Line data Source code
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/errno.h>
14 : #include <linux/fs.h>
15 : #include <linux/limits.h>
16 : #include <linux/mm.h>
17 : #include <linux/slab.h>
18 : #include <linux/string.h>
19 : #include <linux/string_helpers.h>
20 :
21 : /**
22 : * string_get_size - get the size in the specified units
23 : * @size: The size to be converted in blocks
24 : * @blk_size: Size of the block (use 1 for size in bytes)
25 : * @units: units to use (powers of 1000 or 1024)
26 : * @buf: buffer to format to
27 : * @len: length of buffer
28 : *
29 : * This function returns a string formatted to 3 significant figures
30 : * giving the size in the required units. @buf should have room for
31 : * at least 9 bytes and will always be zero terminated.
32 : *
33 : */
34 2 : void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
35 : char *buf, int len)
36 : {
37 2 : static const char *const units_10[] = {
38 : "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"
39 : };
40 2 : static const char *const units_2[] = {
41 : "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"
42 : };
43 2 : static const char *const *const units_str[] = {
44 : [STRING_UNITS_10] = units_10,
45 : [STRING_UNITS_2] = units_2,
46 : };
47 2 : static const unsigned int divisor[] = {
48 : [STRING_UNITS_10] = 1000,
49 : [STRING_UNITS_2] = 1024,
50 : };
51 2 : static const unsigned int rounding[] = { 500, 50, 5 };
52 2 : int i = 0, j;
53 2 : u32 remainder = 0, sf_cap;
54 2 : char tmp[8];
55 2 : const char *unit;
56 :
57 2 : tmp[0] = '\0';
58 :
59 2 : if (blk_size == 0)
60 : size = 0;
61 2 : if (size == 0)
62 0 : goto out;
63 :
64 : /* This is Napier's algorithm. Reduce the original block size to
65 : *
66 : * coefficient * divisor[units]^i
67 : *
68 : * we do the reduction so both coefficients are just under 32 bits so
69 : * that multiplying them together won't overflow 64 bits and we keep
70 : * as much precision as possible in the numbers.
71 : *
72 : * Note: it's safe to throw away the remainders here because all the
73 : * precision is in the coefficients.
74 : */
75 2 : while (blk_size >> 32) {
76 0 : do_div(blk_size, divisor[units]);
77 0 : i++;
78 : }
79 :
80 2 : while (size >> 32) {
81 0 : do_div(size, divisor[units]);
82 0 : i++;
83 : }
84 :
85 : /* now perform the actual multiplication keeping i as the sum of the
86 : * two logarithms */
87 2 : size *= blk_size;
88 :
89 : /* and logarithmically reduce it until it's just under the divisor */
90 8 : while (size >= divisor[units]) {
91 6 : remainder = do_div(size, divisor[units]);
92 6 : i++;
93 : }
94 :
95 : /* work out in j how many digits of precision we need from the
96 : * remainder */
97 2 : sf_cap = size;
98 6 : for (j = 0; sf_cap*10 < 1000; j++)
99 4 : sf_cap *= 10;
100 :
101 2 : if (units == STRING_UNITS_2) {
102 : /* express the remainder as a decimal. It's currently the
103 : * numerator of a fraction whose denominator is
104 : * divisor[units], which is 1 << 10 for STRING_UNITS_2 */
105 1 : remainder *= 1000;
106 1 : remainder >>= 10;
107 : }
108 :
109 : /* add a 5 to the digit below what will be printed to ensure
110 : * an arithmetical round up and carry it through to size */
111 2 : remainder += rounding[j];
112 2 : if (remainder >= 1000) {
113 0 : remainder -= 1000;
114 0 : size += 1;
115 : }
116 :
117 2 : if (j) {
118 2 : snprintf(tmp, sizeof(tmp), ".%03u", remainder);
119 2 : tmp[j+1] = '\0';
120 : }
121 :
122 0 : out:
123 2 : if (i >= ARRAY_SIZE(units_2))
124 : unit = "UNK";
125 : else
126 2 : unit = units_str[units][i];
127 :
128 2 : snprintf(buf, len, "%u%s %s", (u32)size,
129 : tmp, unit);
130 2 : }
131 : EXPORT_SYMBOL(string_get_size);
132 :
133 0 : static bool unescape_space(char **src, char **dst)
134 : {
135 0 : char *p = *dst, *q = *src;
136 :
137 0 : switch (*q) {
138 0 : case 'n':
139 0 : *p = '\n';
140 0 : break;
141 0 : case 'r':
142 0 : *p = '\r';
143 0 : break;
144 0 : case 't':
145 0 : *p = '\t';
146 0 : break;
147 0 : case 'v':
148 0 : *p = '\v';
149 0 : break;
150 0 : case 'f':
151 0 : *p = '\f';
152 0 : break;
153 : default:
154 : return false;
155 : }
156 0 : *dst += 1;
157 0 : *src += 1;
158 0 : return true;
159 : }
160 :
161 0 : static bool unescape_octal(char **src, char **dst)
162 : {
163 0 : char *p = *dst, *q = *src;
164 0 : u8 num;
165 :
166 0 : if (isodigit(*q) == 0)
167 : return false;
168 :
169 0 : num = (*q++) & 7;
170 0 : while (num < 32 && isodigit(*q) && (q - *src < 3)) {
171 0 : num <<= 3;
172 0 : num += (*q++) & 7;
173 : }
174 0 : *p = num;
175 0 : *dst += 1;
176 0 : *src = q;
177 0 : return true;
178 : }
179 :
180 0 : static bool unescape_hex(char **src, char **dst)
181 : {
182 0 : char *p = *dst, *q = *src;
183 0 : int digit;
184 0 : u8 num;
185 :
186 0 : if (*q++ != 'x')
187 : return false;
188 :
189 0 : num = digit = hex_to_bin(*q++);
190 0 : if (digit < 0)
191 : return false;
192 :
193 0 : digit = hex_to_bin(*q);
194 0 : if (digit >= 0) {
195 0 : q++;
196 0 : num = (num << 4) | digit;
197 : }
198 0 : *p = num;
199 0 : *dst += 1;
200 0 : *src = q;
201 0 : return true;
202 : }
203 :
204 0 : static bool unescape_special(char **src, char **dst)
205 : {
206 0 : char *p = *dst, *q = *src;
207 :
208 0 : switch (*q) {
209 0 : case '\"':
210 0 : *p = '\"';
211 0 : break;
212 0 : case '\\':
213 0 : *p = '\\';
214 0 : break;
215 0 : case 'a':
216 0 : *p = '\a';
217 0 : break;
218 0 : case 'e':
219 0 : *p = '\e';
220 0 : break;
221 : default:
222 : return false;
223 : }
224 0 : *dst += 1;
225 0 : *src += 1;
226 0 : return true;
227 : }
228 :
229 : /**
230 : * string_unescape - unquote characters in the given string
231 : * @src: source buffer (escaped)
232 : * @dst: destination buffer (unescaped)
233 : * @size: size of the destination buffer (0 to unlimit)
234 : * @flags: combination of the flags.
235 : *
236 : * Description:
237 : * The function unquotes characters in the given string.
238 : *
239 : * Because the size of the output will be the same as or less than the size of
240 : * the input, the transformation may be performed in place.
241 : *
242 : * Caller must provide valid source and destination pointers. Be aware that
243 : * destination buffer will always be NULL-terminated. Source string must be
244 : * NULL-terminated as well. The supported flags are::
245 : *
246 : * UNESCAPE_SPACE:
247 : * '\f' - form feed
248 : * '\n' - new line
249 : * '\r' - carriage return
250 : * '\t' - horizontal tab
251 : * '\v' - vertical tab
252 : * UNESCAPE_OCTAL:
253 : * '\NNN' - byte with octal value NNN (1 to 3 digits)
254 : * UNESCAPE_HEX:
255 : * '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
256 : * UNESCAPE_SPECIAL:
257 : * '\"' - double quote
258 : * '\\' - backslash
259 : * '\a' - alert (BEL)
260 : * '\e' - escape
261 : * UNESCAPE_ANY:
262 : * all previous together
263 : *
264 : * Return:
265 : * The amount of the characters processed to the destination buffer excluding
266 : * trailing '\0' is returned.
267 : */
268 0 : int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
269 : {
270 0 : char *out = dst;
271 :
272 0 : while (*src && --size) {
273 0 : if (src[0] == '\\' && src[1] != '\0' && size > 1) {
274 0 : src++;
275 0 : size--;
276 :
277 0 : if (flags & UNESCAPE_SPACE &&
278 0 : unescape_space(&src, &out))
279 0 : continue;
280 :
281 0 : if (flags & UNESCAPE_OCTAL &&
282 0 : unescape_octal(&src, &out))
283 0 : continue;
284 :
285 0 : if (flags & UNESCAPE_HEX &&
286 0 : unescape_hex(&src, &out))
287 0 : continue;
288 :
289 0 : if (flags & UNESCAPE_SPECIAL &&
290 0 : unescape_special(&src, &out))
291 0 : continue;
292 :
293 0 : *out++ = '\\';
294 : }
295 0 : *out++ = *src++;
296 : }
297 0 : *out = '\0';
298 :
299 0 : return out - dst;
300 : }
301 : EXPORT_SYMBOL(string_unescape);
302 :
303 58455 : static bool escape_passthrough(unsigned char c, char **dst, char *end)
304 : {
305 58455 : char *out = *dst;
306 :
307 58455 : if (out < end)
308 58454 : *out = c;
309 58455 : *dst = out + 1;
310 58455 : return true;
311 : }
312 :
313 0 : static bool escape_space(unsigned char c, char **dst, char *end)
314 : {
315 0 : char *out = *dst;
316 0 : unsigned char to;
317 :
318 0 : switch (c) {
319 : case '\n':
320 : to = 'n';
321 : break;
322 : case '\r':
323 : to = 'r';
324 : break;
325 : case '\t':
326 : to = 't';
327 : break;
328 : case '\v':
329 : to = 'v';
330 : break;
331 : case '\f':
332 : to = 'f';
333 : break;
334 : default:
335 : return false;
336 : }
337 :
338 0 : if (out < end)
339 0 : *out = '\\';
340 0 : ++out;
341 0 : if (out < end)
342 0 : *out = to;
343 0 : ++out;
344 :
345 0 : *dst = out;
346 0 : return true;
347 : }
348 :
349 0 : static bool escape_special(unsigned char c, char **dst, char *end)
350 : {
351 0 : char *out = *dst;
352 0 : unsigned char to;
353 :
354 0 : switch (c) {
355 : case '\\':
356 : to = '\\';
357 : break;
358 0 : case '\a':
359 0 : to = 'a';
360 0 : break;
361 0 : case '\e':
362 0 : to = 'e';
363 0 : break;
364 : default:
365 : return false;
366 : }
367 :
368 0 : if (out < end)
369 0 : *out = '\\';
370 0 : ++out;
371 0 : if (out < end)
372 0 : *out = to;
373 0 : ++out;
374 :
375 0 : *dst = out;
376 0 : return true;
377 : }
378 :
379 0 : static bool escape_null(unsigned char c, char **dst, char *end)
380 : {
381 0 : char *out = *dst;
382 :
383 0 : if (c)
384 : return false;
385 :
386 0 : if (out < end)
387 0 : *out = '\\';
388 0 : ++out;
389 0 : if (out < end)
390 0 : *out = '0';
391 0 : ++out;
392 :
393 0 : *dst = out;
394 0 : return true;
395 : }
396 :
397 0 : static bool escape_octal(unsigned char c, char **dst, char *end)
398 : {
399 0 : char *out = *dst;
400 :
401 0 : if (out < end)
402 0 : *out = '\\';
403 0 : ++out;
404 0 : if (out < end)
405 0 : *out = ((c >> 6) & 0x07) + '0';
406 0 : ++out;
407 0 : if (out < end)
408 0 : *out = ((c >> 3) & 0x07) + '0';
409 0 : ++out;
410 0 : if (out < end)
411 0 : *out = ((c >> 0) & 0x07) + '0';
412 0 : ++out;
413 :
414 0 : *dst = out;
415 0 : return true;
416 : }
417 :
418 0 : static bool escape_hex(unsigned char c, char **dst, char *end)
419 : {
420 0 : char *out = *dst;
421 :
422 0 : if (out < end)
423 0 : *out = '\\';
424 0 : ++out;
425 0 : if (out < end)
426 0 : *out = 'x';
427 0 : ++out;
428 0 : if (out < end)
429 0 : *out = hex_asc_hi(c);
430 0 : ++out;
431 0 : if (out < end)
432 0 : *out = hex_asc_lo(c);
433 0 : ++out;
434 :
435 0 : *dst = out;
436 0 : return true;
437 : }
438 :
439 : /**
440 : * string_escape_mem - quote characters in the given memory buffer
441 : * @src: source buffer (unescaped)
442 : * @isz: source buffer size
443 : * @dst: destination buffer (escaped)
444 : * @osz: destination buffer size
445 : * @flags: combination of the flags
446 : * @only: NULL-terminated string containing characters used to limit
447 : * the selected escape class. If characters are included in @only
448 : * that would not normally be escaped by the classes selected
449 : * in @flags, they will be copied to @dst unescaped.
450 : *
451 : * Description:
452 : * The process of escaping byte buffer includes several parts. They are applied
453 : * in the following sequence.
454 : *
455 : * 1. The character is matched to the printable class, if asked, and in
456 : * case of match it passes through to the output.
457 : * 2. The character is not matched to the one from @only string and thus
458 : * must go as-is to the output.
459 : * 3. The character is checked if it falls into the class given by @flags.
460 : * %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
461 : * character. Note that they actually can't go together, otherwise
462 : * %ESCAPE_HEX will be ignored.
463 : *
464 : * Caller must provide valid source and destination pointers. Be aware that
465 : * destination buffer will not be NULL-terminated, thus caller have to append
466 : * it if needs. The supported flags are::
467 : *
468 : * %ESCAPE_SPACE: (special white space, not space itself)
469 : * '\f' - form feed
470 : * '\n' - new line
471 : * '\r' - carriage return
472 : * '\t' - horizontal tab
473 : * '\v' - vertical tab
474 : * %ESCAPE_SPECIAL:
475 : * '\\' - backslash
476 : * '\a' - alert (BEL)
477 : * '\e' - escape
478 : * %ESCAPE_NULL:
479 : * '\0' - null
480 : * %ESCAPE_OCTAL:
481 : * '\NNN' - byte with octal value NNN (3 digits)
482 : * %ESCAPE_ANY:
483 : * all previous together
484 : * %ESCAPE_NP:
485 : * escape only non-printable characters (checked by isprint)
486 : * %ESCAPE_ANY_NP:
487 : * all previous together
488 : * %ESCAPE_HEX:
489 : * '\xHH' - byte with hexadecimal value HH (2 digits)
490 : *
491 : * Return:
492 : * The total size of the escaped output that would be generated for
493 : * the given input and flags. To check whether the output was
494 : * truncated, compare the return value to osz. There is room left in
495 : * dst for a '\0' terminator if and only if ret < osz.
496 : */
497 10889 : int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
498 : unsigned int flags, const char *only)
499 : {
500 10889 : char *p = dst;
501 10889 : char *end = p + osz;
502 10889 : bool is_dict = only && *only;
503 :
504 10889 : while (isz--) {
505 58453 : unsigned char c = *src++;
506 :
507 : /*
508 : * Apply rules in the following sequence:
509 : * - the character is printable, when @flags has
510 : * %ESCAPE_NP bit set
511 : * - the @only string is supplied and does not contain a
512 : * character under question
513 : * - the character doesn't fall into a class of symbols
514 : * defined by given @flags
515 : * In these cases we just pass through a character to the
516 : * output buffer.
517 : */
518 58453 : if ((flags & ESCAPE_NP && isprint(c)) ||
519 58447 : (is_dict && !strchr(only, c))) {
520 : /* do nothing */
521 : } else {
522 0 : if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
523 0 : continue;
524 :
525 0 : if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
526 0 : continue;
527 :
528 0 : if (flags & ESCAPE_NULL && escape_null(c, &p, end))
529 0 : continue;
530 :
531 : /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
532 0 : if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
533 0 : continue;
534 :
535 0 : if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
536 0 : continue;
537 : }
538 :
539 127799 : escape_passthrough(c, &p, end);
540 : }
541 :
542 10891 : return p - dst;
543 : }
544 : EXPORT_SYMBOL(string_escape_mem);
545 :
546 0 : int string_escape_mem_ascii(const char *src, size_t isz, char *dst,
547 : size_t osz)
548 : {
549 0 : char *p = dst;
550 0 : char *end = p + osz;
551 :
552 0 : while (isz--) {
553 0 : unsigned char c = *src++;
554 :
555 0 : if (!isprint(c) || !isascii(c) || c == '"' || c == '\\')
556 0 : escape_hex(c, &p, end);
557 : else
558 0 : escape_passthrough(c, &p, end);
559 : }
560 :
561 0 : return p - dst;
562 : }
563 : EXPORT_SYMBOL(string_escape_mem_ascii);
564 :
565 : /*
566 : * Return an allocated string that has been escaped of special characters
567 : * and double quotes, making it safe to log in quotes.
568 : */
569 0 : char *kstrdup_quotable(const char *src, gfp_t gfp)
570 : {
571 0 : size_t slen, dlen;
572 0 : char *dst;
573 0 : const int flags = ESCAPE_HEX;
574 0 : const char esc[] = "\f\n\r\t\v\a\e\\\"";
575 :
576 0 : if (!src)
577 : return NULL;
578 0 : slen = strlen(src);
579 :
580 0 : dlen = string_escape_mem(src, slen, NULL, 0, flags, esc);
581 0 : dst = kmalloc(dlen + 1, gfp);
582 0 : if (!dst)
583 : return NULL;
584 :
585 0 : WARN_ON(string_escape_mem(src, slen, dst, dlen, flags, esc) != dlen);
586 0 : dst[dlen] = '\0';
587 :
588 0 : return dst;
589 : }
590 : EXPORT_SYMBOL_GPL(kstrdup_quotable);
591 :
592 : /*
593 : * Returns allocated NULL-terminated string containing process
594 : * command line, with inter-argument NULLs replaced with spaces,
595 : * and other special characters escaped.
596 : */
597 0 : char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
598 : {
599 0 : char *buffer, *quoted;
600 0 : int i, res;
601 :
602 0 : buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
603 0 : if (!buffer)
604 : return NULL;
605 :
606 0 : res = get_cmdline(task, buffer, PAGE_SIZE - 1);
607 0 : buffer[res] = '\0';
608 :
609 : /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
610 0 : while (--res >= 0 && buffer[res] == '\0')
611 0 : ;
612 :
613 : /* Replace inter-argument NULLs. */
614 0 : for (i = 0; i <= res; i++)
615 0 : if (buffer[i] == '\0')
616 0 : buffer[i] = ' ';
617 :
618 : /* Make sure result is printable. */
619 0 : quoted = kstrdup_quotable(buffer, gfp);
620 0 : kfree(buffer);
621 0 : return quoted;
622 : }
623 : EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
624 :
625 : /*
626 : * Returns allocated NULL-terminated string containing pathname,
627 : * with special characters escaped, able to be safely logged. If
628 : * there is an error, the leading character will be "<".
629 : */
630 0 : char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
631 : {
632 0 : char *temp, *pathname;
633 :
634 0 : if (!file)
635 0 : return kstrdup("<unknown>", gfp);
636 :
637 : /* We add 11 spaces for ' (deleted)' to be appended */
638 0 : temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
639 0 : if (!temp)
640 0 : return kstrdup("<no_memory>", gfp);
641 :
642 0 : pathname = file_path(file, temp, PATH_MAX + 11);
643 0 : if (IS_ERR(pathname))
644 0 : pathname = kstrdup("<too_long>", gfp);
645 : else
646 0 : pathname = kstrdup_quotable(pathname, gfp);
647 :
648 0 : kfree(temp);
649 0 : return pathname;
650 : }
651 : EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
652 :
653 : /**
654 : * kfree_strarray - free a number of dynamically allocated strings contained
655 : * in an array and the array itself
656 : *
657 : * @array: Dynamically allocated array of strings to free.
658 : * @n: Number of strings (starting from the beginning of the array) to free.
659 : *
660 : * Passing a non-NULL @array and @n == 0 as well as NULL @array are valid
661 : * use-cases. If @array is NULL, the function does nothing.
662 : */
663 0 : void kfree_strarray(char **array, size_t n)
664 : {
665 0 : unsigned int i;
666 :
667 0 : if (!array)
668 : return;
669 :
670 0 : for (i = 0; i < n; i++)
671 0 : kfree(array[i]);
672 0 : kfree(array);
673 : }
674 : EXPORT_SYMBOL_GPL(kfree_strarray);
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