aboutsummaryrefslogtreecommitdiff
path: root/lib/libc/snprintf.c
blob: 29c50df4d366c0c93ad2e549b652e3793811fccf (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
/*
 * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <assert.h>
#include <stdarg.h>
#include <stdlib.h>

#include <common/debug.h>
#include <plat/common/platform.h>

#define get_num_va_args(_args, _lcount)				\
	(((_lcount) > 1)  ? va_arg(_args, long long int) :	\
	(((_lcount) == 1) ? va_arg(_args, long int) :		\
			    va_arg(_args, int)))

#define get_unum_va_args(_args, _lcount)				\
	(((_lcount) > 1)  ? va_arg(_args, unsigned long long int) :	\
	(((_lcount) == 1) ? va_arg(_args, unsigned long int) :		\
			    va_arg(_args, unsigned int)))

static void string_print(char **s, size_t n, size_t *chars_printed,
			 const char *str)
{
	while (*str != '\0') {
		if (*chars_printed < n) {
			*(*s) = *str;
			(*s)++;
		}

		(*chars_printed)++;
		str++;
	}
}

static void unsigned_num_print(char **s, size_t n, size_t *count,
			      unsigned long long int unum, unsigned int radix,
			      char padc, int padn)
{
	/* Just need enough space to store 64 bit decimal integer */
	char num_buf[20];
	int i = 0;
	int width;
	unsigned int rem;

	do {
		rem = unum % radix;
		if (rem < 0xa)
			num_buf[i] = '0' + rem;
		else
			num_buf[i] = 'a' + (rem - 0xa);
		i++;
		unum /= radix;
	} while (unum > 0U);

	width = i;

	if (padn > 0) {
		while (width < padn) {
			if (*count < n) {
				*(*s) = padc;
				(*s)++;
			}
			(*count)++;
			padn--;
		}
	}

	while (--i >= 0) {
		if (*count < n) {
			*(*s) = num_buf[i];
			(*s)++;
		}
		(*count)++;
	}

	if (padn < 0) {
		while (width < -padn) {
			if (*count < n) {
				*(*s) = padc;
				(*s)++;
			}
			(*count)++;
			padn++;
		}
	}
}

/*
 * Scaled down version of vsnprintf(3).
 */
int vsnprintf(char *s, size_t n, const char *fmt, va_list args)
{
	int l_count;
	int left;
	char *str;
	int num;
	unsigned long long int unum;
	char padc; /* Padding character */
	int padn; /* Number of characters to pad */
	size_t count = 0U;

	if (n == 0U) {
		/* There isn't space for anything. */
	} else if (n == 1U) {
		/* Buffer is too small to actually write anything else. */
		*s = '\0';
		n = 0U;
	} else {
		/* Reserve space for the terminator character. */
		n--;
	}

	while (*fmt != '\0') {
		l_count = 0;
		left = 0;
		padc = '\0';
		padn = 0;

		if (*fmt == '%') {
			fmt++;
			/* Check the format specifier. */
loop:
			switch (*fmt) {
			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
				padc = ' ';
				for (padn = 0; *fmt >= '0' && *fmt <= '9'; fmt++)
					padn = (padn * 10) + (*fmt - '0');
				if (left)
					padn = -padn;
				goto loop;
			case '-':
				left = 1;
				fmt++;
				goto loop;
			case 'i':
			case 'd':
				num = get_num_va_args(args, l_count);

				if (num < 0) {
					if (count < n) {
						*s = '-';
						s++;
					}
					count++;

					unum = (unsigned int)-num;
				} else {
					unum = (unsigned int)num;
				}

				unsigned_num_print(&s, n, &count, unum, 10,
						   padc, padn);
				break;
			case 'l':
				l_count++;
				fmt++;
				goto loop;
			case 's':
				str = va_arg(args, char *);
				string_print(&s, n, &count, str);
				break;
			case 'u':
				unum = get_unum_va_args(args, l_count);
				unsigned_num_print(&s, n, &count, unum, 10,
						   padc, padn);
				break;
			case 'x':
				unum = get_unum_va_args(args, l_count);
				unsigned_num_print(&s, n, &count, unum, 16,
						   padc, padn);
				break;
			case '0':
				padc = '0';
				padn = 0;
				fmt++;

				for (;;) {
					char ch = *fmt;
					if ((ch < '0') || (ch > '9')) {
						goto loop;
					}
					padn = (padn * 10) + (ch - '0');
					fmt++;
				}
				assert(0); /* Unreachable */
			default:
				/*
				 * Exit on any other format specifier and abort
				 * when in debug mode.
				 */
				WARN("snprintf: specifier with ASCII code '%d' not supported.\n",
				     *fmt);
				assert(0);
				return -1;
			}
			fmt++;
			continue;
		}

		if (count < n) {
			*s = *fmt;
			s++;
		}

		fmt++;
		count++;
	}

	if (n > 0U)
		*s = '\0';

	return (int)count;
}

/*******************************************************************
 * Reduced snprintf to be used for Trusted firmware.
 * The following type specifiers are supported:
 *
 * %d or %i - signed decimal format
 * %s - string format
 * %u - unsigned decimal format
 *
 * The function panics on all other formats specifiers.
 *
 * It returns the number of characters that would be written if the
 * buffer was big enough. If it returns a value lower than n, the
 * whole string has been written.
 *******************************************************************/
int snprintf(char *s, size_t n, const char *fmt, ...)
{
	va_list args;
	int chars_printed;

	va_start(args, fmt);
	chars_printed = vsnprintf(s, n, fmt, args);
	va_end(args);

	return chars_printed;
}