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 void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
35 char *buf, int len)
36 {
37 static const char *const units_10[] = {
38 "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"
39 };
40 static const char *const units_2[] = {
41 "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"
42 };
43 static const char *const *const units_str[] = {
44 [STRING_UNITS_10] = units_10,
45 [STRING_UNITS_2] = units_2,
46 };
47 static const unsigned int divisor[] = {
48 [STRING_UNITS_10] = 1000,
49 [STRING_UNITS_2] = 1024,
50 };
51 static const unsigned int rounding[] = { 500, 50, 5 };
52 int i = 0, j;
53 u32 remainder = 0, sf_cap;
54 char tmp[8];
55 const char *unit;
56
57 tmp[0] = '\0';
58
59 if (blk_size == 0)
60 size = 0;
61 if (size == 0)
62 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 while (blk_size >> 32) {
76 do_div(blk_size, divisor[units]);
77 i++;
78 }
79
80 while (size >> 32) {
81 do_div(size, divisor[units]);
82 i++;
83 }
84
85 /* now perform the actual multiplication keeping i as the sum of the
86 * two logarithms */
87 size *= blk_size;
88
89 /* and logarithmically reduce it until it's just under the divisor */
90 while (size >= divisor[units]) {
91 remainder = do_div(size, divisor[units]);
92 i++;
93 }
94
95 /* work out in j how many digits of precision we need from the
96 * remainder */
97 sf_cap = size;
98 for (j = 0; sf_cap*10 < 1000; j++)
99 sf_cap *= 10;
100
101 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 remainder *= 1000;
106 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 remainder += rounding[j];
112 if (remainder >= 1000) {
113 remainder -= 1000;
114 size += 1;
115 }
116
117 if (j) {
118 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
119 tmp[j+1] = '\0';
120 }
121
122 out:
123 if (i >= ARRAY_SIZE(units_2))
124 unit = "UNK";
125 else
126 unit = units_str[units][i];
127
128 snprintf(buf, len, "%u%s %s", (u32)size,
129 tmp, unit);
130 }
131 EXPORT_SYMBOL(string_get_size);
132
133 static bool unescape_space(char **src, char **dst)
134 {
135 char *p = *dst, *q = *src;
136
137 switch (*q) {
138 case 'n':
139 *p = '\n';
140 break;
141 case 'r':
142 *p = '\r';
143 break;
144 case 't':
145 *p = '\t';
146 break;
147 case 'v':
148 *p = '\v';
149 break;
150 case 'f':
151 *p = '\f';
152 break;
153 default:
154 return false;
155 }
156 *dst += 1;
157 *src += 1;
158 return true;
159 }
160
161 static bool unescape_octal(char **src, char **dst)
162 {
163 char *p = *dst, *q = *src;
164 u8 num;
165
166 if (isodigit(*q) == 0)
167 return false;
168
169 num = (*q++) & 7;
170 while (num < 32 && isodigit(*q) && (q - *src < 3)) {
171 num <<= 3;
172 num += (*q++) & 7;
173 }
174 *p = num;
175 *dst += 1;
176 *src = q;
177 return true;
178 }
179
180 static bool unescape_hex(char **src, char **dst)
181 {
182 char *p = *dst, *q = *src;
183 int digit;
184 u8 num;
185
186 if (*q++ != 'x')
187 return false;
188
189 num = digit = hex_to_bin(*q++);
190 if (digit < 0)
191 return false;
192
193 digit = hex_to_bin(*q);
194 if (digit >= 0) {
195 q++;
196 num = (num << 4) | digit;
197 }
198 *p = num;
199 *dst += 1;
200 *src = q;
201 return true;
202 }
203
204 static bool unescape_special(char **src, char **dst)
205 {
206 char *p = *dst, *q = *src;
207
208 switch (*q) {
209 case '\"':
210 *p = '\"';
211 break;
212 case '\\':
213 *p = '\\';
214 break;
215 case 'a':
216 *p = '\a';
217 break;
218 case 'e':
219 *p = '\e';
220 break;
221 default:
222 return false;
223 }
224 *dst += 1;
225 *src += 1;
226 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 int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
269 {
270 char *out = dst;
271
272 while (*src && --size) {
273 if (src[0] == '\\' && src[1] != '\0' && size > 1) {
274 src++;
275 size--;
276
277 if (flags & UNESCAPE_SPACE &&
278 unescape_space(&src, &out))
279 continue;
280
281 if (flags & UNESCAPE_OCTAL &&
282 unescape_octal(&src, &out))
283 continue;
284
285 if (flags & UNESCAPE_HEX &&
286 unescape_hex(&src, &out))
287 continue;
288
289 if (flags & UNESCAPE_SPECIAL &&
290 unescape_special(&src, &out))
291 continue;
292
293 *out++ = '\\';
294 }
295 *out++ = *src++;
296 }
297 *out = '\0';
298
299 return out - dst;
300 }
301 EXPORT_SYMBOL(string_unescape);
302
303 static bool escape_passthrough(unsigned char c, char **dst, char *end)
304 {
305 char *out = *dst;
306
307 if (out < end)
308 *out = c;
309 *dst = out + 1;
310 return true;
311 }
312
313 static bool escape_space(unsigned char c, char **dst, char *end)
314 {
315 char *out = *dst;
316 unsigned char to;
317
318 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 if (out < end)
339 *out = '\\';
340 ++out;
341 if (out < end)
342 *out = to;
343 ++out;
344
345 *dst = out;
346 return true;
347 }
348
349 static bool escape_special(unsigned char c, char **dst, char *end)
350 {
351 char *out = *dst;
352 unsigned char to;
353
354 switch (c) {
355 case '\\':
356 to = '\\';
357 break;
358 case '\a':
359 to = 'a';
360 break;
361 case '\e':
362 to = 'e';
363 break;
364 default:
365 return false;
366 }
367
368 if (out < end)
369 *out = '\\';
370 ++out;
371 if (out < end)
372 *out = to;
373 ++out;
374
375 *dst = out;
376 return true;
377 }
378
379 static bool escape_null(unsigned char c, char **dst, char *end)
380 {
381 char *out = *dst;
382
383 if (c)
384 return false;
385
386 if (out < end)
387 *out = '\\';
388 ++out;
389 if (out < end)
390 *out = '0';
391 ++out;
392
393 *dst = out;
394 return true;
395 }
396
397 static bool escape_octal(unsigned char c, char **dst, char *end)
398 {
399 char *out = *dst;
400
401 if (out < end)
402 *out = '\\';
403 ++out;
404 if (out < end)
405 *out = ((c >> 6) & 0x07) + '0';
406 ++out;
407 if (out < end)
408 *out = ((c >> 3) & 0x07) + '0';
409 ++out;
410 if (out < end)
411 *out = ((c >> 0) & 0x07) + '0';
412 ++out;
413
414 *dst = out;
415 return true;
416 }
417
418 static bool escape_hex(unsigned char c, char **dst, char *end)
419 {
420 char *out = *dst;
421
422 if (out < end)
423 *out = '\\';
424 ++out;
425 if (out < end)
426 *out = 'x';
427 ++out;
428 if (out < end)
429 *out = hex_asc_hi(c);
430 ++out;
431 if (out < end)
432 *out = hex_asc_lo(c);
433 ++out;
434
435 *dst = out;
436 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 int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
498 unsigned int flags, const char *only)
499 {
500 char *p = dst;
501 char *end = p + osz;
502 bool is_dict = only && *only;
503
504 while (isz--) {
505 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 if ((flags & ESCAPE_NP && isprint(c)) ||
519 (is_dict && !strchr(only, c))) {
520 /* do nothing */
521 } else {
522 if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
523 continue;
524
525 if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
526 continue;
527
528 if (flags & ESCAPE_NULL && escape_null(c, &p, end))
529 continue;
530
531 /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
532 if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
533 continue;
534
535 if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
536 continue;
537 }
538
539 escape_passthrough(c, &p, end);
540 }
541
542 return p - dst;
543 }
544 EXPORT_SYMBOL(string_escape_mem);
545
546 int string_escape_mem_ascii(const char *src, size_t isz, char *dst,
547 size_t osz)
548 {
549 char *p = dst;
550 char *end = p + osz;
551
552 while (isz--) {
553 unsigned char c = *src++;
554
555 if (!isprint(c) || !isascii(c) || c == '"' || c == '\\')
556 escape_hex(c, &p, end);
557 else
558 escape_passthrough(c, &p, end);
559 }
560
561 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 char *kstrdup_quotable(const char *src, gfp_t gfp)
570 {
571 size_t slen, dlen;
572 char *dst;
573 const int flags = ESCAPE_HEX;
574 const char esc[] = "\f\n\r\t\v\a\e\\\"";
575
576 if (!src)
577 return NULL;
578 slen = strlen(src);
579
580 dlen = string_escape_mem(src, slen, NULL, 0, flags, esc);
581 dst = kmalloc(dlen + 1, gfp);
582 if (!dst)
583 return NULL;
584
585 WARN_ON(string_escape_mem(src, slen, dst, dlen, flags, esc) != dlen);
586 dst[dlen] = '\0';
587
588 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 char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
598 {
599 char *buffer, *quoted;
600 int i, res;
601
602 buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
603 if (!buffer)
604 return NULL;
605
606 res = get_cmdline(task, buffer, PAGE_SIZE - 1);
607 buffer[res] = '\0';
608
609 /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
610 while (--res >= 0 && buffer[res] == '\0')
611 ;
612
613 /* Replace inter-argument NULLs. */
614 for (i = 0; i <= res; i++)
615 if (buffer[i] == '\0')
616 buffer[i] = ' ';
617
618 /* Make sure result is printable. */
619 quoted = kstrdup_quotable(buffer, gfp);
620 kfree(buffer);
621 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 char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
631 {
632 char *temp, *pathname;
633
634 if (!file)
635 return kstrdup("<unknown>", gfp);
636
637 /* We add 11 spaces for ' (deleted)' to be appended */
638 temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
639 if (!temp)
640 return kstrdup("<no_memory>", gfp);
641
642 pathname = file_path(file, temp, PATH_MAX + 11);
643 if (IS_ERR(pathname))
644 pathname = kstrdup("<too_long>", gfp);
645 else
646 pathname = kstrdup_quotable(pathname, gfp);
647
648 kfree(temp);
649 return pathname;
650 }
651 EXPORT_SYMBOL_GPL(kstrdup_quotable_file);