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ladybird/Kernel/TTY/TTY.cpp
sin-ack 3f3f45580a Everywhere: Add sv suffix to strings relying on StringView(char const*) 
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).

No functional changes.
2022-07-12 23:11:35 +02:00

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/StringView.h>
#include <Kernel/API/POSIX/errno.h>
#include <Kernel/Arch/InterruptDisabler.h>
#include <Kernel/Debug.h>
#include <Kernel/Process.h>
#include <Kernel/TTY/TTY.h>
#include <LibC/signal_numbers.h>
#include <LibC/sys/ioctl_numbers.h>
#define TTYDEFCHARS
#include <LibC/sys/ttydefaults.h>
#undef TTYDEFCHARS
namespace Kernel {
TTY::TTY(MajorNumber major, MinorNumber minor)
: CharacterDevice(major, minor)
{
set_default_termios();
}
TTY::~TTY() = default;
void TTY::set_default_termios()
{
memset(&m_termios, 0, sizeof(m_termios));
m_termios.c_iflag = TTYDEF_IFLAG;
m_termios.c_oflag = TTYDEF_OFLAG;
m_termios.c_cflag = TTYDEF_CFLAG;
m_termios.c_lflag = TTYDEF_LFLAG;
m_termios.c_ispeed = TTYDEF_SPEED;
m_termios.c_ospeed = TTYDEF_SPEED;
memcpy(m_termios.c_cc, ttydefchars, sizeof(ttydefchars));
}
ErrorOr<size_t> TTY::read(OpenFileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
{
if (Process::current().pgid() != pgid()) {
// FIXME: Should we propagate this error path somehow?
[[maybe_unused]] auto rc = Process::current().send_signal(SIGTTIN, nullptr);
return EINTR;
}
if (m_input_buffer.size() < static_cast<size_t>(size))
size = m_input_buffer.size();
bool need_evaluate_block_conditions = false;
auto result = buffer.write_buffered<512>(size, [&](Bytes data) {
size_t bytes_written = 0;
for (; bytes_written < data.size(); ++bytes_written) {
auto bit_index = m_input_buffer.head_index();
bool is_special_character = m_special_character_bitmask[bit_index / 8] & (1 << (bit_index % 8));
if (in_canonical_mode() && is_special_character) {
u8 ch = m_input_buffer.dequeue();
if (ch == '\0') {
// EOF
m_available_lines--;
need_evaluate_block_conditions = true;
break;
} else {
// '\n' or EOL
data[bytes_written++] = ch;
m_available_lines--;
break;
}
}
data[bytes_written] = m_input_buffer.dequeue();
}
return bytes_written;
});
if ((!result.is_error() && result.value() > 0) || need_evaluate_block_conditions)
evaluate_block_conditions();
return result;
}
ErrorOr<size_t> TTY::write(OpenFileDescription&, u64, UserOrKernelBuffer const& buffer, size_t size)
{
if (m_termios.c_lflag & TOSTOP && Process::current().pgid() != pgid()) {
[[maybe_unused]] auto rc = Process::current().send_signal(SIGTTOU, nullptr);
return EINTR;
}
constexpr size_t num_chars = 256;
return buffer.read_buffered<num_chars>(size, [&](ReadonlyBytes bytes) -> ErrorOr<size_t> {
u8 modified_data[num_chars * 2];
size_t modified_data_size = 0;
for (const auto& byte : bytes) {
process_output(byte, [&modified_data, &modified_data_size](u8 out_ch) {
modified_data[modified_data_size++] = out_ch;
});
}
auto bytes_written_or_error = on_tty_write(UserOrKernelBuffer::for_kernel_buffer(modified_data), modified_data_size);
if (bytes_written_or_error.is_error() || !(m_termios.c_oflag & OPOST) || !(m_termios.c_oflag & ONLCR))
return bytes_written_or_error;
auto bytes_written = bytes_written_or_error.value();
if (bytes_written == modified_data_size)
return bytes.size();
// Degenerate case where we converted some newlines and encountered a partial write
// Calculate where in the input buffer the last character would have been
size_t pos_data = 0;
for (size_t pos_modified_data = 0; pos_modified_data < bytes_written; ++pos_data) {
if (bytes[pos_data] == '\n')
pos_modified_data += 2;
else
pos_modified_data += 1;
// Handle case where the '\r' got written but not the '\n'
// FIXME: Our strategy is to retry writing both. We should really be queuing a write for the corresponding '\n'
if (pos_modified_data > bytes_written)
--pos_data;
}
return pos_data;
});
}
void TTY::echo_with_processing(u8 ch)
{
process_output(ch, [this](u8 out_ch) { echo(out_ch); });
}
template<typename Functor>
void TTY::process_output(u8 ch, Functor put_char)
{
if (m_termios.c_oflag & OPOST) {
if (ch == '\n' && (m_termios.c_oflag & ONLCR))
put_char('\r');
put_char(ch);
} else {
put_char(ch);
}
}
bool TTY::can_read(OpenFileDescription const&, u64) const
{
if (in_canonical_mode()) {
return m_available_lines > 0;
}
return !m_input_buffer.is_empty();
}
bool TTY::can_write(OpenFileDescription const&, u64) const
{
return true;
}
bool TTY::is_eol(u8 ch) const
{
return ch == m_termios.c_cc[VEOL];
}
bool TTY::is_eof(u8 ch) const
{
return ch == m_termios.c_cc[VEOF];
}
bool TTY::is_kill(u8 ch) const
{
return ch == m_termios.c_cc[VKILL];
}
bool TTY::is_erase(u8 ch) const
{
return ch == m_termios.c_cc[VERASE];
}
bool TTY::is_werase(u8 ch) const
{
return ch == m_termios.c_cc[VWERASE];
}
void TTY::emit(u8 ch, bool do_evaluate_block_conditions)
{
if (m_termios.c_iflag & ISTRIP)
ch &= 0x7F;
if (should_generate_signals()) {
if (ch == m_termios.c_cc[VINFO]) {
generate_signal(SIGINFO);
return;
}
if (ch == m_termios.c_cc[VINTR]) {
generate_signal(SIGINT);
return;
}
if (ch == m_termios.c_cc[VQUIT]) {
generate_signal(SIGQUIT);
return;
}
if (ch == m_termios.c_cc[VSUSP]) {
generate_signal(SIGTSTP);
if (auto original_process_parent = m_original_process_parent.strong_ref()) {
[[maybe_unused]] auto rc = original_process_parent->send_signal(SIGCHLD, nullptr);
}
// TODO: Else send it to the session leader maybe?
return;
}
}
ScopeGuard guard([&]() {
if (do_evaluate_block_conditions)
evaluate_block_conditions();
});
if (ch == '\r' && (m_termios.c_iflag & ICRNL))
ch = '\n';
else if (ch == '\n' && (m_termios.c_iflag & INLCR))
ch = '\r';
auto current_char_head_index = (m_input_buffer.head_index() + m_input_buffer.size()) % TTY_BUFFER_SIZE;
m_special_character_bitmask[current_char_head_index / 8] &= ~(1u << (current_char_head_index % 8));
auto set_special_bit = [&] {
m_special_character_bitmask[current_char_head_index / 8] |= (1u << (current_char_head_index % 8));
};
if (in_canonical_mode()) {
if (is_eof(ch)) {
// Since EOF might change between when the data came in and when it is read,
// we use '\0' along with the bitmask to signal EOF. Any non-zero byte with
// the special bit set signals an end-of-line.
set_special_bit();
m_available_lines++;
m_input_buffer.enqueue('\0');
return;
}
if (is_kill(ch) && m_termios.c_lflag & ECHOK) {
kill_line();
return;
}
if (is_erase(ch) && m_termios.c_lflag & ECHOE) {
do_backspace();
return;
}
if (is_werase(ch)) {
erase_word();
return;
}
if (ch == '\n') {
if (m_termios.c_lflag & ECHO || m_termios.c_lflag & ECHONL)
echo_with_processing('\n');
set_special_bit();
m_input_buffer.enqueue('\n');
m_available_lines++;
return;
}
if (is_eol(ch)) {
set_special_bit();
m_available_lines++;
}
}
m_input_buffer.enqueue(ch);
if (m_termios.c_lflag & ECHO)
echo_with_processing(ch);
}
bool TTY::can_do_backspace() const
{
// can't do back space if we're empty. Plus, we don't want to
// remove any lines "committed" by newlines or ^D.
if (!m_input_buffer.is_empty() && !is_eol(m_input_buffer.last()) && m_input_buffer.last() != '\0') {
return true;
}
return false;
}
static size_t length_with_tabs(CircularDeque<u8, TTY_BUFFER_SIZE> const& line)
{
size_t length = 0;
for (auto& ch : line) {
length += (ch == '\t') ? 8 - (length % 8) : 1;
}
return length;
}
void TTY::do_backspace()
{
if (can_do_backspace()) {
auto ch = m_input_buffer.dequeue_end();
size_t to_delete = 1;
if (ch == '\t') {
auto length = length_with_tabs(m_input_buffer);
to_delete = 8 - (length % 8);
}
for (size_t i = 0; i < to_delete; ++i) {
// We deliberately don't process the output here.
echo('\b');
echo(' ');
echo('\b');
}
evaluate_block_conditions();
}
}
// TODO: Currently, both erase_word() and kill_line work by sending
// a lot of VERASE characters; this is done because Terminal.cpp
// doesn't currently support VWERASE and VKILL. When these are
// implemented we could just send a VKILL or VWERASE.
void TTY::erase_word()
{
// Note: if we have leading whitespace before the word
// we want to delete we have to also delete that.
bool first_char = false;
bool did_dequeue = false;
while (can_do_backspace()) {
u8 ch = m_input_buffer.last();
if (ch == ' ' && first_char)
break;
if (ch != ' ')
first_char = true;
m_input_buffer.dequeue_end();
did_dequeue = true;
erase_character();
}
if (did_dequeue)
evaluate_block_conditions();
}
void TTY::kill_line()
{
bool did_dequeue = false;
while (can_do_backspace()) {
m_input_buffer.dequeue_end();
did_dequeue = true;
erase_character();
}
if (did_dequeue)
evaluate_block_conditions();
}
void TTY::erase_character()
{
// We deliberately don't process the output here.
echo(m_termios.c_cc[VERASE]);
echo(' ');
echo(m_termios.c_cc[VERASE]);
}
void TTY::generate_signal(int signal)
{
if (!pgid())
return;
if (should_flush_on_signal())
flush_input();
dbgln_if(TTY_DEBUG, "Send signal {} to everyone in pgrp {}", signal, pgid().value());
InterruptDisabler disabler; // FIXME: Iterate over a set of process handles instead?
Process::for_each_in_pgrp(pgid(), [&](auto& process) {
dbgln_if(TTY_DEBUG, "Send signal {} to {}", signal, process);
// FIXME: Should this error be propagated somehow?
[[maybe_unused]] auto rc = process.send_signal(signal, nullptr);
});
}
void TTY::flush_input()
{
m_available_lines = 0;
m_input_buffer.clear();
evaluate_block_conditions();
}
ErrorOr<void> TTY::set_termios(termios const& t)
{
ErrorOr<void> rc;
m_termios = t;
dbgln_if(TTY_DEBUG, "set_termios: ECHO={}, ISIG={}, ICANON={}, ECHOE={}, ECHOK={}, ECHONL={}, ISTRIP={}, ICRNL={}, INLCR={}, IGNCR={}, OPOST={}, ONLCR={}",
should_echo_input(),
should_generate_signals(),
in_canonical_mode(),
((m_termios.c_lflag & ECHOE) != 0),
((m_termios.c_lflag & ECHOK) != 0),
((m_termios.c_lflag & ECHONL) != 0),
((m_termios.c_iflag & ISTRIP) != 0),
((m_termios.c_iflag & ICRNL) != 0),
((m_termios.c_iflag & INLCR) != 0),
((m_termios.c_iflag & IGNCR) != 0),
((m_termios.c_oflag & OPOST) != 0),
((m_termios.c_oflag & ONLCR) != 0));
struct FlagDescription {
tcflag_t value;
StringView name;
};
constexpr FlagDescription unimplemented_iflags[] = {
{ IGNBRK, "IGNBRK"sv },
{ BRKINT, "BRKINT"sv },
{ IGNPAR, "IGNPAR"sv },
{ PARMRK, "PARMRK"sv },
{ INPCK, "INPCK"sv },
{ IGNCR, "IGNCR"sv },
{ IUCLC, "IUCLC"sv },
{ IXON, "IXON"sv },
{ IXANY, "IXANY"sv },
{ IXOFF, "IXOFF"sv },
{ IMAXBEL, "IMAXBEL"sv },
{ IUTF8, "IUTF8"sv }
};
for (auto flag : unimplemented_iflags) {
if (m_termios.c_iflag & flag.value) {
dbgln("FIXME: iflag {} unimplemented", flag.name);
rc = ENOTIMPL;
}
}
constexpr FlagDescription unimplemented_oflags[] = {
{ OLCUC, "OLCUC"sv },
{ ONOCR, "ONOCR"sv },
{ ONLRET, "ONLRET"sv },
{ OFILL, "OFILL"sv },
{ OFDEL, "OFDEL"sv }
};
for (auto flag : unimplemented_oflags) {
if (m_termios.c_oflag & flag.value) {
dbgln("FIXME: oflag {} unimplemented", flag.name);
rc = ENOTIMPL;
}
}
if ((m_termios.c_cflag & CSIZE) != CS8) {
dbgln("FIXME: Character sizes other than 8 bits are not supported");
rc = ENOTIMPL;
}
constexpr FlagDescription unimplemented_cflags[] = {
{ CSTOPB, "CSTOPB"sv },
{ CREAD, "CREAD"sv },
{ PARENB, "PARENB"sv },
{ PARODD, "PARODD"sv },
{ HUPCL, "HUPCL"sv },
{ CLOCAL, "CLOCAL"sv }
};
for (auto flag : unimplemented_cflags) {
if (m_termios.c_cflag & flag.value) {
dbgln("FIXME: cflag {} unimplemented", flag.name);
rc = ENOTIMPL;
}
}
constexpr FlagDescription unimplemented_lflags[] = {
{ TOSTOP, "TOSTOP"sv },
{ IEXTEN, "IEXTEN"sv }
};
for (auto flag : unimplemented_lflags) {
if (m_termios.c_lflag & flag.value) {
dbgln("FIXME: lflag {} unimplemented", flag.name);
rc = ENOTIMPL;
}
}
return rc;
}
ErrorOr<void> TTY::ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg)
{
auto& current_process = Process::current();
TRY(current_process.require_promise(Pledge::tty));
#if 0
// FIXME: When should we block things?
// How do we make this work together with MasterPTY forwarding to us?
if (current_process.tty() && current_process.tty() != this) {
return ENOTTY;
}
#endif
switch (request) {
case TIOCGPGRP: {
auto user_pgid = static_ptr_cast<pid_t*>(arg);
auto pgid = this->pgid().value();
return copy_to_user(user_pgid, &pgid);
}
case TIOCSPGRP: {
ProcessGroupID pgid = static_cast<pid_t>(arg.ptr());
if (pgid <= 0)
return EINVAL;
InterruptDisabler disabler;
auto process_group = ProcessGroup::from_pgid(pgid);
// Disallow setting a nonexistent PGID.
if (!process_group)
return EINVAL;
auto process = Process::from_pid(ProcessID(pgid.value()));
SessionID new_sid = process ? process->sid() : Process::get_sid_from_pgid(pgid);
if (!new_sid || new_sid != current_process.sid())
return EPERM;
if (process && pgid != process->pgid())
return EPERM;
m_pg = process_group;
if (process) {
if (auto parent = Process::from_pid(process->ppid())) {
m_original_process_parent = *parent;
return {};
}
}
m_original_process_parent = nullptr;
return {};
}
case TCGETS: {
auto user_termios = static_ptr_cast<termios*>(arg);
return copy_to_user(user_termios, &m_termios);
}
case TCSETS:
case TCSETSF:
case TCSETSW: {
auto user_termios = static_ptr_cast<termios const*>(arg);
auto termios = TRY(copy_typed_from_user(user_termios));
auto rc = set_termios(termios);
if (request == TCSETSF)
flush_input();
return rc;
}
case TCFLSH: {
// Serenity's TTY implementation does not use an output buffer, so ignore TCOFLUSH.
auto operation = static_cast<u8>(arg.ptr());
if (operation == TCIFLUSH || operation == TCIOFLUSH) {
flush_input();
} else if (operation != TCOFLUSH) {
return EINVAL;
}
return {};
}
case TIOCGWINSZ: {
auto user_winsize = static_ptr_cast<winsize*>(arg);
winsize ws {};
ws.ws_row = m_rows;
ws.ws_col = m_columns;
ws.ws_xpixel = 0;
ws.ws_ypixel = 0;
return copy_to_user(user_winsize, &ws);
}
case TIOCSWINSZ: {
auto user_winsize = static_ptr_cast<winsize const*>(arg);
auto ws = TRY(copy_typed_from_user(user_winsize));
if (ws.ws_col == m_columns && ws.ws_row == m_rows)
return {};
m_rows = ws.ws_row;
m_columns = ws.ws_col;
generate_signal(SIGWINCH);
return {};
}
case TIOCSCTTY:
current_process.set_tty(this);
return {};
case TIOCSTI:
return EIO;
case TIOCNOTTY:
current_process.set_tty(nullptr);
return {};
case KDSETMODE: {
auto mode = static_cast<unsigned int>(arg.ptr());
if (mode != KD_TEXT && mode != KD_GRAPHICS)
return EINVAL;
set_graphical(mode == KD_GRAPHICS);
return {};
}
case KDGETMODE: {
auto mode_ptr = static_ptr_cast<int*>(arg);
int mode = (is_graphical()) ? KD_GRAPHICS : KD_TEXT;
return copy_to_user(mode_ptr, &mode);
}
}
return EINVAL;
}
void TTY::set_size(unsigned short columns, unsigned short rows)
{
m_rows = rows;
m_columns = columns;
}
void TTY::hang_up()
{
generate_signal(SIGHUP);
}
}
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