// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
 */

#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;

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 "bool";
        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";
        }
        return "???";
}

struct property *sym_get_choice_prop(struct symbol *sym)
{
        struct property *prop;

        for_all_choices(sym, prop)
                return prop;
        return NULL;
}

static 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;
}

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 = xstrdup(str);
}

static 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;
        }
}

static void sym_set_all_changed(void)
{
        struct symbol *sym;
        int i;

        for_all_symbols(i, sym)
                sym_set_changed(sym);
}

static void sym_calc_visibility(struct symbol *sym)
{
        struct property *prop;
        struct symbol *choice_sym = NULL;
        tristate tri;

        /* any prompt visible? */
        tri = no;

        if (sym_is_choice_value(sym))
                choice_sym = prop_get_symbol(sym_get_choice_prop(sym));

        for_all_prompts(sym, prop) {
                prop->visible.tri = expr_calc_value(prop->visible.expr);
                /*
                 * Tristate choice_values with visibility 'mod' are
                 * not visible if the corresponding choice's value is
                 * 'yes'.
                 */
                if (choice_sym && sym->type == S_TRISTATE &&
                    prop->visible.tri == mod && choice_sym->curr.tri == yes)
                        prop->visible.tri = no;

                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 && sym_get_type(sym) == S_BOOLEAN)
                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);
        }
        tri = no;
        if (sym->implied.expr)
                tri = expr_calc_value(sym->implied.expr);
        if (tri == mod && sym_get_type(sym) == S_BOOLEAN)
                tri = yes;
        if (sym->implied.tri != tri) {
                sym->implied.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;
}

static void sym_warn_unmet_dep(struct symbol *sym)
{
        struct gstr gs = str_new();

        str_printf(&gs,
                   "\nWARNING: unmet direct dependencies detected for %s\n",
                   sym->name);
        str_printf(&gs,
                   "  Depends on [%c]: ",
                   sym->dir_dep.tri == mod ? 'm' : 'n');
        expr_gstr_print(sym->dir_dep.expr, &gs);
        str_printf(&gs, "\n");

        expr_gstr_print_revdep(sym->rev_dep.expr, &gs, yes,
                               "  Selected by [y]:\n");
        expr_gstr_print_revdep(sym->rev_dep.expr, &gs, mod,
                               "  Selected by [m]:\n");

        fputs(str_get(&gs), stderr);
}

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;
        }
        sym->flags &= ~SYMBOL_WRITE;

        sym_calc_visibility(sym);

        if (sym->visible != no)
                sym->flags |= SYMBOL_WRITE;

        /* 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
                                 */
                                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) {
                                        newval.tri = EXPR_AND(expr_calc_value(prop->expr),
                                                              prop->visible.tri);
                                        if (newval.tri != no)
                                                sym->flags |= SYMBOL_WRITE;
                                }
                                if (sym->implied.tri != no) {
                                        sym->flags |= SYMBOL_WRITE;
                                        newval.tri = EXPR_OR(newval.tri, sym->implied.tri);
                                        newval.tri = EXPR_AND(newval.tri,
                                                              sym->dir_dep.tri);
                                }
                        }
                calc_newval:
                        if (sym->dir_dep.tri < sym->rev_dep.tri)
                                sym_warn_unmet_dep(sym);
                        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_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_NO_WRITE)
                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);
        sym_calc_value(modules_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;

        /* adjust the default value if this symbol is implied by another */
        if (val < sym->implied.tri)
                val = sym->implied.tri;

        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_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_changeable(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 = xstrdup(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;
}

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\n");
                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!\n",
                                prop->file->name, prop->lineno);

                if (sym_is_choice(sym)) {
                        fprintf(stderr, "%s:%d:\tchoice %s contains symbol %s\n",
                                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\n",
                                menu->file->name, menu->lineno,
                                sym->name ? sym->name : "<choice>",
                                next_sym->name ? next_sym->name : "<choice>");
                } else if (stack->expr == &sym->dir_dep.expr) {
                        fprintf(stderr, "%s:%d:\tsymbol %s depends on %s\n",
                                prop->file->name, prop->lineno,
                                sym->name ? sym->name : "<choice>",
                                next_sym->name ? next_sym->name : "<choice>");
                } else if (stack->expr == &sym->rev_dep.expr) {
                        fprintf(stderr, "%s:%d:\tsymbol %s is selected by %s\n",
                                prop->file->name, prop->lineno,
                                sym->name ? sym->name : "<choice>",
                                next_sym->name ? next_sym->name : "<choice>");
                } else if (stack->expr == &sym->implied.expr) {
                        fprintf(stderr, "%s:%d:\tsymbol %s is implied by %s\n",
                                prop->file->name, prop->lineno,
                                sym->name ? sym->name : "<choice>",
                                next_sym->name ? next_sym->name : "<choice>");
                } else if (stack->expr) {
                        fprintf(stderr, "%s:%d:\tsymbol %s %s value contains %s\n",
                                prop->file->name, prop->lineno,
                                sym->name ? sym->name : "<choice>",
                                prop_get_type_name(prop->type),
                                next_sym->name ? next_sym->name : "<choice>");
                } else {
                        fprintf(stderr, "%s:%d:\tsymbol %s %s is visible depending on %s\n",
                                prop->file->name, prop->lineno,
                                sym->name ? sym->name : "<choice>",
                                prop_get_type_name(prop->type),
                                next_sym->name ? next_sym->name : "<choice>");
                }
        }

        fprintf(stderr,
                "For a resolution refer to Documentation/kbuild/kconfig-language.rst\n"
                "subsection \"Kconfig recursive dependency limitations\"\n"
                "\n");

        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_GEQ:
        case E_GTH:
        case E_LEQ:
        case E_LTH:
        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;
        }
        fprintf(stderr, "Oops! How to check %d?\n", 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);

        stack.expr = &sym->dir_dep.expr;
        sym2 = sym_check_expr_deps(sym->dir_dep.expr);
        if (sym2)
                goto out;

        stack.expr = &sym->rev_dep.expr;
        sym2 = sym_check_expr_deps(sym->rev_dep.expr);
        if (sym2)
                goto out;

        stack.expr = &sym->implied.expr;
        sym2 = sym_check_expr_deps(sym->implied.expr);
        if (sym2)
                goto out;

        stack.expr = NULL;

        for (prop = sym->prop; prop; prop = prop->next) {
                if (prop->type == P_CHOICE || prop->type == P_SELECT ||
                    prop->type == P_IMPLY)
                        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;
        }

        return sym2;
}

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_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_IMPLY:
                return "imply";
        case P_RANGE:
                return "range";
        case P_SYMBOL:
                return "symbol";
        case P_UNKNOWN:
                break;
        }
        return "unknown";
}