mirror of https://github.com/torvalds/linux.git
69 lines
1.4 KiB
C
69 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Manage a cache of file names' existence */
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#include <pthread.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <linux/compiler.h>
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#include "fncache.h"
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#include "hashmap.h"
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static struct hashmap *fncache;
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static size_t fncache__hash(long key, void *ctx __maybe_unused)
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{
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return str_hash((const char *)key);
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}
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static bool fncache__equal(long key1, long key2, void *ctx __maybe_unused)
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{
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return strcmp((const char *)key1, (const char *)key2) == 0;
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}
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static void fncache__init(void)
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{
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fncache = hashmap__new(fncache__hash, fncache__equal, /*ctx=*/NULL);
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}
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static struct hashmap *fncache__get(void)
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{
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static pthread_once_t fncache_once = PTHREAD_ONCE_INIT;
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pthread_once(&fncache_once, fncache__init);
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return fncache;
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}
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static bool lookup_fncache(const char *name, bool *res)
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{
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long val;
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if (!hashmap__find(fncache__get(), name, &val))
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return false;
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*res = (val != 0);
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return true;
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}
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static void update_fncache(const char *name, bool res)
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{
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char *old_key = NULL, *key = strdup(name);
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if (key) {
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hashmap__set(fncache__get(), key, res, &old_key, /*old_value*/NULL);
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free(old_key);
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}
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}
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/* No LRU, only use when bounded in some other way. */
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bool file_available(const char *name)
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{
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bool res;
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if (lookup_fncache(name, &res))
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return res;
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res = access(name, R_OK) == 0;
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update_fncache(name, res);
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return res;
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}
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