Use ByteReader in BatchFile

Abstracts away file management in BatchFile.

Prevents a crash when attempting to read a file without
the necessary permissions.

include/shell.h

@@ -54,7 +54,7 @@ public:
 
 class BatchFile {
 public:
-	BatchFile(DOS_Shell* host, const char* const resolved_name,
+	BatchFile(DOS_Shell* host, std::unique_ptr<ByteReader> input_reader,
 	          const char* const entered_name, const char* const cmd_line);
 	BatchFile(const BatchFile&)            = delete; // prevent copying
 	BatchFile& operator=(const BatchFile&) = delete; // prevent assignment
@@ -62,17 +62,16 @@ public:
 	virtual bool ReadLine(char* line);
 	bool Goto(std::string_view label);
 	void Shift();
-	uint16_t file_handle             = 0;
-	uint32_t location                = 0;
 	bool echo                        = false;
 	DOS_Shell* shell                 = nullptr;
 	std::shared_ptr<BatchFile> prev  = {}; // shared with Shell.bf
 	std::unique_ptr<CommandLine> cmd = {};
-	std::string filename{};
 
 private:
 	[[nodiscard]] std::string ExpandedBatchLine(std::string_view line) const;
 	[[nodiscard]] std::string GetLine();
+	
+	std::unique_ptr<ByteReader> reader;
 };
 
 class AutoexecEditor;

src/dos/program_mount.cpp

@@ -72,13 +72,6 @@ void MOUNT::Move_Z(char new_z)
 		tempenv += "COMMAND.COM";
 		first_shell->SetEnv("COMSPEC",tempenv.c_str());
 
-		/* Update batch file if running from Z: (very likely: autoexec) */
-		if (first_shell->bf) {
-			std::string &name = first_shell->bf->filename;
-			if (starts_with(name, "Z:")) {
-				name[0] = new_drive_z;
-			}
-		}
 		/* Change the active drive */
 		if (DOS_GetDefaultDrive() == 25)
 			DOS_SetDrive(new_idx);

src/shell/shell_batch.cpp

@@ -24,31 +24,19 @@
 #include "string_utils.h"
 
 // Permitted ASCII control characters in batch files
-constexpr uint8_t Esc           = 27;
-constexpr uint8_t UnitSeparator = 31;
+constexpr char Esc           = 27;
+constexpr char UnitSeparator = 31;
 
 [[nodiscard]] static bool found_label(std::string_view line, std::string_view label);
 
-BatchFile::BatchFile(DOS_Shell* const host, const char* const resolved_name,
+BatchFile::BatchFile(DOS_Shell* const host, std::unique_ptr<ByteReader> input_reader,
                      const char* const entered_name, const char* const cmd_line)
         : echo(host->echo),
           shell(host),
           prev(host->bf),
-          cmd(new CommandLine(entered_name, cmd_line))
+          cmd(new CommandLine(entered_name, cmd_line)),
+          reader(std::move(input_reader))
 {
-	char totalname[DOS_PATHLENGTH + 4];
-
-	// Get fullname including drive specification
-	if (!DOS_Canonicalize(resolved_name, totalname)) {
-		E_Exit("SHELL: Can't determine path to batch file %s", resolved_name);
-	}
-
-	filename = totalname;
-	// Test if file is openable
-	if (!DOS_OpenFile(totalname, (DOS_NOT_INHERIT | OPEN_READ), &file_handle)) {
-		shell->WriteOut("SHELL: Can't open BatchFile %s\n", totalname);
-	}
-	DOS_CloseFile(file_handle);
 }
 
 BatchFile::~BatchFile()
@@ -87,25 +75,19 @@ bool BatchFile::ReadLine(char* lineout)
 
 std::string BatchFile::GetLine()
 {
-	if (!DOS_OpenFile(filename.c_str(), (DOS_NOT_INHERIT | OPEN_READ), &file_handle)) {
-		LOG(LOG_MISC, LOG_ERROR)
-		("ReadLine Can't open BatchFile %s", filename.c_str());
-		return "";
-	}
-	DOS_SeekFile(file_handle, &(this->location), DOS_SEEK_SET);
-
-	uint8_t data        = 0;
-	uint16_t bytes_read = 1;
-	std::string line    = {};
+	char data        = 0;
+	std::string line = {};
 
 	while (data != '\n') {
-		DOS_ReadFile(file_handle, &data, &bytes_read);
+		const auto result = reader->Read();
 
 		// EOF
-		if (bytes_read == 0) {
+		if (!result) {
 			break;
 		}
 
+		data = *result;
+
 		/* Inclusion criteria:
 		 *  - backspace for alien odyssey
 		 *  - tab for batch files
@@ -117,14 +99,10 @@ std::string BatchFile::GetLine()
 			              data,
 			              data);
 		} else {
-			line += static_cast<char>(data);
+			line += data;
 		}
 	}
 
-	this->location = 0;
-	DOS_SeekFile(file_handle, &(this->location), DOS_SEEK_CUR);
-	DOS_CloseFile(file_handle);
-
 	return line;
 }
 
@@ -175,7 +153,7 @@ std::string BatchFile::ExpandedBatchLine(std::string_view line) const
 bool BatchFile::Goto(const std::string_view label)
 {
 	std::string line = " ";
-	this->location = 0;
+	reader->Reset();
 
 	while (!line.empty()) {
 		line = GetLine();

src/shell/shell_misc.cpp

@@ -21,9 +21,11 @@
 
 #include <algorithm>
 #include <cstring>
+#include <memory>
 
 #include "../ints/int10.h"
 #include "callback.h"
+#include "file_reader.h"
 #include "keyboard.h"
 #include "regs.h"
 #include "string_utils.h"
@@ -468,11 +470,19 @@ bool DOS_Shell::Execute(std::string_view name, std::string_view args)
 		if (bf && !call) {
 			bf.reset();
 		}
-		bf   = std::make_shared<BatchFile>(this,
-                                                 fullname.c_str(),
-                                                 std::string(name).c_str(),
-                                                 std::string(args).c_str());
+
+		auto reader = FileReader::GetFileReader(fullname);
+		if (reader) {
+			bf = std::make_shared<BatchFile>(this,
+			                                 std::move(*reader),
+			                                 std::string(name).c_str(),
+			                                 std::string(args).c_str());
+		} else {
+			WriteOut("Could not open %s", fullname.c_str());
+		}
+
 		echo = temp_echo;
+
 		return true;
 	}