FileReader: Normalize base path and strip it from normalized source p…

…aths

Changelog.md

@@ -5,6 +5,7 @@ Language Features:
 
 Compiler Features:
  * AssemblyStack: Also run opcode-based optimizer when compiling Yul code.
+ * Commandline Interface: Normalize paths specified on the command line and make them relative whenever files are located inside base path.
  * Yul EVM Code Transform: Do not reuse stack slots that immediately become unreachable.
  * Yul EVM Code Transform: Also pop unused argument slots for functions without return variables (under the same restrictions as for functions with return variables).
  * Yul Optimizer: Move function arguments and return variables to memory with the experimental Stack Limit Evader (which is not enabled by default).

docs/path-resolution.rst

@@ -71,8 +71,10 @@ The initial content of the VFS depends on how you invoke the compiler:
 
        solc contract.sol /usr/local/dapp-bin/token.sol
 
-   The source unit name of a file loaded this way is simply the specified path after shell expansion
-   and with platform-specific separators converted to forward slashes.
+   The source unit name of a file loaded this way is constructed by converting its path to a
+   canonical form and making it relative to the base path if it is located inside.
+   See :ref:`Base Path Normalization and Stripping <base-path-normalization-and-stripping>` for
+   a detailed description of this process.
 
    .. index:: standard JSON
 
@@ -313,6 +315,46 @@ interpreted as absolute paths on disk.
 If the base path itself is relative, it is also interpreted as relative to the current working
 directory of the compiler.
 
+.. _base-path-normalization-and-stripping:
+
+Base Path Normalization and Stripping
+-------------------------------------
+
+When source file paths are specified on the command line, the base path affects the source unit
+names assigned to them in the compiler's VFS.
+To compute the names, both base path and source file paths must first be converted to a canonical form.
+This ensures that the result is predictable and as platform-independent as possible:
+
+- If a path is relative, it is made absolute by prepending the current working directory to it.
+
+  - If the path to the working directory contains symbolic links, they are resolved into actual
+    directories.
+
+- Internal ``.`` and ``..`` segments are collapsed.
+- Platform-specific path separators are replaced with forward slashes.
+- Sequences of multiple consecutive path separators are squashed into a single separator (unless
+  they are the leading slashes of an `UNC path <https://en.wikipedia.org/wiki/Path_(computing)#UNC>`_).
+- If the path includes a root name (e.g. a drive letter on Windows) and the root is the same as the
+  root of the current working directory, the root is replaced with ``/``.
+- Symbolic links in the path itself are **not** resolved.
+- The original case of the path is preserved even if the filesystem is case-insensitive but
+  `case-preserving <https://en.wikipedia.org/wiki/Case_preservation>`_ and the actual case on
+  disk is different.
+
+.. note::
+
+    There are situations where paths cannot be made platform-independent.
+    For example on Windows the compiler can avoid using drive letters by referring to the root
+    directory of the current drive as ``/`` but drive letters are still necessary for paths leading
+    to other drives.
+    You can avoid such situations by ensuring that all the files are available within a single
+    directory tree on the same drive.
+
+Once canonicalized, the base path is stripped from all source file paths that start with it.
+If the base path is empty (e.g. if it is not explicitly provided), it is treated as if it was equal
+to the path to the current working directory with all symbolic links resolved.
+The result becomes the source unit name.
+
 .. index:: ! remapping; import, ! import; remapping, ! remapping; context, ! remapping; prefix, ! remapping; target
 .. _import-remapping:
 
@@ -414,7 +456,7 @@ Here are the detailed rules governing the behaviour of remappings:
 
      .. code-block:: bash
 
-         solc /project/=/contracts/ /project/contract.sol --base-path /project # source unit name: /project/contract.sol
+         solc /project/=/contracts/ /project/contract.sol --base-path /project # source unit name: contract.sol
 
      .. code-block:: solidity
          :caption: /project/contract.sol

libsolidity/interface/FileReader.cpp

@@ -22,6 +22,8 @@
 #include <libsolutil/CommonIO.h>
 #include <libsolutil/Exceptions.h>
 
+#include <boost/algorithm/string/predicate.hpp>
+
 using solidity::frontend::ReadCallback;
 using solidity::langutil::InternalCompilerError;
 using solidity::util::errinfo_comment;
@@ -31,9 +33,20 @@ using std::string;
 namespace solidity::frontend
 {
 
+void FileReader::setBasePath(boost::filesystem::path const& _path)
+{
+	if (_path.empty())
+		m_basePath = "";
+	else
+		m_basePath = normalizeCLIPathForVFS(_path);
+}
+
 void FileReader::setSource(boost::filesystem::path const& _path, SourceCode _source)
 {
-	m_sourceCodes[_path.generic_string()] = std::move(_source);
+	boost::filesystem::path normalizedPath = normalizeCLIPathForVFS(_path);
+	boost::filesystem::path prefix = (m_basePath.empty() ? normalizeCLIPathForVFS(".") : m_basePath);
+
+	m_sourceCodes[stripPrefixIfPresent(prefix, normalizedPath).generic_string()] = std::move(_source);
 }
 
 void FileReader::setSources(StringMap _sources)
@@ -92,5 +105,152 @@ ReadCallback::Result FileReader::readFile(string const& _kind, string const& _so
 	}
 }
 
+boost::filesystem::path FileReader::normalizeCLIPathForVFS(boost::filesystem::path const& _path)
+{
+	// Detailed normalization rules:
+	// - Makes the path either be absolute or have slash as root (note that on Windows paths with
+	//   slash as root are not considered absolute by Boost). If it is empty, it becomes
+	//   the current working directory.
+	// - Collapses redundant . and .. segments.
+	// - Removes leading .. segments from an absolute path (i.e. /../../ becomes just /).
+	// - Squashes sequences of multiple path separators into one.
+	// - Ensures that forward slashes are used as path separators on all platforms.
+	// - Removes the root name (e.g. drive letter on Windows) when it matches the root name in the
+	//   path to the current working directory.
+	//
+	// Also note that this function:
+	// - Does NOT resolve symlinks (except for symlinks in the path to the current working directory).
+	// - Does NOT check if the path refers to a file or a directory. If the path ends with a slash,
+	//   the slash is preserved even if it's a file.
+	// - Preserves case. Even if the filesystem is case-insensitive but case-preserving and the
+	//   case differs, the actual case from disk is NOT detected.
+
+	boost::filesystem::path canonicalWorkDir = boost::filesystem::weakly_canonical(boost::filesystem::current_path());
+
+	// NOTE: On UNIX systems the path returned from current_path() has symlinks resolved while on
+	// Windows it does not. To get consistent results we resolve them on all platforms.
+	boost::filesystem::path absolutePath = boost::filesystem::absolute(_path, canonicalWorkDir);
+
+	// NOTE: boost path preserves certain differences that are ignored by its operator ==.
+	// E.g. "a//b" vs "a/b" or "a/b/" vs "a/b/.". lexically_normal() does remove these differences.
+	boost::filesystem::path normalizedPath =  absolutePath.lexically_normal();
+	solAssert(normalizedPath.is_absolute() || normalizedPath.root_path() == "/", "");
+
+	// lexically_normal() will not squash paths like "/../../" into "/". We have to do it manually.
+	boost::filesystem::path dotDotPrefix = absoluteDotDotPrefix(normalizedPath);
+
+	// If the path is on the same drive as the working dir, for portability we prefer not to
+	// include the root name. Do this only for non-UNC paths - my experiments show that on Windows
+	// when the working dir is an UNC path, / does not not actually refer to the root of the UNC path.
+	// For UNC paths only normalize the root name to start with //.
+	boost::filesystem::path normalizedRootPath = normalizedPath.root_path();
+	if (!isUNCPath(normalizedPath))
+	{
+		boost::filesystem::path workingDirRootPath = canonicalWorkDir.root_path();
+		if (normalizedRootPath == workingDirRootPath)
+			normalizedRootPath = "/";
+	}
+	else
+	{
+		solAssert(
+			boost::starts_with(normalizedPath.root_name().string(), "//") ||
+			boost::starts_with(normalizedPath.root_name().string(), "\\\\"),
+			""
+		);
+
+		string rootName = normalizedPath.root_name().string();
+		boost::filesystem::path normalizedRootPath =
+			normalizedPath.root_directory().string() +
+			"//" +
+			(rootName.size() > 2 ? rootName.substr(2, string::npos) : "");
+	}
+
+	boost::filesystem::path normalizedPathNoDotDot = normalizedPath;
+	if (dotDotPrefix.empty())
+		normalizedPathNoDotDot = normalizedRootPath / normalizedPath.relative_path();
+	else
+		normalizedPathNoDotDot = normalizedRootPath / normalizedPath.lexically_relative(normalizedPath.root_path() / dotDotPrefix);
+	solAssert(!hasDotDotSegments(normalizedPathNoDotDot), "");
+
+	// NOTE: On Windows lexically_normal() converts all separators to forward slashes. Convert them back.
+	// Separators do not affect path comparison but remain in internal representation returned by native().
+	normalizedPathNoDotDot = normalizedPathNoDotDot.generic_string();
+
+	// For some reason boost considers "/." different than "/" even though for other directories
+	// the trailing dot is ignored.
+	if (normalizedPathNoDotDot == "/.")
+		return "/";
+
+	return normalizedPathNoDotDot;
+}
+
+bool FileReader::isPathPrefix(boost::filesystem::path _prefix, boost::filesystem::path const& _path)
+{
+	solAssert(!_prefix.empty() && !_path.empty(), "");
+	// NOTE: On Windows paths starting with a slash (rather than a drive letter) are considered relative by boost.
+	solAssert(_prefix.is_absolute() || isUNCPath(_prefix) || _prefix.root_path() == "/", "");
+	solAssert(_path.is_absolute() || isUNCPath(_path) || _path.root_path() == "/", "");
+	solAssert(_prefix == _prefix.lexically_normal() && _path == _path.lexically_normal(), "");
+	solAssert(!hasDotDotSegments(_prefix) && !hasDotDotSegments(_path), "");
+
+	// Before 1.72.0 lexically_relative() was not handling paths with empty, dot and dot dot segments
+	// correctly (see https://github.com/boostorg/filesystem/issues/76). The only case where this
+	// is possible after our normalization is a directory name ending in a slash (filename is a dot).
+	if (_prefix.filename_is_dot())
+		_prefix.remove_filename();
+
+	boost::filesystem::path strippedPath = _path.lexically_relative(_prefix);
+	return !strippedPath.empty() && *strippedPath.begin() != "..";
+}
+
+boost::filesystem::path FileReader::stripPrefixIfPresent(boost::filesystem::path _prefix, boost::filesystem::path const& _path)
+{
+	if (!isPathPrefix(_prefix, _path))
+		return _path;
+
+	if (_prefix.filename_is_dot())
+		_prefix.remove_filename();
+
+	boost::filesystem::path strippedPath = _path.lexically_relative(_prefix);
+	solAssert(strippedPath.empty() || *strippedPath.begin() != "..", "");
+	return strippedPath;
+}
+
+boost::filesystem::path FileReader::absoluteDotDotPrefix(boost::filesystem::path const& _path)
+{
+	solAssert(_path.is_absolute() || _path.root_path() == "/", "");
+
+	boost::filesystem::path _pathWithoutRoot = _path.relative_path();
+	boost::filesystem::path prefix;
+	for (boost::filesystem::path const& segment: _pathWithoutRoot)
+		if (segment.filename_is_dot_dot())
+			prefix /= segment;
+
+	return prefix;
+}
+
+bool FileReader::hasDotDotSegments(boost::filesystem::path const& _path)
+{
+	for (boost::filesystem::path const& segment: _path)
+		if (segment.filename_is_dot_dot())
+			return true;
+
+	return false;
 }
 
+bool FileReader::isUNCPath(boost::filesystem::path const& _path)
+{
+	string rootName = _path.root_name().string();
+
+	return (
+		rootName.size() == 2 ||
+		(rootName.size() > 2 && rootName[2] != rootName[1])
+	) && (
+		(rootName[0] == '/' && rootName[1] == '/')
+#if defined(_WIN32)
+		|| (rootName[0] == '\\' && rootName[1] == '\\')
+#endif
+	);
+}
+
+}

libsolidity/interface/FileReader.h

@@ -45,27 +45,28 @@ class FileReader
 		boost::filesystem::path _basePath = {},
 		FileSystemPathSet _allowedDirectories = {}
 	):
-		m_basePath(std::move(_basePath)),
 		m_allowedDirectories(std::move(_allowedDirectories)),
 		m_sourceCodes()
-	{}
+	{
+		setBasePath(_basePath);
+	}
 
-	void setBasePath(boost::filesystem::path _path) { m_basePath = std::move(_path); }
+	void setBasePath(boost::filesystem::path const& _path);
 	boost::filesystem::path const& basePath() const noexcept { return m_basePath; }
 
 	void allowDirectory(boost::filesystem::path _path) { m_allowedDirectories.insert(std::move(_path)); }
 	FileSystemPathSet const& allowedDirectories() const noexcept { return m_allowedDirectories; }
 
 	StringMap const& sourceCodes() const noexcept { return m_sourceCodes; }
 
-	/// Retrieves the source code for a given source unit ID.
+	/// Retrieves the source code for a given source unit name.
 	SourceCode const& sourceCode(SourceUnitName const& _sourceUnitName) const { return m_sourceCodes.at(_sourceUnitName); }
 
-	/// Resets all sources to the given map of source unit ID to source codes.
+	/// Resets all sources to the given map of source unit name to source codes.
 	/// Does not enforce @a allowedDirectories().
 	void setSources(StringMap _sources);
 
-	/// Adds the source code for a given source unit ID.
+	/// Adds the source code under a source unit name created by normalizing the file path.
 	/// Does not enforce @a allowedDirectories().
 	void setSource(boost::filesystem::path const& _path, SourceCode _source);
 
@@ -83,7 +84,42 @@ class FileReader
 		return [this](std::string const& _kind, std::string const& _path) { return readFile(_kind, _path); };
 	}
 
+	/// Normalizes a filesystem path to make it include all components up to the filesystem root,
+	/// remove small, inconsequential differences that do not affect the meaning and make it look
+	/// the same on all platforms (if possible). Symlinks in the path are not resolved.
+	/// The resulting path uses forward slashes as path separators, has no redundant separators,
+	/// has no redundant . or .. segments and has no root name if removing it does not change the meaning.
+	/// The path does not have to actually exist.
+	static boost::filesystem::path normalizeCLIPathForVFS(boost::filesystem::path const& _path);
+
+	/// Returns true if all the path components of @a _prefix are present at the beginning of @a _path.
+	/// Both paths must be absolute (or have slash as root) and normalized (no . or .. segments, no
+	/// multiple consecutive slashes).
+	/// Paths are treated as case-sensitive. Does not require the path to actually exist in the
+	/// filesystem and does not follow symlinks. Only considers whole segments, e.g. /abc/d is not
+	/// considered a prefix of /abc/def. Both paths must be non-empty.
+	static bool isPathPrefix(boost::filesystem::path _prefix, boost::filesystem::path const& _path);
+
+	/// If @a _prefix is actually a prefix of @p _path, removes it from @a _path to make it relative.
+	/// Otherwise returns @a _path unchanged.
+	/// Returns '.' if @a _path and @_prefix are identical.
+	static boost::filesystem::path stripPrefixIfPresent(boost::filesystem::path _prefix, boost::filesystem::path const& _path);
+
+	// Returns true if the specified path is an UNC path.
+	// UNC paths start with // followed by a name (on Windows they can also start with \\).
+	// They are used for network shares on Windows. On UNIX systems they do not have the same
+	// functionality but usually they are still recognized and treated in a special way.
+	static bool isUNCPath(boost::filesystem::path const& _path);
+
 private:
+	/// If @a _path starts with a number of .. segments, returns a path consisting only of those
+	/// segments (root name is not included). Otherwise returns an empty path. @a _path must be
+	/// absolute (or have slash as root).
+	static boost::filesystem::path absoluteDotDotPrefix(boost::filesystem::path const& _path);
+
+	/// Returns true if the path contains any .. segments.
+	static bool hasDotDotSegments(boost::filesystem::path const& _path);
+
 	/// Base path, used for resolving relative paths in imports.
 	boost::filesystem::path m_basePath;
 

test/CMakeLists.txt

@@ -103,6 +103,7 @@ set(libsolidity_sources
     libsolidity/SyntaxTest.h
     libsolidity/ViewPureChecker.cpp
     libsolidity/analysis/FunctionCallGraph.cpp
+    libsolidity/interface/FileReader.cpp
 )
 detect_stray_source_files("${libsolidity_sources}" "libsolidity/")