root/tools/gn/filesystem_utils.cc

DEFINITIONS

1. ClassifyAfterDot
2. NormalizeWindowsPathChar
3. AreAbsoluteWindowsPathsEqual
4. DoesBeginWindowsDriveLetter
5. GetPathComponents
6. FilesystemStringsEqual
7. GetSourceFileType
8. GetExtensionForOutputType
9. FilePathToUTF8
10. UTF8ToFilePath
11. FindExtensionOffset
12. FindExtension
13. FindFilenameOffset
14. FindFilename
15. FindFilenameNoExtension
16. RemoveFilename
17. EndsWithSlash
18. FindDir
19. EnsureStringIsInOutputDir
20. IsPathAbsolute
21. MakeAbsolutePathRelativeIfPossible
22. InvertDir
23. NormalizePath
24. ConvertPathToSystem
25. RebaseSourceAbsolutePath
26. DirectoryWithNoLastSlash
27. SourceDirForPath
28. SourceDirForCurrentDirectory
29. GetToolchainOutputDir
30. GetToolchainGenDir
31. GetOutputDirForSourceDir
32. GetGenDirForSourceDir
33. GetTargetOutputDir
34. GetTargetGenDir
35. GetCurrentOutputDir
36. GetCurrentGenDir

// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "tools/gn/filesystem_utils.h"

#include <algorithm>

#include "base/file_util.h"
#include "base/logging.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "build/build_config.h"
#include "tools/gn/location.h"
#include "tools/gn/settings.h"
#include "tools/gn/source_dir.h"

namespace {

enum DotDisposition {
  // The given dot is just part of a filename and is not special.
  NOT_A_DIRECTORY,

  // The given dot is the current directory.
  DIRECTORY_CUR,

  // The given dot is the first of a double dot that should take us up one.
  DIRECTORY_UP
};

// When we find a dot, this function is called with the character following
// that dot to see what it is. The return value indicates what type this dot is
// (see above). This code handles the case where the dot is at the end of the
// input.
//
// |*consumed_len| will contain the number of characters in the input that
// express what we found.
DotDisposition ClassifyAfterDot(const std::string& path,
                                size_t after_dot,
                                size_t* consumed_len) {
  if (after_dot == path.size()) {
    // Single dot at the end.
    *consumed_len = 1;
    return DIRECTORY_CUR;
  }
  if (IsSlash(path[after_dot])) {
    // Single dot followed by a slash.
    *consumed_len = 2;  // Consume the slash
    return DIRECTORY_CUR;
  }

  if (path[after_dot] == '.') {
    // Two dots.
    if (after_dot + 1 == path.size()) {
      // Double dot at the end.
      *consumed_len = 2;
      return DIRECTORY_UP;
    }
    if (IsSlash(path[after_dot + 1])) {
      // Double dot folowed by a slash.
      *consumed_len = 3;
      return DIRECTORY_UP;
    }
  }

  // The dots are followed by something else, not a directory.
  *consumed_len = 1;
  return NOT_A_DIRECTORY;
}

#if defined(OS_WIN)
inline char NormalizeWindowsPathChar(char c) {
  if (c == '/')
    return '\\';
  return base::ToLowerASCII(c);
}

// Attempts to do a case and slash-insensitive comparison of two 8-bit Windows
// paths.
bool AreAbsoluteWindowsPathsEqual(const base::StringPiece& a,
                                  const base::StringPiece& b) {
  if (a.size() != b.size())
    return false;

  // For now, just do a case-insensitive ASCII comparison. We could convert to
  // UTF-16 and use ICU if necessary. Or maybe base::strcasecmp is good enough?
  for (size_t i = 0; i < a.size(); i++) {
    if (NormalizeWindowsPathChar(a[i]) != NormalizeWindowsPathChar(b[i]))
      return false;
  }
  return true;
}

bool DoesBeginWindowsDriveLetter(const base::StringPiece& path) {
  if (path.size() < 3)
    return false;

  // Check colon first, this will generally fail fastest.
  if (path[1] != ':')
    return false;

  // Check drive letter
  if (!((path[0] >= 'A' && path[0] <= 'Z') ||
         path[0] >= 'a' && path[0] <= 'z'))
    return false;

  if (!IsSlash(path[2]))
    return false;
  return true;
}
#endif

// A wrapper around FilePath.GetComponents that works the way we need. This is
// not super efficient since it does some O(n) transformations on the path. If
// this is called a lot, we might want to optimize.
std::vector<base::FilePath::StringType> GetPathComponents(
    const base::FilePath& path) {
  std::vector<base::FilePath::StringType> result;
  path.GetComponents(&result);

  if (result.empty())
    return result;

  // GetComponents will preserve the "/" at the beginning, which confuses us.
  // We don't expect to have relative paths in this function.
  // Don't use IsSeparator since we always want to allow backslashes.
  if (result[0] == FILE_PATH_LITERAL("/") ||
      result[0] == FILE_PATH_LITERAL("\\"))
    result.erase(result.begin());

#if defined(OS_WIN)
  // On Windows, GetComponents will give us [ "C:", "/", "foo" ], and we
  // don't want the slash in there. This doesn't support input like "C:foo"
  // which means foo relative to the current directory of the C drive but
  // that's basically legacy DOS behavior we don't need to support.
  if (result.size() >= 2 && result[1].size() == 1 && IsSlash(result[1][0]))
    result.erase(result.begin() + 1);
#endif

  return result;
}

// Provides the equivalent of == for filesystem strings, trying to do
// approximately the right thing with case.
bool FilesystemStringsEqual(const base::FilePath::StringType& a,
                            const base::FilePath::StringType& b) {
#if defined(OS_WIN)
  // Assume case-insensitive filesystems on Windows. We use the CompareString
  // function to do a case-insensitive comparison based on the current locale
  // (we don't want GN to depend on ICU which is large and requires data
  // files). This isn't perfect, but getting this perfectly right is very
  // difficult and requires I/O, and this comparison should cover 99.9999% of
  // all cases.
  //
  // Note: The documentation for CompareString says it runs fastest on
  // null-terminated strings with -1 passed for the length, so we do that here.
  // There should not be embedded nulls in filesystem strings.
  return ::CompareString(LOCALE_USER_DEFAULT, LINGUISTIC_IGNORECASE,
                         a.c_str(), -1, b.c_str(), -1) == CSTR_EQUAL;
#else
  // Assume case-sensitive filesystems on non-Windows.
  return a == b;
#endif
}

}  // namespace

SourceFileType GetSourceFileType(const SourceFile& file,
                                 Settings::TargetOS os) {
  base::StringPiece extension = FindExtension(&file.value());
  if (extension == "cc" || extension == "cpp" || extension == "cxx")
    return SOURCE_CC;
  if (extension == "h")
    return SOURCE_H;
  if (extension == "c")
    return SOURCE_C;

  switch (os) {
    case Settings::MAC:
      if (extension == "m")
        return SOURCE_M;
      if (extension == "mm")
        return SOURCE_MM;
      break;

    case Settings::WIN:
      if (extension == "rc")
        return SOURCE_RC;
      // TODO(brettw) asm files.
      break;

    default:
      break;
  }

  if (os != Settings::WIN) {
    if (extension == "S")
      return SOURCE_S;
  }

  return SOURCE_UNKNOWN;
}

const char* GetExtensionForOutputType(Target::OutputType type,
                                      Settings::TargetOS os) {
  switch (os) {
    case Settings::MAC:
      switch (type) {
        case Target::EXECUTABLE:
          return "";
        case Target::SHARED_LIBRARY:
          return "dylib";
        case Target::STATIC_LIBRARY:
          return "a";
        default:
          NOTREACHED();
      }
      break;

    case Settings::WIN:
      switch (type) {
        case Target::EXECUTABLE:
          return "exe";
        case Target::SHARED_LIBRARY:
          return "dll.lib";  // Extension of import library.
        case Target::STATIC_LIBRARY:
          return "lib";
        default:
          NOTREACHED();
      }
      break;

    case Settings::LINUX:
      switch (type) {
        case Target::EXECUTABLE:
          return "";
        case Target::SHARED_LIBRARY:
          return "so";
        case Target::STATIC_LIBRARY:
          return "a";
        default:
          NOTREACHED();
      }
      break;

    default:
      NOTREACHED();
  }
  return "";
}

std::string FilePathToUTF8(const base::FilePath::StringType& str) {
#if defined(OS_WIN)
  return base::WideToUTF8(str);
#else
  return str;
#endif
}

base::FilePath UTF8ToFilePath(const base::StringPiece& sp) {
#if defined(OS_WIN)
  return base::FilePath(base::UTF8ToWide(sp));
#else
  return base::FilePath(sp.as_string());
#endif
}

size_t FindExtensionOffset(const std::string& path) {
  for (int i = static_cast<int>(path.size()); i >= 0; i--) {
    if (IsSlash(path[i]))
      break;
    if (path[i] == '.')
      return i + 1;
  }
  return std::string::npos;
}

base::StringPiece FindExtension(const std::string* path) {
  size_t extension_offset = FindExtensionOffset(*path);
  if (extension_offset == std::string::npos)
    return base::StringPiece();
  return base::StringPiece(&path->data()[extension_offset],
                           path->size() - extension_offset);
}

size_t FindFilenameOffset(const std::string& path) {
  for (int i = static_cast<int>(path.size()) - 1; i >= 0; i--) {
    if (IsSlash(path[i]))
      return i + 1;
  }
  return 0;  // No filename found means everything was the filename.
}

base::StringPiece FindFilename(const std::string* path) {
  size_t filename_offset = FindFilenameOffset(*path);
  if (filename_offset == 0)
    return base::StringPiece(*path);  // Everything is the file name.
  return base::StringPiece(&(*path).data()[filename_offset],
                           path->size() - filename_offset);
}

base::StringPiece FindFilenameNoExtension(const std::string* path) {
  if (path->empty())
    return base::StringPiece();
  size_t filename_offset = FindFilenameOffset(*path);
  size_t extension_offset = FindExtensionOffset(*path);

  size_t name_len;
  if (extension_offset == std::string::npos)
    name_len = path->size() - filename_offset;
  else
    name_len = extension_offset - filename_offset - 1;

  return base::StringPiece(&(*path).data()[filename_offset], name_len);
}

void RemoveFilename(std::string* path) {
  path->resize(FindFilenameOffset(*path));
}

bool EndsWithSlash(const std::string& s) {
  return !s.empty() && IsSlash(s[s.size() - 1]);
}

base::StringPiece FindDir(const std::string* path) {
  size_t filename_offset = FindFilenameOffset(*path);
  if (filename_offset == 0u)
    return base::StringPiece();
  return base::StringPiece(path->data(), filename_offset);
}

bool EnsureStringIsInOutputDir(const SourceDir& dir,
                               const std::string& str,
                               const Value& originating,
                               Err* err) {
  // The last char of the dir will be a slash. We don't care if the input ends
  // in a slash or not, so just compare up until there.
  //
  // This check will be wrong for all proper prefixes "e.g. "/output" will
  // match "/out" but we don't really care since this is just a sanity check.
  const std::string& dir_str = dir.value();
  if (str.compare(0, dir_str.length() - 1, dir_str, 0, dir_str.length() - 1)
      != 0) {
    *err = Err(originating, "File is not inside output directory.",
        "The given file should be in the output directory. Normally you would "
        "specify\n\"$target_out_dir/foo\" or "
        "\"$target_gen_dir/foo\". I interpreted this as\n\""
        + str + "\".");
    return false;
  }
  return true;
}

bool IsPathAbsolute(const base::StringPiece& path) {
  if (path.empty())
    return false;

  if (!IsSlash(path[0])) {
#if defined(OS_WIN)
    // Check for Windows system paths like "C:\foo".
    if (path.size() > 2 && path[1] == ':' && IsSlash(path[2]))
      return true;
#endif
    return false;  // Doesn't begin with a slash, is relative.
  }

  // Double forward slash at the beginning means source-relative (we don't
  // allow backslashes for denoting this).
  if (path.size() > 1 && path[1] == '/')
    return false;

  return true;
}

bool MakeAbsolutePathRelativeIfPossible(const base::StringPiece& source_root,
                                        const base::StringPiece& path,
                                        std::string* dest) {
  DCHECK(IsPathAbsolute(source_root));
  DCHECK(IsPathAbsolute(path));

  dest->clear();

  if (source_root.size() > path.size())
    return false;  // The source root is longer: the path can never be inside.

#if defined(OS_WIN)
  // Source root should be canonical on Windows. Note that the initial slash
  // must be forward slash, but that the other ones can be either forward or
  // backward.
  DCHECK(source_root.size() > 2 && source_root[0] != '/' &&
         source_root[1] == ':' && IsSlash(source_root[2]));

  size_t after_common_index = std::string::npos;
  if (DoesBeginWindowsDriveLetter(path)) {
    // Handle "C:\foo"
    if (AreAbsoluteWindowsPathsEqual(source_root,
                                     path.substr(0, source_root.size())))
      after_common_index = source_root.size();
    else
      return false;
  } else if (path[0] == '/' && source_root.size() <= path.size() - 1 &&
             DoesBeginWindowsDriveLetter(path.substr(1))) {
    // Handle "/C:/foo"
    if (AreAbsoluteWindowsPathsEqual(source_root,
                                     path.substr(1, source_root.size())))
      after_common_index = source_root.size() + 1;
    else
      return false;
  } else {
    return false;
  }

  // If we get here, there's a match and after_common_index identifies the
  // part after it.

  // The base may or may not have a trailing slash, so skip all slashes from
  // the path after our prefix match.
  size_t first_after_slash = after_common_index;
  while (first_after_slash < path.size() && IsSlash(path[first_after_slash]))
    first_after_slash++;

  dest->assign("//");  // Result is source root relative.
  dest->append(&path.data()[first_after_slash],
               path.size() - first_after_slash);
  return true;

#else

  // On non-Windows this is easy. Since we know both are absolute, just do a
  // prefix check.
  if (path.substr(0, source_root.size()) == source_root) {
    // The base may or may not have a trailing slash, so skip all slashes from
    // the path after our prefix match.
    size_t first_after_slash = source_root.size();
    while (first_after_slash < path.size() && IsSlash(path[first_after_slash]))
      first_after_slash++;

    dest->assign("//");  // Result is source root relative.
    dest->append(&path.data()[first_after_slash],
                 path.size() - first_after_slash);
    return true;
  }
  return false;
#endif
}

std::string InvertDir(const SourceDir& path) {
  const std::string value = path.value();
  if (value.empty())
    return std::string();

  DCHECK(value[0] == '/');
  size_t begin_index = 1;

  // If the input begins with two slashes, skip over both (this is a
  // source-relative dir). These must be forward slashes only.
  if (value.size() > 1 && value[1] == '/')
    begin_index = 2;

  std::string ret;
  for (size_t i = begin_index; i < value.size(); i++) {
    if (IsSlash(value[i]))
      ret.append("../");
  }
  return ret;
}

void NormalizePath(std::string* path) {
  char* pathbuf = path->empty() ? NULL : &(*path)[0];

  // top_index is the first character we can modify in the path. Anything
  // before this indicates where the path is relative to.
  size_t top_index = 0;
  bool is_relative = true;
  if (!path->empty() && pathbuf[0] == '/') {
    is_relative = false;

    if (path->size() > 1 && pathbuf[1] == '/') {
      // Two leading slashes, this is a path into the source dir.
      top_index = 2;
    } else {
      // One leading slash, this is a system-absolute path.
      top_index = 1;
    }
  }

  size_t dest_i = top_index;
  for (size_t src_i = top_index; src_i < path->size(); /* nothing */) {
    if (pathbuf[src_i] == '.') {
      if (src_i == 0 || IsSlash(pathbuf[src_i - 1])) {
        // Slash followed by a dot, see if it's something special.
        size_t consumed_len;
        switch (ClassifyAfterDot(*path, src_i + 1, &consumed_len)) {
          case NOT_A_DIRECTORY:
            // Copy the dot to the output, it means nothing special.
            pathbuf[dest_i++] = pathbuf[src_i++];
            break;
          case DIRECTORY_CUR:
            // Current directory, just skip the input.
            src_i += consumed_len;
            break;
          case DIRECTORY_UP:
            // Back up over previous directory component. If we're already
            // at the top, preserve the "..".
            if (dest_i > top_index) {
              // The previous char was a slash, remove it.
              dest_i--;
            }

            if (dest_i == top_index) {
              if (is_relative) {
                // We're already at the beginning of a relative input, copy the
                // ".." and continue. We need the trailing slash if there was
                // one before (otherwise we're at the end of the input).
                pathbuf[dest_i++] = '.';
                pathbuf[dest_i++] = '.';
                if (consumed_len == 3)
                  pathbuf[dest_i++] = '/';

                // This also makes a new "root" that we can't delete by going
                // up more levels.  Otherwise "../.." would collapse to
                // nothing.
                top_index = dest_i;
              }
              // Otherwise we're at the beginning of an absolute path. Don't
              // allow ".." to go up another level and just eat it.
            } else {
              // Just find the previous slash or the beginning of input.
              while (dest_i > 0 && !IsSlash(pathbuf[dest_i - 1]))
                dest_i--;
            }
            src_i += consumed_len;
        }
      } else {
        // Dot not preceeded by a slash, copy it literally.
        pathbuf[dest_i++] = pathbuf[src_i++];
      }
    } else if (IsSlash(pathbuf[src_i])) {
      if (src_i > 0 && IsSlash(pathbuf[src_i - 1])) {
        // Two slashes in a row, skip over it.
        src_i++;
      } else {
        // Just one slash, copy it, normalizing to foward slash.
        pathbuf[dest_i] = '/';
        dest_i++;
        src_i++;
      }
    } else {
      // Input nothing special, just copy it.
      pathbuf[dest_i++] = pathbuf[src_i++];
    }
  }
  path->resize(dest_i);
}

void ConvertPathToSystem(std::string* path) {
#if defined(OS_WIN)
  for (size_t i = 0; i < path->size(); i++) {
    if ((*path)[i] == '/')
      (*path)[i] = '\\';
  }
#endif
}

std::string RebaseSourceAbsolutePath(const std::string& input,
                                     const SourceDir& dest_dir) {
  CHECK(input.size() >= 2 && input[0] == '/' && input[1] == '/')
      << "Input to rebase isn't source-absolute: " << input;
  CHECK(dest_dir.is_source_absolute())
      << "Dir to rebase to isn't source-absolute: " << dest_dir.value();

  const std::string& dest = dest_dir.value();

  // Skip the common prefixes of the source and dest as long as they end in
  // a [back]slash.
  size_t common_prefix_len = 2;  // The beginning two "//" are always the same.
  size_t max_common_length = std::min(input.size(), dest.size());
  for (size_t i = common_prefix_len; i < max_common_length; i++) {
    if (IsSlash(input[i]) && IsSlash(dest[i]))
      common_prefix_len = i + 1;
    else if (input[i] != dest[i])
      break;
  }

  // Invert the dest dir starting from the end of the common prefix.
  std::string ret;
  for (size_t i = common_prefix_len; i < dest.size(); i++) {
    if (IsSlash(dest[i]))
      ret.append("../");
  }

  // Append any remaining unique input.
  ret.append(&input[common_prefix_len], input.size() - common_prefix_len);

  // If the result is still empty, the paths are the same.
  if (ret.empty())
    ret.push_back('.');

  return ret;
}

std::string DirectoryWithNoLastSlash(const SourceDir& dir) {
  std::string ret;

  if (dir.value().empty()) {
    // Just keep input the same.
  } else if (dir.value() == "/") {
    ret.assign("/.");
  } else if (dir.value() == "//") {
    ret.assign("//.");
  } else {
    ret.assign(dir.value());
    ret.resize(ret.size() - 1);
  }
  return ret;
}

SourceDir SourceDirForPath(const base::FilePath& source_root,
                           const base::FilePath& path) {
  std::vector<base::FilePath::StringType> source_comp =
      GetPathComponents(source_root);
  std::vector<base::FilePath::StringType> path_comp =
      GetPathComponents(path);

  // See if path is inside the source root by looking for each of source root's
  // components at the beginning of path.
  bool is_inside_source;
  if (path_comp.size() < source_comp.size()) {
    // Too small to fit.
    is_inside_source = false;
  } else {
    is_inside_source = true;
    for (size_t i = 0; i < source_comp.size(); i++) {
      if (!FilesystemStringsEqual(source_comp[i], path_comp[i])) {
        is_inside_source = false;
        break;
      }
    }
  }

  std::string result_str;
  size_t initial_path_comp_to_use;
  if (is_inside_source) {
    // Construct a source-relative path beginning in // and skip all of the
    // shared directories.
    result_str = "//";
    initial_path_comp_to_use = source_comp.size();
  } else {
    // Not inside source code, construct a system-absolute path.
    result_str = "/";
    initial_path_comp_to_use = 0;
  }

  for (size_t i = initial_path_comp_to_use; i < path_comp.size(); i++) {
    result_str.append(FilePathToUTF8(path_comp[i]));
    result_str.push_back('/');
  }
  return SourceDir(result_str);
}

SourceDir SourceDirForCurrentDirectory(const base::FilePath& source_root) {
  base::FilePath cd;
  base::GetCurrentDirectory(&cd);
  return SourceDirForPath(source_root, cd);
}

SourceDir GetToolchainOutputDir(const Settings* settings) {
  const OutputFile& toolchain_subdir = settings->toolchain_output_subdir();

  std::string result = settings->build_settings()->build_dir().value();
  if (!toolchain_subdir.value().empty())
    result.append(toolchain_subdir.value());

  return SourceDir(SourceDir::SWAP_IN, &result);
}

SourceDir GetToolchainGenDir(const Settings* settings) {
  const OutputFile& toolchain_subdir = settings->toolchain_output_subdir();

  std::string result = settings->build_settings()->build_dir().value();
  if (!toolchain_subdir.value().empty())
    result.append(toolchain_subdir.value());

  result.append("gen/");
  return SourceDir(SourceDir::SWAP_IN, &result);
}

SourceDir GetOutputDirForSourceDir(const Settings* settings,
                                   const SourceDir& source_dir) {
  SourceDir toolchain = GetToolchainOutputDir(settings);

  std::string ret;
  toolchain.SwapValue(&ret);
  ret.append("obj/");

  // The source dir should be source-absolute, so we trim off the two leading
  // slashes to append to the toolchain object directory.
  DCHECK(source_dir.is_source_absolute());
  ret.append(&source_dir.value()[2], source_dir.value().size() - 2);

  return SourceDir(SourceDir::SWAP_IN, &ret);
}

SourceDir GetGenDirForSourceDir(const Settings* settings,
                                const SourceDir& source_dir) {
  SourceDir toolchain = GetToolchainGenDir(settings);

  std::string ret;
  toolchain.SwapValue(&ret);

  // The source dir should be source-absolute, so we trim off the two leading
  // slashes to append to the toolchain object directory.
  DCHECK(source_dir.is_source_absolute());
  ret.append(&source_dir.value()[2], source_dir.value().size() - 2);

  return SourceDir(SourceDir::SWAP_IN, &ret);
}

SourceDir GetTargetOutputDir(const Target* target) {
  return GetOutputDirForSourceDir(target->settings(), target->label().dir());
}

SourceDir GetTargetGenDir(const Target* target) {
  return GetGenDirForSourceDir(target->settings(), target->label().dir());
}

SourceDir GetCurrentOutputDir(const Scope* scope) {
  return GetOutputDirForSourceDir(scope->settings(), scope->GetSourceDir());
}

SourceDir GetCurrentGenDir(const Scope* scope) {
  return GetGenDirForSourceDir(scope->settings(), scope->GetSourceDir());
}