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// @ Copyright 2020
#include "libserial/serial.hpp"
#include <iostream>
#include <memory>
#include <poll.h>
#include <string>
#include <vector>
namespace libserial {
Serial::Serial(const std::string& port) {
this->open(port);
this->setBaudRate(BaudRate::BAUD_RATE_9600);
}
Serial::~Serial() {
if (fd_serial_port_ != -1) {
::close(fd_serial_port_);
fd_serial_port_ = -1;
}
}
void Serial::open(const std::string& port) {
// Open the serial port with read/write access, no controlling terminal, and non-blocking mode.
// On many serial devices, opening a port without O_NONBLOCK can block waiting for modem
// control lines/carrier detect, which is a behavior change that can hang callers. By opening
// in non-blocking mode and then immediately clearing that flag, we can avoid this issue while
// still allowing blocking reads/writes as expected.
fd_serial_port_ = ::open(port.c_str(), O_RDWR | O_NOCTTY | O_NONBLOCK);
if (fd_serial_port_ == -1) {
throw SerialException("Error opening port " + port + ": " + strerror(errno));
}
int flags = ::fcntl(fd_serial_port_, F_GETFL);
if (flags == -1) {
int saved_errno = errno;
::close(fd_serial_port_);
throw SerialException("Error configuring port " + port + ": " + strerror(saved_errno));
}
if (::fcntl(fd_serial_port_, F_SETFL, flags & ~O_NONBLOCK) == -1) {
int saved_errno = errno;
::close(fd_serial_port_);
throw SerialException("Error configuring port " + port + ": " + strerror(saved_errno));
}
}
void Serial::close() {
if (fd_serial_port_ != -1) {
ssize_t error = ::close(fd_serial_port_);
if (error < 0) {
throw SerialException("Error closing port: " + std::string(strerror(errno)));
}
fd_serial_port_ = -1;
}
}
void Serial::write(std::string_view data) {
if (data.empty()) {
throw IOException("Empty string passed to write function");
}
size_t total_written = 0;
while (total_written < data.size()) {
ssize_t ret = write_(fd_serial_port_,
data.data() + total_written,
data.size() - total_written);
if (ret < 0) {
if (errno == EINTR) continue;
throw IOException("Error writing to serial port: " + std::string(strerror(errno)));
}
if (ret == 0) {
throw IOException("Error writing to serial port: write returned 0");
}
total_written += static_cast<size_t>(ret);
}
}
ssize_t Serial::writeRaw(const uint8_t* data, size_t size) {
if (canonical_mode_ == CanonicalMode::ENABLE) {
throw IOException(
"writeRaw() is not supported in canonical mode; use write() instead");
}
if (!data || size == 0) {
throw IOException("Invalid buffer passed to writeRaw");
}
size_t total_written = 0;
auto start_time = std::chrono::steady_clock::now();
while (total_written < size) {
int timeout_ms = -1;
if (write_timeout_ms_.count() > 0) {
auto now = std::chrono::steady_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start_time);
if (elapsed >= write_timeout_ms_) {
break;
}
timeout_ms = static_cast<int>((write_timeout_ms_ - elapsed).count());
}
struct pollfd fd_poll;
fd_poll.fd = fd_serial_port_;
fd_poll.events = POLLOUT;
int pool_result = poll_(&fd_poll, 1, timeout_ms);
if (pool_result < 0) {
if (errno == EINTR) continue;
throw IOException("Error in poll(): " + std::string(strerror(errno)));
}
if (pool_result == 0) {
break;
}
// Check for error conditions signaled by poll
if (fd_poll.revents & (POLLERR | POLLHUP | POLLNVAL)) {
throw IOException("Serial port not writable (poll error state)");
}
ssize_t ret = write_(fd_serial_port_,
data + total_written,
size - total_written);
if (ret < 0) {
if (errno == EINTR) continue;
// Defensive: if fd was toggled non-blocking somewhere
if (errno == EAGAIN || errno == EWOULDBLOCK) {
continue;
}
throw IOException("Error writing raw data: " + std::string(strerror(errno)));
}
if (ret == 0) {
throw IOException("Error writing to serial port: write returned 0");
}
total_written += static_cast<size_t>(ret);
}
return static_cast<ssize_t>(total_written);
}
ssize_t Serial::writeRaw(const std::vector<uint8_t>& data) {
if (data.empty()) {
throw IOException("Data vector is empty");
}
return writeRaw(data.data(), data.size());
}
size_t Serial::read(std::string & buffer) {
if (canonical_mode_ == CanonicalMode::DISABLE) {
throw IOException(
"read() is not supported in non-canonical mode; use readBytes(), readUntil() or readRaw() instead");
}
struct pollfd fd_poll;
fd_poll.fd = fd_serial_port_;
fd_poll.events = POLLIN;
int timeout_ms = static_cast<int>(read_timeout_ms_.count());
int poll_result = poll_(&fd_poll, 1, timeout_ms);
if (poll_result < 0) {
throw IOException(std::string("Error in poll(): ") + strerror(errno));
}
if (poll_result == 0) {
throw IOException("Read operation timed out after " + std::to_string(timeout_ms) +
" milliseconds");
}
buffer.resize(max_safe_read_size_);
ssize_t bytes_read = read_(fd_serial_port_, buffer.data(), max_safe_read_size_);
if (bytes_read < 0) {
throw IOException(std::string("Error reading from serial port: ") + strerror(errno));
}
buffer.resize(static_cast<size_t>(bytes_read));
return static_cast<size_t>(bytes_read);
}
size_t Serial::readBytes(std::string & buffer, size_t num_bytes) {
if (canonical_mode_ == CanonicalMode::ENABLE) {
throw IOException(
"readBytes() is not supported in canonical mode; use read() or readUntil() instead");
}
if (num_bytes == 0) {
throw IOException("Number of bytes requested must be greater than zero");
}
buffer.clear();
buffer.resize(num_bytes);
ssize_t bytes_read = read_(fd_serial_port_, buffer.data(), num_bytes); // codacy-ignore[buffer-boundary]
if (bytes_read < 0) {
throw IOException("Error reading from serial port: " + std::string(strerror(errno)));
}
buffer.resize(static_cast<size_t>(bytes_read));
return static_cast<size_t>(bytes_read);
}
size_t Serial::readUntil(std::string & buffer, char terminator) {
buffer.clear();
char temp_char = '\0';
auto start_time = std::chrono::steady_clock::now();
while (temp_char != terminator) {
if (buffer.size() >= max_safe_read_size_) {
throw IOException("Read buffer exceeded maximum size limit of " +
std::to_string(max_safe_read_size_) +
" bytes without finding terminator");
}
// Check timeout if enabled (0 means no timeout)
if (read_timeout_ms_.count() > 0) {
auto current_time = std::chrono::steady_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(current_time -
start_time).count();
if (elapsed >= static_cast<int64_t>(read_timeout_ms_.count())) {
throw IOException("Read timeout exceeded while waiting for terminator");
}
// Use poll() to check if data is available with remaining timeout.
struct pollfd fd_poll;
fd_poll.fd = fd_serial_port_;
fd_poll.events = POLLIN;
int64_t remaining_timeout = read_timeout_ms_.count() - elapsed;
int timeout_ms = static_cast<int>(remaining_timeout);
int poll_result = poll_(&fd_poll, 1, timeout_ms);
if (poll_result < 0) {
throw IOException("Error in poll(): " + std::string(strerror(errno)));
}
else if (poll_result == 0) {
throw IOException("Read timeout exceeded while waiting for data");
}
}
ssize_t bytes_read = read_(fd_serial_port_, &temp_char, 1);
if (bytes_read < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
std::this_thread::sleep_for(std::chrono::milliseconds(1));
continue;
}
throw IOException("Error reading from serial port: " + std::string(strerror(errno)));
}
else if (bytes_read == 0) {
throw IOException("Connection closed while reading: no terminator found");
}
buffer.push_back(temp_char);
}
return buffer.size();
}
ssize_t Serial::readRaw(uint8_t* buffer, size_t size) {
if (canonical_mode_ == CanonicalMode::ENABLE) {
throw IOException(
"readRaw() is not supported in canonical mode; use read() or readUntil() instead");
}
if (!buffer || size == 0) {
throw IOException("Invalid buffer passed to readRaw");
}
size_t total_read = 0;
auto start_time = std::chrono::steady_clock::now();
while (total_read < size) {
int timeout_ms = -1;
if (read_timeout_ms_.count() > 0) {
auto now = std::chrono::steady_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start_time);
if (elapsed >= read_timeout_ms_) {
break; // timeout reached → return what we have
}
timeout_ms = static_cast<int>((read_timeout_ms_ - elapsed).count());
}
struct pollfd fd_poll;
fd_poll.fd = fd_serial_port_;
fd_poll.events = POLLIN;
int poll_result = poll_(&fd_poll, 1, timeout_ms);
if (poll_result < 0) {
if (errno == EINTR) continue;
throw IOException("Error in poll(): " + std::string(strerror(errno)));
}
if (poll_result == 0) {
break;
}
ssize_t ret = read_(fd_serial_port_,
buffer + total_read,
size - total_read);
if (ret < 0) {
if (errno == EINTR) continue;
if (errno == EAGAIN || errno == EWOULDBLOCK) {
continue;
}
throw IOException("Error reading raw data: " + std::string(strerror(errno)));
}
if (ret == 0) {
break;
}
total_read += static_cast<size_t>(ret);
}
return static_cast<ssize_t>(total_read);
}
void Serial::flushInputBuffer() {
if (ioctl_(fd_serial_port_, TCFLSH, TCIFLUSH) != 0) {
throw SerialException("Error flushing input buffer: " + std::string(strerror(errno)));
}
}
void Serial::setTermios2() {
ssize_t error = ioctl_(fd_serial_port_, TCSETS2, &options_);
if (error < 0) {
throw SerialException("Error set Termios2: " + std::string(strerror(errno)));
}
}
void Serial::setBaudRate(unsigned int baud_rate) {
this->getTermios2();
options_.c_cflag &= ~CBAUD;
options_.c_cflag |= BOTHER;
options_.c_ispeed = baud_rate;
options_.c_ospeed = baud_rate;
this->setTermios2();
}
void Serial::setBaudRate(BaudRate baud_rate) {
this->setBaudRate(static_cast<unsigned int>(baud_rate));
}
void Serial::setReadTimeout(std::chrono::milliseconds timeout) {
read_timeout_ms_ = timeout;
this->setTimeOut(static_cast<uint16_t>(timeout.count() / 100));
}
void Serial::setWriteTimeout(std::chrono::milliseconds timeout) {
write_timeout_ms_ = timeout;
}
void Serial::setDataLength(DataLength nbits) {
this->getTermios2();
options_.c_cflag &= ~CSIZE;
switch (nbits) {
case DataLength::FIVE:
options_.c_cflag |= CS5;
break;
case DataLength::SIX:
options_.c_cflag |= CS6;
break;
case DataLength::SEVEN:
options_.c_cflag |= CS7;
break;
case DataLength::EIGHT:
options_.c_cflag |= CS8;
break;
}
this->setTermios2();
}
void Serial::setParity(Parity parity) {
this->getTermios2();
switch (parity) {
case Parity::DISABLE:
options_.c_cflag &= ~PARENB;
break;
case Parity::ENABLE:
options_.c_cflag |= PARENB;
break;
}
this->setTermios2();
}
void Serial::setStopBits(StopBits stop_bits) {
this->getTermios2();
switch (stop_bits) {
case StopBits::ONE:
options_.c_cflag &= ~CSTOP;
break;
case StopBits::TWO:
options_.c_cflag |= CSTOP;
break;
}
this->setTermios2();
}
void Serial::setFlowControl([[maybe_unused]] FlowControl flow_control) {
// this->getTermios2();
// switch (flow_control) {
// case FlowControl::Software:
// // options_.c_cflag &= ~CRTSCTS;
// // options_.c_oflag |= (OPOST | ONLCR);
// // options_.c_iflag |= (IXON | IXOFF );
// options_.c_cflag &= ~PARENB; // Clear parity bit, disabling parity (most common)
// options_.c_cflag &= ~CSTOPB; // Clear stop field, only one stop bit used in communication (most common)
// options_.c_cflag &= ~CSIZE; // Clear all bits that set the data size
// options_.c_cflag |= CS8; // 8 bits per byte (most common)
// options_.c_cflag &= ~CRTSCTS; // DISABLE RTS/CTS hardware flow control (most common)
// options_.c_cflag |= CREAD | CLOCAL; // Turn on READ & ignore ctrl lines (CLOCAL = 1)
// options_.c_lflag &= ~ICANON;
// options_.c_lflag &= ~ECHO; // DISABLE echo
// options_.c_lflag &= ~ECHOE; // DISABLE erasure
// options_.c_lflag &= ~ECHONL; // DISABLE new-line echo
// options_.c_lflag &= ~ISIG; // DISABLE interpretation of INTR, QUIT and SUSP
// options_.c_iflag &= ~(IXON | IXOFF | IXANY); // Turn off s/w flow ctrl
// options_.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL); // DISABLE any special handling of received bytes
// options_.c_oflag &= ~OPOST; // Prevent special interpretation of output bytes (e.g. newline chars)
// options_.c_oflag &= ~ONLCR; // Prevent conversion of newline to carriage return/line feed
// // options_.c_oflag &= ~OXTABS; // Prevent conversion of tabs to spaces (NOT PRESENT ON LINUX)
// // options_.c_oflag &= ~ONOEOT; // Prevent removal of C-d chars (0x004) in output (NOT PRESENT ON LINUX)
// options_.c_cc[VTIME] = 10; // Wait for up to 1s (10 deciseconds), returning as soon as any data is received.
// options_.c_cc[VMIN] = 0;
// // options_.c_cc[VEOF] = '\r';
// break;
// case FlowControl::Hardware:
// options_.c_cflag |= CRTSCTS;
// options_.c_iflag &= ~(IXON | IXOFF | IXANY);
// default:
// options_.c_cflag &= ~CRTSCTS;
// break;
// }
// this->setTermios2();
}
void Serial::setCanonicalMode(CanonicalMode mode) {
canonical_mode_ = mode;
this->getTermios2();
switch (canonical_mode_) {
case CanonicalMode::ENABLE:
options_.c_lflag |= (ICANON);
break;
case CanonicalMode::DISABLE:
options_.c_lflag &= ~(ICANON);
break;
}
this->setTermios2();
}
void Serial::setTerminator(Terminator term) {
terminator_ = term;
}
void Serial::setTimeOut(uint16_t time) {
this->getTermios2();
options_.c_cc[VTIME] = time;
this->setTermios2();
}
void Serial::setMinNumberCharRead(uint16_t num) {
min_number_char_read_ = num;
this->getTermios2();
options_.c_cc[VMIN] = min_number_char_read_;
this->setTermios2();
}
void Serial::setMaxSafeReadSize(size_t size) {
max_safe_read_size_ = size;
}
size_t Serial::getMaxSafeReadSize() const {
return max_safe_read_size_;
}
int Serial::getAvailableData() const {
int bytes_available;
if (ioctl_(fd_serial_port_, FIONREAD, &bytes_available) < 0) {
throw SerialException("Error getting available data: " + std::string(strerror(errno)));
}
return bytes_available;
}
int Serial::getBaudRate() const {
this->getTermios2();
return (static_cast<int>(options_.c_ispeed));
}
DataLength Serial::getDataLength() const {
this->getTermios2();
switch (options_.c_cflag & CSIZE) {
case CS5: return DataLength::FIVE;
case CS6: return DataLength::SIX;
case CS7: return DataLength::SEVEN;
case CS8: return DataLength::EIGHT;
default: return DataLength::EIGHT;
}
}
std::chrono::milliseconds Serial::getReadTimeout() const {
this->getTermios2();
return std::chrono::milliseconds(options_.c_cc[VTIME] * 100);
}
uint16_t Serial::getMinNumberCharRead() const {
this->getTermios2();
return static_cast<uint16_t>(options_.c_cc[VMIN]);
}
void Serial::getTermios2() const {
ssize_t error = ioctl_(fd_serial_port_, TCGETS2, &options_);
if (error < 0) {
throw SerialException("Error get Termios2: " + std::string(strerror(errno)));
}
}
} // namespace libserial
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