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

#include <sys/stat.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "lkc.h"

/* return true if 'path' exists, false otherwise */
static bool is_present(const char *path)
{
        struct stat st;

        return !stat(path, &st);
}

/* return true if 'path' exists and it is a directory, false otherwise */
static bool is_dir(const char *path)
{
        struct stat st;

        if (stat(path, &st))
                return 0;

        return S_ISDIR(st.st_mode);
}

/*
 * Create the parent directory of the given path.
 *
 * For example, if 'include/config/auto.conf' is given, create 'include/config'.
 */
static int make_parent_dir(const char *path)
{
        char tmp[PATH_MAX + 1];
        char *p;

        strncpy(tmp, path, sizeof(tmp));
        tmp[sizeof(tmp) - 1] = 0;

        /* Remove the base name. Just return if nothing is left */
        p = strrchr(tmp, '/');
        if (!p)
                return 0;
        *(p + 1) = 0;

        /* Just in case it is an absolute path */
        p = tmp;
        while (*p == '/')
                p++;

        while ((p = strchr(p, '/'))) {
                *p = 0;

                /* skip if the directory exists */
                if (!is_dir(tmp) && mkdir(tmp, 0755))
                        return -1;

                *p = '/';
                while (*p == '/')
                        p++;
        }

        return 0;
}

static char depfile_path[PATH_MAX];
static size_t depfile_prefix_len;

/* touch depfile for symbol 'name' */
static int conf_touch_dep(const char *name)
{
        int fd, ret;
        const char *s;
        char *d, c;

        /* check overflow: prefix + name + ".h" + '\0' must fit in buffer. */
        if (depfile_prefix_len + strlen(name) + 3 > sizeof(depfile_path))
                return -1;

        d = depfile_path + depfile_prefix_len;
        s = name;

        while ((c = *s++))
                *d++ = (c == '_') ? '/' : tolower(c);
        strcpy(d, ".h");

        /* Assume directory path already exists. */
        fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
        if (fd == -1) {
                if (errno != ENOENT)
                        return -1;

                ret = make_parent_dir(depfile_path);
                if (ret)
                        return ret;

                /* Try it again. */
                fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
                if (fd == -1)
                        return -1;
        }
        close(fd);

        return 0;
}

struct conf_printer {
        void (*print_symbol)(FILE *, struct symbol *, const char *, void *);
        void (*print_comment)(FILE *, const char *, void *);
};

static void conf_warning(const char *fmt, ...)
        __attribute__ ((format (printf, 1, 2)));

static void conf_message(const char *fmt, ...)
        __attribute__ ((format (printf, 1, 2)));

static const char *conf_filename;
static int conf_lineno, conf_warnings;

const char conf_defname[] = "arch/$(ARCH)/defconfig";

static void conf_warning(const char *fmt, ...)
{
        va_list ap;
        va_start(ap, fmt);
        fprintf(stderr, "%s:%d:warning: ", conf_filename, conf_lineno);
        vfprintf(stderr, fmt, ap);
        fprintf(stderr, "\n");
        va_end(ap);
        conf_warnings++;
}

static void conf_default_message_callback(const char *s)
{
        printf("#\n# ");
        printf("%s", s);
        printf("\n#\n");
}

static void (*conf_message_callback)(const char *s) =
        conf_default_message_callback;
void conf_set_message_callback(void (*fn)(const char *s))
{
        conf_message_callback = fn;
}

static void conf_message(const char *fmt, ...)
{
        va_list ap;
        char buf[4096];

        if (!conf_message_callback)
                return;

        va_start(ap, fmt);

        vsnprintf(buf, sizeof(buf), fmt, ap);
        conf_message_callback(buf);
        va_end(ap);
}

const char *conf_get_configname(void)
{
        char *name = getenv("KCONFIG_CONFIG");

        return name ? name : ".config";
}

const char *conf_get_autoconfig_name(void)
{
        char *name = getenv("KCONFIG_AUTOCONFIG");

        return name ? name : "include/config/auto.conf";
}

char *conf_get_default_confname(void)
{
        static char fullname[PATH_MAX+1];
        char *env, *name;

        name = expand_string(conf_defname);
        env = getenv(SRCTREE);
        if (env) {
                sprintf(fullname, "%s/%s", env, name);
                if (is_present(fullname))
                        return fullname;
        }
        return name;
}

static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
{
        char *p2;

        switch (sym->type) {
        case S_TRISTATE:
                if (p[0] == 'm') {
                        sym->def[def].tri = mod;
                        sym->flags |= def_flags;
                        break;
                }
                /* fall through */
        case S_BOOLEAN:
                if (p[0] == 'y') {
                        sym->def[def].tri = yes;
                        sym->flags |= def_flags;
                        break;
                }
                if (p[0] == 'n') {
                        sym->def[def].tri = no;
                        sym->flags |= def_flags;
                        break;
                }
                if (def != S_DEF_AUTO)
                        conf_warning("symbol value '%s' invalid for %s",
                                     p, sym->name);
                return 1;
        case S_STRING:
                if (*p++ != '"')
                        break;
                for (p2 = p; (p2 = strpbrk(p2, "\"\\")); p2++) {
                        if (*p2 == '"') {
                                *p2 = 0;
                                break;
                        }
                        memmove(p2, p2 + 1, strlen(p2));
                }
                if (!p2) {
                        if (def != S_DEF_AUTO)
                                conf_warning("invalid string found");
                        return 1;
                }
                /* fall through */
        case S_INT:
        case S_HEX:
                if (sym_string_valid(sym, p)) {
                        sym->def[def].val = xstrdup(p);
                        sym->flags |= def_flags;
                } else {
                        if (def != S_DEF_AUTO)
                                conf_warning("symbol value '%s' invalid for %s",
                                             p, sym->name);
                        return 1;
                }
                break;
        default:
                ;
        }
        return 0;
}

#define LINE_GROWTH 16
static int add_byte(int c, char **lineptr, size_t slen, size_t *n)
{
        char *nline;
        size_t new_size = slen + 1;
        if (new_size > *n) {
                new_size += LINE_GROWTH - 1;
                new_size *= 2;
                nline = xrealloc(*lineptr, new_size);
                if (!nline)
                        return -1;

                *lineptr = nline;
                *n = new_size;
        }

        (*lineptr)[slen] = c;

        return 0;
}

static ssize_t compat_getline(char **lineptr, size_t *n, FILE *stream)
{
        char *line = *lineptr;
        size_t slen = 0;

        for (;;) {
                int c = getc(stream);

                switch (c) {
                case '\n':
                        if (add_byte(c, &line, slen, n) < 0)
                                goto e_out;
                        slen++;
                        /* fall through */
                case EOF:
                        if (add_byte('\0', &line, slen, n) < 0)
                                goto e_out;
                        *lineptr = line;
                        if (slen == 0)
                                return -1;
                        return slen;
                default:
                        if (add_byte(c, &line, slen, n) < 0)
                                goto e_out;
                        slen++;
                }
        }

e_out:
        line[slen-1] = '\0';
        *lineptr = line;
        return -1;
}

int conf_read_simple(const char *name, int def)
{
        FILE *in = NULL;
        char   *line = NULL;
        size_t  line_asize = 0;
        char *p, *p2;
        struct symbol *sym;
        int i, def_flags;

        if (name) {
                in = zconf_fopen(name);
        } else {
                struct property *prop;

                name = conf_get_configname();
                in = zconf_fopen(name);
                if (in)
                        goto load;
                sym_add_change_count(1);
                if (!sym_defconfig_list)
                        return 1;

                for_all_defaults(sym_defconfig_list, prop) {
                        if (expr_calc_value(prop->visible.expr) == no ||
                            prop->expr->type != E_SYMBOL)
                                continue;
                        sym_calc_value(prop->expr->left.sym);
                        name = sym_get_string_value(prop->expr->left.sym);
                        in = zconf_fopen(name);
                        if (in) {
                                conf_message("using defaults found in %s",
                                         name);
                                goto load;
                        }
                }
        }
        if (!in)
                return 1;

load:
        conf_filename = name;
        conf_lineno = 0;
        conf_warnings = 0;

        def_flags = SYMBOL_DEF << def;
        for_all_symbols(i, sym) {
                sym->flags |= SYMBOL_CHANGED;
                sym->flags &= ~(def_flags|SYMBOL_VALID);
                if (sym_is_choice(sym))
                        sym->flags |= def_flags;
                switch (sym->type) {
                case S_INT:
                case S_HEX:
                case S_STRING:
                        if (sym->def[def].val)
                                free(sym->def[def].val);
                        /* fall through */
                default:
                        sym->def[def].val = NULL;
                        sym->def[def].tri = no;
                }
        }

        while (compat_getline(&line, &line_asize, in) != -1) {
                conf_lineno++;
                sym = NULL;
                if (line[0] == '#') {
                        if (memcmp(line + 2, CONFIG_, strlen(CONFIG_)))
                                continue;
                        p = strchr(line + 2 + strlen(CONFIG_), ' ');
                        if (!p)
                                continue;
                        *p++ = 0;
                        if (strncmp(p, "is not set", 10))
                                continue;
                        if (def == S_DEF_USER) {
                                sym = sym_find(line + 2 + strlen(CONFIG_));
                                if (!sym) {
                                        sym_add_change_count(1);
                                        continue;
                                }
                        } else {
                                sym = sym_lookup(line + 2 + strlen(CONFIG_), 0);
                                if (sym->type == S_UNKNOWN)
                                        sym->type = S_BOOLEAN;
                        }
                        if (sym->flags & def_flags) {
                                conf_warning("override: reassigning to symbol %s", sym->name);
                        }
                        switch (sym->type) {
                        case S_BOOLEAN:
                        case S_TRISTATE:
                                sym->def[def].tri = no;
                                sym->flags |= def_flags;
                                break;
                        default:
                                ;
                        }
                } else if (memcmp(line, CONFIG_, strlen(CONFIG_)) == 0) {
                        p = strchr(line + strlen(CONFIG_), '=');
                        if (!p)
                                continue;
                        *p++ = 0;
                        p2 = strchr(p, '\n');
                        if (p2) {
                                *p2-- = 0;
                                if (*p2 == '\r')
                                        *p2 = 0;
                        }

                        sym = sym_find(line + strlen(CONFIG_));
                        if (!sym) {
                                if (def == S_DEF_AUTO)
                                        /*
                                         * Reading from include/config/auto.conf
                                         * If CONFIG_FOO previously existed in
                                         * auto.conf but it is missing now,
                                         * include/config/foo.h must be touched.
                                         */
                                        conf_touch_dep(line + strlen(CONFIG_));
                                else
                                        sym_add_change_count(1);
                                continue;
                        }

                        if (sym->flags & def_flags) {
                                conf_warning("override: reassigning to symbol %s", sym->name);
                        }
                        if (conf_set_sym_val(sym, def, def_flags, p))
                                continue;
                } else {
                        if (line[0] != '\r' && line[0] != '\n')
                                conf_warning("unexpected data: %.*s",
                                             (int)strcspn(line, "\r\n"), line);

                        continue;
                }

                if (sym && sym_is_choice_value(sym)) {
                        struct symbol *cs = prop_get_symbol(sym_get_choice_prop(sym));
                        switch (sym->def[def].tri) {
                        case no:
                                break;
                        case mod:
                                if (cs->def[def].tri == yes) {
                                        conf_warning("%s creates inconsistent choice state", sym->name);
                                        cs->flags &= ~def_flags;
                                }
                                break;
                        case yes:
                                if (cs->def[def].tri != no)
                                        conf_warning("override: %s changes choice state", sym->name);
                                cs->def[def].val = sym;
                                break;
                        }
                        cs->def[def].tri = EXPR_OR(cs->def[def].tri, sym->def[def].tri);
                }
        }
        free(line);
        fclose(in);
        return 0;
}

int conf_read(const char *name)
{
        struct symbol *sym;
        int conf_unsaved = 0;
        int i;

        sym_set_change_count(0);

        if (conf_read_simple(name, S_DEF_USER)) {
                sym_calc_value(modules_sym);
                return 1;
        }

        sym_calc_value(modules_sym);

        for_all_symbols(i, sym) {
                sym_calc_value(sym);
                if (sym_is_choice(sym) || (sym->flags & SYMBOL_NO_WRITE))
                        continue;
                if (sym_has_value(sym) && (sym->flags & SYMBOL_WRITE)) {
                        /* check that calculated value agrees with saved value */
                        switch (sym->type) {
                        case S_BOOLEAN:
                        case S_TRISTATE:
                                if (sym->def[S_DEF_USER].tri != sym_get_tristate_value(sym))
                                        break;
                                if (!sym_is_choice(sym))
                                        continue;
                                /* fall through */
                        default:
                                if (!strcmp(sym->curr.val, sym->def[S_DEF_USER].val))
                                        continue;
                                break;
                        }
                } else if (!sym_has_value(sym) && !(sym->flags & SYMBOL_WRITE))
                        /* no previous value and not saved */
                        continue;
                conf_unsaved++;
                /* maybe print value in verbose mode... */
        }

        for_all_symbols(i, sym) {
                if (sym_has_value(sym) && !sym_is_choice_value(sym)) {
                        /* Reset values of generates values, so they'll appear
                         * as new, if they should become visible, but that
                         * doesn't quite work if the Kconfig and the saved
                         * configuration disagree.
                         */
                        if (sym->visible == no && !conf_unsaved)
                                sym->flags &= ~SYMBOL_DEF_USER;
                        switch (sym->type) {
                        case S_STRING:
                        case S_INT:
                        case S_HEX:
                                /* Reset a string value if it's out of range */
                                if (sym_string_within_range(sym, sym->def[S_DEF_USER].val))
                                        break;
                                sym->flags &= ~(SYMBOL_VALID|SYMBOL_DEF_USER);
                                conf_unsaved++;
                                break;
                        default:
                                break;
                        }
                }
        }

        sym_add_change_count(conf_warnings || conf_unsaved);

        return 0;
}

/*
 * Kconfig configuration printer
 *
 * This printer is used when generating the resulting configuration after
 * kconfig invocation and `defconfig' files. Unset symbol might be omitted by
 * passing a non-NULL argument to the printer.
 *
 */
static void
kconfig_print_symbol(FILE *fp, struct symbol *sym, const char *value, void *arg)
{

        switch (sym->type) {
        case S_BOOLEAN:
        case S_TRISTATE:
                if (*value == 'n') {
                        bool skip_unset = (arg != NULL);

                        if (!skip_unset)
                                fprintf(fp, "# %s%s is not set\n",
                                    CONFIG_, sym->name);
                        return;
                }
                break;
        default:
                break;
        }

        fprintf(fp, "%s%s=%s\n", CONFIG_, sym->name, value);
}

static void
kconfig_print_comment(FILE *fp, const char *value, void *arg)
{
        const char *p = value;
        size_t l;

        for (;;) {
                l = strcspn(p, "\n");
                fprintf(fp, "#");
                if (l) {
                        fprintf(fp, " ");
                        xfwrite(p, l, 1, fp);
                        p += l;
                }
                fprintf(fp, "\n");
                if (*p++ == '\0')
                        break;
        }
}

static struct conf_printer kconfig_printer_cb =
{
        .print_symbol = kconfig_print_symbol,
        .print_comment = kconfig_print_comment,
};

/*
 * Header printer
 *
 * This printer is used when generating the `include/generated/autoconf.h' file.
 */
static void
header_print_symbol(FILE *fp, struct symbol *sym, const char *value, void *arg)
{

        switch (sym->type) {
        case S_BOOLEAN:
        case S_TRISTATE: {
                const char *suffix = "";

                switch (*value) {
                case 'n':
                        break;
                case 'm':
                        suffix = "_MODULE";
                        /* fall through */
                default:
                        fprintf(fp, "#define %s%s%s 1\n",
                            CONFIG_, sym->name, suffix);
                }
                break;
        }
        case S_HEX: {
                const char *prefix = "";

                if (value[0] != '0' || (value[1] != 'x' && value[1] != 'X'))
                        prefix = "0x";
                fprintf(fp, "#define %s%s %s%s\n",
                    CONFIG_, sym->name, prefix, value);
                break;
        }
        case S_STRING:
        case S_INT:
                fprintf(fp, "#define %s%s %s\n",
                    CONFIG_, sym->name, value);
                break;
        default:
                break;
        }

}

static void
header_print_comment(FILE *fp, const char *value, void *arg)
{
        const char *p = value;
        size_t l;

        fprintf(fp, "/*\n");
        for (;;) {
                l = strcspn(p, "\n");
                fprintf(fp, " *");
                if (l) {
                        fprintf(fp, " ");
                        xfwrite(p, l, 1, fp);
                        p += l;
                }
                fprintf(fp, "\n");
                if (*p++ == '\0')
                        break;
        }
        fprintf(fp, " */\n");
}

static struct conf_printer header_printer_cb =
{
        .print_symbol = header_print_symbol,
        .print_comment = header_print_comment,
};

/*
 * Tristate printer
 *
 * This printer is used when generating the `include/config/tristate.conf' file.
 */
static void
tristate_print_symbol(FILE *fp, struct symbol *sym, const char *value, void *arg)
{

        if (sym->type == S_TRISTATE && *value != 'n')
                fprintf(fp, "%s%s=%c\n", CONFIG_, sym->name, (char)toupper(*value));
}

static struct conf_printer tristate_printer_cb =
{
        .print_symbol = tristate_print_symbol,
        .print_comment = kconfig_print_comment,
};

static void conf_write_symbol(FILE *fp, struct symbol *sym,
                              struct conf_printer *printer, void *printer_arg)
{
        const char *str;

        switch (sym->type) {
        case S_UNKNOWN:
                break;
        case S_STRING:
                str = sym_get_string_value(sym);
                str = sym_escape_string_value(str);
                printer->print_symbol(fp, sym, str, printer_arg);
                free((void *)str);
                break;
        default:
                str = sym_get_string_value(sym);
                printer->print_symbol(fp, sym, str, printer_arg);
        }
}

static void
conf_write_heading(FILE *fp, struct conf_printer *printer, void *printer_arg)
{
        char buf[256];

        snprintf(buf, sizeof(buf),
            "\n"
            "Automatically generated file; DO NOT EDIT.\n"
            "%s\n",
            rootmenu.prompt->text);

        printer->print_comment(fp, buf, printer_arg);
}

/*
 * Write out a minimal config.
 * All values that has default values are skipped as this is redundant.
 */
int conf_write_defconfig(const char *filename)
{
        struct symbol *sym;
        struct menu *menu;
        FILE *out;

        out = fopen(filename, "w");
        if (!out)
                return 1;

        sym_clear_all_valid();

        /* Traverse all menus to find all relevant symbols */
        menu = rootmenu.list;

        while (menu != NULL)
        {
                sym = menu->sym;
                if (sym == NULL) {
                        if (!menu_is_visible(menu))
                                goto next_menu;
                } else if (!sym_is_choice(sym)) {
                        sym_calc_value(sym);
                        if (!(sym->flags & SYMBOL_WRITE))
                                goto next_menu;
                        sym->flags &= ~SYMBOL_WRITE;
                        /* If we cannot change the symbol - skip */
                        if (!sym_is_changable(sym))
                                goto next_menu;
                        /* If symbol equals to default value - skip */
                        if (strcmp(sym_get_string_value(sym), sym_get_string_default(sym)) == 0)
                                goto next_menu;

                        /*
                         * If symbol is a choice value and equals to the
                         * default for a choice - skip.
                         * But only if value is bool and equal to "y" and
                         * choice is not "optional".
                         * (If choice is "optional" then all values can be "n")
                         */
                        if (sym_is_choice_value(sym)) {
                                struct symbol *cs;
                                struct symbol *ds;

                                cs = prop_get_symbol(sym_get_choice_prop(sym));
                                ds = sym_choice_default(cs);
                                if (!sym_is_optional(cs) && sym == ds) {
                                        if ((sym->type == S_BOOLEAN) &&
                                            sym_get_tristate_value(sym) == yes)
                                                goto next_menu;
                                }
                        }
                        conf_write_symbol(out, sym, &kconfig_printer_cb, NULL);
                }
next_menu:
                if (menu->list != NULL) {
                        menu = menu->list;
                }
                else if (menu->next != NULL) {
                        menu = menu->next;
                } else {
                        while ((menu = menu->parent)) {
                                if (menu->next != NULL) {
                                        menu = menu->next;
                                        break;
                                }
                        }
                }
        }
        fclose(out);
        return 0;
}

int conf_write(const char *name)
{
        FILE *out;
        struct symbol *sym;
        struct menu *menu;
        const char *basename;
        const char *str;
        char dirname[PATH_MAX+1], tmpname[PATH_MAX+22], newname[PATH_MAX+8];
        char *env;

        dirname[0] = 0;
        if (name && name[0]) {
                char *slash;

                if (is_dir(name)) {
                        strcpy(dirname, name);
                        strcat(dirname, "/");
                        basename = conf_get_configname();
                } else if ((slash = strrchr(name, '/'))) {
                        int size = slash - name + 1;
                        memcpy(dirname, name, size);
                        dirname[size] = 0;
                        if (slash[1])
                                basename = slash + 1;
                        else
                                basename = conf_get_configname();
                } else
                        basename = name;
        } else
                basename = conf_get_configname();

        sprintf(newname, "%s%s", dirname, basename);
        env = getenv("KCONFIG_OVERWRITECONFIG");
        if (!env || !*env) {
                sprintf(tmpname, "%s.tmpconfig.%d", dirname, (int)getpid());
                out = fopen(tmpname, "w");
        } else {
                *tmpname = 0;
                out = fopen(newname, "w");
        }
        if (!out)
                return 1;

        conf_write_heading(out, &kconfig_printer_cb, NULL);

        if (!conf_get_changed())
                sym_clear_all_valid();

        menu = rootmenu.list;
        while (menu) {
                sym = menu->sym;
                if (!sym) {
                        if (!menu_is_visible(menu))
                                goto next;
                        str = menu_get_prompt(menu);
                        fprintf(out, "\n"
                                     "#\n"
                                     "# %s\n"
                                     "#\n", str);
                } else if (!(sym->flags & SYMBOL_CHOICE)) {
                        sym_calc_value(sym);
                        if (!(sym->flags & SYMBOL_WRITE))
                                goto next;
                        sym->flags &= ~SYMBOL_WRITE;

                        conf_write_symbol(out, sym, &kconfig_printer_cb, NULL);
                }

next:
                if (menu->list) {
                        menu = menu->list;
                        continue;
                }
                if (menu->next)
                        menu = menu->next;
                else while ((menu = menu->parent)) {
                        if (menu->next) {
                                menu = menu->next;
                                break;
                        }
                }
        }
        fclose(out);

        if (*tmpname) {
                strcat(dirname, basename);
                strcat(dirname, ".old");
                rename(newname, dirname);
                if (rename(tmpname, newname))
                        return 1;
        }

        conf_message("configuration written to %s", newname);

        sym_set_change_count(0);

        return 0;
}

/* write a dependency file as used by kbuild to track dependencies */
static int conf_write_dep(const char *name)
{
        struct file *file;
        FILE *out;

        if (!name)
                name = ".kconfig.d";
        out = fopen("..config.tmp", "w");
        if (!out)
                return 1;
        fprintf(out, "deps_config := \\\n");
        for (file = file_list; file; file = file->next) {
                if (file->next)
                        fprintf(out, "\t%s \\\n", file->name);
                else
                        fprintf(out, "\t%s\n", file->name);
        }
        fprintf(out, "\n%s: \\\n"
                     "\t$(deps_config)\n\n", conf_get_autoconfig_name());

        env_write_dep(out, conf_get_autoconfig_name());

        fprintf(out, "\n$(deps_config): ;\n");
        fclose(out);

        if (make_parent_dir(name))
                return 1;
        rename("..config.tmp", name);
        return 0;
}

static int conf_touch_deps(void)
{
        const char *name;
        struct symbol *sym;
        int res, i;

        strcpy(depfile_path, "include/config/");
        depfile_prefix_len = strlen(depfile_path);

        name = conf_get_autoconfig_name();
        conf_read_simple(name, S_DEF_AUTO);
        sym_calc_value(modules_sym);

        for_all_symbols(i, sym) {
                sym_calc_value(sym);
                if ((sym->flags & SYMBOL_NO_WRITE) || !sym->name)
                        continue;
                if (sym->flags & SYMBOL_WRITE) {
                        if (sym->flags & SYMBOL_DEF_AUTO) {
                                /*
                                 * symbol has old and new value,
                                 * so compare them...
                                 */
                                switch (sym->type) {
                                case S_BOOLEAN:
                                case S_TRISTATE:
                                        if (sym_get_tristate_value(sym) ==
                                            sym->def[S_DEF_AUTO].tri)
                                                continue;
                                        break;
                                case S_STRING:
                                case S_HEX:
                                case S_INT:
                                        if (!strcmp(sym_get_string_value(sym),
                                                    sym->def[S_DEF_AUTO].val))
                                                continue;
                                        break;
                                default:
                                        break;
                                }
                        } else {
                                /*
                                 * If there is no old value, only 'no' (unset)
                                 * is allowed as new value.
                                 */
                                switch (sym->type) {
                                case S_BOOLEAN:
                                case S_TRISTATE:
                                        if (sym_get_tristate_value(sym) == no)
                                                continue;
                                        break;
                                default:
                                        break;
                                }
                        }

                } else if (!(sym->flags & SYMBOL_DEF_AUTO))
                        /* There is neither an old nor a new value. */
                        continue;
                /* else
                 *      There is an old value, but no new value ('no' (unset)
                 *      isn't saved in auto.conf, so the old value is always
                 *      different from 'no').
                 */

                res = conf_touch_dep(sym->name);
                if (res)
                        return res;
        }

        return 0;
}

int conf_write_autoconf(int overwrite)
{
        struct symbol *sym;
        const char *name;
        const char *autoconf_name = conf_get_autoconfig_name();
        FILE *out, *tristate, *out_h;
        int i;

        if (!overwrite && is_present(autoconf_name))
                return 0;

        sym_clear_all_valid();

        conf_write_dep("include/config/auto.conf.cmd");

        if (conf_touch_deps())
                return 1;

        out = fopen(".tmpconfig", "w");
        if (!out)
                return 1;

        tristate = fopen(".tmpconfig_tristate", "w");
        if (!tristate) {
                fclose(out);
                return 1;
        }

        out_h = fopen(".tmpconfig.h", "w");
        if (!out_h) {
                fclose(out);
                fclose(tristate);
                return 1;
        }

        conf_write_heading(out, &kconfig_printer_cb, NULL);

        conf_write_heading(tristate, &tristate_printer_cb, NULL);

        conf_write_heading(out_h, &header_printer_cb, NULL);

        for_all_symbols(i, sym) {
                sym_calc_value(sym);
                if (!(sym->flags & SYMBOL_WRITE) || !sym->name)
                        continue;

                /* write symbol to auto.conf, tristate and header files */
                conf_write_symbol(out, sym, &kconfig_printer_cb, (void *)1);

                conf_write_symbol(tristate, sym, &tristate_printer_cb, (void *)1);

                conf_write_symbol(out_h, sym, &header_printer_cb, NULL);
        }
        fclose(out);
        fclose(tristate);
        fclose(out_h);

        name = getenv("KCONFIG_AUTOHEADER");
        if (!name)
                name = "include/generated/autoconf.h";
        if (make_parent_dir(name))
                return 1;
        if (rename(".tmpconfig.h", name))
                return 1;

        name = getenv("KCONFIG_TRISTATE");
        if (!name)
                name = "include/config/tristate.conf";
        if (make_parent_dir(name))
                return 1;
        if (rename(".tmpconfig_tristate", name))
                return 1;

        if (make_parent_dir(autoconf_name))
                return 1;
        /*
         * This must be the last step, kbuild has a dependency on auto.conf
         * and this marks the successful completion of the previous steps.
         */
        if (rename(".tmpconfig", autoconf_name))
                return 1;

        return 0;
}

static int sym_change_count;
static void (*conf_changed_callback)(void);

void sym_set_change_count(int count)
{
        int _sym_change_count = sym_change_count;
        sym_change_count = count;
        if (conf_changed_callback &&
            (bool)_sym_change_count != (bool)count)
                conf_changed_callback();
}

void sym_add_change_count(int count)
{
        sym_set_change_count(count + sym_change_count);
}

bool conf_get_changed(void)
{
        return sym_change_count;
}

void conf_set_changed_callback(void (*fn)(void))
{
        conf_changed_callback = fn;
}

static bool randomize_choice_values(struct symbol *csym)
{
        struct property *prop;
        struct symbol *sym;
        struct expr *e;
        int cnt, def;

        /*
         * If choice is mod then we may have more items selected
         * and if no then no-one.
         * In both cases stop.
         */
        if (csym->curr.tri != yes)
                return false;

        prop = sym_get_choice_prop(csym);

        /* count entries in choice block */
        cnt = 0;
        expr_list_for_each_sym(prop->expr, e, sym)
                cnt++;

        /*
         * find a random value and set it to yes,
         * set the rest to no so we have only one set
         */
        def = (rand() % cnt);

        cnt = 0;
        expr_list_for_each_sym(prop->expr, e, sym) {
                if (def == cnt++) {
                        sym->def[S_DEF_USER].tri = yes;
                        csym->def[S_DEF_USER].val = sym;
                }
                else {
                        sym->def[S_DEF_USER].tri = no;
                }
                sym->flags |= SYMBOL_DEF_USER;
                /* clear VALID to get value calculated */
                sym->flags &= ~SYMBOL_VALID;
        }
        csym->flags |= SYMBOL_DEF_USER;
        /* clear VALID to get value calculated */
        csym->flags &= ~(SYMBOL_VALID);

        return true;
}

void set_all_choice_values(struct symbol *csym)
{
        struct property *prop;
        struct symbol *sym;
        struct expr *e;

        prop = sym_get_choice_prop(csym);

        /*
         * Set all non-assinged choice values to no
         */
        expr_list_for_each_sym(prop->expr, e, sym) {
                if (!sym_has_value(sym))
                        sym->def[S_DEF_USER].tri = no;
        }
        csym->flags |= SYMBOL_DEF_USER;
        /* clear VALID to get value calculated */
        csym->flags &= ~(SYMBOL_VALID | SYMBOL_NEED_SET_CHOICE_VALUES);
}

bool conf_set_all_new_symbols(enum conf_def_mode mode)
{
        struct symbol *sym, *csym;
        int i, cnt, pby, pty, ptm;      /* pby: probability of bool     = y
                                         * pty: probability of tristate = y
                                         * ptm: probability of tristate = m
                                         */

        pby = 50; pty = ptm = 33; /* can't go as the default in switch-case
                                   * below, otherwise gcc whines about
                                   * -Wmaybe-uninitialized */
        if (mode == def_random) {
                int n, p[3];
                char *env = getenv("KCONFIG_PROBABILITY");
                n = 0;
                while( env && *env ) {
                        char *endp;
                        int tmp = strtol( env, &endp, 10 );
                        if( tmp >= 0 && tmp <= 100 ) {
                                p[n++] = tmp;
                        } else {
                                errno = ERANGE;
                                perror( "KCONFIG_PROBABILITY" );
                                exit( 1 );
                        }
                        env = (*endp == ':') ? endp+1 : endp;
                        if( n >=3 ) {
                                break;
                        }
                }
                switch( n ) {
                case 1:
                        pby = p[0]; ptm = pby/2; pty = pby-ptm;
                        break;
                case 2:
                        pty = p[0]; ptm = p[1]; pby = pty + ptm;
                        break;
                case 3:
                        pby = p[0]; pty = p[1]; ptm = p[2];
                        break;
                }

                if( pty+ptm > 100 ) {
                        errno = ERANGE;
                        perror( "KCONFIG_PROBABILITY" );
                        exit( 1 );
                }
        }
        bool has_changed = false;

        for_all_symbols(i, sym) {
                if (sym_has_value(sym) || (sym->flags & SYMBOL_VALID))
                        continue;
                switch (sym_get_type(sym)) {
                case S_BOOLEAN:
                case S_TRISTATE:
                        has_changed = true;
                        switch (mode) {
                        case def_yes:
                                sym->def[S_DEF_USER].tri = yes;
                                break;
                        case def_mod:
                                sym->def[S_DEF_USER].tri = mod;
                                break;
                        case def_no:
                                if (sym->flags & SYMBOL_ALLNOCONFIG_Y)
                                        sym->def[S_DEF_USER].tri = yes;
                                else
                                        sym->def[S_DEF_USER].tri = no;
                                break;
                        case def_random:
                                sym->def[S_DEF_USER].tri = no;
                                cnt = rand() % 100;
                                if (sym->type == S_TRISTATE) {
                                        if (cnt < pty)
                                                sym->def[S_DEF_USER].tri = yes;
                                        else if (cnt < (pty+ptm))
                                                sym->def[S_DEF_USER].tri = mod;
                                } else if (cnt < pby)
                                        sym->def[S_DEF_USER].tri = yes;
                                break;
                        default:
                                continue;
                        }
                        if (!(sym_is_choice(sym) && mode == def_random))
                                sym->flags |= SYMBOL_DEF_USER;
                        break;
                default:
                        break;
                }

        }

        sym_clear_all_valid();

        /*
         * We have different type of choice blocks.
         * If curr.tri equals to mod then we can select several
         * choice symbols in one block.
         * In this case we do nothing.
         * If curr.tri equals yes then only one symbol can be
         * selected in a choice block and we set it to yes,
         * and the rest to no.
         */
        if (mode != def_random) {
                for_all_symbols(i, csym) {
                        if ((sym_is_choice(csym) && !sym_has_value(csym)) ||
                            sym_is_choice_value(csym))
                                csym->flags |= SYMBOL_NEED_SET_CHOICE_VALUES;
                }
        }

        for_all_symbols(i, csym) {
                if (sym_has_value(csym) || !sym_is_choice(csym))
                        continue;

                sym_calc_value(csym);
                if (mode == def_random)
                        has_changed = randomize_choice_values(csym);
                else {
                        set_all_choice_values(csym);
                        has_changed = true;
                }
        }

        return has_changed;
}