Implement MORE.COM command

6 files changed, 593 insertions, 0 deletions

diff --git a/src/dos/dos_programs.cpp b/src/dos/dos_programs.cpp
index 3e587a2e3..617fb9f46 100644
--- a/src/dos/dos_programs.cpp
+++ b/src/dos/dos_programs.cpp
@@ -32,6 +32,7 @@
 #include "program_loadrom.h"
 #include "program_ls.h"
 #include "program_mem.h"
+#include "program_more.h"
 #include "program_mount.h"
 #include "program_mousectl.h"
 #include "program_placeholder.h"
@@ -75,6 +76,7 @@ void Add_VFiles(const bool add_autoexec)
 	PROGRAMS_MakeFile("LOADROM.COM", ProgramCreate<LOADROM>);
 	PROGRAMS_MakeFile("LS.COM", ProgramCreate<LS>);
 	PROGRAMS_MakeFile("MEM.COM", ProgramCreate<MEM>);
+	PROGRAMS_MakeFile("MORE.COM", ProgramCreate<MORE>);
 	PROGRAMS_MakeFile("MOUNT.COM", ProgramCreate<MOUNT>);
 	PROGRAMS_MakeFile("MOUSECTL.COM", ProgramCreate<MOUSECTL>);
 	PROGRAMS_MakeFile("RESCAN.COM", ProgramCreate<RESCAN>);
diff --git a/src/dos/meson.build b/src/dos/meson.build
index c7521b460..da69c78cc 100644
--- a/src/dos/meson.build
+++ b/src/dos/meson.build
@@ -34,6 +34,7 @@ libdos_sources = files(
     'program_loadrom.cpp',
     'program_ls.cpp',
     'program_mem.cpp',
+    'program_more.cpp',
     'program_mount.cpp',
     'program_mount_common.cpp',
     'program_mousectl.cpp',
diff --git a/src/dos/program_more.cpp b/src/dos/program_more.cpp
new file mode 100644
index 000000000..ba1849702
--- /dev/null
+++ b/src/dos/program_more.cpp
@@ -0,0 +1,504 @@
+/*
+ *  SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ *  Copyright (C) 2022-2022  The DOSBox Staging Team
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "program_more.h"
+
+#include "../ints/int10.h"
+#include "callback.h"
+#include "checks.h"
+#include "dos_inc.h"
+#include "string_utils.h"
+
+#include <algorithm>
+#include <array>
+#include <cctype>
+
+CHECK_NARROWING();
+
+// ASCII control characters
+constexpr char code_ctrl_c = 0x03; // end of text
+constexpr char code_lf     = 0x0a; // line feed
+constexpr char code_cr     = 0x0d; // carriage return
+constexpr char code_esc    = 0x1b; // escape
+
+void MORE::Run()
+{
+	// Handle command line
+	if (HelpRequested()) {
+		WriteOut(MSG_Get("SHELL_CMD_MORE_HELP_LONG"));
+		return;
+	}
+	if (!ParseCommandLine() || shutdown_requested)
+		return;
+
+	// Retrieve screen size, prepare limits
+	constexpr uint16_t min_lines   = 10;
+	constexpr uint16_t min_columns = 40;
+	max_lines   = std::max(min_lines, INT10_GetTextRows());
+	max_columns = std::max(min_columns, INT10_GetTextColumns());
+	// The prompt at the bottom will cause scrolling,
+	// so reduce the maximum number of lines accordingly
+	max_lines = static_cast<uint16_t>(max_lines - 1);
+
+	line_counter = 0;
+
+	// Show STDIN or input file(s) content
+	if (input_files.empty()) {
+		DisplayInputStream();
+	} else {
+		DisplayInputFiles();
+
+		// End message and command prompt is going to appear; ensure the
+		// scrolling won't make top lines disappear before user reads them
+		const int free_rows_threshold = 2;
+		if (max_lines - line_counter < free_rows_threshold)
+			PromptUser();
+
+		WriteOut(MSG_Get("SHELL_CMD_MORE_END"));
+		WriteOut("\n");
+	}
+
+	WriteOut("\n");
+}
+
+bool MORE::ParseCommandLine()
+{
+	// Put all the parameters into vector
+	std::vector<std::string> params;
+	cmd->FillVector(params);
+
+	// Check if specified tabulation size
+	if (!params.empty()) {
+		const auto &param = params[0];
+		if ((starts_with("/t", param) || starts_with("/T", param)) &&
+		    (param.length() == 3) && (param.back() >= '1') &&
+		    (param.back() <= '9')) {
+			// FreeDOS extension - custom TAB size
+			tab_size = static_cast<uint8_t>(param.back() - '0');
+			params.erase(params.begin());
+		}
+	}
+
+	// Make sure no other switches are supplied
+	for (const auto &param : params)
+		if (starts_with("/", param)) {
+			WriteOut(MSG_Get("SHELL_ILLEGAL_SWITCH"), param.c_str());
+			return false;
+		}
+
+	// Create list of input files
+	return FindInputFiles(params);
+}
+
+bool MORE::FindInputFiles(const std::vector<std::string> &params)
+{
+	input_files.clear();
+	if (params.empty())
+		return true;
+
+	constexpr auto search_attr = UINT16_MAX & ~DOS_ATTR_DIRECTORY &
+	                             ~DOS_ATTR_VOLUME;
+
+	RealPt save_dta = dos.dta();
+	dos.dta(dos.tables.tempdta);
+
+	for (const auto &param : params) {
+		// Retrieve path to current file/pattern
+		char path[DOS_PATHLENGTH];
+		if (!DOS_Canonicalize(param.c_str(), path))
+			continue;
+		char *const end = strrchr(path, '\\') + 1;
+		assert(end);
+		*end = 0;
+
+		// Search for the first file from pattern
+		if (!DOS_FindFirst(param.c_str(),
+		                   static_cast<uint16_t>(search_attr))) {
+			LOG_WARNING("DOS: MORE.COM - no match for pattern '%s'",
+			            param.c_str());
+			continue;
+		}
+
+		while (!shutdown_requested) {
+			CALLBACK_Idle();
+
+			char name[DOS_NAMELENGTH_ASCII];
+			uint32_t size = 0;
+			uint16_t time = 0;
+			uint16_t date = 0;
+			uint8_t attr  = 0;
+
+			DOS_DTA dta(dos.dta());
+			dta.GetResult(name, size, date, time, attr);
+			assert(name);
+
+			input_files.emplace_back();
+			auto &entry = input_files.back();
+
+			if (attr & DOS_ATTR_DEVICE) {
+				entry.is_device = true;
+				entry.name      = std::string(name);
+			} else {
+				entry.is_device = false;
+				entry.name = std::string(path) + std::string(name);
+			}
+
+			if (!DOS_FindNext()) {
+				break;
+			}
+		}
+	}
+
+	dos.dta(save_dta);
+
+	if (!shutdown_requested && input_files.empty()) {
+		WriteOut(MSG_Get("SHELL_CMD_MORE_NO_FILE"));
+		WriteOut("\n");
+		return false;
+	}
+
+	return true;
+}
+
+std::string MORE::GetShortName(const std::string &file_name, const char *msg_id)
+{
+	assert(msg_id);
+
+	// The shortest name we should be able to display is:
+	// - 3 dots
+	// - 1 path separator
+	// - 8 characters of name
+	// - 1 dot
+	// - 3 characters of extension
+	// This gives 16 characters.
+	// We need to keep the last column free (reduces max length by 1).
+	// Format string contains '%s' (increases max length by 2).
+	constexpr size_t min = 16;
+	const auto max_len   = std::max(min, max_columns - std::strlen(MSG_Get(msg_id)) + 1);
+
+	// Nothing to do if file name maches the constraint
+	if (file_name.length() <= max_len)
+		return file_name;
+
+	// We need to shorten the name - try to strip part of the path
+	auto shortened = file_name;
+	while (shortened.length() > max_len &&
+	       std::count(shortened.begin(), shortened.end(), '\\') > 1) {
+		// Strip one level of path at a time
+		const auto pos = shortened.find('\\', shortened.find('\\') + 1);
+		shortened      = std::string("...") + shortened.substr(pos);
+	}
+
+	// If still too long, just cut away the beginning
+	const auto len = shortened.length();
+	if (len > max_len)
+		shortened = std::string("...") + shortened.substr(len - max_len + 3);
+
+	return shortened;
+}
+
+void MORE::DisplayInputFiles()
+{
+	WriteOut("\n");
+
+	bool first = true;
+	for (const auto &input_file : input_files) {
+		if (!first && Decision::Terminate == PromptUser())
+			break;
+		first = false;
+
+		if (!DOS_OpenFile(input_file.name.c_str(), 0, &input_handle)) {
+			LOG_WARNING("DOS: MORE.COM - could not open '%s'",
+			            input_file.name.c_str());
+			const auto short_name = GetShortName(input_file.name,
+			                                     "SHELL_CMD_MORE_OPEN_ERROR");
+			WriteOut(MSG_Get("SHELL_CMD_MORE_OPEN_ERROR"), short_name.c_str());
+			WriteOut("\n");
+			++line_counter;
+			continue;
+		}
+
+		if (input_file.is_device) {
+			const auto short_name = GetShortName(input_file.name,
+			                                     "SHELL_CMD_MORE_NEW_DEVICE");
+			WriteOut(MSG_Get("SHELL_CMD_MORE_NEW_DEVICE"), short_name.c_str());
+		} else {
+			const auto short_name = GetShortName(input_file.name,
+			                                     "SHELL_CMD_MORE_NEW_FILE");
+			WriteOut(MSG_Get("SHELL_CMD_MORE_NEW_FILE"), short_name.c_str());
+		}
+		WriteOut("\n");
+		++line_counter;
+
+		// If input from a device, CTRL+C shall quit
+		ctrl_c_enable = input_file.is_device;
+
+		const auto decision = DisplaySingleStream();
+		DOS_CloseFile(input_handle);
+		if (decision == Decision::Terminate) {
+			break;
+		}
+	}
+}
+
+void MORE::DisplayInputStream()
+{
+	// We need to be able to read STDIN for key presses, but it is most
+	// likely redirected - so clone the handle, and reconstruct real STDIN
+	// from STDERR (idea from FreeDOS implementation,
+	// https://github.com/FDOS/more/blob/master/src/more.c)
+	if (!DOS_DuplicateEntry(STDIN, &input_handle) ||
+	    !DOS_ForceDuplicateEntry(STDERR, STDIN)) {
+		LOG_ERR("DOS: Unable to prepare handles in MORE.COM");
+		return;
+	}
+
+	WriteOut("\n");
+
+	// Since this CAN be STDIN input (there is no way to check),
+	// CTRL+C shall quit
+	ctrl_c_enable = true;
+	DisplaySingleStream();
+}
+
+MORE::Decision MORE::DisplaySingleStream()
+{
+	auto previous_column = GetCurrentColumn();
+
+	tabs_remaining = 0;
+	skip_next_cr   = false;
+	skip_next_lf   = false;
+
+	auto decision = Decision::NextFile;
+	while (true) {
+		if (shutdown_requested) {
+			decision = Decision::Terminate;
+			break;
+		}
+
+		// Read character
+		char code = 0;
+		if (!GetCharacter(code)) {
+			decision = Decision::NextFile; // end of file
+			break;
+		}
+
+		// A trick to make it more resistant to ANSI cursor movements
+		const auto current_row = GetCurrentRow();
+		if (line_counter > current_row)
+			line_counter = current_row;
+
+		// Handle new line characters
+		bool new_line = false;
+		if (code == code_cr) {
+			skip_next_lf = true;
+			new_line     = true;
+		} else if (code == code_lf) {
+			skip_next_cr = true;
+			new_line     = true;
+		} else {
+			skip_next_cr = false;
+			skip_next_lf = false;
+		}
+
+		// Duplicate character on the output
+		if (new_line)
+			code = '\n';
+		WriteOut("%c", code);
+
+		// Detect 'new line' due to character passing the last column
+		const auto current_column = GetCurrentColumn();
+		if (!current_column && previous_column) {
+			new_line = true;
+		}
+		previous_column = current_column;
+
+		// Update new line counter, decide if pause needed
+		if (new_line && current_row) {
+			++line_counter;
+		}
+		if (line_counter < max_lines) {
+			continue;
+		}
+
+		// New line occured just enough times for a pause
+		decision = PromptUser();
+		if (decision == Decision::Terminate || decision == Decision::NextFile) {
+			break;
+		}
+	}
+
+	if (GetCurrentColumn()) {
+		++line_counter;
+		WriteOut("\n");
+	}
+
+	return decision;
+}
+
+MORE::Decision MORE::PromptUser()
+{
+	line_counter = 0;
+	const bool multiple_files = input_files.size() > 1;
+
+	if (GetCurrentColumn())
+		WriteOut("\n");
+
+	if (multiple_files)
+		WriteOut(MSG_Get("SHELL_CMD_MORE_PROMPT_MULTI"));
+	else
+		WriteOut(MSG_Get("SHELL_CMD_MORE_PROMPT_SINGLE"));
+
+	auto decision = Decision::Terminate;
+	while (!shutdown_requested) {
+		CALLBACK_Idle();
+
+		uint16_t count = 1;
+		char choice    = 0;
+		DOS_ReadFile(STDIN, reinterpret_cast<uint8_t *>(&choice), &count);
+
+		if (count == 0 || choice == code_ctrl_c || choice == code_esc ||
+		    choice == 'q' || choice == 'Q') {
+			decision = Decision::Terminate;
+			break;
+		}
+
+		if (choice == code_cr || choice == ' ') {
+			decision = Decision::More;
+			break;
+		}
+
+		if (!multiple_files)
+			continue;
+
+		if (choice == 'n' || choice == 'N') {
+			decision = Decision::NextFile;
+			break;
+		}
+	}
+
+	if (decision == Decision::Terminate || decision == Decision::NextFile) {
+		WriteOut(" ");
+		WriteOut(MSG_Get("SHELL_CMD_MORE_TERMINATE"));
+		WriteOut("\n");
+		++line_counter;
+	} else {
+		// We are going to continue - erase the prompt
+		WriteOut("\033[M"); // clear line
+		auto counter = GetCurrentColumn();
+		while (counter--)
+			WriteOut("\033[D"); // cursor one position back
+	}
+
+	return decision;
+}
+
+bool MORE::GetCharacter(char &code)
+{
+	if (!tabs_remaining) {
+		while (true) {
+			// Retrieve character from input stream
+			uint16_t count = 1;
+			DOS_ReadFile(input_handle,
+			             reinterpret_cast<uint8_t *>(&code),
+			             &count);
+
+			if (!count) {
+				return false; // end of stream
+			}
+
+			if (ctrl_c_enable && code == code_ctrl_c) {
+				if (input_files.empty()) {
+					WriteOut("^C");
+				}
+				return false; // quit by CTRL+C
+			}
+
+			// Skip CR/LF characters if requested
+			if (skip_next_cr && code == code_cr) {
+				skip_next_cr = false;
+			} else if (skip_next_lf && code == code_lf) {
+				skip_next_lf = false;
+			} else {
+				break;
+			}
+		}
+
+		// If TAB found, replace it with given number of spaces
+		if (code == '\t') {
+			tabs_remaining = tab_size;
+		}
+	}
+
+	if (tabs_remaining) {
+		--tabs_remaining;
+		code = ' ';
+	}
+
+	return true;
+}
+
+uint8_t MORE::GetCurrentColumn()
+{
+	const auto page = real_readb(BIOSMEM_SEG, BIOSMEM_CURRENT_PAGE);
+	return CURSOR_POS_COL(page);
+}
+
+uint8_t MORE::GetCurrentRow()
+{
+	const auto page = real_readb(BIOSMEM_SEG, BIOSMEM_CURRENT_PAGE);
+	return CURSOR_POS_ROW(page);
+}
+
+void MORE::AddMessages()
+{
+	MSG_Add("SHELL_CMD_MORE_HELP",
+	        "Display command output or text file one screen at a time.\n");
+	MSG_Add("SHELL_CMD_MORE_HELP_LONG",
+	        "Display command output or text file one screen at a time.\n"
+	        "\n"
+	        "Usage:\n"
+	        "  [color=cyan]COMMAND[reset] | [color=green]more[reset] [/t[color=white]n[reset]]\n"
+	        "  [color=green]more[reset] [/t[color=white]n[reset]] < [color=cyan]FILE[reset]\n"
+	        "  [color=green]more[reset] [/t[color=white]n[reset]] [color=cyan]PATTERN[reset] [[color=cyan]PATTERN[reset] ...]\n"
+	        "\n"
+	        "Where:\n"
+	        "  [color=cyan]COMMAND[reset] is the command to display the output of.\n"
+	        "  [color=cyan]FILE[reset]    is an exact name of the file to display, optionally with a path.\n"
+	        "  [color=cyan]PATTERN[reset] is either a path to a single file or a path with wildcards,\n"
+	        "          which are the asterisk (*) and the question mark (?).\n"
+	        "  [color=white]n[reset]       is the tab size, 1-9, default is 8.\n"
+	        "\n"
+	        "Notes:\n"
+	        "  This command is only for viewing text files, not binary files.\n"
+	        "\n"
+	        "Examples:\n"
+	        "  [color=cyan]dir /on[reset] | [color=green]more[reset]             ; displays sorted directory one screen at a time\n"
+	        "  [color=green]more[reset] /t[color=white]4[reset] < [color=cyan]A:\\MANUAL.TXT[reset]   ; shows the file's content with tab size 4\n");
+
+	MSG_Add("SHELL_CMD_MORE_NO_FILE",       "No input file found.");
+	MSG_Add("SHELL_CMD_MORE_END",           "[reset][color=light-yellow]--- end of input ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_NEW_FILE",      "[reset][color=light-yellow]--- file %s ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_NEW_DEVICE",    "[reset][color=light-yellow]--- device %s ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_PROMPT_SINGLE", "[reset][color=light-yellow]--- press SPACE for more ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_PROMPT_MULTI",  "[reset][color=light-yellow]--- press SPACE for more, N for next file ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_OPEN_ERROR",    "[reset][color=red]--- could not open %s ---[reset]");
+	MSG_Add("SHELL_CMD_MORE_TERMINATE",     "[reset][color=light-yellow](terminated)[reset]");
+}
diff --git a/src/dos/program_more.h b/src/dos/program_more.h
new file mode 100644
index 000000000..e5266a929
--- /dev/null
+++ b/src/dos/program_more.h
@@ -0,0 +1,82 @@
+/*
+ *  SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ *  Copyright (C) 2022-2022  The DOSBox Staging Team
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef DOSBOX_PROGRAM_MORE_H
+#define DOSBOX_PROGRAM_MORE_H
+
+#include "programs.h"
+
+#include <vector>
+
+class MORE final : public Program {
+public:
+	MORE()
+	{
+		AddMessages();
+		help_detail = {HELP_Filter::All,
+		               HELP_Category::Dosbox,
+		               HELP_CmdType::Program,
+		               "MORE"};
+	}
+	void Run();
+
+private:
+	enum class Decision {
+		More,
+		Terminate,
+		NextFile,
+	};
+
+	bool ParseCommandLine();
+	bool FindInputFiles(const std::vector<std::string> &params);
+
+	void DisplayInputFiles();
+	void DisplayInputStream();
+	Decision DisplaySingleStream();
+	Decision PromptUser();
+
+	std::string GetShortName(const std::string &file_name, const char *msg_id);
+	static uint8_t GetCurrentColumn();
+	static uint8_t GetCurrentRow();
+	bool GetCharacter(char &code);
+
+	void AddMessages();
+
+	struct InputFile {
+		std::string name = ""; // file name with path
+		bool is_device   = false;
+	};
+
+	std::vector<InputFile> input_files = {};
+
+	uint16_t max_lines    = 0;
+	uint16_t max_columns  = 0;
+	uint16_t line_counter = 0;
+
+	uint8_t tab_size       = 8;
+	uint8_t tabs_remaining = 0;
+	bool skip_next_cr      = false;
+	bool skip_next_lf      = false;
+
+	uint16_t input_handle = 0;  // DOS handle of the input stream
+	bool ctrl_c_enable = false; // if CTRL+C in the input stream should quit
+};
+
+#endif
diff --git a/vs/dosbox.vcxproj b/vs/dosbox.vcxproj
index 0cd20276d..70e5b568c 100644
--- a/vs/dosbox.vcxproj
+++ b/vs/dosbox.vcxproj
@@ -553,6 +553,7 @@ IF %ERRORLEVEL% LSS 8 SET ERRORLEVEL = 0</Command>
     <ClCompile Include="..\src\dos\program_loadrom.cpp" />
     <ClCompile Include="..\src\dos\program_ls.cpp" />
     <ClCompile Include="..\src\dos\program_mem.cpp" />
+    <ClCompile Include="..\src\dos\program_more.cpp" />
     <ClCompile Include="..\src\dos\program_mount_common.cpp" />
     <ClCompile Include="..\src\dos\program_mount.cpp" />
     <ClCompile Include="..\src\dos\program_mousectl.cpp" />
diff --git a/vs/dosbox.vcxproj.filters b/vs/dosbox.vcxproj.filters
index 236e17de2..f999c4834 100644
--- a/vs/dosbox.vcxproj.filters
+++ b/vs/dosbox.vcxproj.filters
@@ -589,6 +589,9 @@
     <ClCompile Include="..\src\dos\program_mem.cpp">
       <Filter>src\dos</Filter>
     </ClCompile>
+    <ClCompile Include="..\src\dos\program_more.cpp">
+      <Filter>src\dos</Filter>
+    </ClCompile>
     <ClCompile Include="..\src\dos\program_mount.cpp">
       <Filter>src\dos</Filter>
     </ClCompile>