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/* Copyright 2017-present Facebook, Inc.
* Licensed under the Apache License, Version 2.0 */
#include "ContentHash.h"
#include "ThreadPool.h"
#include "watchman_hash.h"
#include "watchman_stream.h"
#ifdef __APPLE__
#define COMMON_DIGEST_FOR_OPENSSL
#include "CommonCrypto/CommonDigest.h"
#elif defined(_WIN32)
#include <Wincrypt.h>
#else
#include <openssl/sha.h>
#endif
#include <string>
#include "Logging.h"
#include "FileSystem.h"
#include "watchman_scopeguard.h"
namespace watchman {
using HashValue = typename ContentHashCache::HashValue;
using Node = typename ContentHashCache::Node;
bool ContentHashCacheKey::operator==(const ContentHashCacheKey& other) const {
return fileSize == other.fileSize && mtime.tv_sec == other.mtime.tv_sec &&
mtime.tv_nsec == other.mtime.tv_nsec &&
relativePath == other.relativePath;
}
std::size_t ContentHashCacheKey::hashValue() const {
return hash_128_to_64(
w_string_hval(relativePath),
hash_128_to_64(fileSize, hash_128_to_64(mtime.tv_sec, mtime.tv_nsec)));
}
ContentHashCache::ContentHashCache(
const w_string& rootPath,
size_t maxItems,
std::chrono::milliseconds errorTTL)
: cache_(maxItems, errorTTL), rootPath_(rootPath) {}
Future<std::shared_ptr<const Node>> ContentHashCache::get(
const ContentHashCacheKey& key) {
return cache_.get(
key, [this](const ContentHashCacheKey& k) { return computeHash(k); });
}
HashValue ContentHashCache::computeHashImmediate(
const ContentHashCacheKey& key) const {
HashValue result;
uint8_t buf[8192];
auto fullPath = w_string::pathCat({rootPath_, key.relativePath});
auto stm = w_stm_open(fullPath.c_str(), O_RDONLY);
if (!stm) {
throw std::system_error(
errno,
std::generic_category(),
to<std::string>("w_stm_open ", fullPath));
}
#ifndef _WIN32
SHA_CTX ctx;
SHA1_Init(&ctx);
while (true) {
auto n = stm->read(buf, sizeof(buf));
if (n == 0) {
break;
}
if (n < 0) {
throw std::system_error(
errno,
std::generic_category(),
to<std::string>("while reading from ", fullPath));
}
SHA1_Update(&ctx, buf, n);
}
SHA1_Final(result.data(), &ctx);
#else
// Use the built-in crypt provider API on windows to avoid introducing a
// dependency on openssl in the windows build.
HCRYPTPROV provider{0};
HCRYPTHASH ctx{0};
if (!CryptAcquireContext(
&provider,
nullptr,
nullptr,
PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
throw std::system_error(
GetLastError(), std::system_category(), "CryptAcquireContext");
}
SCOPE_EXIT {
CryptReleaseContext(provider, 0);
};
if (!CryptCreateHash(provider, CALG_SHA1, 0, 0, &ctx)) {
throw std::system_error(
GetLastError(), std::system_category(), "CryptCreateHash");
}
SCOPE_EXIT {
CryptDestroyHash(ctx);
};
while (true) {
auto n = stm->read(buf, sizeof(buf));
if (n == 0) {
break;
}
if (n < 0) {
throw std::system_error(
errno,
std::generic_category(),
to<std::string>("while reading from ", fullPath));
}
if (!CryptHashData(ctx, buf, n, 0)) {
throw std::system_error(
GetLastError(), std::system_category(), "CryptHashData");
}
}
DWORD size = result.size();
if (!CryptGetHashParam(ctx, HP_HASHVAL, result.data(), &size, 0)) {
throw std::system_error(
GetLastError(), std::system_category(), "CryptGetHashParam HP_HASHVAL");
}
#endif
// Since TOCTOU is everywhere and everything, double check to make sure that
// the file looks like we were expecting at the start. If it isn't, then
// we want to throw an exception and avoid associating the hash of whatever
// state we just read with this cache key.
auto stat = getFileInformation(fullPath.c_str());
if (size_t(stat.size) != key.fileSize ||
stat.mtime.tv_sec != key.mtime.tv_sec ||
stat.mtime.tv_nsec != key.mtime.tv_nsec) {
throw std::runtime_error(
"metadata changed during hashing; query again to get latest status");
}
return result;
}
Future<HashValue> ContentHashCache::computeHash(
const ContentHashCacheKey& key) const {
return makeFuture(key)
.via(&getThreadPool())
.then([this](Result<ContentHashCacheKey>&& key) {
return computeHashImmediate(key.value());
});
}
const w_string& ContentHashCache::rootPath() const {
return rootPath_;
}
CacheStats ContentHashCache::stats() const {
return cache_.stats();
}
}
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