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#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <libgen.h>
#include <openssl/sha.h>
#include "read-cache.h"
char *cache;
char *cache_end;
char *current_cache_entry;
void cache_init(const char *path)
{
FILE *f = cache_open(path, "r");
if (!f) {
printf("no cache\n");
return;
}
struct stat buf;
fstat(fileno(f), &buf);
cache = malloc(buf.st_size);
fread(cache, 1, buf.st_size, f);
fclose(f);
/* set the current entry to the begining of the cache */
current_cache_entry = cache;
cache_end = cache + buf.st_size;
}
FILE *cache_open(const char *path, const char *mode)
{
FILE *cache;
char *cache_path;
char *path_copy = strdup(path);
char *dir = dirname(path_copy);
asprintf(&cache_path, "%s/cache", dir);
cache = fopen(cache_path, mode);
free(cache_path);
free(path_copy);
return cache;
}
#define MIN(a, b) (a) < (b) ? (a) : (b)
static void print_hash(const unsigned char *hash)
{
int i;
for (i=0; i<SHA_DIGEST_LENGTH; i++) {
printf("%02x", hash[i]);
}
printf("\n");
}
static int cache_misses;
static int cache_hits;
void cache_stats_print(void)
{
printf("cache: %d of %d hits\n", cache_hits, cache_misses + cache_hits);
}
int cache_compare(const char *path, const unsigned char *buffer, unsigned int length)
{
char *path_copy = strdup(path);
char *name = basename(path_copy);
int match = 0;
//printf("compare: %s\n", path);
int name_length = strlen(name);
while (current_cache_entry < cache_end) {
int cache_length = strlen(current_cache_entry);
int min_length = MIN(cache_length, name_length);
int result = memcmp(name, current_cache_entry, min_length);
if (result == 0) {
char *cache_hash = current_cache_entry + cache_length + 1;
unsigned char hash[SHA_DIGEST_LENGTH];
//printf("found entry\n");
SHA1(buffer, length, hash);
//print_hash(cache_hash);
//print_hash(hash);
current_cache_entry = cache_hash + SHA_DIGEST_LENGTH;
match = memcmp(hash, cache_hash, SHA_DIGEST_LENGTH) == 0 ? 1 : 0;
//printf("match %d\n", match);
break;
} else if (result < 0) {
break;
} else {
//printf("trying next entry: %s vs. %s did not match\n", name, current_cache_entry);
current_cache_entry += cache_length + 1 + SHA_DIGEST_LENGTH;
}
}
free(path_copy);
if (match)
cache_hits++;
else
cache_misses++;
return match;
}
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