bt-unix.c

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#include <unistd.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/stat.h>

#include "defs.h"
#define BT "/dev/cu.EV3-SerialPort"
// ^ TODO: add ability to find differently named EV3's
enum {READ=0, WRITE=1};
void *bt_open(const char *file, const char*file2)
{
    int *fd = malloc(2*sizeof(int));
    if (file2)
    {
        fd[READ] = open(file ?: BT, O_RDONLY);
        fd[WRITE] = open(file ?: BT, O_WRONLY);
    }else 
        fd[0] = fd[1] = open(file ?: BT, O_RDWR);

    if (fd[WRITE] == -1 || fd[READ] == -1) return NULL;
    return fd;
}

int bt_write(void* fd_, const u8* buf, size_t count)
{
    int fd = ((int*)fd_)[WRITE];
    buf++;count--; // omit HID report number
    size_t sent;
    for (ssize_t ret = sent = 0; sent < count; sent += ret)
    {
        ret = write(fd, buf, count-sent);
        if (ret == -1)
        {
            // set some error msg
            break; 
        }
    }
    return sent;
}

int bt_read(void* fd_, u8* buf, size_t count, int milliseconds)
{
    (void) milliseconds;
    int fd = ((int*)fd_)[READ];
    size_t recvd =0;
    size_t packet_len = 2;
    ssize_t ret;
    do {
        ret = read(fd, buf+recvd, packet_len-recvd);
        if (ret <= 0)
        {
                perror("read failed"); return -1; 
        }
    }while ((recvd += ret) != 2);

    packet_len += buf[0] | (buf[1] << 8);

    if (packet_len > 2*count) //FIXME: remove 2*
        return -1;

    for (ssize_t ret=recvd; recvd < packet_len; recvd += ret)
    {
        ret = read(fd, buf+recvd, packet_len-recvd);
        if (ret == 0) break; // EOF; turning off bluetooth during transfer
        //FIXME: would returning -1 for EOF make more sense?
        if (ret == -1)
        {
            perror("read failed");
            return -1; 
        }
    }

return recvd;
}

void bt_close(void *handle)
{
    close(((int*)handle)[WRITE]);
    close(((int*)handle)[READ]);
    free(handle);
}
const wchar_t *bt_error(void* fd_) { 
    (void)fd_; 
    const char *errstr = strerror(errno);
    size_t wlen = strlen(errstr);
    wchar_t *werrstr = malloc(sizeof (wchar_t[wlen]));
    return (mbstowcs(werrstr, errstr, wlen) != (size_t)-1) ?
        werrstr :
        L"Error in printing error";
}