// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) /* Copyright (c) 2021 Facebook */ #include <stdint.h> #include <stdlib.h> #include <stdio.h> #include <errno.h> #include <linux/err.h> #include "hashmap.h" #include "libbpf_internal.h" #include "strset.h" struct strset { void *strs_data; size_t strs_data_len; size_t strs_data_cap; size_t strs_data_max_len; /* lookup index for each unique string in strings set */ struct hashmap *strs_hash; }; static size_t strset_hash_fn(const void *key, void *ctx) { const struct strset *s = ctx; const char *str = s->strs_data + (long)key; return str_hash(str); } static bool strset_equal_fn(const void *key1, const void *key2, void *ctx) { const struct strset *s = ctx; const char *str1 = s->strs_data + (long)key1; const char *str2 = s->strs_data + (long)key2; return strcmp(str1, str2) == 0; } struct strset *strset__new(size_t max_data_sz, const char *init_data, size_t init_data_sz) { struct strset *set = calloc(1, sizeof(*set)); struct hashmap *hash; int err = -ENOMEM; if (!set) return ERR_PTR(-ENOMEM); hash = hashmap__new(strset_hash_fn, strset_equal_fn, set); if (IS_ERR(hash)) goto err_out; set->strs_data_max_len = max_data_sz; set->strs_hash = hash; if (init_data) { long off; set->strs_data = malloc(init_data_sz); if (!set->strs_data) goto err_out; memcpy(set->strs_data, init_data, init_data_sz); set->strs_data_len = init_data_sz; set->strs_data_cap = init_data_sz; for (off = 0; off < set->strs_data_len; off += strlen(set->strs_data + off) + 1) { /* hashmap__add() returns EEXIST if string with the same * content already is in the hash map */ err = hashmap__add(hash, (void *)off, (void *)off); if (err == -EEXIST) continue; /* duplicate */ if (err) goto err_out; } } return set; err_out: strset__free(set); return ERR_PTR(err); } void strset__free(struct strset *set) { if (IS_ERR_OR_NULL(set)) return; hashmap__free(set->strs_hash); free(set->strs_data); } size_t strset__data_size(const struct strset *set) { return set->strs_data_len; } const char *strset__data(const struct strset *set) { return set->strs_data; } static void *strset_add_str_mem(struct strset *set, size_t add_sz) { return libbpf_add_mem(&set->strs_data, &set->strs_data_cap, 1, set->strs_data_len, set->strs_data_max_len, add_sz); } /* Find string offset that corresponds to a given string *s*. * Returns: * - >0 offset into string data, if string is found; * - -ENOENT, if string is not in the string data; * - <0, on any other error. */ int strset__find_str(struct strset *set, const char *s) { long old_off, new_off, len; void *p; /* see strset__add_str() for why we do this */ len = strlen(s) + 1; p = strset_add_str_mem(set, len); if (!p) return -ENOMEM; new_off = set->strs_data_len; memcpy(p, s, len); if (hashmap__find(set->strs_hash, (void *)new_off, (void **)&old_off)) return old_off; return -ENOENT; } /* Add a string s to the string data. If the string already exists, return its * offset within string data. * Returns: * - > 0 offset into string data, on success; * - < 0, on error. */ int strset__add_str(struct strset *set, const char *s) { long old_off, new_off, len; void *p; int err; /* Hashmap keys are always offsets within set->strs_data, so to even * look up some string from the "outside", we need to first append it * at the end, so that it can be addressed with an offset. Luckily, * until set->strs_data_len is incremented, that string is just a piece * of garbage for the rest of the code, so no harm, no foul. On the * other hand, if the string is unique, it's already appended and * ready to be used, only a simple set->strs_data_len increment away. */ len = strlen(s) + 1; p = strset_add_str_mem(set, len); if (!p) return -ENOMEM; new_off = set->strs_data_len; memcpy(p, s, len); /* Now attempt to add the string, but only if the string with the same * contents doesn't exist already (HASHMAP_ADD strategy). If such * string exists, we'll get its offset in old_off (that's old_key). */ err = hashmap__insert(set->strs_hash, (void *)new_off, (void *)new_off, HASHMAP_ADD, (const void **)&old_off, NULL); if (err == -EEXIST) return old_off; /* duplicated string, return existing offset */ if (err) return err; set->strs_data_len += len; /* new unique string, adjust data length */ return new_off; }