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(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(-ENOMEM); 47 48 hash = hashmap__new(strset_hash_fn, strset_equal_fn, set); 49 if (IS_ERR(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(err); 82 } 83 84 void strset__free(struct strset *set) 85 { 86 if (IS_ERR_OR_NULL(set)) 87 return; 88 89 hashmap__free(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(&set->strs_data, &set->strs_data_cap, 1, 107 set->strs_data_len, set->strs_data_max_len, 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, 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, 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