Packages

nerves_runtime

0.6.0
0.13.13 0.13.12 0.13.11 retired 0.13.10 0.13.9 0.13.8 0.13.7 0.13.6 0.13.5 0.13.4 0.13.3 0.13.2 0.13.1 0.13.0 0.12.0 0.11.10 0.11.9 0.11.8 0.11.7 0.11.6 0.11.5 0.11.4 0.11.3 0.11.2 0.11.1 0.11.0 0.10.3 0.10.2 0.10.1 0.10.0 retired 0.9.5 0.9.4 0.9.3 0.9.2 0.9.1 0.9.0 0.8.0 0.7.0 0.6.5 0.6.4 0.6.3 0.6.2 0.6.1 0.6.0 0.5.3 0.5.2 0.5.1 0.5.0 0.4.4 0.4.3 0.4.2 0.4.1 0.4.0 0.3.1 0.3.0 0.2.0 0.1.2 0.1.1 0.1.0

Small, general runtime utilities for Nerves devices

HexDocs

Current section

Files

Jump to
Readme
59 Versions
2 Dependencies
Dependants
Files
Activity
nerves_runtime src log_tailer.c
Raw

src/log_tailer.c 

#include <err.h>

#include <fcntl.h>

#include <stdlib.h>

#include <string.h>

#include <sys/stat.h>

#include <sys/un.h>

#include <unistd.h>

#include <arpa/inet.h>



#define KMSG_PATH "/proc/kmsg"

#define SYSLOG_PATH "/dev/log"

#define BUFFER_SIZE 1024



static char buffer[BUFFER_SIZE];



static void usage()

{

    errx(EXIT_FAILURE, "Specify either syslog or kmsg as the parameter");

}



static int open_syslog()

{

    int fd = socket(AF_UNIX, SOCK_DGRAM, 0);

    if (fd < 0)

        err(EXIT_FAILURE, "socket");



    // Erase the old log file (if any) so that we can bind to it

    unlink(SYSLOG_PATH);



    struct sockaddr_un addr;

    memset(&addr, 0, sizeof(addr));

    addr.sun_family = AF_UNIX;

    strcpy(addr.sun_path, SYSLOG_PATH);



    if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0)

        err(EXIT_FAILURE, "bind %s", SYSLOG_PATH);



    // Make the syslog file writable

    chmod(SYSLOG_PATH, 0666);



    return fd;

}



static int open_klog()

{

    int fd = open(KMSG_PATH, O_RDONLY);

    if (fd < 0)

        err(EXIT_FAILURE, "open %s", KMSG_PATH);

    return fd;

}



int main(int argc, char *argv[])

{

    if (argc != 2)

        usage();



    int fd = 0;

    if (strcmp(argv[1], "syslog"))

        fd = open_syslog();

    else if (strcmp(argv[1], "kmsg"))

        fd = open_klog();

    else

        usage();



    for (;;) {

        ssize_t amt = read(fd, buffer, sizeof(buffer));

        if (amt < 0)

            err(EXIT_FAILURE, "%s: read", argv[1]);



        if (write(STDOUT_FILENO, &buffer, amt) < 0)

            err(EXIT_FAILURE, "%s: write", argv[1]);

    }

}