symbol.c

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/*
 * Copyright (C) 2002 Roman Zippel <[email protected]>
 * 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 int 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 strtol(sym->curr.val, NULL, base);
}

static void sym_validate_range(struct symbol *sym)
{
    struct property *prop;
    int base, 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 = strtol(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, "%d", val2);
    else
        sprintf(str, "0x%x", 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;
    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, ")\n");
                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;
}

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;
    int 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 = strtol(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 = strtol(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 = malloc(size);
        *val++ = '0';
        *val++ = 'x';
    } else if (!oldval || strcmp(oldval, newval))
        sym->def[S_DEF_USER].val = val = malloc(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 = malloc(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 = malloc(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 = malloc(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 symbol **sym_re_search(const char *pattern)
{
    struct symbol *sym, **sym_arr = NULL;
    int i, cnt, size;
    regex_t re;

    cnt = size = 0;
    /* Skip if empty */
    if (strlen(pattern) == 0)
        return NULL;
    if (regcomp(&re, pattern, REG_EXTENDED|REG_NOSUB|REG_ICASE))
        return NULL;

    for_all_symbols(i, sym) {
        if (sym->flags & SYMBOL_CONST || !sym->name)
            continue;
        if (regexec(&re, sym->name, 0, NULL, 0))
            continue;
        if (cnt + 1 >= size) {
            void *tmp = sym_arr;
            size += 16;
            sym_arr = realloc(sym_arr, size * sizeof(struct symbol *));
            if (!sym_arr) {
                free(tmp);
                return NULL;
            }
        }
        sym_calc_value(sym);
        sym_arr[cnt++] = sym;
    }
    if (sym_arr)
        sym_arr[cnt] = NULL;
    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 inser() 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 (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 if (stack->prop) {
            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 (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 {
            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>");
        }
    }

    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?\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);

    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 = malloc(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);
}