[Reproducers] Add file provider
This patch adds the file provider which is responsible for capturing
files used by LLDB.
When capturing a reproducer, we use a file collector that is very
similar to the one used in clang. For every file that we touch, we add
an entry with a mapping from its virtual to its real path. When we
decide to generate a reproducer we copy over the files and their
permission into to reproducer folder.
When replaying a reproducer, we load the VFS mapping and instantiate a
RedirectingFileSystem. The latter will transparently use the files
available in the reproducer.
I've tested this on two macOS machines with an artificial example.
Still, it is very likely that I missed some places where we (still) use
native file system calls. I'm hoping to flesh those out while testing
with more advanced examples. However, I will fix those things in
separate patches.
Differential revision: https://reviews.llvm.org/D54617
llvm-svn: 352538
diff --git a/lldb/source/Utility/FileCollector.cpp b/lldb/source/Utility/FileCollector.cpp
new file mode 100644
index 0000000..1758ad8c
--- /dev/null
+++ b/lldb/source/Utility/FileCollector.cpp
@@ -0,0 +1,148 @@
+//===-- FileCollector.cpp ---------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Utility/FileCollector.h"
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+
+using namespace lldb_private;
+using namespace llvm;
+
+static bool IsCaseSensitivePath(StringRef path) {
+ SmallString<256> tmp_dest = path, upper_dest, real_dest;
+
+ // Remove component traversals, links, etc.
+ if (!sys::fs::real_path(path, tmp_dest))
+ return true; // Current default value in vfs.yaml
+ path = tmp_dest;
+
+ // Change path to all upper case and ask for its real path, if the latter
+ // exists and is equal to path, it's not case sensitive. Default to case
+ // sensitive in the absence of real_path, since this is the YAMLVFSWriter
+ // default.
+ upper_dest = path.upper();
+ if (sys::fs::real_path(upper_dest, real_dest) && path.equals(real_dest))
+ return false;
+ return true;
+}
+
+FileCollector::FileCollector(const FileSpec &root) : m_root(root) {
+ sys::fs::create_directories(m_root.GetPath(), true);
+}
+
+bool FileCollector::GetRealPath(StringRef src_path,
+ SmallVectorImpl<char> &result) {
+ SmallString<256> real_path;
+ StringRef FileName = sys::path::filename(src_path);
+ std::string directory = sys::path::parent_path(src_path).str();
+ auto dir_with_symlink = m_symlink_map.find(directory);
+
+ // Use real_path to fix any symbolic link component present in a path.
+ // Computing the real path is expensive, cache the search through the
+ // parent path directory.
+ if (dir_with_symlink == m_symlink_map.end()) {
+ auto ec = sys::fs::real_path(directory, real_path);
+ if (ec)
+ return false;
+ m_symlink_map[directory] = real_path.str();
+ } else {
+ real_path = dir_with_symlink->second;
+ }
+
+ sys::path::append(real_path, FileName);
+ result.swap(real_path);
+ return true;
+}
+
+void FileCollector::AddFile(const Twine &file) {
+ std::lock_guard<std::mutex> lock(m_mutex);
+ std::string file_str = file.str();
+ if (MarkAsSeen(file_str))
+ AddFileImpl(file_str);
+}
+
+void FileCollector::AddFileImpl(StringRef src_path) {
+ std::string root = m_root.GetPath();
+
+ // We need an absolute src path to append to the root.
+ SmallString<256> absolute_src = src_path;
+ sys::fs::make_absolute(absolute_src);
+
+ // Canonicalize src to a native path to avoid mixed separator styles.
+ sys::path::native(absolute_src);
+
+ // Remove redundant leading "./" pieces and consecutive separators.
+ absolute_src = sys::path::remove_leading_dotslash(absolute_src);
+
+ // Canonicalize the source path by removing "..", "." components.
+ SmallString<256> virtual_path = absolute_src;
+ sys::path::remove_dots(virtual_path, /*remove_dot_dot=*/true);
+
+ // If a ".." component is present after a symlink component, remove_dots may
+ // lead to the wrong real destination path. Let the source be canonicalized
+ // like that but make sure we always use the real path for the destination.
+ SmallString<256> copy_from;
+ if (!GetRealPath(absolute_src, copy_from))
+ copy_from = virtual_path;
+
+ SmallString<256> dst_path = StringRef(root);
+ sys::path::append(dst_path, sys::path::relative_path(copy_from));
+
+ // Always map a canonical src path to its real path into the YAML, by doing
+ // this we map different virtual src paths to the same entry in the VFS
+ // overlay, which is a way to emulate symlink inside the VFS; this is also
+ // needed for correctness, not doing that can lead to module redefinition
+ // errors.
+ AddFileToMapping(virtual_path, dst_path);
+}
+
+std::error_code FileCollector::CopyFiles(bool stop_on_error) {
+ for (auto &entry : m_vfs_writer.getMappings()) {
+ // Create directory tree.
+ if (std::error_code ec =
+ sys::fs::create_directories(sys::path::parent_path(entry.RPath),
+ /*IgnoreExisting=*/true)) {
+ if (stop_on_error)
+ return ec;
+ }
+
+ // Copy file over.
+ if (std::error_code ec = sys::fs::copy_file(entry.VPath, entry.RPath)) {
+ if (stop_on_error)
+ return ec;
+ }
+
+ // Copy over permissions.
+ if (auto perms = sys::fs::getPermissions(entry.VPath)) {
+ if (std::error_code ec = sys::fs::setPermissions(entry.RPath, *perms)) {
+ if (stop_on_error)
+ return ec;
+ }
+ }
+ }
+ return {};
+}
+
+std::error_code FileCollector::WriteMapping(const FileSpec &mapping_file) {
+ std::lock_guard<std::mutex> lock(m_mutex);
+
+ const std::string root = m_root.GetPath();
+ m_vfs_writer.setCaseSensitivity(IsCaseSensitivePath(root));
+ m_vfs_writer.setUseExternalNames(false);
+
+ std::error_code ec;
+ raw_fd_ostream os(mapping_file.GetPath(), ec, sys::fs::F_Text);
+ if (ec)
+ return ec;
+
+ m_vfs_writer.write(os);
+
+ return {};
+}