lldb/source/Utility/RealpathPrefixes.cpp

   1 //===-- RealpathPrefixes.cpp ----------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Utility/RealpathPrefixes.h"
  10
  11 #include "lldb/Utility/FileSpec.h"
  12 #include "lldb/Utility/FileSpecList.h"
  13 #include "lldb/Utility/LLDBLog.h"
  14 #include "lldb/Utility/Log.h"
  15 #include "lldb/lldb-private-types.h"
  16
  17 using namespace lldb_private;
  18
  19 RealpathPrefixes::RealpathPrefixes(
  20     const FileSpecList &file_spec_list,
  21     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs)
  22     : m_fs(fs) {
  23   m_prefixes.reserve(file_spec_list.GetSize());
  24   for (const FileSpec &file_spec : file_spec_list) {
  25     m_prefixes.emplace_back(file_spec.GetPath());
  26   }
  27 }
  28
  29 std::optional<FileSpec>
  30 RealpathPrefixes::ResolveSymlinks(const FileSpec &file_spec) {
  31   if (m_prefixes.empty())
  32     return std::nullopt;
  33
  34   // Test if `b` is a *path* prefix of `a` (not just *string* prefix).
  35   // E.g. "/foo/bar" is a path prefix of "/foo/bar/baz" but not "/foo/barbaz".
  36   auto is_path_prefix = [](llvm::StringRef a, llvm::StringRef b,
  37                            bool case_sensitive,
  38                            llvm::sys::path::Style style) -> bool {
  39     if (case_sensitive ? a.consume_front(b) : a.consume_front_insensitive(b))
  40       // If `b` isn't "/", then it won't end with "/" because it comes from
  41       // `FileSpec`. After `a` consumes `b`, `a` should either be empty (i.e.
  42       // `a` == `b`) or end with "/" (the remainder of `a` is a subdirectory).
  43       return b == "/" || a.empty() ||
  44              llvm::sys::path::is_separator(a[0], style);
  45     return false;
  46   };
  47   std::string file_spec_path = file_spec.GetPath();
  48   for (const std::string &prefix : m_prefixes) {
  49     if (is_path_prefix(file_spec_path, prefix, file_spec.IsCaseSensitive(),
  50                        file_spec.GetPathStyle())) {
  51       // Stats and logging.
  52       IncreaseSourceRealpathAttemptCount();
  53       Log *log = GetLog(LLDBLog::Source);
  54       LLDB_LOGF(log, "Realpath'ing support file %s", file_spec_path.c_str());
  55
  56       // One prefix matched. Try to realpath.
  57       PathSmallString buff;
  58       std::error_code ec = m_fs->getRealPath(file_spec_path, buff);
  59       if (ec)
  60         return std::nullopt;
  61       FileSpec realpath(buff, file_spec.GetPathStyle());
  62
  63       // Only return realpath if it is different from the original file_spec.
  64       if (realpath != file_spec)
  65         return realpath;
  66       return std::nullopt;
  67     }
  68   }
  69   // No prefix matched
  70   return std::nullopt;
  71 }