summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/vsprintf.c
blob: e65ef49a54cdf1e797af1587e10164b401ec45f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
// SPDX-License-Identifier: GPL-2.0-only
/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright (C) 1991, 1992 Linus Torvalds
 *   Copyright 2007 rPath, Inc. - All Rights Reserved
 *
 * ----------------------------------------------------------------------- */

/*
 * Oh, it's a waste of space, but oh-so-yummy for debugging.
 */

#include <stdarg.h>

#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/string.h>
#include <linux/types.h>

static
int skip_atoi(const char **s)
{
	int i = 0;

	while (isdigit(**s))
		i = i * 10 + *((*s)++) - '0';
	return i;
}

/*
 * put_dec_full4 handles numbers in the range 0 <= r < 10000.
 * The multiplier 0xccd is round(2^15/10), and the approximation
 * r/10 == (r * 0xccd) >> 15 is exact for all r < 16389.
 */
static
void put_dec_full4(char *end, unsigned int r)
{
	int i;

	for (i = 0; i < 3; i++) {
		unsigned int q = (r * 0xccd) >> 15;
		*--end = '0' + (r - q * 10);
		r = q;
	}
	*--end = '0' + r;
}

/* put_dec is copied from lib/vsprintf.c with small modifications */

/*
 * Call put_dec_full4 on x % 10000, return x / 10000.
 * The approximation x/10000 == (x * 0x346DC5D7) >> 43
 * holds for all x < 1,128,869,999.  The largest value this
 * helper will ever be asked to convert is 1,125,520,955.
 * (second call in the put_dec code, assuming n is all-ones).
 */
static
unsigned int put_dec_helper4(char *end, unsigned int x)
{
	unsigned int q = (x * 0x346DC5D7ULL) >> 43;

	put_dec_full4(end, x - q * 10000);
	return q;
}

/* Based on code by Douglas W. Jones found at
 * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
 * (with permission from the author).
 * Performs no 64-bit division and hence should be fast on 32-bit machines.
 */
static
char *put_dec(char *end, unsigned long long n)
{
	unsigned int d3, d2, d1, q, h;
	char *p = end;

	d1  = ((unsigned int)n >> 16); /* implicit "& 0xffff" */
	h   = (n >> 32);
	d2  = (h      ) & 0xffff;
	d3  = (h >> 16); /* implicit "& 0xffff" */

	/* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
	     = 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
	q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((unsigned int)n & 0xffff);
	q = put_dec_helper4(p, q);
	p -= 4;

	q += 7671 * d3 + 9496 * d2 + 6 * d1;
	q = put_dec_helper4(p, q);
	p -= 4;

	q += 4749 * d3 + 42 * d2;
	q = put_dec_helper4(p, q);
	p -= 4;

	q += 281 * d3;
	q = put_dec_helper4(p, q);
	p -= 4;

	put_dec_full4(p, q);
	p -= 4;

	/* strip off the extra 0's we printed */
	while (p < end && *p == '0')
		++p;

	return p;
}

static
char *number(char *end, unsigned long long num, int base, char locase)
{
	/*
	 * locase = 0 or 0x20. ORing digits or letters with 'locase'
	 * produces same digits or (maybe lowercased) letters
	 */

	/* we are called with base 8, 10 or 16, only, thus don't need "G..."  */
	static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */

	switch (base) {
	case 10:
		if (num != 0)
			end = put_dec(end, num);
		break;
	case 8:
		for (; num != 0; num >>= 3)
			*--end = '0' + (num & 07);
		break;
	case 16:
		for (; num != 0; num >>= 4)
			*--end = digits[num & 0xf] | locase;
		break;
	default:
		unreachable();
	};

	return end;
}

#define ZEROPAD	1		/* pad with zero */
#define SIGN	2		/* unsigned/signed long */
#define PLUS	4		/* show plus */
#define SPACE	8		/* space if plus */
#define LEFT	16		/* left justified */
#define SMALL	32		/* Must be 32 == 0x20 */
#define SPECIAL	64		/* 0x */
#define WIDE	128		/* UTF-16 string */

static
int get_flags(const char **fmt)
{
	int flags = 0;

	do {
		switch (**fmt) {
		case '-':
			flags |= LEFT;
			break;
		case '+':
			flags |= PLUS;
			break;
		case ' ':
			flags |= SPACE;
			break;
		case '#':
			flags |= SPECIAL;
			break;
		case '0':
			flags |= ZEROPAD;
			break;
		default:
			return flags;
		}
		++(*fmt);
	} while (1);
}

static
int get_int(const char **fmt, va_list *ap)
{
	if (isdigit(**fmt))
		return skip_atoi(fmt);
	if (**fmt == '*') {
		++(*fmt);
		/* it's the next argument */
		return va_arg(*ap, int);
	}
	return 0;
}

static
unsigned long long get_number(int sign, int qualifier, va_list *ap)
{
	if (sign) {
		switch (qualifier) {
		case 'L':
			return va_arg(*ap, long long);
		case 'l':
			return va_arg(*ap, long);
		case 'h':
			return (short)va_arg(*ap, int);
		case 'H':
			return (signed char)va_arg(*ap, int);
		default:
			return va_arg(*ap, int);
		};
	} else {
		switch (qualifier) {
		case 'L':
			return va_arg(*ap, unsigned long long);
		case 'l':
			return va_arg(*ap, unsigned long);
		case 'h':
			return (unsigned short)va_arg(*ap, int);
		case 'H':
			return (unsigned char)va_arg(*ap, int);
		default:
			return va_arg(*ap, unsigned int);
		}
	}
}

static
char get_sign(long long *num, int flags)
{
	if (!(flags & SIGN))
		return 0;
	if (*num < 0) {
		*num = -(*num);
		return '-';
	}
	if (flags & PLUS)
		return '+';
	if (flags & SPACE)
		return ' ';
	return 0;
}

static
size_t utf16s_utf8nlen(const u16 *s16, size_t maxlen)
{
	size_t len, clen;

	for (len = 0; len < maxlen && *s16; len += clen) {
		u16 c0 = *s16++;

		/* First, get the length for a BMP character */
		clen = 1 + (c0 >= 0x80) + (c0 >= 0x800);
		if (len + clen > maxlen)
			break;
		/*
		 * If this is a high surrogate, and we're already at maxlen, we
		 * can't include the character if it's a valid surrogate pair.
		 * Avoid accessing one extra word just to check if it's valid
		 * or not.
		 */
		if ((c0 & 0xfc00) == 0xd800) {
			if (len + clen == maxlen)
				break;
			if ((*s16 & 0xfc00) == 0xdc00) {
				++s16;
				++clen;
			}
		}
	}

	return len;
}

static
u32 utf16_to_utf32(const u16 **s16)
{
	u16 c0, c1;

	c0 = *(*s16)++;
	/* not a surrogate */
	if ((c0 & 0xf800) != 0xd800)
		return c0;
	/* invalid: low surrogate instead of high */
	if (c0 & 0x0400)
		return 0xfffd;
	c1 = **s16;
	/* invalid: missing low surrogate */
	if ((c1 & 0xfc00) != 0xdc00)
		return 0xfffd;
	/* valid surrogate pair */
	++(*s16);
	return (0x10000 - (0xd800 << 10) - 0xdc00) + (c0 << 10) + c1;
}

#define PUTC(c) \
do {				\
	if (pos < size)		\
		buf[pos] = (c);	\
	++pos;			\
} while (0);

int vsnprintf(char *buf, size_t size, const char *fmt, va_list ap)
{
	/* The maximum space required is to print a 64-bit number in octal */
	char tmp[(sizeof(unsigned long long) * 8 + 2) / 3];
	char *tmp_end = &tmp[ARRAY_SIZE(tmp)];
	long long num;
	int base;
	const char *s;
	size_t len, pos;
	char sign;

	int flags;		/* flags to number() */

	int field_width;	/* width of output field */
	int precision;		/* min. # of digits for integers; max
				   number of chars for from string */
	int qualifier;		/* 'h', 'hh', 'l' or 'll' for integer fields */

	va_list args;

	/*
	 * We want to pass our input va_list to helper functions by reference,
	 * but there's an annoying edge case. If va_list was originally passed
	 * to us by value, we could just pass &ap down to the helpers. This is
	 * the case on, for example, X86_32.
	 * However, on X86_64 (and possibly others), va_list is actually a
	 * size-1 array containing a structure. Our function parameter ap has
	 * decayed from T[1] to T*, and &ap has type T** rather than T(*)[1],
	 * which is what will be expected by a function taking a va_list *
	 * parameter.
	 * One standard way to solve this mess is by creating a copy in a local
	 * variable of type va_list and then passing a pointer to that local
	 * copy instead, which is what we do here.
	 */
	va_copy(args, ap);

	for (pos = 0; *fmt; ++fmt) {
		if (*fmt != '%' || *++fmt == '%') {
			PUTC(*fmt);
			continue;
		}

		/* process flags */
		flags = get_flags(&fmt);

		/* get field width */
		field_width = get_int(&fmt, &args);
		if (field_width < 0) {
			field_width = -field_width;
			flags |= LEFT;
		}

		if (flags & LEFT)
			flags &= ~ZEROPAD;

		/* get the precision */
		precision = -1;
		if (*fmt == '.') {
			++fmt;
			precision = get_int(&fmt, &args);
			if (precision >= 0)
				flags &= ~ZEROPAD;
		}

		/* get the conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || *fmt == 'l') {
			qualifier = *fmt;
			++fmt;
			if (qualifier == *fmt) {
				qualifier -= 'a'-'A';
				++fmt;
			}
		}

		sign = 0;

		switch (*fmt) {
		case 'c':
			flags &= LEFT;
			s = tmp;
			if (qualifier == 'l') {
				((u16 *)tmp)[0] = (u16)va_arg(args, unsigned int);
				((u16 *)tmp)[1] = L'\0';
				precision = INT_MAX;
				goto wstring;
			} else {
				tmp[0] = (unsigned char)va_arg(args, int);
				precision = len = 1;
			}
			goto output;

		case 's':
			flags &= LEFT;
			if (precision < 0)
				precision = INT_MAX;
			s = va_arg(args, void *);
			if (!s)
				s = precision < 6 ? "" : "(null)";
			else if (qualifier == 'l') {
		wstring:
				flags |= WIDE;
				precision = len = utf16s_utf8nlen((const u16 *)s, precision);
				goto output;
			}
			precision = len = strnlen(s, precision);
			goto output;

			/* integer number formats - set up the flags and "break" */
		case 'o':
			base = 8;
			break;

		case 'p':
			if (precision < 0)
				precision = 2 * sizeof(void *);
			fallthrough;
		case 'x':
			flags |= SMALL;
			fallthrough;
		case 'X':
			base = 16;
			break;

		case 'd':
		case 'i':
			flags |= SIGN;
			fallthrough;
		case 'u':
			flags &= ~SPECIAL;
			base = 10;
			break;

		default:
			/*
			 * Bail out if the conversion specifier is invalid.
			 * There's probably a typo in the format string and the
			 * remaining specifiers are unlikely to match up with
			 * the arguments.
			 */
			goto fail;
		}
		if (*fmt == 'p') {
			num = (unsigned long)va_arg(args, void *);
		} else {
			num = get_number(flags & SIGN, qualifier, &args);
		}

		sign = get_sign(&num, flags);
		if (sign)
			--field_width;

		s = number(tmp_end, num, base, flags & SMALL);
		len = tmp_end - s;
		/* default precision is 1 */
		if (precision < 0)
			precision = 1;
		/* precision is minimum number of digits to print */
		if (precision < len)
			precision = len;
		if (flags & SPECIAL) {
			/*
			 * For octal, a leading 0 is printed only if necessary,
			 * i.e. if it's not already there because of the
			 * precision.
			 */
			if (base == 8 && precision == len)
				++precision;
			/*
			 * For hexadecimal, the leading 0x is skipped if the
			 * output is empty, i.e. both the number and the
			 * precision are 0.
			 */
			if (base == 16 && precision > 0)
				field_width -= 2;
			else
				flags &= ~SPECIAL;
		}
		/*
		 * For zero padding, increase the precision to fill the field
		 * width.
		 */
		if ((flags & ZEROPAD) && field_width > precision)
			precision = field_width;

output:
		/* Calculate the padding necessary */
		field_width -= precision;
		/* Leading padding with ' ' */
		if (!(flags & LEFT))
			while (field_width-- > 0)
				PUTC(' ');
		/* sign */
		if (sign)
			PUTC(sign);
		/* 0x/0X for hexadecimal */
		if (flags & SPECIAL) {
			PUTC('0');
			PUTC( 'X' | (flags & SMALL));
		}
		/* Zero padding and excess precision */
		while (precision-- > len)
			PUTC('0');
		/* Actual output */
		if (flags & WIDE) {
			const u16 *ws = (const u16 *)s;

			while (len-- > 0) {
				u32 c32 = utf16_to_utf32(&ws);
				u8 *s8;
				size_t clen;

				if (c32 < 0x80) {
					PUTC(c32);
					continue;
				}

				/* Number of trailing octets */
				clen = 1 + (c32 >= 0x800) + (c32 >= 0x10000);

				len -= clen;
				s8 = (u8 *)&buf[pos];

				/* Avoid writing partial character */
				PUTC('\0');
				pos += clen;
				if (pos >= size)
					continue;

				/* Set high bits of leading octet */
				*s8 = (0xf00 >> 1) >> clen;
				/* Write trailing octets in reverse order */
				for (s8 += clen; clen; --clen, c32 >>= 6)
					*s8-- = 0x80 | (c32 & 0x3f);
				/* Set low bits of leading octet */
				*s8 |= c32;
			}
		} else {
			while (len-- > 0)
				PUTC(*s++);
		}
		/* Trailing padding with ' ' */
		while (field_width-- > 0)
			PUTC(' ');
	}
fail:
	va_end(args);

	if (size)
		buf[min(pos, size-1)] = '\0';

	return pos;
}

int snprintf(char *buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	i = vsnprintf(buf, size, fmt, args);
	va_end(args);
	return i;
}