fpv-tools/fpvextract.c

# include <stdio.h>
# include <stdint.h>
# include <unistd.h>
# include <string.h>
# include <errno.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <fcntl.h>
# include <arpa/inet.h>

struct fpv
{
        uint32_t        		len;
        uint8_t         		type;
        uint32_t        		ms;
        uint8_t         		pad[8];
} __attribute__((packed));

size_t out(int fd, uint8_t *data, size_t len)
{
        int res = 0;

        while (len > 0) {
                size_t n;

                if ((n = write(fd, data, len)) > 0) {
                        len -= n;
                        data += n;
                        res  += n;
                } else {
                        if (errno != EAGAIN) {
                                printf("write: %s\n", strerror(errno));
                        } else {
                                continue;
                        }
                        break;
                }
        }
        return res;
}

size_t in(int fd, uint8_t *data, size_t len)
{
        int res = 0;

        while (len > 0) {
                size_t n = read(fd, data, len);
                if (n > 0) {
                        len -= n;
                        data += n;
                        res  += n;
                } else {
                        if (n < 0) {
                                if (errno != EAGAIN) {
                                        printf("read: %s\n", strerror(errno));
                                } else {
                                        continue;
                                }
                        }
                        break;
                }
        }
        return res;
}

int main(int argc, char *argv[])
{
        struct fpv fpv;
        static uint8_t data[8 * 1024 * 1024];
        int i;

        for (i = 1; i < argc; i++) {
                int fd = open(argv[i], O_RDONLY);

                if (fd >= 0) {
                        while (1) {
                                if (in(fd, (uint8_t*)&fpv, sizeof(fpv)) > 0) {
                                        if (in(fd, data, fpv.len) > 0) {
                                                switch (fpv.type) {
                                                case 0:
                                                        out(fileno(stdout), data, fpv.len);
                                                        break;

                                                default:
                                                        continue;
                                                }
                                        } else {
                                                break;
                                        }
                                } else {
                                        break;
                                }
                        }
                        close(fd);
                }
        }
        return 0;
}