1/*
2 * Copyright (c) 2010 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29#include "string.h"
30
31static const char hex[] = "0123456789abcdef";
32
33static int
34_mach_strlen(const char *str)
35{
36	const char *p;
37	for (p = str; p; p++) {
38		if (*p == '\0') {
39			return (int)(p - str);
40		}
41	}
42	/* NOTREACHED */
43	return 0;
44}
45
46static void
47_mach_hex(char **buffer, int *length, unsigned long long n)
48{
49	char buf[32];
50	char *cp = buf + sizeof(buf);
51
52	if (n) {
53		*--cp = '\0';
54		while (n) {
55			*--cp = hex[n & 0xf];
56			n >>= 4;
57		}
58
59		int width = _mach_strlen(cp);
60		while (width > 0 && length > 0) {
61			*(*buffer)++ = *cp++;
62			(*length)--;
63			width--;
64		}
65	}
66}
67
68int
69_mach_vsnprintf(char *buffer, int length, const char *fmt, va_list ap)
70{
71	int width, max = length;
72	char *out_ptr = buffer;
73
74	// we only ever write n-1 bytes so we can put a \0 at the end
75	length--;
76	while (length > 0 && *fmt) {
77		if (*fmt == '\0') {
78			break;
79		}
80		if (*fmt != '%') {
81			*(out_ptr++) = *(fmt++);
82			length--;
83			continue;
84		}
85		fmt++;
86		// only going to support a specific subset of sprintf flags
87		// namely %s, %x, with no padding modifiers
88		switch (*fmt++) {
89			case 's':
90			{
91				char *cp = va_arg(ap, char*);
92				width = _mach_strlen(cp);
93				while (width > 0 && length > 0) {
94					*(out_ptr++) = *(cp++);
95					width--;
96					length--;
97				}
98				break;
99			}
100			case 'x':
101			{
102				_mach_hex(&out_ptr, &length, va_arg(ap, unsigned int));
103				break;
104			}
105		}
106	}
107	*out_ptr = '\0';
108	return max - length;
109}
110
111int
112_mach_snprintf(char *buffer, int length, const char *fmt, ...)
113{
114	int ret;
115	va_list ap;
116	va_start(ap, fmt);
117	ret = _mach_vsnprintf(buffer, length, fmt, ap);
118	va_end(ap);
119	return ret;
120}
121