projects/linux·blob v6.7 · refs

1051 lines · 24.6 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Helpers for formatting and printing strings
4 *
5 * Copyright 31 August 2008 James Bottomley
6 * Copyright (C) 2013, Intel Corporation
7 */
8#include <linux/bug.h>
9#include <linux/kernel.h>
10#include <linux/math64.h>
11#include <linux/export.h>
12#include <linux/ctype.h>
13#include <linux/device.h>
14#include <linux/errno.h>
15#include <linux/fs.h>
16#include <linux/limits.h>
17#include <linux/mm.h>
18#include <linux/slab.h>
19#include <linux/string.h>
20#include <linux/string_helpers.h>
21
22/**
23 * string_get_size - get the size in the specified units
24 * @size: The size to be converted in blocks
25 * @blk_size: Size of the block (use 1 for size in bytes)
26 * @units: units to use (powers of 1000 or 1024)
27 * @buf: buffer to format to
28 * @len: length of buffer
29 *
30 * This function returns a string formatted to 3 significant figures
31 * giving the size in the required units. @buf should have room for
32 * at least 9 bytes and will always be zero terminated.
33 *
34 * Return value: number of characters of output that would have been written
35 * (which may be greater than len, if output was truncated).
36 */
37int string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
38 char *buf, int len)
39{
40 static const char *const units_10[] = {
41 "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"
42 };
43 static const char *const units_2[] = {
44 "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"
45 };
46 static const char *const *const units_str[] = {
47 [STRING_UNITS_10] = units_10,
48 [STRING_UNITS_2] = units_2,
49 };
50 static const unsigned int divisor[] = {
51 [STRING_UNITS_10] = 1000,
52 [STRING_UNITS_2] = 1024,
53 };
54 static const unsigned int rounding[] = { 500, 50, 5 };
55 int i = 0, j;
56 u32 remainder = 0, sf_cap;
57 char tmp[8];
58 const char *unit;
59
60 tmp[0] = '\0';
61
62 if (blk_size == 0)
63 size = 0;
64 if (size == 0)
65 goto out;
66
67 /* This is Napier's algorithm. Reduce the original block size to
68 *
69 * coefficient * divisor[units]^i
70 *
71 * we do the reduction so both coefficients are just under 32 bits so
72 * that multiplying them together won't overflow 64 bits and we keep
73 * as much precision as possible in the numbers.
74 *
75 * Note: it's safe to throw away the remainders here because all the
76 * precision is in the coefficients.
77 */
78 while (blk_size >> 32) {
79 do_div(blk_size, divisor[units]);
80 i++;
81 }
82
83 while (size >> 32) {
84 do_div(size, divisor[units]);
85 i++;
86 }
87
88 /* now perform the actual multiplication keeping i as the sum of the
89 * two logarithms */
90 size *= blk_size;
91
92 /* and logarithmically reduce it until it's just under the divisor */
93 while (size >= divisor[units]) {
94 remainder = do_div(size, divisor[units]);
95 i++;
96 }
97
98 /* work out in j how many digits of precision we need from the
99 * remainder */
100 sf_cap = size;
101 for (j = 0; sf_cap*10 < 1000; j++)
102 sf_cap *= 10;
103
104 if (units == STRING_UNITS_2) {
105 /* express the remainder as a decimal. It's currently the
106 * numerator of a fraction whose denominator is
107 * divisor[units], which is 1 << 10 for STRING_UNITS_2 */
108 remainder *= 1000;
109 remainder >>= 10;
110 }
111
112 /* add a 5 to the digit below what will be printed to ensure
113 * an arithmetical round up and carry it through to size */
114 remainder += rounding[j];
115 if (remainder >= 1000) {
116 remainder -= 1000;
117 size += 1;
118 }
119
120 if (j) {
121 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
122 tmp[j+1] = '\0';
123 }
124
125 out:
126 if (i >= ARRAY_SIZE(units_2))
127 unit = "UNK";
128 else
129 unit = units_str[units][i];
130
131 return snprintf(buf, len, "%u%s %s", (u32)size,
132 tmp, unit);
133}
134EXPORT_SYMBOL(string_get_size);
135
136/**
137 * parse_int_array_user - Split string into a sequence of integers
138 * @from: The user space buffer to read from
139 * @count: The maximum number of bytes to read
140 * @array: Returned pointer to sequence of integers
141 *
142 * On success @array is allocated and initialized with a sequence of
143 * integers extracted from the @from plus an additional element that
144 * begins the sequence and specifies the integers count.
145 *
146 * Caller takes responsibility for freeing @array when it is no longer
147 * needed.
148 */
149int parse_int_array_user(const char __user *from, size_t count, int **array)
150{
151 int *ints, nints;
152 char *buf;
153 int ret = 0;
154
155 buf = memdup_user_nul(from, count);
156 if (IS_ERR(buf))
157 return PTR_ERR(buf);
158
159 get_options(buf, 0, &nints);
160 if (!nints) {
161 ret = -ENOENT;
162 goto free_buf;
163 }
164
165 ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL);
166 if (!ints) {
167 ret = -ENOMEM;
168 goto free_buf;
169 }
170
171 get_options(buf, nints + 1, ints);
172 *array = ints;
173
174free_buf:
175 kfree(buf);
176 return ret;
177}
178EXPORT_SYMBOL(parse_int_array_user);
179
180static bool unescape_space(char **src, char **dst)
181{
182 char *p = *dst, *q = *src;
183
184 switch (*q) {
185 case 'n':
186 *p = '\n';
187 break;
188 case 'r':
189 *p = '\r';
190 break;
191 case 't':
192 *p = '\t';
193 break;
194 case 'v':
195 *p = '\v';
196 break;
197 case 'f':
198 *p = '\f';
199 break;
200 default:
201 return false;
202 }
203 *dst += 1;
204 *src += 1;
205 return true;
206}
207
208static bool unescape_octal(char **src, char **dst)
209{
210 char *p = *dst, *q = *src;
211 u8 num;
212
213 if (isodigit(*q) == 0)
214 return false;
215
216 num = (*q++) & 7;
217 while (num < 32 && isodigit(*q) && (q - *src < 3)) {
218 num <<= 3;
219 num += (*q++) & 7;
220 }
221 *p = num;
222 *dst += 1;
223 *src = q;
224 return true;
225}
226
227static bool unescape_hex(char **src, char **dst)
228{
229 char *p = *dst, *q = *src;
230 int digit;
231 u8 num;
232
233 if (*q++ != 'x')
234 return false;
235
236 num = digit = hex_to_bin(*q++);
237 if (digit < 0)
238 return false;
239
240 digit = hex_to_bin(*q);
241 if (digit >= 0) {
242 q++;
243 num = (num << 4) | digit;
244 }
245 *p = num;
246 *dst += 1;
247 *src = q;
248 return true;
249}
250
251static bool unescape_special(char **src, char **dst)
252{
253 char *p = *dst, *q = *src;
254
255 switch (*q) {
256 case '\"':
257 *p = '\"';
258 break;
259 case '\\':
260 *p = '\\';
261 break;
262 case 'a':
263 *p = '\a';
264 break;
265 case 'e':
266 *p = '\e';
267 break;
268 default:
269 return false;
270 }
271 *dst += 1;
272 *src += 1;
273 return true;
274}
275
276/**
277 * string_unescape - unquote characters in the given string
278 * @src: source buffer (escaped)
279 * @dst: destination buffer (unescaped)
280 * @size: size of the destination buffer (0 to unlimit)
281 * @flags: combination of the flags.
282 *
283 * Description:
284 * The function unquotes characters in the given string.
285 *
286 * Because the size of the output will be the same as or less than the size of
287 * the input, the transformation may be performed in place.
288 *
289 * Caller must provide valid source and destination pointers. Be aware that
290 * destination buffer will always be NULL-terminated. Source string must be
291 * NULL-terminated as well. The supported flags are::
292 *
293 * UNESCAPE_SPACE:
294 * '\f' - form feed
295 * '\n' - new line
296 * '\r' - carriage return
297 * '\t' - horizontal tab
298 * '\v' - vertical tab
299 * UNESCAPE_OCTAL:
300 * '\NNN' - byte with octal value NNN (1 to 3 digits)
301 * UNESCAPE_HEX:
302 * '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
303 * UNESCAPE_SPECIAL:
304 * '\"' - double quote
305 * '\\' - backslash
306 * '\a' - alert (BEL)
307 * '\e' - escape
308 * UNESCAPE_ANY:
309 * all previous together
310 *
311 * Return:
312 * The amount of the characters processed to the destination buffer excluding
313 * trailing '\0' is returned.
314 */
315int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
316{
317 char *out = dst;
318
319 while (*src && --size) {
320 if (src[0] == '\\' && src[1] != '\0' && size > 1) {
321 src++;
322 size--;
323
324 if (flags & UNESCAPE_SPACE &&
325 unescape_space(&src, &out))
326 continue;
327
328 if (flags & UNESCAPE_OCTAL &&
329 unescape_octal(&src, &out))
330 continue;
331
332 if (flags & UNESCAPE_HEX &&
333 unescape_hex(&src, &out))
334 continue;
335
336 if (flags & UNESCAPE_SPECIAL &&
337 unescape_special(&src, &out))
338 continue;
339
340 *out++ = '\\';
341 }
342 *out++ = *src++;
343 }
344 *out = '\0';
345
346 return out - dst;
347}
348EXPORT_SYMBOL(string_unescape);
349
350static bool escape_passthrough(unsigned char c, char **dst, char *end)
351{
352 char *out = *dst;
353
354 if (out < end)
355 *out = c;
356 *dst = out + 1;
357 return true;
358}
359
360static bool escape_space(unsigned char c, char **dst, char *end)
361{
362 char *out = *dst;
363 unsigned char to;
364
365 switch (c) {
366 case '\n':
367 to = 'n';
368 break;
369 case '\r':
370 to = 'r';
371 break;
372 case '\t':
373 to = 't';
374 break;
375 case '\v':
376 to = 'v';
377 break;
378 case '\f':
379 to = 'f';
380 break;
381 default:
382 return false;
383 }
384
385 if (out < end)
386 *out = '\\';
387 ++out;
388 if (out < end)
389 *out = to;
390 ++out;
391
392 *dst = out;
393 return true;
394}
395
396static bool escape_special(unsigned char c, char **dst, char *end)
397{
398 char *out = *dst;
399 unsigned char to;
400
401 switch (c) {
402 case '\\':
403 to = '\\';
404 break;
405 case '\a':
406 to = 'a';
407 break;
408 case '\e':
409 to = 'e';
410 break;
411 case '"':
412 to = '"';
413 break;
414 default:
415 return false;
416 }
417
418 if (out < end)
419 *out = '\\';
420 ++out;
421 if (out < end)
422 *out = to;
423 ++out;
424
425 *dst = out;
426 return true;
427}
428
429static bool escape_null(unsigned char c, char **dst, char *end)
430{
431 char *out = *dst;
432
433 if (c)
434 return false;
435
436 if (out < end)
437 *out = '\\';
438 ++out;
439 if (out < end)
440 *out = '0';
441 ++out;
442
443 *dst = out;
444 return true;
445}
446
447static bool escape_octal(unsigned char c, char **dst, char *end)
448{
449 char *out = *dst;
450
451 if (out < end)
452 *out = '\\';
453 ++out;
454 if (out < end)
455 *out = ((c >> 6) & 0x07) + '0';
456 ++out;
457 if (out < end)
458 *out = ((c >> 3) & 0x07) + '0';
459 ++out;
460 if (out < end)
461 *out = ((c >> 0) & 0x07) + '0';
462 ++out;
463
464 *dst = out;
465 return true;
466}
467
468static bool escape_hex(unsigned char c, char **dst, char *end)
469{
470 char *out = *dst;
471
472 if (out < end)
473 *out = '\\';
474 ++out;
475 if (out < end)
476 *out = 'x';
477 ++out;
478 if (out < end)
479 *out = hex_asc_hi(c);
480 ++out;
481 if (out < end)
482 *out = hex_asc_lo(c);
483 ++out;
484
485 *dst = out;
486 return true;
487}
488
489/**
490 * string_escape_mem - quote characters in the given memory buffer
491 * @src: source buffer (unescaped)
492 * @isz: source buffer size
493 * @dst: destination buffer (escaped)
494 * @osz: destination buffer size
495 * @flags: combination of the flags
496 * @only: NULL-terminated string containing characters used to limit
497 * the selected escape class. If characters are included in @only
498 * that would not normally be escaped by the classes selected
499 * in @flags, they will be copied to @dst unescaped.
500 *
501 * Description:
502 * The process of escaping byte buffer includes several parts. They are applied
503 * in the following sequence.
504 *
505 * 1. The character is not matched to the one from @only string and thus
506 * must go as-is to the output.
507 * 2. The character is matched to the printable and ASCII classes, if asked,
508 * and in case of match it passes through to the output.
509 * 3. The character is matched to the printable or ASCII class, if asked,
510 * and in case of match it passes through to the output.
511 * 4. The character is checked if it falls into the class given by @flags.
512 * %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
513 * character. Note that they actually can't go together, otherwise
514 * %ESCAPE_HEX will be ignored.
515 *
516 * Caller must provide valid source and destination pointers. Be aware that
517 * destination buffer will not be NULL-terminated, thus caller have to append
518 * it if needs. The supported flags are::
519 *
520 * %ESCAPE_SPACE: (special white space, not space itself)
521 * '\f' - form feed
522 * '\n' - new line
523 * '\r' - carriage return
524 * '\t' - horizontal tab
525 * '\v' - vertical tab
526 * %ESCAPE_SPECIAL:
527 * '\"' - double quote
528 * '\\' - backslash
529 * '\a' - alert (BEL)
530 * '\e' - escape
531 * %ESCAPE_NULL:
532 * '\0' - null
533 * %ESCAPE_OCTAL:
534 * '\NNN' - byte with octal value NNN (3 digits)
535 * %ESCAPE_ANY:
536 * all previous together
537 * %ESCAPE_NP:
538 * escape only non-printable characters, checked by isprint()
539 * %ESCAPE_ANY_NP:
540 * all previous together
541 * %ESCAPE_HEX:
542 * '\xHH' - byte with hexadecimal value HH (2 digits)
543 * %ESCAPE_NA:
544 * escape only non-ascii characters, checked by isascii()
545 * %ESCAPE_NAP:
546 * escape only non-printable or non-ascii characters
547 * %ESCAPE_APPEND:
548 * append characters from @only to be escaped by the given classes
549 *
550 * %ESCAPE_APPEND would help to pass additional characters to the escaped, when
551 * one of %ESCAPE_NP, %ESCAPE_NA, or %ESCAPE_NAP is provided.
552 *
553 * One notable caveat, the %ESCAPE_NAP, %ESCAPE_NP and %ESCAPE_NA have the
554 * higher priority than the rest of the flags (%ESCAPE_NAP is the highest).
555 * It doesn't make much sense to use either of them without %ESCAPE_OCTAL
556 * or %ESCAPE_HEX, because they cover most of the other character classes.
557 * %ESCAPE_NAP can utilize %ESCAPE_SPACE or %ESCAPE_SPECIAL in addition to
558 * the above.
559 *
560 * Return:
561 * The total size of the escaped output that would be generated for
562 * the given input and flags. To check whether the output was
563 * truncated, compare the return value to osz. There is room left in
564 * dst for a '\0' terminator if and only if ret < osz.
565 */
566int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
567 unsigned int flags, const char *only)
568{
569 char *p = dst;
570 char *end = p + osz;
571 bool is_dict = only && *only;
572 bool is_append = flags & ESCAPE_APPEND;
573
574 while (isz--) {
575 unsigned char c = *src++;
576 bool in_dict = is_dict && strchr(only, c);
577
578 /*
579 * Apply rules in the following sequence:
580 * - the @only string is supplied and does not contain a
581 * character under question
582 * - the character is printable and ASCII, when @flags has
583 * %ESCAPE_NAP bit set
584 * - the character is printable, when @flags has
585 * %ESCAPE_NP bit set
586 * - the character is ASCII, when @flags has
587 * %ESCAPE_NA bit set
588 * - the character doesn't fall into a class of symbols
589 * defined by given @flags
590 * In these cases we just pass through a character to the
591 * output buffer.
592 *
593 * When %ESCAPE_APPEND is passed, the characters from @only
594 * have been excluded from the %ESCAPE_NAP, %ESCAPE_NP, and
595 * %ESCAPE_NA cases.
596 */
597 if (!(is_append || in_dict) && is_dict &&
598 escape_passthrough(c, &p, end))
599 continue;
600
601 if (!(is_append && in_dict) && isascii(c) && isprint(c) &&
602 flags & ESCAPE_NAP && escape_passthrough(c, &p, end))
603 continue;
604
605 if (!(is_append && in_dict) && isprint(c) &&
606 flags & ESCAPE_NP && escape_passthrough(c, &p, end))
607 continue;
608
609 if (!(is_append && in_dict) && isascii(c) &&
610 flags & ESCAPE_NA && escape_passthrough(c, &p, end))
611 continue;
612
613 if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
614 continue;
615
616 if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
617 continue;
618
619 if (flags & ESCAPE_NULL && escape_null(c, &p, end))
620 continue;
621
622 /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
623 if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
624 continue;
625
626 if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
627 continue;
628
629 escape_passthrough(c, &p, end);
630 }
631
632 return p - dst;
633}
634EXPORT_SYMBOL(string_escape_mem);
635
636/*
637 * Return an allocated string that has been escaped of special characters
638 * and double quotes, making it safe to log in quotes.
639 */
640char *kstrdup_quotable(const char *src, gfp_t gfp)
641{
642 size_t slen, dlen;
643 char *dst;
644 const int flags = ESCAPE_HEX;
645 const char esc[] = "\f\n\r\t\v\a\e\\\"";
646
647 if (!src)
648 return NULL;
649 slen = strlen(src);
650
651 dlen = string_escape_mem(src, slen, NULL, 0, flags, esc);
652 dst = kmalloc(dlen + 1, gfp);
653 if (!dst)
654 return NULL;
655
656 WARN_ON(string_escape_mem(src, slen, dst, dlen, flags, esc) != dlen);
657 dst[dlen] = '\0';
658
659 return dst;
660}
661EXPORT_SYMBOL_GPL(kstrdup_quotable);
662
663/*
664 * Returns allocated NULL-terminated string containing process
665 * command line, with inter-argument NULLs replaced with spaces,
666 * and other special characters escaped.
667 */
668char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
669{
670 char *buffer, *quoted;
671 int i, res;
672
673 buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
674 if (!buffer)
675 return NULL;
676
677 res = get_cmdline(task, buffer, PAGE_SIZE - 1);
678 buffer[res] = '\0';
679
680 /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
681 while (--res >= 0 && buffer[res] == '\0')
682 ;
683
684 /* Replace inter-argument NULLs. */
685 for (i = 0; i <= res; i++)
686 if (buffer[i] == '\0')
687 buffer[i] = ' ';
688
689 /* Make sure result is printable. */
690 quoted = kstrdup_quotable(buffer, gfp);
691 kfree(buffer);
692 return quoted;
693}
694EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
695
696/*
697 * Returns allocated NULL-terminated string containing pathname,
698 * with special characters escaped, able to be safely logged. If
699 * there is an error, the leading character will be "<".
700 */
701char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
702{
703 char *temp, *pathname;
704
705 if (!file)
706 return kstrdup("<unknown>", gfp);
707
708 /* We add 11 spaces for ' (deleted)' to be appended */
709 temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
710 if (!temp)
711 return kstrdup("<no_memory>", gfp);
712
713 pathname = file_path(file, temp, PATH_MAX + 11);
714 if (IS_ERR(pathname))
715 pathname = kstrdup("<too_long>", gfp);
716 else
717 pathname = kstrdup_quotable(pathname, gfp);
718
719 kfree(temp);
720 return pathname;
721}
722EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
723
724/*
725 * Returns duplicate string in which the @old characters are replaced by @new.
726 */
727char *kstrdup_and_replace(const char *src, char old, char new, gfp_t gfp)
728{
729 char *dst;
730
731 dst = kstrdup(src, gfp);
732 if (!dst)
733 return NULL;
734
735 return strreplace(dst, old, new);
736}
737EXPORT_SYMBOL_GPL(kstrdup_and_replace);
738
739/**
740 * kasprintf_strarray - allocate and fill array of sequential strings
741 * @gfp: flags for the slab allocator
742 * @prefix: prefix to be used
743 * @n: amount of lines to be allocated and filled
744 *
745 * Allocates and fills @n strings using pattern "%s-%zu", where prefix
746 * is provided by caller. The caller is responsible to free them with
747 * kfree_strarray() after use.
748 *
749 * Returns array of strings or NULL when memory can't be allocated.
750 */
751char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n)
752{
753 char **names;
754 size_t i;
755
756 names = kcalloc(n + 1, sizeof(char *), gfp);
757 if (!names)
758 return NULL;
759
760 for (i = 0; i < n; i++) {
761 names[i] = kasprintf(gfp, "%s-%zu", prefix, i);
762 if (!names[i]) {
763 kfree_strarray(names, i);
764 return NULL;
765 }
766 }
767
768 return names;
769}
770EXPORT_SYMBOL_GPL(kasprintf_strarray);
771
772/**
773 * kfree_strarray - free a number of dynamically allocated strings contained
774 * in an array and the array itself
775 *
776 * @array: Dynamically allocated array of strings to free.
777 * @n: Number of strings (starting from the beginning of the array) to free.
778 *
779 * Passing a non-NULL @array and @n == 0 as well as NULL @array are valid
780 * use-cases. If @array is NULL, the function does nothing.
781 */
782void kfree_strarray(char **array, size_t n)
783{
784 unsigned int i;
785
786 if (!array)
787 return;
788
789 for (i = 0; i < n; i++)
790 kfree(array[i]);
791 kfree(array);
792}
793EXPORT_SYMBOL_GPL(kfree_strarray);
794
795struct strarray {
796 char **array;
797 size_t n;
798};
799
800static void devm_kfree_strarray(struct device *dev, void *res)
801{
802 struct strarray *array = res;
803
804 kfree_strarray(array->array, array->n);
805}
806
807char **devm_kasprintf_strarray(struct device *dev, const char *prefix, size_t n)
808{
809 struct strarray *ptr;
810
811 ptr = devres_alloc(devm_kfree_strarray, sizeof(*ptr), GFP_KERNEL);
812 if (!ptr)
813 return ERR_PTR(-ENOMEM);
814
815 ptr->array = kasprintf_strarray(GFP_KERNEL, prefix, n);
816 if (!ptr->array) {
817 devres_free(ptr);
818 return ERR_PTR(-ENOMEM);
819 }
820
821 ptr->n = n;
822 devres_add(dev, ptr);
823
824 return ptr->array;
825}
826EXPORT_SYMBOL_GPL(devm_kasprintf_strarray);
827
828/**
829 * strscpy_pad() - Copy a C-string into a sized buffer
830 * @dest: Where to copy the string to
831 * @src: Where to copy the string from
832 * @count: Size of destination buffer
833 *
834 * Copy the string, or as much of it as fits, into the dest buffer. The
835 * behavior is undefined if the string buffers overlap. The destination
836 * buffer is always %NUL terminated, unless it's zero-sized.
837 *
838 * If the source string is shorter than the destination buffer, zeros
839 * the tail of the destination buffer.
840 *
841 * For full explanation of why you may want to consider using the
842 * 'strscpy' functions please see the function docstring for strscpy().
843 *
844 * Returns:
845 * * The number of characters copied (not including the trailing %NUL)
846 * * -E2BIG if count is 0 or @src was truncated.
847 */
848ssize_t strscpy_pad(char *dest, const char *src, size_t count)
849{
850 ssize_t written;
851
852 written = strscpy(dest, src, count);
853 if (written < 0 || written == count - 1)
854 return written;
855
856 memset(dest + written + 1, 0, count - written - 1);
857
858 return written;
859}
860EXPORT_SYMBOL(strscpy_pad);
861
862/**
863 * skip_spaces - Removes leading whitespace from @str.
864 * @str: The string to be stripped.
865 *
866 * Returns a pointer to the first non-whitespace character in @str.
867 */
868char *skip_spaces(const char *str)
869{
870 while (isspace(*str))
871 ++str;
872 return (char *)str;
873}
874EXPORT_SYMBOL(skip_spaces);
875
876/**
877 * strim - Removes leading and trailing whitespace from @s.
878 * @s: The string to be stripped.
879 *
880 * Note that the first trailing whitespace is replaced with a %NUL-terminator
881 * in the given string @s. Returns a pointer to the first non-whitespace
882 * character in @s.
883 */
884char *strim(char *s)
885{
886 size_t size;
887 char *end;
888
889 size = strlen(s);
890 if (!size)
891 return s;
892
893 end = s + size - 1;
894 while (end >= s && isspace(*end))
895 end--;
896 *(end + 1) = '\0';
897
898 return skip_spaces(s);
899}
900EXPORT_SYMBOL(strim);
901
902/**
903 * sysfs_streq - return true if strings are equal, modulo trailing newline
904 * @s1: one string
905 * @s2: another string
906 *
907 * This routine returns true iff two strings are equal, treating both
908 * NUL and newline-then-NUL as equivalent string terminations. It's
909 * geared for use with sysfs input strings, which generally terminate
910 * with newlines but are compared against values without newlines.
911 */
912bool sysfs_streq(const char *s1, const char *s2)
913{
914 while (*s1 && *s1 == *s2) {
915 s1++;
916 s2++;
917 }
918
919 if (*s1 == *s2)
920 return true;
921 if (!*s1 && *s2 == '\n' && !s2[1])
922 return true;
923 if (*s1 == '\n' && !s1[1] && !*s2)
924 return true;
925 return false;
926}
927EXPORT_SYMBOL(sysfs_streq);
928
929/**
930 * match_string - matches given string in an array
931 * @array: array of strings
932 * @n: number of strings in the array or -1 for NULL terminated arrays
933 * @string: string to match with
934 *
935 * This routine will look for a string in an array of strings up to the
936 * n-th element in the array or until the first NULL element.
937 *
938 * Historically the value of -1 for @n, was used to search in arrays that
939 * are NULL terminated. However, the function does not make a distinction
940 * when finishing the search: either @n elements have been compared OR
941 * the first NULL element was found.
942 *
943 * Return:
944 * index of a @string in the @array if matches, or %-EINVAL otherwise.
945 */
946int match_string(const char * const *array, size_t n, const char *string)
947{
948 int index;
949 const char *item;
950
951 for (index = 0; index < n; index++) {
952 item = array[index];
953 if (!item)
954 break;
955 if (!strcmp(item, string))
956 return index;
957 }
958
959 return -EINVAL;
960}
961EXPORT_SYMBOL(match_string);
962
963/**
964 * __sysfs_match_string - matches given string in an array
965 * @array: array of strings
966 * @n: number of strings in the array or -1 for NULL terminated arrays
967 * @str: string to match with
968 *
969 * Returns index of @str in the @array or -EINVAL, just like match_string().
970 * Uses sysfs_streq instead of strcmp for matching.
971 *
972 * This routine will look for a string in an array of strings up to the
973 * n-th element in the array or until the first NULL element.
974 *
975 * Historically the value of -1 for @n, was used to search in arrays that
976 * are NULL terminated. However, the function does not make a distinction
977 * when finishing the search: either @n elements have been compared OR
978 * the first NULL element was found.
979 */
980int __sysfs_match_string(const char * const *array, size_t n, const char *str)
981{
982 const char *item;
983 int index;
984
985 for (index = 0; index < n; index++) {
986 item = array[index];
987 if (!item)
988 break;
989 if (sysfs_streq(item, str))
990 return index;
991 }
992
993 return -EINVAL;
994}
995EXPORT_SYMBOL(__sysfs_match_string);
996
997/**
998 * strreplace - Replace all occurrences of character in string.
999 * @str: The string to operate on.
1000 * @old: The character being replaced.
1001 * @new: The character @old is replaced with.
1002 *
1003 * Replaces the each @old character with a @new one in the given string @str.
1004 *
1005 * Return: pointer to the string @str itself.
1006 */
1007char *strreplace(char *str, char old, char new)
1008{
1009 char *s = str;
1010
1011 for (; *s; ++s)
1012 if (*s == old)
1013 *s = new;
1014 return str;
1015}
1016EXPORT_SYMBOL(strreplace);
1017
1018/**
1019 * memcpy_and_pad - Copy one buffer to another with padding
1020 * @dest: Where to copy to
1021 * @dest_len: The destination buffer size
1022 * @src: Where to copy from
1023 * @count: The number of bytes to copy
1024 * @pad: Character to use for padding if space is left in destination.
1025 */
1026void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
1027 int pad)
1028{
1029 if (dest_len > count) {
1030 memcpy(dest, src, count);
1031 memset(dest + count, pad, dest_len - count);
1032 } else {
1033 memcpy(dest, src, dest_len);
1034 }
1035}
1036EXPORT_SYMBOL(memcpy_and_pad);
1037
1038#ifdef CONFIG_FORTIFY_SOURCE
1039/* These are placeholders for fortify compile-time warnings. */
1040void __read_overflow2_field(size_t avail, size_t wanted) { }
1041EXPORT_SYMBOL(__read_overflow2_field);
1042void __write_overflow_field(size_t avail, size_t wanted) { }
1043EXPORT_SYMBOL(__write_overflow_field);
1044
1045void fortify_panic(const char *name)
1046{
1047 pr_emerg("detected buffer overflow in %s\n", name);
1048 BUG();
1049}
1050EXPORT_SYMBOL(fortify_panic);
1051#endif /* CONFIG_FORTIFY_SOURCE */