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