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在 Beaglebone Black 上使用 Debian GNU/Linux 7.4 读取两条不同的串行通信线路时出现段错误错误。其中之一是 CAN-BUS 数据。我为此使用 Waveshares RS485/CAN CAPE 模块并使用 can-utils 包。 "https://github.com/linux-can/can-utils/blob/master/candump.c "
另一个是来自名为 uBlox GY-NEO6MV2 模块的 GPS 模块的 UART 数据。对于 GPS，我有完美运行的代码；
#include <stdio.h>
#include <fcntl.h> /* File Control Definitions */
#include <termios.h> /* POSIX Terminal Control Definitions */
#include <unistd.h> /* UNIX Standard Definitions */
#include <errno.h> /* ERROR Number Definitions */
#include <string.h> /* Array to String */
void main(void){
int fd;/*File Descriptor*/
/*------------------------------- Opening the Serial Port -------------------------------*/
/* Change /dev/ttyUSB0 to the one corresponding to your system */
while(1){
fd = open("/dev/ttyO2",O_RDWR | O_NOCTTY); /* ttyUSB0 is the FT232 based USB2SERIAL Converter */
/* O_RDWR - Read/Write access to serial port */
/* O_NOCTTY - No terminal will control the process */
/* Open in blocking mode,read will wait */
if(fd == -1) /* Error Checking */
printf("\n Error! in Opening ttyO2 ");
else
printf("\n ttyO2 Opened Successfully ");
/*---------- Setting the Attributes of the serial port using termios structure --------- */
struct termios SerialPortSettings; /* Create the structure */
tcgetattr(fd, &SerialPortSettings); /* Get the current attributes of the Serial port */
/* Setting the Baud rate */
cfsetispeed(&SerialPortSettings,B9600); /* Set Read Speed as 9600 */
cfsetospeed(&SerialPortSettings,B9600); /* Set Write Speed as 9600 */
/* 8N1 Mode */
SerialPortSettings.c_cflag &= ~PARENB; /* Disables the Parity Enable bit(PARENB),So No Parity */
SerialPortSettings.c_cflag &= ~CSTOPB; /* CSTOPB = 2 Stop bits,here it is cleared so 1 Stop bit */
SerialPortSettings.c_cflag &= ~CSIZE; /* Clears the mask for setting the data size */
SerialPortSettings.c_cflag |= CS8; /* Set the data bits = 8 */
SerialPortSettings.c_cflag &= ~CRTSCTS; /* No Hardware flow Control */
SerialPortSettings.c_cflag |= CREAD | CLOCAL; /* Enable receiver,Ignore Modem Control lines */
SerialPortSettings.c_iflag &= ~(IXON | IXOFF | IXANY); /* Disable XON/XOFF flow control both i/p and o/p */
SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG); /* Non Cannonical mode */
SerialPortSettings.c_oflag &= ~OPOST;/*No Output Processing*/
/* Setting Time outs */
SerialPortSettings.c_cc[VMIN] = 42; /* Read at least 51 characters */
SerialPortSettings.c_cc[VTIME] = 0; /* Wait indefinetly */
if((tcsetattr(fd,TCSANOW,&SerialPortSettings)) != 0) /* Set the attributes to the termios structure*/
printf("\n ERROR ! in Setting attributes");
else
printf("\n BaudRate = 9600 \n StopBits = 1 \n Parity = none \n\n");
/*------------------------------- Read data from serial port -----------------------------*/
tcflush(fd, TCIFLUSH); /* Discards old data in the rx buffer */
char read_buffer[42]; /* Buffer to store the data received */
int bytes_read = 0; /* Number of bytes read by the read() system call */
int ia = 0; int a;
int test = 0;
char new_read[38];
char curr_read[33];
a = 0;
do{
bytes_read = read(fd,&read_buffer,42); /* Read the data */
if(read_buffer[0] == '$')
if(read_buffer[1] == 'G')
if(read_buffer[2] == 'P')
if(read_buffer[3] == 'G')
if(read_buffer[4] == 'G'){
for(ia=7;ia<bytes_read;ia++){ /*printing only the received characters*/
new_read[a] = read_buffer[ia];
printf("%c",read_buffer[ia]);
a = a+1;
test = 1;
}
strcpy(curr_read, new_read);
printf("\n%s \n", curr_read);
}
else
test = 0;
else
test = 0;
else
test = 0;
else
test = 0;
else
test = 0;
}while(test == 0);
close(fd); /* Close the serial port */
}
}
对于 CAN 日志记录，我使用上面链接中的代码。我试图实现的是将两个数据记录到同一个日志文件中。我稍微修改了上面的代码以仅获取我需要的数据；这是时间戳和位置坐标。
GPS 模块每秒提供数据，所以我正在尝试从 GPS 获取一个数据并将其附加到下一个 1000 个 CAN 数据，然后写入 .log 文件，然后从 GPS 读取一个新值。 GPS 模块通信比特率为 9600kbps，CAN 比特率为 125000 kbps。 GPS 连接到 UART2 引脚，CAN 连接到 UART1。当我尝试将两个代码合二为一时，出现了Segmentation fault 错误。我在违反受限制的内存空间时对其UNIX错误代码进行了一些研究。但是这两个代码在单独工作时完美地工作。这就是我被卡住的地方。我尝试合并的代码是这样的；
/* for hardware timestamps - since Linux 2.6.30 */
#ifndef SO_TIMESTAMPING
#define SO_TIMESTAMPING 37
#endif
/* from #include <linux/net_tstamp.h> - since Linux 2.6.30 */
#define SOF_TIMESTAMPING_SOFTWARE (1<<4)
#define SOF_TIMESTAMPING_RX_SOFTWARE (1<<3)
#define SOF_TIMESTAMPING_RAW_HARDWARE (1<<6)
#define MAXSOCK 16 /* max. number of CAN interfaces given on the cmdline */
#define MAXIFNAMES 30 /* size of receive name index to omit ioctls */
#define MAXCOL 6 /* number of different colors for colorized output */
#define ANYDEV "any" /* name of interface to receive from any CAN interface */
#define ANL "\r\n" /* newline in ASC mode */
#define SILENT_INI 42 /* detect user setting on commandline */
#define SILENT_OFF 0 /* no silent mode */
#define SILENT_ANI 1 /* silent mode with animation */
#define SILENT_ON 2 /* silent mode (completely silent) */
static char *cmdlinename[MAXSOCK];
static __u32 dropcnt[MAXSOCK];
static __u32 last_dropcnt[MAXSOCK];
static char devname[MAXIFNAMES][IFNAMSIZ+1];
static int dindex[MAXIFNAMES];
static int max_devname_len; /* to prevent frazzled device name output */
const int canfd_on = 1;
#define MAXANI 4
const char anichar[MAXANI] = {'|', '/', '-', '\\'};
const char extra_m_info[4][4] = {"- -", "B -", "- E", "B E"};
extern int optind, opterr, optopt;
static volatile int running = 1;
void sigterm(int signo)
{
running = 0;
}
int idx2dindex(int ifidx, int socket) {
int i;
struct ifreq ifr;
for (i=0; i < MAXIFNAMES; i++) {
if (dindex[i] == ifidx)
return i;
}
/* create new interface index cache entry */
/* remove index cache zombies first */
for (i=0; i < MAXIFNAMES; i++) {
if (dindex[i]) {
ifr.ifr_ifindex = dindex[i];
if (ioctl(socket, SIOCGIFNAME, &ifr) < 0)
dindex[i] = 0;
}
}
for (i=0; i < MAXIFNAMES; i++)
if (!dindex[i]) /* free entry */
break;
if (i == MAXIFNAMES) {
fprintf(stderr, "Interface index cache only supports %d interfaces.\n",
MAXIFNAMES);
exit(1);
}
dindex[i] = ifidx;
ifr.ifr_ifindex = ifidx;
if (ioctl(socket, SIOCGIFNAME, &ifr) < 0)
perror("SIOCGIFNAME");
if (max_devname_len < strlen(ifr.ifr_name))
max_devname_len = strlen(ifr.ifr_name);
strcpy(devname[i], ifr.ifr_name);
#ifdef DEBUG
printf("new index %d (%s)\n", i, devname[i]);
#endif
return i;
}
int main(int argc, char **argv)
{
fd_set rdfs;
int s[MAXSOCK];
int bridge = 0;
useconds_t bridge_delay = 0;
unsigned char timestamp = 0;
unsigned char hwtimestamp = 0;
unsigned char down_causes_exit = 1;
unsigned char dropmonitor = 0;
unsigned char extra_msg_info = 0;
unsigned char silent = SILENT_INI;
unsigned char silentani = 0;
unsigned char color = 0;
unsigned char view = 0;
unsigned char log = 0;
unsigned char logfrmt = 0;
int count = 0;
int rcvbuf_size = 0;
int opt, ret;
int currmax, numfilter;
int join_filter;
char *ptr, *nptr;
struct sockaddr_can addr;
char ctrlmsg[CMSG_SPACE(sizeof(struct timeval) + 3*sizeof(struct timespec) + sizeof(__u32))];
struct iovec iov;
struct msghdr msg;
struct cmsghdr *cmsg;
struct can_filter *rfilter;
can_err_mask_t err_mask;
struct canfd_frame frame;
int nbytes, i, maxdlen;
struct ifreq ifr;
struct timeval tv, last_tv;
struct timeval timeout, timeout_config = { 0, 0 }, *timeout_current = NULL;
FILE *logfile = NULL;
int fd;/*File Descriptor*/
struct termios SerialPortSettings; /* Create the structure */
signal(SIGTERM, sigterm);
signal(SIGHUP, sigterm);
signal(SIGINT, sigterm);
last_tv.tv_sec = 0;
last_tv.tv_usec = 0;
if (optind == argc) {
print_usage(basename(argv[0]));
exit(0);
}
if (logfrmt && view) {
fprintf(stderr, "Log file format selected: Please disable ASCII/BINARY/SWAP options!\n");
exit(0);
}
if (silent == SILENT_INI) {
if (log) {
fprintf(stderr, "Disabled standard output while logging.\n");
silent = SILENT_ON; /* disable output on stdout */
} else
silent = SILENT_OFF; /* default output */
}
currmax = argc - optind; /* find real number of CAN devices */
if (currmax > MAXSOCK) {
fprintf(stderr, "More than %d CAN devices given on commandline!\n", MAXSOCK);
return 1;
}
for (i=0; i < currmax; i++) {
ptr = argv[optind+i];
nptr = strchr(ptr, ',');
#ifdef DEBUG
printf("open %d '%s'.\n", i, ptr);
#endif
s[i] = socket(PF_CAN, SOCK_RAW, CAN_RAW);
if (s[i] < 0) {
perror("socket");
return 1;
}
cmdlinename[i] = ptr; /* save pointer to cmdline name of this socket */
if (nptr)
nbytes = nptr - ptr; /* interface name is up the first ',' */
else
nbytes = strlen(ptr); /* no ',' found => no filter definitions */
if (nbytes >= IFNAMSIZ) {
fprintf(stderr, "name of CAN device '%s' is too long!\n", ptr);
return 1;
}
if (nbytes > max_devname_len)
max_devname_len = nbytes; /* for nice printing */
addr.can_family = AF_CAN;
memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
strncpy(ifr.ifr_name, ptr, nbytes);
#ifdef DEBUG
printf("using interface name '%s'.\n", ifr.ifr_name);
#endif
if (strcmp(ANYDEV, ifr.ifr_name)) {
if (ioctl(s[i], SIOCGIFINDEX, &ifr) < 0) {
perror("SIOCGIFINDEX");
exit(1);
}
addr.can_ifindex = ifr.ifr_ifindex;
} else
addr.can_ifindex = 0; /* any can interface */
if (nptr) {
/* found a ',' after the interface name => check for filters */
/* determine number of filters to alloc the filter space */
numfilter = 0;
ptr = nptr;
while (ptr) {
numfilter++;
ptr++; /* hop behind the ',' */
ptr = strchr(ptr, ','); /* exit condition */
}
rfilter = malloc(sizeof(struct can_filter) * numfilter);
if (!rfilter) {
fprintf(stderr, "Failed to create filter space!\n");
return 1;
}
numfilter = 0;
err_mask = 0;
join_filter = 0;
while (nptr) {
ptr = nptr+1; /* hop behind the ',' */
nptr = strchr(ptr, ','); /* update exit condition */
if (sscanf(ptr, "%x:%x",
&rfilter[numfilter].can_id,
&rfilter[numfilter].can_mask) == 2) {
rfilter[numfilter].can_mask &= ~CAN_ERR_FLAG;
numfilter++;
} else if (sscanf(ptr, "%x~%x",
&rfilter[numfilter].can_id,
&rfilter[numfilter].can_mask) == 2) {
rfilter[numfilter].can_id |= CAN_INV_FILTER;
rfilter[numfilter].can_mask &= ~CAN_ERR_FLAG;
numfilter++;
} else if (*ptr == 'j' || *ptr == 'J') {
join_filter = 1;
} else if (sscanf(ptr, "#%x", &err_mask) != 1) {
fprintf(stderr, "Error in filter option parsing: '%s'\n", ptr);
return 1;
}
}
if (err_mask)
setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
&err_mask, sizeof(err_mask));
if (join_filter && setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_JOIN_FILTERS,
&join_filter, sizeof(join_filter)) < 0) {
perror("setsockopt CAN_RAW_JOIN_FILTERS not supported by your Linux Kernel");
return 1;
}
if (numfilter)
setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_FILTER,
rfilter, numfilter * sizeof(struct can_filter));
free(rfilter);
} /* if (nptr) */
/* try to switch the socket into CAN FD mode */
setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_FD_FRAMES, &canfd_on, sizeof(canfd_on));
if (rcvbuf_size) {
int curr_rcvbuf_size;
socklen_t curr_rcvbuf_size_len = sizeof(curr_rcvbuf_size);
/* try SO_RCVBUFFORCE first, if we run with CAP_NET_ADMIN */
if (setsockopt(s[i], SOL_SOCKET, SO_RCVBUFFORCE,
&rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
#ifdef DEBUG
printf("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
#endif
if (setsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
&rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
perror("setsockopt SO_RCVBUF");
return 1;
}
if (getsockopt(s[i], SOL_SOCKET, SO_RCVBUF,
&curr_rcvbuf_size, &curr_rcvbuf_size_len) < 0) {
perror("getsockopt SO_RCVBUF");
return 1;
}
/* Only print a warning the first time we detect the adjustment */
/* n.b.: The wanted size is doubled in Linux in net/sore/sock.c */
if (!i && curr_rcvbuf_size < rcvbuf_size*2)
fprintf(stderr, "The socket receive buffer size was "
"adjusted due to /proc/sys/net/core/rmem_max.\n");
}
}
if (timestamp || log || logfrmt) {
if (hwtimestamp) {
const int timestamping_flags = (SOF_TIMESTAMPING_SOFTWARE | \
SOF_TIMESTAMPING_RX_SOFTWARE | \
SOF_TIMESTAMPING_RAW_HARDWARE);
if (setsockopt(s[i], SOL_SOCKET, SO_TIMESTAMPING,
×tamping_flags, sizeof(timestamping_flags)) < 0) {
perror("setsockopt SO_TIMESTAMPING is not supported by your Linux kernel");
return 1;
}
} else {
const int timestamp_on = 1;
if (setsockopt(s[i], SOL_SOCKET, SO_TIMESTAMP,
×tamp_on, sizeof(timestamp_on)) < 0) {
perror("setsockopt SO_TIMESTAMP");
return 1;
}
}
}
if (dropmonitor) {
const int dropmonitor_on = 1;
if (setsockopt(s[i], SOL_SOCKET, SO_RXQ_OVFL,
&dropmonitor_on, sizeof(dropmonitor_on)) < 0) {
perror("setsockopt SO_RXQ_OVFL not supported by your Linux Kernel");
return 1;
}
}
if (bind(s[i], (struct sockaddr *)&addr, sizeof(addr)) < 0) {
perror("bind");
return 1;
}
}
if (log) {
time_t currtime;
struct tm now;
char fname[sizeof("candump-2006-11-20_202026.log")+1];
if (time(&currtime) == (time_t)-1) {
perror("time");
return 1;
}
localtime_r(&currtime, &now);
sprintf(fname, "candump-%04d-%02d-%02d_%02d%02d%02d.log",
now.tm_year + 1900,
now.tm_mon + 1,
now.tm_mday,
now.tm_hour,
now.tm_min,
now.tm_sec);
if (silent != SILENT_ON)
printf("\nWarning: console output active while logging!");
fprintf(stderr, "\nEnabling Logfile '%s'\n\n", fname);
logfile = fopen(fname, "w");
if (!logfile) {
perror("logfile");
return 1;
}
}
/* these settings are static and can be held out of the hot path */
iov.iov_base = &frame;
msg.msg_name = &addr;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = &ctrlmsg;
while (running) {
/*------------------------------- Opening the Serial Port -------------------------------*/
/* Change /dev/ttyUSB0 to the one corresponding to your system */
fd = open("/dev/ttyO2",O_RDWR | O_NOCTTY); /* ttyUSB0 is the FT232 based USB2SERIAL Converter */
/* O_RDWR - Read/Write access to serial port */
/* O_NOCTTY - No terminal will control the process */
/* Open in blocking mode,read will wait */
/* Error Checking */
if(fd == -1)
printf("\n Error! in Opening ttyO2 ");
else
printf("\n ttyO2 Opened Successfully ");
/*---------- Setting the Attributes of the serial port using termios structure --------- */
//struct termios SerialPortSettings; /* Create the structure */
tcgetattr(fd, &SerialPortSettings); /* Get the current attributes of the Serial port */
/* Setting the Baud rate */
cfsetispeed(&SerialPortSettings,B9600); /* Set Read Speed as 9600 */
cfsetospeed(&SerialPortSettings,B9600); /* Set Write Speed as 9600 */
/* 8N1 Mode */
SerialPortSettings.c_cflag &= ~PARENB; /* Disables the Parity Enable bit(PARENB),So No Parity */
SerialPortSettings.c_cflag &= ~CSTOPB; /* CSTOPB = 2 Stop bits,here it is cleared so 1 Stop bit */
SerialPortSettings.c_cflag &= ~CSIZE; /* Clears the mask for setting the data size */
SerialPortSettings.c_cflag |= CS8; /* Set the data bits = 8 */
SerialPortSettings.c_cflag &= ~CRTSCTS; /* No Hardware flow Control */
SerialPortSettings.c_cflag |= CREAD | CLOCAL; /* Enable receiver,Ignore Modem Control lines */
SerialPortSettings.c_iflag &= ~(IXON | IXOFF | IXANY); /* Disable XON/XOFF flow control both i/p and o/p */
SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG); /* Non Cannonical mode */
SerialPortSettings.c_oflag &= ~OPOST;/*No Output Processing*/
/* Setting Time outs */
SerialPortSettings.c_cc[VMIN] = 42; /* Read at least 42 characters */
SerialPortSettings.c_cc[VTIME] = 0; /* Wait indefinetly */
if((tcsetattr(fd,TCSANOW,&SerialPortSettings)) != 0) /* Set the attributes to the termios structure*/
printf("\n ERROR ! in Setting attributes");
else
printf("\n BaudRate = 9600 \n StopBits = 1 \n Parity = none \n\n");
/*------------------------------- Read data from serial port -----------------------------*/
tcflush(fd, TCIFLUSH); /* Discards old data in the rx buffer */
char read_buffer[42]; /* Buffer to store the data received */
int bytes_read = 0; /* Number of bytes read by the read() system call */
int ia = 0; int a;
int test = 0;
char new_read[38];
char curr_read[33];
int countc = 0;
a = 0;
do{
bytes_read = read(fd,&read_buffer,42); /* Read the data */
if(read_buffer[0] == '$')
if(read_buffer[1] == 'G')
if(read_buffer[2] == 'P')
if(read_buffer[3] == 'G')
if(read_buffer[4] == 'G'){
for(ia=7;ia<bytes_read;ia++){ /*printing only the received characters*/
new_read[a] = read_buffer[ia];
//printf("%c",read_buffer[ia]);
a = a+1;
test = 1;
}
strcpy(curr_read, new_read);
//printf("\n%s \n", curr_read);
}
else
test = 0;
else
test = 0;
else
test = 0;
else
test = 0;
else
test = 0;
}while(test == 0);
//tcflush(fd, TCIFLUSH); /* Discards old data in the rx buffer */
close(fd); /* Close the serial port */
while(countc < 1000){
FD_ZERO(&rdfs);
for (i=0; i<currmax; i++)
FD_SET(s[i], &rdfs);
if (timeout_current)
*timeout_current = timeout_config;
if ((ret = select(s[currmax-1]+1, &rdfs, NULL, NULL, timeout_current)) <= 0) {
//perror("select");
running = 0;
continue;
}
for (i=0; i<currmax; i++) { /* check all CAN RAW sockets */
if (FD_ISSET(s[i], &rdfs)) {
int idx;
/* these settings may be modified by recvmsg() */
iov.iov_len = sizeof(frame);
msg.msg_namelen = sizeof(addr);
msg.msg_controllen = sizeof(ctrlmsg);
msg.msg_flags = 0;
nbytes = recvmsg(s[i], &msg, 0);
idx = idx2dindex(addr.can_ifindex, s[i]);
if (nbytes < 0) {
if ((errno == ENETDOWN) && !down_causes_exit) {
fprintf(stderr, "%s: interface down\n", devname[idx]);
continue;
}
perror("read");
return 1;
}
if ((size_t)nbytes == CAN_MTU)
maxdlen = CAN_MAX_DLEN;
else if ((size_t)nbytes == CANFD_MTU)
maxdlen = CANFD_MAX_DLEN;
else {
fprintf(stderr, "read: incomplete CAN frame\n");
return 1;
}
if (count && (--count == 0))
running = 0;
if (bridge) {
if (bridge_delay)
usleep(bridge_delay);
nbytes = write(bridge, &frame, nbytes);
if (nbytes < 0) {
perror("bridge write");
return 1;
} else if ((size_t)nbytes != CAN_MTU && (size_t)nbytes != CANFD_MTU) {
fprintf(stderr,"bridge write: incomplete CAN frame\n");
return 1;
}
}
for (cmsg = CMSG_FIRSTHDR(&msg);
cmsg && (cmsg->cmsg_level == SOL_SOCKET);
cmsg = CMSG_NXTHDR(&msg,cmsg)) {
if (cmsg->cmsg_type == SO_TIMESTAMP) {
memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv));
} else if (cmsg->cmsg_type == SO_TIMESTAMPING) {
struct timespec *stamp = (struct timespec *)CMSG_DATA(cmsg);
/*
* stamp[0] is the software timestamp
* stamp[1] is deprecated
* stamp[2] is the raw hardware timestamp
* See chapter 2.1.2 Receive timestamps in
* linux/Documentation/networking/timestamping.txt
*/
tv.tv_sec = stamp[2].tv_sec;
tv.tv_usec = stamp[2].tv_nsec/1000;
} else if (cmsg->cmsg_type == SO_RXQ_OVFL)
memcpy(&dropcnt[i], CMSG_DATA(cmsg), sizeof(__u32));
}
/* check for (unlikely) dropped frames on this specific socket */
if (dropcnt[i] != last_dropcnt[i]) {
__u32 frames = dropcnt[i] - last_dropcnt[i];
if (silent != SILENT_ON)
printf("DROPCOUNT: dropped %d CAN frame%s on '%s' socket (total drops %d)\n",
frames, (frames > 1)?"s":"", devname[idx], dropcnt[i]);
if (log)
fprintf(logfile, "DROPCOUNT: dropped %d CAN frame%s on '%s' socket (total drops %d)\n",
frames, (frames > 1)?"s":"", devname[idx], dropcnt[i]);
last_dropcnt[i] = dropcnt[i];
}
/* once we detected a EFF frame indent SFF frames accordingly */
if (frame.can_id & CAN_EFF_FLAG)
view |= CANLIB_VIEW_INDENT_SFF;
if (log) { /* CODE GETS IN TO THIS PART */
char buf[CL_CFSZ]; /* max length */ /* WHEN PRINTING INTO FILE */
/* */
/* log CAN frame with absolute timestamp & device */ /* */
sprint_canframe(buf, &frame, 0, maxdlen); /* */
fprintf(logfile, "%s %*s %s\n", /* */
curr_read, /* */
max_devname_len, devname[idx], buf); /* */
} /* */
if (logfrmt) {
char buf[CL_CFSZ]; /* max length */
/* print CAN frame in log file style to stdout */
sprint_canframe(buf, &frame, 0, maxdlen);
printf("(%010ld.%06ld) %*s %s\n",
tv.tv_sec, tv.tv_usec,
max_devname_len, devname[idx], buf);
goto out_fflush; /* no other output to stdout */
}
if (silent != SILENT_OFF){
if (silent == SILENT_ANI) {
printf("%c\b", anichar[silentani%=MAXANI]);
silentani++;
}
goto out_fflush; /* no other output to stdout */
}
printf(" %s", (color>2)?col_on[idx%MAXCOL]:"");
switch (timestamp) {
case 'a': /* absolute with timestamp */
printf("(%010ld.%06ld) ", tv.tv_sec, tv.tv_usec);
break;
case 'A': /* absolute with date */
{
struct tm tm;
char timestring[25];
tm = *localtime(&tv.tv_sec);
strftime(timestring, 24, "%Y-%m-%d %H:%M:%S", &tm);
printf("(%s.%06ld) ", timestring, tv.tv_usec);
}
break;
case 'd': /* delta */
case 'z': /* starting with zero */
{
struct timeval diff;
if (last_tv.tv_sec == 0) /* first init */
last_tv = tv;
diff.tv_sec = tv.tv_sec - last_tv.tv_sec;
diff.tv_usec = tv.tv_usec - last_tv.tv_usec;
if (diff.tv_usec < 0)
diff.tv_sec--, diff.tv_usec += 1000000;
if (diff.tv_sec < 0)
diff.tv_sec = diff.tv_usec = 0;
printf("(%03ld.%06ld) ", diff.tv_sec, diff.tv_usec);
if (timestamp == 'd')
last_tv = tv; /* update for delta calculation */
}
break;
default: /* no timestamp output */
break;
}
printf(" %s", (color && (color<3))?col_on[idx%MAXCOL]:"");
printf("%*s", max_devname_len, devname[idx]);
if (extra_msg_info) {
if (msg.msg_flags & MSG_DONTROUTE)
printf (" TX %s", extra_m_info[frame.flags & 3]);
else
printf (" RX %s", extra_m_info[frame.flags & 3]);
}
printf("%s ", (color==1)?col_off:"");
fprint_long_canframe(stdout, &frame, NULL, view, maxdlen);
printf("%s", (color>1)?col_off:"");
printf("\n");
}
out_fflush:
fflush(stdout);
}
countc = countc +1;
}
}
for (i=0; i<currmax; i++)
close(s[i]);
if (bridge)
close(bridge);
if (log)
fclose(logfile);
return 0;
}
实际上，所有重要的事情都在 while(running) block 中进行。在这个 block 中，当我将 bytes_read = read(fd,&read_buffer,42); 作为注释时，它没有写任何东西，但也没有给出 Segmentation fault 错误。当我将 GPS 的 TX 引脚连接到 BBB 时，也会发生同样的情况。因此，当数据来自 GPS 并由 BBB 读取时，问题开始出现。
我该怎么办？
谢谢。
最佳答案
您的 GPS 读取代码
char new_read[38];
char curr_read[33];
strcpy(curr_read, new_read);
正在将 38 个字符的缓冲区复制到 33 个字符的缓冲区中，这可能会导致不好的结果。
Strcpy 会将源缓冲区的内容复制到目标缓冲区，直到它从源缓冲区读取 NULL。如果 NULL 字符位于 new_read 的第 36 个位置，strcpy 将写入随机内存，这会导致段错误。
我猜测，当您独立运行 GPS 读取代码时，写入随机内存的操作不会被注意到，但是当您将它与 CAN 总线读取结合使用时，它会写入分配的空间并发生错误。
关于linux - 使用 BeagleBone Black 读取两个串口时出现 Segmentation Fault 错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52766862/
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