summaryrefslogtreecommitdiff
path: root/lib/sqfs/str_table.c
blob: 1ec0ef733f656d211c6fc658c9b727948d419bd5 (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
/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
 * str_table.c
 *
 * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
 */
#include "config.h"

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "sqfs/error.h"
#include "util/util.h"
#include "str_table.h"

/* R5 hash function (borrowed from reiserfs) */
static sqfs_u32 strhash(const char *s)
{
	const signed char *str = (const signed char *)s;
	sqfs_u32 a = 0;

	while (*str != '\0') {
		a += *str << 4;
		a += *str >> 4;
		a *= 11;
		str++;
	}

	return a;
}

static int strings_grow(str_table_t *table)
{
	size_t newsz;
	void *new;

	if (table->num_strings < table->max_strings)
		return 0;

	newsz = table->max_strings ? (table->max_strings * 2) : 16;
	new = realloc(table->strings, sizeof(table->strings[0]) * newsz);

	if (new == NULL)
		return SQFS_ERROR_ALLOC;

	table->strings = new;
	table->max_strings = newsz;
	return 0;
}

int str_table_init(str_table_t *table, size_t size)
{
	memset(table, 0, sizeof(*table));

	table->buckets = alloc_array(size, sizeof(table->buckets[0]));
	table->num_buckets = size;

	if (table->buckets == NULL)
		return SQFS_ERROR_ALLOC;

	return 0;
}

void str_table_cleanup(str_table_t *table)
{
	str_bucket_t *bucket;
	size_t i;

	for (i = 0; i < table->num_buckets; ++i) {
		while (table->buckets[i] != NULL) {
			bucket = table->buckets[i];
			table->buckets[i] = bucket->next;

			free(bucket->str);
			free(bucket);
		}
	}

	free(table->buckets);
	free(table->strings);
	memset(table, 0, sizeof(*table));
}

int str_table_get_index(str_table_t *table, const char *str, size_t *idx)
{
	str_bucket_t *bucket;
	sqfs_u32 hash;
	size_t index;
	int err;

	hash = strhash(str);
	index = hash % table->num_buckets;
	bucket = table->buckets[index];

	while (bucket != NULL) {
		if (strcmp(bucket->str, str) == 0) {
			*idx = bucket->index;
			return 0;
		}

		bucket = bucket->next;
	}

	err = strings_grow(table);
	if (err)
		return err;

	bucket = calloc(1, sizeof(*bucket));
	if (bucket == NULL)
		goto fail_oom;

	bucket->str = strdup(str);
	if (bucket->str == NULL)
		goto fail_oom;

	bucket->index = table->num_strings;
	table->strings[table->num_strings++] = bucket->str;
	*idx = bucket->index;

	bucket->next = table->buckets[index];
	table->buckets[index] = bucket;
	return 0;
fail_oom:
	free(bucket);
	return SQFS_ERROR_ALLOC;
}

const char *str_table_get_string(str_table_t *table, size_t index)
{
	if (index >= table->num_strings)
		return NULL;

	return table->strings[index];
}

static str_bucket_t *bucket_by_index(str_table_t *table, size_t index)
{
	str_bucket_t *bucket = NULL;
	sqfs_u32 hash;

	if (index < table->num_strings) {
		hash = strhash(table->strings[index]);
		bucket = table->buckets[hash % table->num_buckets];

		while (bucket != NULL && bucket->index != index)
			bucket = bucket->next;
	}

	return bucket;
}

void str_table_add_ref(str_table_t *table, size_t index)
{
	str_bucket_t *bucket = bucket_by_index(table, index);

	if (bucket != NULL && bucket->refcount < ~((size_t)0))
		bucket->refcount += 1;
}

void str_table_del_ref(str_table_t *table, size_t index)
{
	str_bucket_t *bucket = bucket_by_index(table, index);

	if (bucket != NULL && bucket->refcount > 0)
		bucket->refcount -= 1;
}

size_t str_table_get_ref_count(str_table_t *table, size_t index)
{
	str_bucket_t *bucket = bucket_by_index(table, index);

	return bucket != NULL ? bucket->refcount : 0;
}