		 * we can use match[0].rm_[se]o without further checks
  		 */
  		sym_match_arr[cnt].so = match[0].rm_so;
  		sym_match_arr[cnt].eo = match[0].rm_eo;
  		sym_match_arr[cnt++].sym = sym;
  	}
  	if (sym_match_arr) {
  		qsort(sym_match_arr, cnt, sizeof(struct sym_match), sym_rel_comp);
  		sym_arr = malloc((cnt+1) * sizeof(struct symbol));
  		if (!sym_arr)
  			goto sym_re_search_free;
  		for (i = 0; i < cnt; i++)
  			sym_arr[i] = sym_match_arr[i].sym;
  		sym_arr[cnt] = NULL;
  	}
  sym_re_search_free:
  	/* sym_match_arr can be NULL if no match, but free(NULL) is OK */
  	free(sym_match_arr);
  	regfree(&re);
  
  	return sym_arr;
  }
  
  /*
   * When we check for recursive dependencies we use a stack to save
   * current state so we can print out relevant info to user.
   * The entries are located on the call stack so no need to free memory.
   * Note insert() remove() must always match to properly clear the stack.
   */
  static struct dep_stack {
  	struct dep_stack *prev, *next;
  	struct symbol *sym;
  	struct property *prop;
  	struct expr *expr;
  } *check_top;
  
  static void dep_stack_insert(struct dep_stack *stack, struct symbol *sym)
  {
  	memset(stack, 0, sizeof(*stack));
  	if (check_top)
  		check_top->next = stack;
  	stack->prev = check_top;
  	stack->sym = sym;
  	check_top = stack;
  }
  
  static void dep_stack_remove(void)
  {
  	check_top = check_top->prev;
  	if (check_top)
  		check_top->next = NULL;
  }
  
  /*
   * Called when we have detected a recursive dependency.
   * check_top point to the top of the stact so we use
   * the ->prev pointer to locate the bottom of the stack.
   */
  static void sym_check_print_recursive(struct symbol *last_sym)
  {
  	struct dep_stack *stack;
  	struct symbol *sym, *next_sym;
  	struct menu *menu = NULL;
  	struct property *prop;
  	struct dep_stack cv_stack;
  
  	if (sym_is_choice_value(last_sym)) {
  		dep_stack_insert(&cv_stack, last_sym);
  		last_sym = prop_get_symbol(sym_get_choice_prop(last_sym));
  	}
  
  	for (stack = check_top; stack != NULL; stack = stack->prev)
  		if (stack->sym == last_sym)
  			break;
  	if (!stack) {
  		fprintf(stderr, "unexpected recursive dependency error
  ");
  		return;
  	}
  
  	for (; stack; stack = stack->next) {
  		sym = stack->sym;
  		next_sym = stack->next ? stack->next->sym : last_sym;
  		prop = stack->prop;
  		if (prop == NULL)
  			prop = stack->sym->prop;
  
  		/* for choice values find the menu entry (used below) */
  		if (sym_is_choice(sym) || sym_is_choice_value(sym)) {
  			for (prop = sym->prop; prop; prop = prop->next) {
  				menu = prop->menu;
  				if (prop->menu)
  					break;
  			}
  		}
  		if (stack->sym == last_sym)
  			fprintf(stderr, "%s:%d:error: recursive dependency detected!
  ",
  				prop->file->name, prop->lineno);
  		if (stack->expr) {
  			fprintf(stderr, "%s:%d:\tsymbol %s %s value contains %s
  ",
  				prop->file->name, prop->lineno,
  				sym->name ? sym->name : "<choice>",
  				prop_get_type_name(prop->type),
  				next_sym->name ? next_sym->name : "<choice>");
  		} else if (stack->prop) {
  			fprintf(stderr, "%s:%d:\tsymbol %s depends on %s
  ",
  				prop->file->name, prop->lineno,
  				sym->name ? sym->name : "<choice>",
  				next_sym->name ? next_sym->name : "<choice>");
  		} else if (sym_is_choice(sym)) {
  			fprintf(stderr, "%s:%d:\tchoice %s contains symbol %s
  ",
  				menu->file->name, menu->lineno,
  				sym->name ? sym->name : "<choice>",
  				next_sym->name ? next_sym->name : "<choice>");
  		} else if (sym_is_choice_value(sym)) {
  			fprintf(stderr, "%s:%d:\tsymbol %s is part of choice %s
  ",
  				menu->file->name, menu->lineno,
  				sym->name ? sym->name : "<choice>",
  				next_sym->name ? next_sym->name : "<choice>");
  		} else {
  			fprintf(stderr, "%s:%d:\tsymbol %s is selected by %s
  ",
  				prop->file->name, prop->lineno,
  				sym->name ? sym->name : "<choice>",
  				next_sym->name ? next_sym->name : "<choice>");
  		}
  	}
  
  	if (check_top == &cv_stack)
  		dep_stack_remove();
  }
  
  static struct symbol *sym_check_expr_deps(struct expr *e)
  {
  	struct symbol *sym;
  
  	if (!e)
  		return NULL;
  	switch (e->type) {
  	case E_OR:
  	case E_AND:
  		sym = sym_check_expr_deps(e->left.expr);
  		if (sym)
  			return sym;
  		return sym_check_expr_deps(e->right.expr);
  	case E_NOT:
  		return sym_check_expr_deps(e->left.expr);
  	case E_EQUAL:
  	case E_UNEQUAL:
  		sym = sym_check_deps(e->left.sym);
  		if (sym)
  			return sym;
  		return sym_check_deps(e->right.sym);
  	case E_SYMBOL:
  		return sym_check_deps(e->left.sym);
  	default:
  		break;
  	}
  	printf("Oops! How to check %d?
  ", e->type);
  	return NULL;
  }
  
  /* return NULL when dependencies are OK */
  static struct symbol *sym_check_sym_deps(struct symbol *sym)
  {
  	struct symbol *sym2;
  	struct property *prop;
  	struct dep_stack stack;
  
  	dep_stack_insert(&stack, sym);
  
  	sym2 = sym_check_expr_deps(sym->rev_dep.expr);
  	if (sym2)
  		goto out;
  
  	for (prop = sym->prop; prop; prop = prop->next) {
  		if (prop->type == P_CHOICE || prop->type == P_SELECT)
  			continue;
  		stack.prop = prop;
  		sym2 = sym_check_expr_deps(prop->visible.expr);
  		if (sym2)
  			break;
  		if (prop->type != P_DEFAULT || sym_is_choice(sym))
  			continue;
  		stack.expr = prop->expr;
  		sym2 = sym_check_expr_deps(prop->expr);
  		if (sym2)
  			break;
  		stack.expr = NULL;
  	}
  
  out:
  	dep_stack_remove();
  
  	return sym2;
  }
  
  static struct symbol *sym_check_choice_deps(struct symbol *choice)
  {
  	struct symbol *sym, *sym2;
  	struct property *prop;
  	struct expr *e;
  	struct dep_stack stack;
  
  	dep_stack_insert(&stack, choice);
  
  	prop = sym_get_choice_prop(choice);
  	expr_list_for_each_sym(prop->expr, e, sym)
  		sym->flags |= (SYMBOL_CHECK | SYMBOL_CHECKED);
  
  	choice->flags |= (SYMBOL_CHECK | SYMBOL_CHECKED);
  	sym2 = sym_check_sym_deps(choice);
  	choice->flags &= ~SYMBOL_CHECK;
  	if (sym2)
  		goto out;
  
  	expr_list_for_each_sym(prop->expr, e, sym) {
  		sym2 = sym_check_sym_deps(sym);
  		if (sym2)
  			break;
  	}
  out:
  	expr_list_for_each_sym(prop->expr, e, sym)
  		sym->flags &= ~SYMBOL_CHECK;
  
  	if (sym2 && sym_is_choice_value(sym2) &&
  	    prop_get_symbol(sym_get_choice_prop(sym2)) == choice)
  		sym2 = choice;
  
  	dep_stack_remove();
  
  	return sym2;
  }
  
  struct symbol *sym_check_deps(struct symbol *sym)
  {
  	struct symbol *sym2;
  	struct property *prop;
  
  	if (sym->flags & SYMBOL_CHECK) {
  		sym_check_print_recursive(sym);
  		return sym;
  	}
  	if (sym->flags & SYMBOL_CHECKED)
  		return NULL;
  
  	if (sym_is_choice_value(sym)) {
  		struct dep_stack stack;
  
  		/* for choice groups start the check with main choice symbol */
  		dep_stack_insert(&stack, sym);
  		prop = sym_get_choice_prop(sym);
  		sym2 = sym_check_deps(prop_get_symbol(prop));
  		dep_stack_remove();
  	} else if (sym_is_choice(sym)) {
  		sym2 = sym_check_choice_deps(sym);
  	} else {
  		sym->flags |= (SYMBOL_CHECK | SYMBOL_CHECKED);
  		sym2 = sym_check_sym_deps(sym);
  		sym->flags &= ~SYMBOL_CHECK;
  	}
  
  	if (sym2 && sym2 == sym)
  		sym2 = NULL;
  
  	return sym2;
  }
  
  struct property *prop_alloc(enum prop_type type, struct symbol *sym)
  {
  	struct property *prop;
  	struct property **propp;
  
  	prop = xmalloc(sizeof(*prop));
  	memset(prop, 0, sizeof(*prop));
  	prop->type = type;
  	prop->sym = sym;
  	prop->file = current_file;
  	prop->lineno = zconf_lineno();
  
  	/* append property to the prop list of symbol */
  	if (sym) {
  		for (propp = &sym->prop; *propp; propp = &(*propp)->next)
  			;
  		*propp = prop;
  	}
  
  	return prop;
  }
  
  struct symbol *prop_get_symbol(struct property *prop)
  {
  	if (prop->expr && (prop->expr->type == E_SYMBOL ||
  			   prop->expr->type == E_LIST))
  		return prop->expr->left.sym;
  	return NULL;
  }
  
  const char *prop_get_type_name(enum prop_type type)
  {
  	switch (type) {
  	case P_PROMPT:
  		return "prompt";
  	case P_ENV:
  		return "env";
  	case P_COMMENT:
  		return "comment";
  	case P_MENU:
  		return "menu";
  	case P_DEFAULT:
  		return "default";
  	case P_CHOICE:
  		return "choice";
  	case P_SELECT:
  		return "select";
  	case P_RANGE:
  		return "range";
  	case P_SYMBOL:
  		return "symbol";
  	case P_UNKNOWN:
  		break;
  	}
  	return "unknown";
  }
  
  static void prop_add_env(const char *env)
  {
  	struct symbol *sym, *sym2;
  	struct property *prop;
  	char *p;
  
  	sym = current_entry->sym;
  	sym->flags |= SYMBOL_AUTO;
  	for_all_properties(sym, prop, P_ENV) {
  		sym2 = prop_get_symbol(prop);
  		if (strcmp(sym2->name, env))
  			menu_warn(current_entry, "redefining environment symbol from %s",
  				  sym2->name);
  		return;
  	}
  
  	prop = prop_alloc(P_ENV, sym);
  	prop->expr = expr_alloc_symbol(sym_lookup(env, SYMBOL_CONST));
  
  	sym_env_list = expr_alloc_one(E_LIST, sym_env_list);
  	sym_env_list->right.sym = sym;
  
  	p = getenv(env);
  	if (p)
  		sym_add_default(sym, p);
  	else
  		menu_warn(current_entry, "environment variable %s undefined", env);
  }