serial.c

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#include "attr.h"
#include "default.h"
#include "io.h"
#include <lely/io/serial.h>

#include <assert.h>
#include <string.h>

#if defined(_WIN32) || _POSIX_C_SOURCE >= 200112L

static int serial_flush(struct io_handle *handle);
static int serial_purge(struct io_handle *handle, int flags);

static const struct io_handle_vtab serial_vtab = { .type = IO_TYPE_SERIAL,
        .size = sizeof(struct io_handle),
        .fini = &default_fini,
        .flags = &default_flags,
        .read = &default_read,
        .write = &default_write,
        .flush = &serial_flush,
        .purge = &serial_purge };

io_handle_t
io_open_serial(const char *path, io_attr_t *attr)
{
        assert(path);

        int errc = 0;

#ifdef _WIN32
        HANDLE fd = CreateFileA(path, GENERIC_READ | GENERIC_WRITE, 0, NULL,
                        OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
        if (__unlikely(fd == INVALID_HANDLE_VALUE)) {
                errc = get_errc();
                goto error_CreateFile;
        }

        if (__unlikely(!SetCommMask(fd, EV_RXCHAR))) {
                errc = get_errc();
                goto error_SetCommMask;
        }

        DCB DCB;
        memset(&DCB, 0, sizeof(DCB));
        DCB.DCBlength = sizeof(DCB);
        if (__unlikely(!GetCommState(fd, &DCB))) {
                errc = get_errc();
                goto error_GetCommState;
        }

        COMMTIMEOUTS CommTimeouts;
        if (__unlikely(!GetCommTimeouts(fd, &CommTimeouts))) {
                errc = get_errc();
                goto error_GetCommTimeouts;
        }

        if (attr) {
                *io_attr_lpDCB(attr) = DCB;
                *io_attr_lpCommTimeouts(attr) = CommTimeouts;
        }

        DCB.fBinary = TRUE;
        DCB.fParity = FALSE;
        DCB.fOutxCtsFlow = FALSE;
        DCB.fOutxDsrFlow = FALSE;
        DCB.fDtrControl = DTR_CONTROL_ENABLE;
        DCB.fDsrSensitivity = FALSE;
        DCB.fTXContinueOnXoff = TRUE;
        DCB.fOutX = FALSE;
        DCB.fInX = FALSE;
        DCB.fErrorChar = FALSE;
        DCB.fNull = FALSE;
        DCB.fRtsControl = RTS_CONTROL_ENABLE;
        DCB.fAbortOnError = TRUE;
        DCB.ByteSize = 8;
        DCB.Parity = NOPARITY;

        if (__unlikely(!SetCommState(fd, &DCB))) {
                errc = get_errc();
                goto error_SetCommState;
        }

        // Block on reading by waiting as long as possible (MAXDWORD - 1
        // milliseconds) until at least one bytes arrives. serial_read()
        // contains a loop to make this time infinite.
        CommTimeouts.ReadIntervalTimeout = MAXDWORD;
        CommTimeouts.ReadTotalTimeoutMultiplier = MAXDWORD;
        CommTimeouts.ReadTotalTimeoutConstant = MAXDWORD - 1;
        // Do not use timeouts for write operations.
        CommTimeouts.WriteTotalTimeoutMultiplier = 0;
        CommTimeouts.WriteTotalTimeoutConstant = 0;

        if (__unlikely(!SetCommTimeouts(fd, &CommTimeouts))) {
                errc = get_errc();
                goto error_SetCommTimeouts;
        }
#else
        int fd;
        int errsv = errno;
        do {
                errno = errsv;
                fd = open(path, O_RDWR | O_NOCTTY | O_CLOEXEC);
        } while (__unlikely(fd == -1 && errno == EINTR));
        if (__unlikely(fd == -1)) {
                errc = get_errc();
                goto error_open;
        }

        struct termios ios;
        if (__unlikely(tcgetattr(fd, &ios) == -1)) {
                errc = get_errc();
                goto error_tcgetattr;
        }

        if (attr)
                *(struct termios *)attr = ios;

        // These options are taken from cfmakeraw() on BSD.
        ios.c_iflag &= ~(BRKINT | ICRNL | IGNBRK | IGNCR | INLCR | ISTRIP | IXON
                        | PARMRK);
        ios.c_oflag &= ~OPOST;
        ios.c_cflag &= ~(CSIZE | PARENB);
        ios.c_cflag |= CS8;
        ios.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);

        ios.c_iflag |= IGNPAR;
        ios.c_cflag |= CREAD | CLOCAL;

        ios.c_cc[VMIN] = 1;
        ios.c_cc[VTIME] = 0;

        if (__unlikely(tcsetattr(fd, TCSANOW, &ios) == -1)) {
                errc = get_errc();
                goto error_tcsetattr;
        }
#endif

        struct io_handle *handle = io_handle_alloc(&serial_vtab);
        if (__unlikely(!handle)) {
                errc = get_errc();
                goto error_alloc_handle;
        }

        handle->fd = fd;

        return io_handle_acquire(handle);

error_alloc_handle:
#ifdef _WIN32
error_SetCommTimeouts:
error_SetCommState:
error_GetCommTimeouts:
error_GetCommState:
error_SetCommMask:
        CloseHandle(fd);
error_CreateFile:
#else
error_tcsetattr:
error_tcgetattr:
        close(fd);
error_open:
#endif
        set_errc(errc);
        return IO_HANDLE_ERROR;
}

#endif // _WIN32 || _POSIX_C_SOURCE >= 200112L

int
io_purge(io_handle_t handle, int flags)
{
        if (__unlikely(handle == IO_HANDLE_ERROR)) {
                set_errnum(ERRNUM_BADF);
                return -1;
        }

        assert(handle->vtab);
        if (__unlikely(!handle->vtab->purge)) {
                set_errnum(ERRNUM_NOTTY);
                return -1;
        }

        return handle->vtab->purge(handle, flags);
}

#if defined(_WIN32) || _POSIX_C_SOURCE >= 200112L

int
io_serial_get_attr(io_handle_t handle, io_attr_t *attr)
{
        assert(attr);

        if (__unlikely(handle == IO_HANDLE_ERROR)) {
                set_errnum(ERRNUM_BADF);
                return -1;
        }

#ifdef _WIN32
        LPDCB lpDCB = io_attr_lpDCB(attr);
        memset(lpDCB, 0, sizeof(*lpDCB));
        lpDCB->DCBlength = sizeof(*lpDCB);
        if (__unlikely(!GetCommState(handle->fd, lpDCB)))
                return -1;

        // clang-format off
        return GetCommTimeouts(handle->fd, io_attr_lpCommTimeouts(attr))
                        ? 0 : -1;
        // clang-format on
#else
        return tcgetattr(handle->fd, (struct termios *)attr);
#endif
}

int
io_serial_set_attr(io_handle_t handle, const io_attr_t *attr)
{
        assert(attr);

        if (__unlikely(handle == IO_HANDLE_ERROR)) {
                set_errnum(ERRNUM_BADF);
                return -1;
        }

#ifdef _WIN32
        if (__unlikely(!SetCommState(handle->fd, io_attr_lpDCB(attr))))
                return -1;

        // clang-format off
        if (__unlikely(!SetCommTimeouts(
                        handle->fd, io_attr_lpCommTimeouts(attr))))
                // clang-format on
                return -1;

        return 0;
#else
        int result;
        int errsv = errno;
        do {
                errno = errsv;
                result = tcsetattr(handle->fd, TCSANOW,
                                (const struct termios *)attr);
        } while (__unlikely(result == -1 && errno == EINTR));
        return result;
#endif
}

static int
serial_flush(struct io_handle *handle)
{
        assert(handle);

#ifdef _WIN32
        return FlushFileBuffers(handle->fd) ? 0 : -1;
#else
        int result;
        int errsv = errno;
        do {
                errno = errsv;
                result = tcdrain(handle->fd);
        } while (__unlikely(result == -1 && errno == EINTR));
        return result;
#endif
}

static int
serial_purge(struct io_handle *handle, int flags)
{
        assert(handle);

#ifdef _WIN32
        DWORD dwFlags = 0;
        if (flags & IO_PURGE_RX)
                dwFlags |= PURGE_RXABORT | PURGE_RXCLEAR;
        if (flags & IO_PURGE_TX)
                dwFlags |= PURGE_TXABORT | PURGE_TXCLEAR;

        return PurgeComm(handle->fd, dwFlags) ? 0 : -1;
#else
        // clang-format off
        return tcflush(handle->fd, (flags & IO_PURGE_RX)
                        ? (flags & IO_PURGE_TX) ? TCIOFLUSH : TCIFLUSH
                        : (flags & IO_PURGE_TX) ? TCOFLUSH : 0);
        // clang-format on
#endif
}

#endif // _WIN32 || _POSIX_C_SOURCE >= 200112L