summaryrefslogtreecommitdiffstats
path: root/src/dstring.c
blob: f019ba97634b6765415f3ae582050868de4f0883 (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
// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD

#include "dstring.h"
#include "alloc.h"
#include "bit.h"
#include "diag.h"
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/**
 * The memory representation of a dynamic string.  Users get a pointer to data.
 */
struct dstring {
	size_t capacity;
	size_t length;
	char data[];
};

/** Get the string header from the string data pointer. */
static struct dstring *dstrheader(const char *dstr) {
	return (struct dstring *)(dstr - offsetof(struct dstring, data));
}

/** Get the correct size for a dstring with the given capacity. */
static size_t dstrsize(size_t capacity) {
	return sizeof_flex(struct dstring, data, capacity + 1);
}

/** Allocate a dstring with the given contents. */
static char *dstralloc_impl(size_t capacity, size_t length, const char *data) {
	// Avoid reallocations for small strings
	if (capacity < 7) {
		capacity = 7;
	}

	struct dstring *header = malloc(dstrsize(capacity));
	if (!header) {
		return NULL;
	}

	header->capacity = capacity;
	header->length = length;

	memcpy(header->data, data, length);
	header->data[length] = '\0';
	return header->data;
}

char *dstralloc(size_t capacity) {
	return dstralloc_impl(capacity, 0, "");
}

char *dstrdup(const char *str) {
	size_t len = strlen(str);
	return dstralloc_impl(len, len, str);
}

char *dstrndup(const char *str, size_t n) {
	size_t len = strnlen(str, n);
	return dstralloc_impl(len, len, str);
}

size_t dstrlen(const char *dstr) {
	return dstrheader(dstr)->length;
}

int dstreserve(char **dstr, size_t capacity) {
	if (!*dstr) {
		*dstr = dstralloc(capacity);
		return *dstr ? 0 : -1;
	}

	struct dstring *header = dstrheader(*dstr);

	if (capacity > header->capacity) {
		capacity = bit_ceil(capacity + 1) - 1;

		header = realloc(header, dstrsize(capacity));
		if (!header) {
			return -1;
		}
		header->capacity = capacity;

		*dstr = header->data;
	}

	return 0;
}

int dstresize(char **dstr, size_t length) {
	if (dstreserve(dstr, length) != 0) {
		return -1;
	}

	struct dstring *header = dstrheader(*dstr);
	header->length = length;
	header->data[length] = '\0';

	return 0;
}

/** Common implementation of dstr{cat,ncat,app}. */
static int dstrcat_impl(char **dest, const char *src, size_t srclen) {
	size_t oldlen = dstrlen(*dest);
	size_t newlen = oldlen + srclen;

	if (dstresize(dest, newlen) != 0) {
		return -1;
	}

	memcpy(*dest + oldlen, src, srclen);
	return 0;
}

int dstrcat(char **dest, const char *src) {
	return dstrcat_impl(dest, src, strlen(src));
}

int dstrncat(char **dest, const char *src, size_t n) {
	return dstrcat_impl(dest, src, strnlen(src, n));
}

int dstrdcat(char **dest, const char *src) {
	return dstrcat_impl(dest, src, dstrlen(src));
}

int dstrapp(char **str, char c) {
	return dstrcat_impl(str, &c, 1);
}

char *dstrprintf(const char *format, ...) {
	va_list args;

	va_start(args, format);
	char *str = dstrvprintf(format, args);
	va_end(args);

	return str;
}

char *dstrvprintf(const char *format, va_list args) {
	// Guess a capacity to try to avoid reallocating
	char *str = dstralloc(2*strlen(format));
	if (!str) {
		return NULL;
	}

	if (dstrvcatf(&str, format, args) != 0) {
		dstrfree(str);
		return NULL;
	}

	return str;
}

int dstrcatf(char **str, const char *format, ...) {
	va_list args;

	va_start(args, format);
	int ret = dstrvcatf(str, format, args);
	va_end(args);

	return ret;
}

int dstrvcatf(char **str, const char *format, va_list args) {
	// Guess a capacity to try to avoid calling vsnprintf() twice
	size_t len = dstrlen(*str);
	dstreserve(str, len + 2*strlen(format));
	size_t cap = dstrheader(*str)->capacity;

	va_list copy;
	va_copy(copy, args);

	char *tail = *str + len;
	int ret = vsnprintf(tail, cap - len + 1, format, args);
	if (ret < 0) {
		goto fail;
	}

	size_t tail_len = ret;
	if (tail_len > cap - len) {
		cap = len + tail_len;
		if (dstreserve(str, cap) != 0) {
			goto fail;
		}

		tail = *str + len;
		ret = vsnprintf(tail, tail_len + 1, format, copy);
		if (ret < 0 || (size_t)ret != tail_len) {
			bfs_bug("Length of formatted string changed");
			goto fail;
		}
	}

	va_end(copy);

	struct dstring *header = dstrheader(*str);
	header->length += tail_len;
	return 0;

fail:
	*tail = '\0';
	return -1;
}

void dstrfree(char *dstr) {
	if (dstr) {
		free(dstrheader(dstr));
	}
}