CommonIO: Make readFile() check if the file is not a directory and if not fail with a sensible exception rather than std::length_error

libsolutil/CommonIO.cpp

@@ -43,9 +43,17 @@ namespace
 template <typename T>
 inline T readFile(std::string const& _file)
 {
+	assertThrow(boost::filesystem::exists(_file), FileNotFound, _file);
+
+	// ifstream does not always fail when the path leads to a directory. Instead it might succeed
+	// with tellg() returning a nonsensical value so that std::length_error gets raised in resize().
+	assertThrow(boost::filesystem::is_regular_file(_file), NotAFile, _file);
+
 	T ret;
 	size_t const c_elementSize = sizeof(typename T::value_type);
 	std::ifstream is(_file, std::ifstream::binary);
+
+	// Technically, this can still fail even though we checked above because FS content can change at any time.
 	assertThrow(is, FileNotFound, _file);
 
 	// get length of file:

libsolutil/CommonIO.h

@@ -33,6 +33,7 @@ namespace solidity::util
 
 /// Retrieve and returns the contents of the given file as a std::string.
 /// If the file doesn't exist, it will throw a FileNotFound exception.
+/// If the file exists but is not a regular file, it will throw NotAFile exception.
 /// If the file is empty, returns an empty string.
 std::string readFileAsString(std::string const& _file);
 

libsolutil/Exceptions.h

@@ -49,6 +49,7 @@ DEV_SIMPLE_EXCEPTION(InvalidAddress);
 DEV_SIMPLE_EXCEPTION(BadHexCharacter);
 DEV_SIMPLE_EXCEPTION(BadHexCase);
 DEV_SIMPLE_EXCEPTION(FileNotFound);
+DEV_SIMPLE_EXCEPTION(NotAFile);
 DEV_SIMPLE_EXCEPTION(DataTooLong);
 DEV_SIMPLE_EXCEPTION(StringTooLong);
 

solc/CommandLineInterface.cpp

@@ -668,6 +668,10 @@ bool CommandLineInterface::parseLibraryOption(string const& _input)
 	{
 		// Should not happen if `fs::is_regular_file` is correct.
 	}
+	catch (NotAFile const&)
+	{
+		// Should not happen if `fs::is_regular_file` is correct.
+	}
 
 	vector<string> libraries;
 	boost::split(libraries, data, boost::is_space() || boost::is_any_of(","), boost::token_compress_on);
@@ -1263,6 +1267,11 @@ bool CommandLineInterface::processInput()
 				serr() << "File not found: " << jsonFile << endl;
 				return false;
 			}
+			catch (NotAFile const&)
+			{
+				serr() << "Not a regular file: " << jsonFile << endl;
+				return false;
+			}
 		}
 		StandardCompiler compiler(m_fileReader.reader());
 		sout() << compiler.compile(std::move(input)) << endl;

test/tools/yulopti.cpp

@@ -282,6 +282,11 @@ Allowed options)",
 		cerr << "File not found:" << _exception.comment() << endl;
 		return 1;
 	}
+	catch (NotAFile const& _exception)
+	{
+		cerr << "Not a regular file:" << _exception.comment() << endl;
+		return 1;
+	}
 
 	if (arguments.count("input-file"))
 		YulOpti{}.runInteractive(input);

test/tools/yulrun.cpp

@@ -148,6 +148,11 @@ Allowed options)",
 					cerr << "File not found: " << path << endl;
 					return 1;
 				}
+				catch (NotAFile const&)
+				{
+					cerr << "Not a regular file: " << path << endl;
+					return 1;
+				}
 			}
 		else
 			input = readStandardInput();