#include <stdio.h>#include <string.h>#include <unistd.h>#include <termios.h>#include <sys/stat.h>#include <fcntl.h>#include "sentences.h"static int read_message(int fd, char *buf, int bufsiz){  int n = 0;  char c;  memset(buf, 0, bufsiz);  while(n < bufsiz && buf[n-1] != '\n') {    if(read(fd, (char*)&c, 1) > 0) {      buf[n++] = c;    } else {      /* error reading a byte or EOF */      return 0;    }  }  return 1;}int gps_find_sentence(gps_sentence foo, char *buffer, int fd){  char head[8];  char *search_string;  char bigbuf[1024];  memset(head, 0, sizeof(head));  if(foo == GPGLL) {    search_string = "GLL";  }  memset(bigbuf, 0, sizeof(bigbuf));  while(read_message(fd, bigbuf, sizeof(bigbuf))) {    strncpy(head, bigbuf, sizeof(head));    if(strstr(head, search_string)) {      strcpy(buffer,bigbuf);      return 1;    }    memset(bigbuf, 0, sizeof(bigbuf));  }    return 0;}int gps_serial_open (const char *port){  int err = 0;  struct termios options;  int fd = open(port,  O_RDWR | O_NOCTTY | O_NDELAY);  if (fd < 1) {    return -1;  } else {    fcntl(fd,F_SETFL,0);    memset (&options, 0,sizeof(options));    options.c_cflag |= CRTSCTS;            /* hadware flow on */    options.c_cflag  &= ~PARENB;           /* no parity */    options.c_cflag  &= ~CSTOPB;           /* one stopbit */    options.c_cflag  &= CSIZE;    options.c_cflag |= CS8;                /* 8N1 */    options.c_cflag |= (CLOCAL | CREAD);   /* enable Localmode, receiver */    options.c_cc[VMIN] = 0;                /* set min read characters if 0 */    /*   VTIME takes over */    options.c_cc[VTIME] = 40;          /* wait V_TIME ms for character */        err = cfsetospeed(&options, B4800);    if (err < 0) {      printf ("Could not set output speed! Error = %d\n", err);      close (fd);      return -1;    }         err = cfsetispeed(&options, B4800);    if (err < 0) {      printf ("Could not set input speed! Error = %d\n", err);      close (fd);      return -1;    }         if (tcsetattr(fd,TCSANOW, &options) < 0) {      printf ("Failed to set fd port options!\n");      close (fd);      return -1;    }   }     return fd;}