xref: /linux/scripts/kconfig/confdata.c (revision 95573cac25c6b11f02d599d18e9a1c778706e838)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
4  */
5 
6 #include <sys/mman.h>
7 #include <sys/stat.h>
8 #include <sys/types.h>
9 #include <ctype.h>
10 #include <errno.h>
11 #include <fcntl.h>
12 #include <limits.h>
13 #include <stdarg.h>
14 #include <stdbool.h>
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <string.h>
18 #include <time.h>
19 #include <unistd.h>
20 
21 #include <xalloc.h>
22 #include "internal.h"
23 #include "lkc.h"
24 
25 struct gstr autoconf_cmd;
26 
27 /* return true if 'path' exists, false otherwise */
28 static bool is_present(const char *path)
29 {
30 	struct stat st;
31 
32 	return !stat(path, &st);
33 }
34 
35 /* return true if 'path' exists and it is a directory, false otherwise */
36 static bool is_dir(const char *path)
37 {
38 	struct stat st;
39 
40 	if (stat(path, &st))
41 		return false;
42 
43 	return S_ISDIR(st.st_mode);
44 }
45 
46 /* return true if the given two files are the same, false otherwise */
47 static bool is_same(const char *file1, const char *file2)
48 {
49 	int fd1, fd2;
50 	struct stat st1, st2;
51 	void *map1, *map2;
52 	bool ret = false;
53 
54 	fd1 = open(file1, O_RDONLY);
55 	if (fd1 < 0)
56 		return ret;
57 
58 	fd2 = open(file2, O_RDONLY);
59 	if (fd2 < 0)
60 		goto close1;
61 
62 	ret = fstat(fd1, &st1);
63 	if (ret)
64 		goto close2;
65 	ret = fstat(fd2, &st2);
66 	if (ret)
67 		goto close2;
68 
69 	if (st1.st_size != st2.st_size)
70 		goto close2;
71 
72 	map1 = mmap(NULL, st1.st_size, PROT_READ, MAP_PRIVATE, fd1, 0);
73 	if (map1 == MAP_FAILED)
74 		goto close2;
75 
76 	map2 = mmap(NULL, st2.st_size, PROT_READ, MAP_PRIVATE, fd2, 0);
77 	if (map2 == MAP_FAILED)
78 		goto close2;
79 
80 	if (bcmp(map1, map2, st1.st_size))
81 		goto close2;
82 
83 	ret = true;
84 close2:
85 	close(fd2);
86 close1:
87 	close(fd1);
88 
89 	return ret;
90 }
91 
92 /*
93  * Create the parent directory of the given path.
94  *
95  * For example, if 'include/config/auto.conf' is given, create 'include/config'.
96  */
97 static int make_parent_dir(const char *path)
98 {
99 	char tmp[PATH_MAX + 1];
100 	char *p;
101 
102 	strncpy(tmp, path, sizeof(tmp));
103 	tmp[sizeof(tmp) - 1] = 0;
104 
105 	/* Remove the base name. Just return if nothing is left */
106 	p = strrchr(tmp, '/');
107 	if (!p)
108 		return 0;
109 	*(p + 1) = 0;
110 
111 	/* Just in case it is an absolute path */
112 	p = tmp;
113 	while (*p == '/')
114 		p++;
115 
116 	while ((p = strchr(p, '/'))) {
117 		*p = 0;
118 
119 		/* skip if the directory exists */
120 		if (!is_dir(tmp) && mkdir(tmp, 0755))
121 			return -1;
122 
123 		*p = '/';
124 		while (*p == '/')
125 			p++;
126 	}
127 
128 	return 0;
129 }
130 
131 static char depfile_path[PATH_MAX];
132 static size_t depfile_prefix_len;
133 
134 /* touch depfile for symbol 'name' */
135 static int conf_touch_dep(const char *name)
136 {
137 	int fd;
138 
139 	/* check overflow: prefix + name + '\0' must fit in buffer. */
140 	if (depfile_prefix_len + strlen(name) + 1 > sizeof(depfile_path))
141 		return -1;
142 
143 	strcpy(depfile_path + depfile_prefix_len, name);
144 
145 	fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
146 	if (fd == -1)
147 		return -1;
148 	close(fd);
149 
150 	return 0;
151 }
152 
153 static void conf_warning(const char *fmt, ...)
154 	__attribute__ ((format (printf, 1, 2)));
155 
156 static void conf_message(const char *fmt, ...)
157 	__attribute__ ((format (printf, 1, 2)));
158 
159 static const char *conf_filename;
160 static int conf_lineno, conf_warnings;
161 
162 bool conf_errors(void)
163 {
164 	if (conf_warnings)
165 		return getenv("KCONFIG_WERROR");
166 	return false;
167 }
168 
169 static void conf_warning(const char *fmt, ...)
170 {
171 	va_list ap;
172 	va_start(ap, fmt);
173 	fprintf(stderr, "%s:%d:warning: ", conf_filename, conf_lineno);
174 	vfprintf(stderr, fmt, ap);
175 	fprintf(stderr, "\n");
176 	va_end(ap);
177 	conf_warnings++;
178 }
179 
180 static void conf_default_message_callback(const char *s)
181 {
182 	printf("#\n# ");
183 	printf("%s", s);
184 	printf("\n#\n");
185 }
186 
187 static void (*conf_message_callback)(const char *s) =
188 	conf_default_message_callback;
189 void conf_set_message_callback(void (*fn)(const char *s))
190 {
191 	conf_message_callback = fn;
192 }
193 
194 static void conf_message(const char *fmt, ...)
195 {
196 	va_list ap;
197 	char buf[4096];
198 
199 	if (!conf_message_callback)
200 		return;
201 
202 	va_start(ap, fmt);
203 
204 	vsnprintf(buf, sizeof(buf), fmt, ap);
205 	conf_message_callback(buf);
206 	va_end(ap);
207 }
208 
209 const char *conf_get_configname(void)
210 {
211 	char *name = getenv("KCONFIG_CONFIG");
212 
213 	return name ? name : ".config";
214 }
215 
216 static const char *conf_get_autoconfig_name(void)
217 {
218 	char *name = getenv("KCONFIG_AUTOCONFIG");
219 
220 	return name ? name : "include/config/auto.conf";
221 }
222 
223 static const char *conf_get_autoheader_name(void)
224 {
225 	char *name = getenv("KCONFIG_AUTOHEADER");
226 
227 	return name ? name : "include/generated/autoconf.h";
228 }
229 
230 static const char *conf_get_rustccfg_name(void)
231 {
232 	char *name = getenv("KCONFIG_RUSTCCFG");
233 
234 	return name ? name : "include/generated/rustc_cfg";
235 }
236 
237 static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
238 {
239 	char *p2;
240 
241 	switch (sym->type) {
242 	case S_TRISTATE:
243 		if (p[0] == 'm') {
244 			sym->def[def].tri = mod;
245 			sym->flags |= def_flags;
246 			break;
247 		}
248 		/* fall through */
249 	case S_BOOLEAN:
250 		if (p[0] == 'y') {
251 			sym->def[def].tri = yes;
252 			sym->flags |= def_flags;
253 			break;
254 		}
255 		if (p[0] == 'n') {
256 			sym->def[def].tri = no;
257 			sym->flags |= def_flags;
258 			break;
259 		}
260 		if (def != S_DEF_AUTO)
261 			conf_warning("symbol value '%s' invalid for %s",
262 				     p, sym->name);
263 		return 1;
264 	case S_STRING:
265 		/* No escaping for S_DEF_AUTO (include/config/auto.conf) */
266 		if (def != S_DEF_AUTO) {
267 			if (*p++ != '"')
268 				break;
269 			for (p2 = p; (p2 = strpbrk(p2, "\"\\")); p2++) {
270 				if (*p2 == '"') {
271 					*p2 = 0;
272 					break;
273 				}
274 				memmove(p2, p2 + 1, strlen(p2));
275 			}
276 			if (!p2) {
277 				conf_warning("invalid string found");
278 				return 1;
279 			}
280 		}
281 		/* fall through */
282 	case S_INT:
283 	case S_HEX:
284 		if (sym_string_valid(sym, p)) {
285 			sym->def[def].val = xstrdup(p);
286 			sym->flags |= def_flags;
287 		} else {
288 			if (def != S_DEF_AUTO)
289 				conf_warning("symbol value '%s' invalid for %s",
290 					     p, sym->name);
291 			return 1;
292 		}
293 		break;
294 	default:
295 		;
296 	}
297 	return 0;
298 }
299 
300 /* like getline(), but the newline character is stripped away */
301 static ssize_t getline_stripped(char **lineptr, size_t *n, FILE *stream)
302 {
303 	ssize_t len;
304 
305 	len = getline(lineptr, n, stream);
306 
307 	if (len > 0 && (*lineptr)[len - 1] == '\n') {
308 		len--;
309 		(*lineptr)[len] = '\0';
310 
311 		if (len > 0 && (*lineptr)[len - 1] == '\r') {
312 			len--;
313 			(*lineptr)[len] = '\0';
314 		}
315 	}
316 
317 	return len;
318 }
319 
320 int conf_read_simple(const char *name, int def)
321 {
322 	FILE *in = NULL;
323 	char   *line = NULL;
324 	size_t  line_asize = 0;
325 	char *p, *val;
326 	struct symbol *sym;
327 	int def_flags;
328 	const char *warn_unknown, *sym_name;
329 
330 	warn_unknown = getenv("KCONFIG_WARN_UNKNOWN_SYMBOLS");
331 	if (name) {
332 		in = zconf_fopen(name);
333 	} else {
334 		char *env;
335 
336 		name = conf_get_configname();
337 		in = zconf_fopen(name);
338 		if (in)
339 			goto load;
340 		conf_set_changed(true);
341 
342 		env = getenv("KCONFIG_DEFCONFIG_LIST");
343 		if (!env)
344 			return 1;
345 
346 		while (1) {
347 			bool is_last;
348 
349 			while (isspace(*env))
350 				env++;
351 
352 			if (!*env)
353 				break;
354 
355 			p = env;
356 			while (*p && !isspace(*p))
357 				p++;
358 
359 			is_last = (*p == '\0');
360 
361 			*p = '\0';
362 
363 			in = zconf_fopen(env);
364 			if (in) {
365 				conf_message("using defaults found in %s",
366 					     env);
367 				goto load;
368 			}
369 
370 			if (is_last)
371 				break;
372 
373 			env = p + 1;
374 		}
375 	}
376 	if (!in)
377 		return 1;
378 
379 load:
380 	conf_filename = name;
381 	conf_lineno = 0;
382 	conf_warnings = 0;
383 
384 	def_flags = SYMBOL_DEF << def;
385 	for_all_symbols(sym) {
386 		sym->flags &= ~(def_flags|SYMBOL_VALID);
387 		switch (sym->type) {
388 		case S_INT:
389 		case S_HEX:
390 		case S_STRING:
391 			free(sym->def[def].val);
392 			/* fall through */
393 		default:
394 			sym->def[def].val = NULL;
395 			sym->def[def].tri = no;
396 		}
397 	}
398 
399 	expr_invalidate_all();
400 
401 	while (getline_stripped(&line, &line_asize, in) != -1) {
402 		struct menu *choice;
403 
404 		conf_lineno++;
405 
406 		if (!line[0]) /* blank line */
407 			continue;
408 
409 		if (line[0] == '#') {
410 			if (line[1] != ' ')
411 				continue;
412 			p = line + 2;
413 			if (memcmp(p, CONFIG_, strlen(CONFIG_)))
414 				continue;
415 			sym_name = p + strlen(CONFIG_);
416 			p = strchr(sym_name, ' ');
417 			if (!p)
418 				continue;
419 			*p++ = 0;
420 			if (strcmp(p, "is not set"))
421 				continue;
422 
423 			val = "n";
424 		} else {
425 			if (memcmp(line, CONFIG_, strlen(CONFIG_))) {
426 				conf_warning("unexpected data: %s", line);
427 				continue;
428 			}
429 
430 			sym_name = line + strlen(CONFIG_);
431 			p = strchr(sym_name, '=');
432 			if (!p) {
433 				conf_warning("unexpected data: %s", line);
434 				continue;
435 			}
436 			*p = 0;
437 			val = p + 1;
438 		}
439 
440 		sym = sym_find(sym_name);
441 		if (!sym) {
442 			if (def == S_DEF_AUTO) {
443 				/*
444 				 * Reading from include/config/auto.conf.
445 				 * If CONFIG_FOO previously existed in auto.conf
446 				 * but it is missing now, include/config/FOO
447 				 * must be touched.
448 				 */
449 				conf_touch_dep(sym_name);
450 			} else {
451 				if (warn_unknown)
452 					conf_warning("unknown symbol: %s", sym_name);
453 
454 				conf_set_changed(true);
455 			}
456 			continue;
457 		}
458 
459 		if (sym->flags & def_flags)
460 			conf_warning("override: reassigning to symbol %s", sym->name);
461 
462 		if (conf_set_sym_val(sym, def, def_flags, val))
463 			continue;
464 
465 		/*
466 		 * If this is a choice member, give it the highest priority.
467 		 * If conflicting CONFIG options are given from an input file,
468 		 * the last one wins.
469 		 */
470 		choice = sym_get_choice_menu(sym);
471 		if (choice)
472 			list_move(&sym->choice_link, &choice->choice_members);
473 	}
474 	free(line);
475 	fclose(in);
476 
477 	return 0;
478 }
479 
480 int conf_read(const char *name)
481 {
482 	struct symbol *sym;
483 
484 	conf_set_changed(false);
485 
486 	if (conf_read_simple(name, S_DEF_USER)) {
487 		sym_calc_value(modules_sym);
488 		return 1;
489 	}
490 
491 	sym_calc_value(modules_sym);
492 
493 	for_all_symbols(sym) {
494 		sym_calc_value(sym);
495 		if (sym_is_choice(sym))
496 			continue;
497 		if (sym_has_value(sym) && (sym->flags & SYMBOL_WRITE)) {
498 			/* check that calculated value agrees with saved value */
499 			switch (sym->type) {
500 			case S_BOOLEAN:
501 			case S_TRISTATE:
502 				if (sym->def[S_DEF_USER].tri == sym_get_tristate_value(sym))
503 					continue;
504 				break;
505 			default:
506 				if (!strcmp(sym->curr.val, sym->def[S_DEF_USER].val))
507 					continue;
508 				break;
509 			}
510 		} else if (!sym_has_value(sym) && !(sym->flags & SYMBOL_WRITE))
511 			/* no previous value and not saved */
512 			continue;
513 		conf_set_changed(true);
514 		/* maybe print value in verbose mode... */
515 	}
516 
517 	if (conf_warnings)
518 		conf_set_changed(true);
519 
520 	return 0;
521 }
522 
523 struct comment_style {
524 	const char *decoration;
525 	const char *prefix;
526 	const char *postfix;
527 };
528 
529 static const struct comment_style comment_style_pound = {
530 	.decoration = "#",
531 	.prefix = "#",
532 	.postfix = "#",
533 };
534 
535 static const struct comment_style comment_style_c = {
536 	.decoration = " *",
537 	.prefix = "/*",
538 	.postfix = " */",
539 };
540 
541 static void conf_write_heading(FILE *fp, const struct comment_style *cs)
542 {
543 	if (!cs)
544 		return;
545 
546 	fprintf(fp, "%s\n", cs->prefix);
547 
548 	fprintf(fp, "%s Automatically generated file; DO NOT EDIT.\n",
549 		cs->decoration);
550 
551 	fprintf(fp, "%s %s\n", cs->decoration, rootmenu.prompt->text);
552 
553 	fprintf(fp, "%s\n", cs->postfix);
554 }
555 
556 /* The returned pointer must be freed on the caller side */
557 static char *escape_string_value(const char *in)
558 {
559 	const char *p;
560 	char *out;
561 	size_t len;
562 
563 	len = strlen(in) + strlen("\"\"") + 1;
564 
565 	p = in;
566 	while (1) {
567 		p += strcspn(p, "\"\\");
568 
569 		if (p[0] == '\0')
570 			break;
571 
572 		len++;
573 		p++;
574 	}
575 
576 	out = xmalloc(len);
577 	out[0] = '\0';
578 
579 	strcat(out, "\"");
580 
581 	p = in;
582 	while (1) {
583 		len = strcspn(p, "\"\\");
584 		strncat(out, p, len);
585 		p += len;
586 
587 		if (p[0] == '\0')
588 			break;
589 
590 		strcat(out, "\\");
591 		strncat(out, p++, 1);
592 	}
593 
594 	strcat(out, "\"");
595 
596 	return out;
597 }
598 
599 enum output_n { OUTPUT_N, OUTPUT_N_AS_UNSET, OUTPUT_N_NONE };
600 
601 static void __print_symbol(FILE *fp, struct symbol *sym, enum output_n output_n,
602 			   bool escape_string)
603 {
604 	const char *val;
605 	char *escaped = NULL;
606 
607 	if (sym->type == S_UNKNOWN)
608 		return;
609 
610 	val = sym_get_string_value(sym);
611 
612 	if ((sym->type == S_BOOLEAN || sym->type == S_TRISTATE) &&
613 	    output_n != OUTPUT_N && *val == 'n') {
614 		if (output_n == OUTPUT_N_AS_UNSET)
615 			fprintf(fp, "# %s%s is not set\n", CONFIG_, sym->name);
616 		return;
617 	}
618 
619 	if (sym->type == S_STRING && escape_string) {
620 		escaped = escape_string_value(val);
621 		val = escaped;
622 	}
623 
624 	fprintf(fp, "%s%s=%s\n", CONFIG_, sym->name, val);
625 
626 	free(escaped);
627 }
628 
629 static void print_symbol_for_dotconfig(FILE *fp, struct symbol *sym)
630 {
631 	__print_symbol(fp, sym, OUTPUT_N_AS_UNSET, true);
632 }
633 
634 static void print_symbol_for_autoconf(FILE *fp, struct symbol *sym)
635 {
636 	__print_symbol(fp, sym, OUTPUT_N_NONE, false);
637 }
638 
639 void print_symbol_for_listconfig(struct symbol *sym)
640 {
641 	__print_symbol(stdout, sym, OUTPUT_N, true);
642 }
643 
644 static void print_symbol_for_c(FILE *fp, struct symbol *sym)
645 {
646 	const char *val;
647 	const char *sym_suffix = "";
648 	const char *val_prefix = "";
649 	char *escaped = NULL;
650 
651 	if (sym->type == S_UNKNOWN)
652 		return;
653 
654 	val = sym_get_string_value(sym);
655 
656 	switch (sym->type) {
657 	case S_BOOLEAN:
658 	case S_TRISTATE:
659 		switch (*val) {
660 		case 'n':
661 			return;
662 		case 'm':
663 			sym_suffix = "_MODULE";
664 			/* fall through */
665 		default:
666 			val = "1";
667 		}
668 		break;
669 	case S_HEX:
670 		if (val[0] != '0' || (val[1] != 'x' && val[1] != 'X'))
671 			val_prefix = "0x";
672 		break;
673 	case S_STRING:
674 		escaped = escape_string_value(val);
675 		val = escaped;
676 	default:
677 		break;
678 	}
679 
680 	fprintf(fp, "#define %s%s%s %s%s\n", CONFIG_, sym->name, sym_suffix,
681 		val_prefix, val);
682 
683 	free(escaped);
684 }
685 
686 static void print_symbol_for_rustccfg(FILE *fp, struct symbol *sym)
687 {
688 	const char *val;
689 	const char *val_prefix = "";
690 	char *val_prefixed = NULL;
691 	size_t val_prefixed_len;
692 	char *escaped = NULL;
693 
694 	if (sym->type == S_UNKNOWN)
695 		return;
696 
697 	val = sym_get_string_value(sym);
698 
699 	switch (sym->type) {
700 	case S_BOOLEAN:
701 	case S_TRISTATE:
702 		/*
703 		 * We do not care about disabled ones, i.e. no need for
704 		 * what otherwise are "comments" in other printers.
705 		 */
706 		if (*val == 'n')
707 			return;
708 
709 		/*
710 		 * To have similar functionality to the C macro `IS_ENABLED()`
711 		 * we provide an empty `--cfg CONFIG_X` here in both `y`
712 		 * and `m` cases.
713 		 *
714 		 * Then, the common `fprintf()` below will also give us
715 		 * a `--cfg CONFIG_X="y"` or `--cfg CONFIG_X="m"`, which can
716 		 * be used as the equivalent of `IS_BUILTIN()`/`IS_MODULE()`.
717 		 */
718 		fprintf(fp, "--cfg=%s%s\n", CONFIG_, sym->name);
719 		break;
720 	case S_HEX:
721 		if (val[0] != '0' || (val[1] != 'x' && val[1] != 'X'))
722 			val_prefix = "0x";
723 		break;
724 	default:
725 		break;
726 	}
727 
728 	if (strlen(val_prefix) > 0) {
729 		val_prefixed_len = strlen(val) + strlen(val_prefix) + 1;
730 		val_prefixed = xmalloc(val_prefixed_len);
731 		snprintf(val_prefixed, val_prefixed_len, "%s%s", val_prefix, val);
732 		val = val_prefixed;
733 	}
734 
735 	/* All values get escaped: the `--cfg` option only takes strings */
736 	escaped = escape_string_value(val);
737 	val = escaped;
738 
739 	fprintf(fp, "--cfg=%s%s=%s\n", CONFIG_, sym->name, val);
740 
741 	free(escaped);
742 	free(val_prefixed);
743 }
744 
745 /*
746  * Write out a minimal config.
747  * All values that has default values are skipped as this is redundant.
748  */
749 int conf_write_defconfig(const char *filename)
750 {
751 	struct symbol *sym;
752 	struct menu *menu;
753 	FILE *out;
754 
755 	out = fopen(filename, "w");
756 	if (!out)
757 		return 1;
758 
759 	sym_clear_all_valid();
760 
761 	menu_for_each_entry(menu) {
762 		struct menu *choice;
763 
764 		sym = menu->sym;
765 
766 		if (!sym || sym_is_choice(sym))
767 			continue;
768 
769 		sym_calc_value(sym);
770 		if (!(sym->flags & SYMBOL_WRITE))
771 			continue;
772 		sym->flags &= ~SYMBOL_WRITE;
773 		/* Skip unchangeable symbols */
774 		if (!sym_is_changeable(sym))
775 			continue;
776 		/* Skip symbols that are equal to the default */
777 		if (!strcmp(sym_get_string_value(sym), sym_get_string_default(sym)))
778 			continue;
779 
780 		/* Skip choice values that are equal to the default */
781 		choice = sym_get_choice_menu(sym);
782 		if (choice) {
783 			struct symbol *ds;
784 
785 			ds = sym_choice_default(choice);
786 			if (sym == ds && sym_get_tristate_value(sym) == yes)
787 				continue;
788 		}
789 		print_symbol_for_dotconfig(out, sym);
790 	}
791 	fclose(out);
792 	return 0;
793 }
794 
795 int conf_write(const char *name)
796 {
797 	FILE *out;
798 	struct symbol *sym;
799 	struct menu *menu;
800 	const char *str;
801 	char tmpname[PATH_MAX + 1], oldname[PATH_MAX + 1];
802 	char *env;
803 	bool need_newline = false;
804 
805 	if (!name)
806 		name = conf_get_configname();
807 
808 	if (!*name) {
809 		fprintf(stderr, "config name is empty\n");
810 		return -1;
811 	}
812 
813 	if (is_dir(name)) {
814 		fprintf(stderr, "%s: Is a directory\n", name);
815 		return -1;
816 	}
817 
818 	if (make_parent_dir(name))
819 		return -1;
820 
821 	env = getenv("KCONFIG_OVERWRITECONFIG");
822 	if (env && *env) {
823 		*tmpname = 0;
824 		out = fopen(name, "w");
825 	} else {
826 		snprintf(tmpname, sizeof(tmpname), "%s.%d.tmp",
827 			 name, (int)getpid());
828 		out = fopen(tmpname, "w");
829 	}
830 	if (!out)
831 		return 1;
832 
833 	conf_write_heading(out, &comment_style_pound);
834 
835 	if (!conf_get_changed())
836 		sym_clear_all_valid();
837 
838 	menu = rootmenu.list;
839 	while (menu) {
840 		sym = menu->sym;
841 		if (!sym) {
842 			if (!menu_is_visible(menu))
843 				goto next;
844 			str = menu_get_prompt(menu);
845 			fprintf(out, "\n"
846 				     "#\n"
847 				     "# %s\n"
848 				     "#\n", str);
849 			need_newline = false;
850 		} else if (!sym_is_choice(sym) &&
851 			   !(sym->flags & SYMBOL_WRITTEN)) {
852 			sym_calc_value(sym);
853 			if (!(sym->flags & SYMBOL_WRITE))
854 				goto next;
855 			if (need_newline) {
856 				fprintf(out, "\n");
857 				need_newline = false;
858 			}
859 			sym->flags |= SYMBOL_WRITTEN;
860 			print_symbol_for_dotconfig(out, sym);
861 		}
862 
863 next:
864 		if (menu->list) {
865 			menu = menu->list;
866 			continue;
867 		}
868 
869 end_check:
870 		if (!menu->sym && menu_is_visible(menu) && menu != &rootmenu &&
871 		    menu->prompt->type == P_MENU) {
872 			fprintf(out, "# end of %s\n", menu_get_prompt(menu));
873 			need_newline = true;
874 		}
875 
876 		if (menu->next) {
877 			menu = menu->next;
878 		} else {
879 			menu = menu->parent;
880 			if (menu)
881 				goto end_check;
882 		}
883 	}
884 	fclose(out);
885 
886 	for_all_symbols(sym)
887 		sym->flags &= ~SYMBOL_WRITTEN;
888 
889 	if (*tmpname) {
890 		if (is_same(name, tmpname)) {
891 			conf_message("No change to %s", name);
892 			unlink(tmpname);
893 			conf_set_changed(false);
894 			return 0;
895 		}
896 
897 		snprintf(oldname, sizeof(oldname), "%s.old", name);
898 		rename(name, oldname);
899 		if (rename(tmpname, name))
900 			return 1;
901 	}
902 
903 	conf_message("configuration written to %s", name);
904 
905 	conf_set_changed(false);
906 
907 	return 0;
908 }
909 
910 /* write a dependency file as used by kbuild to track dependencies */
911 static int conf_write_autoconf_cmd(const char *autoconf_name)
912 {
913 	char name[PATH_MAX], tmp[PATH_MAX];
914 	FILE *out;
915 	int ret;
916 
917 	ret = snprintf(name, sizeof(name), "%s.cmd", autoconf_name);
918 	if (ret >= sizeof(name)) /* check truncation */
919 		return -1;
920 
921 	if (make_parent_dir(name))
922 		return -1;
923 
924 	ret = snprintf(tmp, sizeof(tmp), "%s.cmd.tmp", autoconf_name);
925 	if (ret >= sizeof(tmp)) /* check truncation */
926 		return -1;
927 
928 	out = fopen(tmp, "w");
929 	if (!out) {
930 		perror("fopen");
931 		return -1;
932 	}
933 
934 	fprintf(out, "autoconfig := %s\n", autoconf_name);
935 
936 	fputs(str_get(&autoconf_cmd), out);
937 
938 	fflush(out);
939 	ret = ferror(out); /* error check for all fprintf() calls */
940 	fclose(out);
941 	if (ret)
942 		return -1;
943 
944 	if (rename(tmp, name)) {
945 		perror("rename");
946 		return -1;
947 	}
948 
949 	return 0;
950 }
951 
952 static int conf_touch_deps(void)
953 {
954 	const char *name, *tmp;
955 	struct symbol *sym;
956 	int res;
957 
958 	name = conf_get_autoconfig_name();
959 	tmp = strrchr(name, '/');
960 	depfile_prefix_len = tmp ? tmp - name + 1 : 0;
961 	if (depfile_prefix_len + 1 > sizeof(depfile_path))
962 		return -1;
963 
964 	strncpy(depfile_path, name, depfile_prefix_len);
965 	depfile_path[depfile_prefix_len] = 0;
966 
967 	conf_read_simple(name, S_DEF_AUTO);
968 	sym_calc_value(modules_sym);
969 
970 	for_all_symbols(sym) {
971 		sym_calc_value(sym);
972 		if (sym_is_choice(sym))
973 			continue;
974 		if (sym->flags & SYMBOL_WRITE) {
975 			if (sym->flags & SYMBOL_DEF_AUTO) {
976 				/*
977 				 * symbol has old and new value,
978 				 * so compare them...
979 				 */
980 				switch (sym->type) {
981 				case S_BOOLEAN:
982 				case S_TRISTATE:
983 					if (sym_get_tristate_value(sym) ==
984 					    sym->def[S_DEF_AUTO].tri)
985 						continue;
986 					break;
987 				case S_STRING:
988 				case S_HEX:
989 				case S_INT:
990 					if (!strcmp(sym_get_string_value(sym),
991 						    sym->def[S_DEF_AUTO].val))
992 						continue;
993 					break;
994 				default:
995 					break;
996 				}
997 			} else {
998 				/*
999 				 * If there is no old value, only 'no' (unset)
1000 				 * is allowed as new value.
1001 				 */
1002 				switch (sym->type) {
1003 				case S_BOOLEAN:
1004 				case S_TRISTATE:
1005 					if (sym_get_tristate_value(sym) == no)
1006 						continue;
1007 					break;
1008 				default:
1009 					break;
1010 				}
1011 			}
1012 		} else if (!(sym->flags & SYMBOL_DEF_AUTO))
1013 			/* There is neither an old nor a new value. */
1014 			continue;
1015 		/* else
1016 		 *	There is an old value, but no new value ('no' (unset)
1017 		 *	isn't saved in auto.conf, so the old value is always
1018 		 *	different from 'no').
1019 		 */
1020 
1021 		res = conf_touch_dep(sym->name);
1022 		if (res)
1023 			return res;
1024 	}
1025 
1026 	return 0;
1027 }
1028 
1029 static int __conf_write_autoconf(const char *filename,
1030 				 void (*print_symbol)(FILE *, struct symbol *),
1031 				 const struct comment_style *comment_style)
1032 {
1033 	char tmp[PATH_MAX];
1034 	FILE *file;
1035 	struct symbol *sym;
1036 	int ret;
1037 
1038 	if (make_parent_dir(filename))
1039 		return -1;
1040 
1041 	ret = snprintf(tmp, sizeof(tmp), "%s.tmp", filename);
1042 	if (ret >= sizeof(tmp)) /* check truncation */
1043 		return -1;
1044 
1045 	file = fopen(tmp, "w");
1046 	if (!file) {
1047 		perror("fopen");
1048 		return -1;
1049 	}
1050 
1051 	conf_write_heading(file, comment_style);
1052 
1053 	for_all_symbols(sym)
1054 		if ((sym->flags & SYMBOL_WRITE) && sym->name)
1055 			print_symbol(file, sym);
1056 
1057 	fflush(file);
1058 	/* check possible errors in conf_write_heading() and print_symbol() */
1059 	ret = ferror(file);
1060 	fclose(file);
1061 	if (ret)
1062 		return -1;
1063 
1064 	if (rename(tmp, filename)) {
1065 		perror("rename");
1066 		return -1;
1067 	}
1068 
1069 	return 0;
1070 }
1071 
1072 int conf_write_autoconf(int overwrite)
1073 {
1074 	struct symbol *sym;
1075 	const char *autoconf_name = conf_get_autoconfig_name();
1076 	int ret;
1077 
1078 	if (!overwrite && is_present(autoconf_name))
1079 		return 0;
1080 
1081 	ret = conf_write_autoconf_cmd(autoconf_name);
1082 	if (ret)
1083 		return -1;
1084 
1085 	if (conf_touch_deps())
1086 		return 1;
1087 
1088 	for_all_symbols(sym)
1089 		sym_calc_value(sym);
1090 
1091 	ret = __conf_write_autoconf(conf_get_autoheader_name(),
1092 				    print_symbol_for_c,
1093 				    &comment_style_c);
1094 	if (ret)
1095 		return ret;
1096 
1097 	ret = __conf_write_autoconf(conf_get_rustccfg_name(),
1098 				    print_symbol_for_rustccfg,
1099 				    NULL);
1100 	if (ret)
1101 		return ret;
1102 
1103 	/*
1104 	 * Create include/config/auto.conf. This must be the last step because
1105 	 * Kbuild has a dependency on auto.conf and this marks the successful
1106 	 * completion of the previous steps.
1107 	 */
1108 	ret = __conf_write_autoconf(conf_get_autoconfig_name(),
1109 				    print_symbol_for_autoconf,
1110 				    &comment_style_pound);
1111 	if (ret)
1112 		return ret;
1113 
1114 	return 0;
1115 }
1116 
1117 static bool conf_changed;
1118 static void (*conf_changed_callback)(bool);
1119 
1120 void conf_set_changed(bool val)
1121 {
1122 	if (conf_changed_callback && conf_changed != val)
1123 		conf_changed_callback(val);
1124 
1125 	conf_changed = val;
1126 }
1127 
1128 bool conf_get_changed(void)
1129 {
1130 	return conf_changed;
1131 }
1132 
1133 void conf_set_changed_callback(void (*fn)(bool))
1134 {
1135 	conf_changed_callback = fn;
1136 }
1137