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//===-- FileCollector.h -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_FILECOLLECTOR_H
#define LLVM_SUPPORT_FILECOLLECTOR_H
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/VirtualFileSystem.h"
#include <mutex>
#include <string>
namespace llvm {
class FileCollectorFileSystem;
class Twine;
class FileCollectorBase {
public:
FileCollectorBase();
virtual ~FileCollectorBase();
void addFile(const Twine &file);
void addDirectory(const Twine &Dir);
protected:
bool markAsSeen(StringRef Path) {
if (Path.empty())
return false;
return Seen.insert(Path).second;
}
virtual void addFileImpl(StringRef SrcPath) = 0;
virtual llvm::vfs::directory_iterator
addDirectoryImpl(const llvm::Twine &Dir,
IntrusiveRefCntPtr<vfs::FileSystem> FS,
std::error_code &EC) = 0;
/// Synchronizes access to internal data structures.
std::mutex Mutex;
/// Tracks already seen files so they can be skipped.
StringSet<> Seen;
};
/// Captures file system interaction and generates data to be later replayed
/// with the RedirectingFileSystem.
///
/// For any file that gets accessed we eventually create:
/// - a copy of the file inside Root
/// - a record in RedirectingFileSystem mapping that maps:
/// current real path -> path to the copy in Root
///
/// That intent is that later when the mapping is used by RedirectingFileSystem
/// it simulates the state of FS that we collected.
///
/// We generate file copies and mapping lazily - see writeMapping and copyFiles.
/// We don't try to capture the state of the file at the exact time when it's
/// accessed. Files might get changed, deleted ... we record only the "final"
/// state.
///
/// In order to preserve the relative topology of files we use their real paths
/// as relative paths inside of the Root.
class FileCollector : public FileCollectorBase {
public:
/// Helper utility that encapsulates the logic for canonicalizing a virtual
/// path and a path to copy from.
class PathCanonicalizer {
public:
struct PathStorage {
SmallString<256> CopyFrom;
SmallString<256> VirtualPath;
};
/// Canonicalize a pair of virtual and real paths.
PathStorage canonicalize(StringRef SrcPath);
private:
/// Replace with a (mostly) real path, or don't modify. Resolves symlinks
/// in the directory, using \a CachedDirs to avoid redundant lookups, but
/// leaves the filename as a possible symlink.
void updateWithRealPath(SmallVectorImpl<char> &Path);
StringMap<std::string> CachedDirs;
};
/// \p Root is the directory where collected files are will be stored.
/// \p OverlayRoot is VFS mapping root.
/// \p Root directory gets created in copyFiles unless it already exists.
FileCollector(std::string Root, std::string OverlayRoot);
/// Write the yaml mapping (for the VFS) to the given file.
std::error_code writeMapping(StringRef MappingFile);
/// Copy the files into the root directory.
///
/// When StopOnError is true (the default) we abort as soon as one file
/// cannot be copied. This is relatively common, for example when a file was
/// removed after it was added to the mapping.
std::error_code copyFiles(bool StopOnError = true);
/// Create a VFS that uses \p Collector to collect files accessed via \p
/// BaseFS.
static IntrusiveRefCntPtr<vfs::FileSystem>
createCollectorVFS(IntrusiveRefCntPtr<vfs::FileSystem> BaseFS,
std::shared_ptr<FileCollector> Collector);
private:
friend FileCollectorFileSystem;
void addFileToMapping(StringRef VirtualPath, StringRef RealPath) {
if (sys::fs::is_directory(VirtualPath))
VFSWriter.addDirectoryMapping(VirtualPath, RealPath);
else
VFSWriter.addFileMapping(VirtualPath, RealPath);
}
protected:
void addFileImpl(StringRef SrcPath) override;
llvm::vfs::directory_iterator
addDirectoryImpl(const llvm::Twine &Dir,
IntrusiveRefCntPtr<vfs::FileSystem> FS,
std::error_code &EC) override;
/// The directory where collected files are copied to in copyFiles().
const std::string Root;
/// The root directory where the VFS overlay lives.
const std::string OverlayRoot;
/// The yaml mapping writer.
vfs::YAMLVFSWriter VFSWriter;
/// Helper utility for canonicalizing paths.
PathCanonicalizer Canonicalizer;
};
} // end namespace llvm
#endif // LLVM_SUPPORT_FILECOLLECTOR_H
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