1/*
2 * Helpers for formatting and printing strings
3 *
4 * Copyright 31 August 2008 James Bottomley
5 * Copyright (C) 2013, Intel Corporation
6 */
7#include <linux/bug.h>
8#include <linux/kernel.h>
9#include <linux/math64.h>
10#include <linux/export.h>
11#include <linux/ctype.h>
12#include <linux/errno.h>
13#include <linux/fs.h>
14#include <linux/limits.h>
15#include <linux/mm.h>
16#include <linux/slab.h>
17#include <linux/string.h>
18#include <linux/string_helpers.h>
19
20/**
21 * string_get_size - get the size in the specified units
22 * @size: The size to be converted in blocks
23 * @blk_size: Size of the block (use 1 for size in bytes)
24 * @units: units to use (powers of 1000 or 1024)
25 * @buf: buffer to format to
26 * @len: length of buffer
27 *
28 * This function returns a string formatted to 3 significant figures
29 * giving the size in the required units. @buf should have room for
30 * at least 9 bytes and will always be zero terminated.
31 *
32 */
33void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
34 char *buf, int len)
35{
36 static const char *const units_10[] = {
37 "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"
38 };
39 static const char *const units_2[] = {
40 "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"
41 };
42 static const char *const *const units_str[] = {
43 [STRING_UNITS_10] = units_10,
44 [STRING_UNITS_2] = units_2,
45 };
46 static const unsigned int divisor[] = {
47 [STRING_UNITS_10] = 1000,
48 [STRING_UNITS_2] = 1024,
49 };
50 static const unsigned int rounding[] = { 500, 50, 5 };
51 int i = 0, j;
52 u32 remainder = 0, sf_cap;
53 char tmp[8];
54 const char *unit;
55
56 tmp[0] = '\0';
57
58 if (blk_size == 0)
59 size = 0;
60 if (size == 0)
61 goto out;
62
63 /* This is Napier's algorithm. Reduce the original block size to
64 *
65 * coefficient * divisor[units]^i
66 *
67 * we do the reduction so both coefficients are just under 32 bits so
68 * that multiplying them together won't overflow 64 bits and we keep
69 * as much precision as possible in the numbers.
70 *
71 * Note: it's safe to throw away the remainders here because all the
72 * precision is in the coefficients.
73 */
74 while (blk_size >> 32) {
75 do_div(blk_size, divisor[units]);
76 i++;
77 }
78
79 while (size >> 32) {
80 do_div(size, divisor[units]);
81 i++;
82 }
83
84 /* now perform the actual multiplication keeping i as the sum of the
85 * two logarithms */
86 size *= blk_size;
87
88 /* and logarithmically reduce it until it's just under the divisor */
89 while (size >= divisor[units]) {
90 remainder = do_div(size, divisor[units]);
91 i++;
92 }
93
94 /* work out in j how many digits of precision we need from the
95 * remainder */
96 sf_cap = size;
97 for (j = 0; sf_cap*10 < 1000; j++)
98 sf_cap *= 10;
99
100 if (units == STRING_UNITS_2) {
101 /* express the remainder as a decimal. It's currently the
102 * numerator of a fraction whose denominator is
103 * divisor[units], which is 1 << 10 for STRING_UNITS_2 */
104 remainder *= 1000;
105 remainder >>= 10;
106 }
107
108 /* add a 5 to the digit below what will be printed to ensure
109 * an arithmetical round up and carry it through to size */
110 remainder += rounding[j];
111 if (remainder >= 1000) {
112 remainder -= 1000;
113 size += 1;
114 }
115
116 if (j) {
117 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
118 tmp[j+1] = '\0';
119 }
120
121 out:
122 if (i >= ARRAY_SIZE(units_2))
123 unit = "UNK";
124 else
125 unit = units_str[units][i];
126
127 snprintf(buf, len, "%u%s %s", (u32)size,
128 tmp, unit);
129}
130EXPORT_SYMBOL(string_get_size);
131
132static bool unescape_space(char **src, char **dst)
133{
134 char *p = *dst, *q = *src;
135
136 switch (*q) {
137 case 'n':
138 *p = '\n';
139 break;
140 case 'r':
141 *p = '\r';
142 break;
143 case 't':
144 *p = '\t';
145 break;
146 case 'v':
147 *p = '\v';
148 break;
149 case 'f':
150 *p = '\f';
151 break;
152 default:
153 return false;
154 }
155 *dst += 1;
156 *src += 1;
157 return true;
158}
159
160static bool unescape_octal(char **src, char **dst)
161{
162 char *p = *dst, *q = *src;
163 u8 num;
164
165 if (isodigit(*q) == 0)
166 return false;
167
168 num = (*q++) & 7;
169 while (num < 32 && isodigit(*q) && (q - *src < 3)) {
170 num <<= 3;
171 num += (*q++) & 7;
172 }
173 *p = num;
174 *dst += 1;
175 *src = q;
176 return true;
177}
178
179static bool unescape_hex(char **src, char **dst)
180{
181 char *p = *dst, *q = *src;
182 int digit;
183 u8 num;
184
185 if (*q++ != 'x')
186 return false;
187
188 num = digit = hex_to_bin(*q++);
189 if (digit < 0)
190 return false;
191
192 digit = hex_to_bin(*q);
193 if (digit >= 0) {
194 q++;
195 num = (num << 4) | digit;
196 }
197 *p = num;
198 *dst += 1;
199 *src = q;
200 return true;
201}
202
203static bool unescape_special(char **src, char **dst)
204{
205 char *p = *dst, *q = *src;
206
207 switch (*q) {
208 case '\"':
209 *p = '\"';
210 break;
211 case '\\':
212 *p = '\\';
213 break;
214 case 'a':
215 *p = '\a';
216 break;
217 case 'e':
218 *p = '\e';
219 break;
220 default:
221 return false;
222 }
223 *dst += 1;
224 *src += 1;
225 return true;
226}
227
228/**
229 * string_unescape - unquote characters in the given string
230 * @src: source buffer (escaped)
231 * @dst: destination buffer (unescaped)
232 * @size: size of the destination buffer (0 to unlimit)
233 * @flags: combination of the flags (bitwise OR):
234 * %UNESCAPE_SPACE:
235 * '\f' - form feed
236 * '\n' - new line
237 * '\r' - carriage return
238 * '\t' - horizontal tab
239 * '\v' - vertical tab
240 * %UNESCAPE_OCTAL:
241 * '\NNN' - byte with octal value NNN (1 to 3 digits)
242 * %UNESCAPE_HEX:
243 * '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
244 * %UNESCAPE_SPECIAL:
245 * '\"' - double quote
246 * '\\' - backslash
247 * '\a' - alert (BEL)
248 * '\e' - escape
249 * %UNESCAPE_ANY:
250 * all previous together
251 *
252 * Description:
253 * The function unquotes characters in the given string.
254 *
255 * Because the size of the output will be the same as or less than the size of
256 * the input, the transformation may be performed in place.
257 *
258 * Caller must provide valid source and destination pointers. Be aware that
259 * destination buffer will always be NULL-terminated. Source string must be
260 * NULL-terminated as well.
261 *
262 * Return:
263 * The amount of the characters processed to the destination buffer excluding
264 * trailing '\0' is returned.
265 */
266int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
267{
268 char *out = dst;
269
270 while (*src && --size) {
271 if (src[0] == '\\' && src[1] != '\0' && size > 1) {
272 src++;
273 size--;
274
275 if (flags & UNESCAPE_SPACE &&
276 unescape_space(&src, &out))
277 continue;
278
279 if (flags & UNESCAPE_OCTAL &&
280 unescape_octal(&src, &out))
281 continue;
282
283 if (flags & UNESCAPE_HEX &&
284 unescape_hex(&src, &out))
285 continue;
286
287 if (flags & UNESCAPE_SPECIAL &&
288 unescape_special(&src, &out))
289 continue;
290
291 *out++ = '\\';
292 }
293 *out++ = *src++;
294 }
295 *out = '\0';
296
297 return out - dst;
298}
299EXPORT_SYMBOL(string_unescape);
300
301static bool escape_passthrough(unsigned char c, char **dst, char *end)
302{
303 char *out = *dst;
304
305 if (out < end)
306 *out = c;
307 *dst = out + 1;
308 return true;
309}
310
311static bool escape_space(unsigned char c, char **dst, char *end)
312{
313 char *out = *dst;
314 unsigned char to;
315
316 switch (c) {
317 case '\n':
318 to = 'n';
319 break;
320 case '\r':
321 to = 'r';
322 break;
323 case '\t':
324 to = 't';
325 break;
326 case '\v':
327 to = 'v';
328 break;
329 case '\f':
330 to = 'f';
331 break;
332 default:
333 return false;
334 }
335
336 if (out < end)
337 *out = '\\';
338 ++out;
339 if (out < end)
340 *out = to;
341 ++out;
342
343 *dst = out;
344 return true;
345}
346
347static bool escape_special(unsigned char c, char **dst, char *end)
348{
349 char *out = *dst;
350 unsigned char to;
351
352 switch (c) {
353 case '\\':
354 to = '\\';
355 break;
356 case '\a':
357 to = 'a';
358 break;
359 case '\e':
360 to = 'e';
361 break;
362 default:
363 return false;
364 }
365
366 if (out < end)
367 *out = '\\';
368 ++out;
369 if (out < end)
370 *out = to;
371 ++out;
372
373 *dst = out;
374 return true;
375}
376
377static bool escape_null(unsigned char c, char **dst, char *end)
378{
379 char *out = *dst;
380
381 if (c)
382 return false;
383
384 if (out < end)
385 *out = '\\';
386 ++out;
387 if (out < end)
388 *out = '0';
389 ++out;
390
391 *dst = out;
392 return true;
393}
394
395static bool escape_octal(unsigned char c, char **dst, char *end)
396{
397 char *out = *dst;
398
399 if (out < end)
400 *out = '\\';
401 ++out;
402 if (out < end)
403 *out = ((c >> 6) & 0x07) + '0';
404 ++out;
405 if (out < end)
406 *out = ((c >> 3) & 0x07) + '0';
407 ++out;
408 if (out < end)
409 *out = ((c >> 0) & 0x07) + '0';
410 ++out;
411
412 *dst = out;
413 return true;
414}
415
416static bool escape_hex(unsigned char c, char **dst, char *end)
417{
418 char *out = *dst;
419
420 if (out < end)
421 *out = '\\';
422 ++out;
423 if (out < end)
424 *out = 'x';
425 ++out;
426 if (out < end)
427 *out = hex_asc_hi(c);
428 ++out;
429 if (out < end)
430 *out = hex_asc_lo(c);
431 ++out;
432
433 *dst = out;
434 return true;
435}
436
437/**
438 * string_escape_mem - quote characters in the given memory buffer
439 * @src: source buffer (unescaped)
440 * @isz: source buffer size
441 * @dst: destination buffer (escaped)
442 * @osz: destination buffer size
443 * @flags: combination of the flags (bitwise OR):
444 * %ESCAPE_SPACE: (special white space, not space itself)
445 * '\f' - form feed
446 * '\n' - new line
447 * '\r' - carriage return
448 * '\t' - horizontal tab
449 * '\v' - vertical tab
450 * %ESCAPE_SPECIAL:
451 * '\\' - backslash
452 * '\a' - alert (BEL)
453 * '\e' - escape
454 * %ESCAPE_NULL:
455 * '\0' - null
456 * %ESCAPE_OCTAL:
457 * '\NNN' - byte with octal value NNN (3 digits)
458 * %ESCAPE_ANY:
459 * all previous together
460 * %ESCAPE_NP:
461 * escape only non-printable characters (checked by isprint)
462 * %ESCAPE_ANY_NP:
463 * all previous together
464 * %ESCAPE_HEX:
465 * '\xHH' - byte with hexadecimal value HH (2 digits)
466 * @only: NULL-terminated string containing characters used to limit
467 * the selected escape class. If characters are included in @only
468 * that would not normally be escaped by the classes selected
469 * in @flags, they will be copied to @dst unescaped.
470 *
471 * Description:
472 * The process of escaping byte buffer includes several parts. They are applied
473 * in the following sequence.
474 * 1. The character is matched to the printable class, if asked, and in
475 * case of match it passes through to the output.
476 * 2. The character is not matched to the one from @only string and thus
477 * must go as-is to the output.
478 * 3. The character is checked if it falls into the class given by @flags.
479 * %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
480 * character. Note that they actually can't go together, otherwise
481 * %ESCAPE_HEX will be ignored.
482 *
483 * Caller must provide valid source and destination pointers. Be aware that
484 * destination buffer will not be NULL-terminated, thus caller have to append
485 * it if needs.
486 *
487 * Return:
488 * The total size of the escaped output that would be generated for
489 * the given input and flags. To check whether the output was
490 * truncated, compare the return value to osz. There is room left in
491 * dst for a '\0' terminator if and only if ret < osz.
492 */
493int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
494 unsigned int flags, const char *only)
495{
496 char *p = dst;
497 char *end = p + osz;
498 bool is_dict = only && *only;
499
500 while (isz--) {
501 unsigned char c = *src++;
502
503 /*
504 * Apply rules in the following sequence:
505 * - the character is printable, when @flags has
506 * %ESCAPE_NP bit set
507 * - the @only string is supplied and does not contain a
508 * character under question
509 * - the character doesn't fall into a class of symbols
510 * defined by given @flags
511 * In these cases we just pass through a character to the
512 * output buffer.
513 */
514 if ((flags & ESCAPE_NP && isprint(c)) ||
515 (is_dict && !strchr(only, c))) {
516 /* do nothing */
517 } else {
518 if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
519 continue;
520
521 if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
522 continue;
523
524 if (flags & ESCAPE_NULL && escape_null(c, &p, end))
525 continue;
526
527 /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
528 if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
529 continue;
530
531 if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
532 continue;
533 }
534
535 escape_passthrough(c, &p, end);
536 }
537
538 return p - dst;
539}
540EXPORT_SYMBOL(string_escape_mem);
541
542/*
543 * Return an allocated string that has been escaped of special characters
544 * and double quotes, making it safe to log in quotes.
545 */
546char *kstrdup_quotable(const char *src, gfp_t gfp)
547{
548 size_t slen, dlen;
549 char *dst;
550 const int flags = ESCAPE_HEX;
551 const char esc[] = "\f\n\r\t\v\a\e\\\"";
552
553 if (!src)
554 return NULL;
555 slen = strlen(src);
556
557 dlen = string_escape_mem(src, slen, NULL, 0, flags, esc);
558 dst = kmalloc(dlen + 1, gfp);
559 if (!dst)
560 return NULL;
561
562 WARN_ON(string_escape_mem(src, slen, dst, dlen, flags, esc) != dlen);
563 dst[dlen] = '\0';
564
565 return dst;
566}
567EXPORT_SYMBOL_GPL(kstrdup_quotable);
568
569/*
570 * Returns allocated NULL-terminated string containing process
571 * command line, with inter-argument NULLs replaced with spaces,
572 * and other special characters escaped.
573 */
574char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
575{
576 char *buffer, *quoted;
577 int i, res;
578
579 buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
580 if (!buffer)
581 return NULL;
582
583 res = get_cmdline(task, buffer, PAGE_SIZE - 1);
584 buffer[res] = '\0';
585
586 /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
587 while (--res >= 0 && buffer[res] == '\0')
588 ;
589
590 /* Replace inter-argument NULLs. */
591 for (i = 0; i <= res; i++)
592 if (buffer[i] == '\0')
593 buffer[i] = ' ';
594
595 /* Make sure result is printable. */
596 quoted = kstrdup_quotable(buffer, gfp);
597 kfree(buffer);
598 return quoted;
599}
600EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
601
602/*
603 * Returns allocated NULL-terminated string containing pathname,
604 * with special characters escaped, able to be safely logged. If
605 * there is an error, the leading character will be "<".
606 */
607char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
608{
609 char *temp, *pathname;
610
611 if (!file)
612 return kstrdup("<unknown>", gfp);
613
614 /* We add 11 spaces for ' (deleted)' to be appended */
615 temp = kmalloc(PATH_MAX + 11, GFP_KERNEL);
616 if (!temp)
617 return kstrdup("<no_memory>", gfp);
618
619 pathname = file_path(file, temp, PATH_MAX + 11);
620 if (IS_ERR(pathname))
621 pathname = kstrdup("<too_long>", gfp);
622 else
623 pathname = kstrdup_quotable(pathname, gfp);
624
625 kfree(temp);
626 return pathname;
627}
628EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
629