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https://github.com/facebook/sapling.git
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62c802bfdc
Summary: This allows hg on EdenFS to be able to create symlinks with absolute paths on Windows as well as check out commits with absolute path symlinks. There are a few caveats here: - Symlinks with absolute paths will only be usable on the same type of OS (Windows vs. POSIX) they were created. - Checking out commits with absolute paths created on POSIX (i.e., starting with `/`) aren't usable on Windows - Symlinks with absolute paths created on Windows will keep the same drive letter across different checkouts. - E.g., if the root of the EdenFS checkout is somewhere at `C:\` and there is a symlink pointing to somewhere like `D:\foo\bar.txt`, and then that same commit is checked out in a different Windows machine with that same repo mounted at `E:\`, that symlink will still point to `D:\foo\bar.txt` If there seems to be some UNC wonkiness in this commit, it is because UNC usage on symlinks is quite inconsistent on Windows: - Things that use UNC for absolute path symlinks: - Windows' `mklink` command (creates symlinks with UNC paths) - Python's `os.symlink` (same as above) - Hg commits - EdenFS (when stored as Inodes; some functions like `realpath`) - Things that don't use UNC for absolute path symlinks: - `PrjWritePlaceholderInfo2` - `PrjFillDirEntryBuffer2` - `std::filesystem::read_symlink` Reviewed By: xavierd Differential Revision: D47227590 fbshipit-source-id: b92c8462ad3f13c2724b76ee61f8c095695027cd
117 lines
3.2 KiB
C++
117 lines
3.2 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#include <folly/portability/OpenSSL.h>
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#include <filesystem>
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#include "eden/common/utils/WinError.h"
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#include "eden/fs/digest/Blake3.h"
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#include "eden/fs/utils/FileHash.h"
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namespace facebook::eden {
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#ifdef _WIN32
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namespace {
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constexpr size_t kBufSize = 8192;
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template <typename Hasher>
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void hash(Hasher&& hasher, AbsolutePathPiece filePath) {
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const auto widePath = filePath.wide();
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// On Windows we need to calculate the hash of symlinks for commands such as
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// `hg status` and `hg goto`. In POSIX FileInode::isSameAsFast overlay info
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// that is not available on Windows allows us to avoid comparing symlinks by
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// hash, whereas on Windows we have to go through this somewhat slower step.
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std::error_code ec;
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auto stdPath = std::filesystem::path(widePath);
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auto lnk = std::filesystem::read_symlink(stdPath, ec);
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if (ec.value() == 0) {
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std::wstring lnkW = lnk.wstring();
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std::string content;
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std::transform(
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lnkW.begin(), lnkW.end(), std::back_inserter(content), [](wchar_t c) {
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return (char)c;
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});
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if (std::isalpha(content[0]) && content[1] == ':') {
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// Symlinks with absolute paths use UNC paths. However, std's read_symlink
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// returns the target without its UNC prefix. If this is not converted
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// back to an UNC path, we get hashing errors.
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content = canonicalPath(content).asString();
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}
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std::replace(content.begin(), content.end(), '\\', '/');
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hasher(content.c_str(), content.size());
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return;
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}
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HANDLE fileHandle = CreateFileW(
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widePath.c_str(),
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GENERIC_READ,
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FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
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nullptr,
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OPEN_EXISTING,
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FILE_ATTRIBUTE_NORMAL,
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nullptr);
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if (INVALID_HANDLE_VALUE == fileHandle) {
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throw makeWin32ErrorExplicit(
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GetLastError(), fmt::format(FMT_STRING("couldn't open {}"), filePath));
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}
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SCOPE_EXIT {
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CloseHandle(fileHandle);
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};
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uint8_t buf[kBufSize];
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while (true) {
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DWORD bytesRead;
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if (!ReadFile(fileHandle, buf, sizeof(buf), &bytesRead, nullptr)) {
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throw makeWin32ErrorExplicit(
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GetLastError(),
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fmt::format(
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FMT_STRING("Error while computing SHA1 of {}"), filePath));
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}
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if (bytesRead == 0) {
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break;
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}
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hasher(buf, bytesRead);
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}
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}
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} // namespace
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Hash32 getFileBlake3(
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AbsolutePathPiece filePath,
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const std::optional<std::string>& maybeBlake3Key) {
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auto hasher = Blake3::create(maybeBlake3Key);
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hash(
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[&hasher](const auto* buf, auto len) { hasher.update(buf, len); },
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filePath);
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static_assert(Hash32::RAW_SIZE == BLAKE3_OUT_LEN);
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Hash32 blake3;
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hasher.finalize(blake3.mutableBytes());
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return blake3;
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}
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Hash20 getFileSha1(AbsolutePathPiece filePath) {
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SHA_CTX ctx;
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SHA1_Init(&ctx);
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hash(
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[&ctx](const auto* buf, auto len) { SHA1_Update(&ctx, buf, len); },
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filePath);
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static_assert(Hash20::RAW_SIZE == SHA_DIGEST_LENGTH);
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Hash20 sha1;
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SHA1_Final(sha1.mutableBytes().begin(), &ctx);
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return sha1;
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}
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#endif
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} // namespace facebook::eden
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