1 | // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) |
2 | /* Copyright (c) 2021 Facebook */ |
3 | #include <stdint.h> |
4 | #include <stdlib.h> |
5 | #include <stdio.h> |
6 | #include <errno.h> |
7 | #include <linux/err.h> |
8 | #include "hashmap.h" |
9 | #include "libbpf_internal.h" |
10 | #include "strset.h" |
11 | |
12 | struct strset { |
13 | void *strs_data; |
14 | size_t strs_data_len; |
15 | size_t strs_data_cap; |
16 | size_t strs_data_max_len; |
17 | |
18 | /* lookup index for each unique string in strings set */ |
19 | struct hashmap *strs_hash; |
20 | }; |
21 | |
22 | static size_t strset_hash_fn(long key, void *ctx) |
23 | { |
24 | const struct strset *s = ctx; |
25 | const char *str = s->strs_data + key; |
26 | |
27 | return str_hash(s: str); |
28 | } |
29 | |
30 | static bool strset_equal_fn(long key1, long key2, void *ctx) |
31 | { |
32 | const struct strset *s = ctx; |
33 | const char *str1 = s->strs_data + key1; |
34 | const char *str2 = s->strs_data + key2; |
35 | |
36 | return strcmp(str1, str2) == 0; |
37 | } |
38 | |
39 | struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t init_data_sz) |
40 | { |
41 | struct strset *set = calloc(1, sizeof(*set)); |
42 | struct hashmap *hash; |
43 | int err = -ENOMEM; |
44 | |
45 | if (!set) |
46 | return ERR_PTR(error: -ENOMEM); |
47 | |
48 | hash = hashmap__new(hash_fn: strset_hash_fn, equal_fn: strset_equal_fn, ctx: set); |
49 | if (IS_ERR(ptr: hash)) |
50 | goto err_out; |
51 | |
52 | set->strs_data_max_len = max_data_sz; |
53 | set->strs_hash = hash; |
54 | |
55 | if (init_data) { |
56 | long off; |
57 | |
58 | set->strs_data = malloc(init_data_sz); |
59 | if (!set->strs_data) |
60 | goto err_out; |
61 | |
62 | memcpy(set->strs_data, init_data, init_data_sz); |
63 | set->strs_data_len = init_data_sz; |
64 | set->strs_data_cap = init_data_sz; |
65 | |
66 | for (off = 0; off < set->strs_data_len; off += strlen(set->strs_data + off) + 1) { |
67 | /* hashmap__add() returns EEXIST if string with the same |
68 | * content already is in the hash map |
69 | */ |
70 | err = hashmap__add(hash, off, off); |
71 | if (err == -EEXIST) |
72 | continue; /* duplicate */ |
73 | if (err) |
74 | goto err_out; |
75 | } |
76 | } |
77 | |
78 | return set; |
79 | err_out: |
80 | strset__free(set); |
81 | return ERR_PTR(error: err); |
82 | } |
83 | |
84 | void strset__free(struct strset *set) |
85 | { |
86 | if (IS_ERR_OR_NULL(ptr: set)) |
87 | return; |
88 | |
89 | hashmap__free(map: set->strs_hash); |
90 | free(set->strs_data); |
91 | free(set); |
92 | } |
93 | |
94 | size_t strset__data_size(const struct strset *set) |
95 | { |
96 | return set->strs_data_len; |
97 | } |
98 | |
99 | const char *strset__data(const struct strset *set) |
100 | { |
101 | return set->strs_data; |
102 | } |
103 | |
104 | static void *strset_add_str_mem(struct strset *set, size_t add_sz) |
105 | { |
106 | return libbpf_add_mem(data: &set->strs_data, cap_cnt: &set->strs_data_cap, elem_sz: 1, |
107 | cur_cnt: set->strs_data_len, max_cnt: set->strs_data_max_len, add_cnt: add_sz); |
108 | } |
109 | |
110 | /* Find string offset that corresponds to a given string *s*. |
111 | * Returns: |
112 | * - >0 offset into string data, if string is found; |
113 | * - -ENOENT, if string is not in the string data; |
114 | * - <0, on any other error. |
115 | */ |
116 | int strset__find_str(struct strset *set, const char *s) |
117 | { |
118 | long old_off, new_off, len; |
119 | void *p; |
120 | |
121 | /* see strset__add_str() for why we do this */ |
122 | len = strlen(s) + 1; |
123 | p = strset_add_str_mem(set, add_sz: len); |
124 | if (!p) |
125 | return -ENOMEM; |
126 | |
127 | new_off = set->strs_data_len; |
128 | memcpy(p, s, len); |
129 | |
130 | if (hashmap__find(set->strs_hash, new_off, &old_off)) |
131 | return old_off; |
132 | |
133 | return -ENOENT; |
134 | } |
135 | |
136 | /* Add a string s to the string data. If the string already exists, return its |
137 | * offset within string data. |
138 | * Returns: |
139 | * - > 0 offset into string data, on success; |
140 | * - < 0, on error. |
141 | */ |
142 | int strset__add_str(struct strset *set, const char *s) |
143 | { |
144 | long old_off, new_off, len; |
145 | void *p; |
146 | int err; |
147 | |
148 | /* Hashmap keys are always offsets within set->strs_data, so to even |
149 | * look up some string from the "outside", we need to first append it |
150 | * at the end, so that it can be addressed with an offset. Luckily, |
151 | * until set->strs_data_len is incremented, that string is just a piece |
152 | * of garbage for the rest of the code, so no harm, no foul. On the |
153 | * other hand, if the string is unique, it's already appended and |
154 | * ready to be used, only a simple set->strs_data_len increment away. |
155 | */ |
156 | len = strlen(s) + 1; |
157 | p = strset_add_str_mem(set, add_sz: len); |
158 | if (!p) |
159 | return -ENOMEM; |
160 | |
161 | new_off = set->strs_data_len; |
162 | memcpy(p, s, len); |
163 | |
164 | /* Now attempt to add the string, but only if the string with the same |
165 | * contents doesn't exist already (HASHMAP_ADD strategy). If such |
166 | * string exists, we'll get its offset in old_off (that's old_key). |
167 | */ |
168 | err = hashmap__insert(set->strs_hash, new_off, new_off, |
169 | HASHMAP_ADD, &old_off, NULL); |
170 | if (err == -EEXIST) |
171 | return old_off; /* duplicated string, return existing offset */ |
172 | if (err) |
173 | return err; |
174 | |
175 | set->strs_data_len += len; /* new unique string, adjust data length */ |
176 | return new_off; |
177 | } |
178 | |