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nerves_runtime

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Small, general runtime utilities for Nerves devices

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nerves_runtime src kmsg_tailer.c
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src/kmsg_tailer.c 

#include <err.h>

#include <errno.h>

#include <fcntl.h>

#include <stdlib.h>

#include <sys/stat.h>

#include <unistd.h>



#define KMSG_PATH "/dev/kmsg"

#define BUFFER_SIZE 4096



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

{

    int fd = open(KMSG_PATH, O_RDONLY);

    if (fd < 0)

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



    for (;;) {

        char buffer[BUFFER_SIZE];

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

        while (amt > 0) {

            ssize_t written = write(STDOUT_FILENO, buffer, amt);

            if (written < 0)

                err(EXIT_FAILURE, "write stdout");

            amt -= written;

        }

        if (amt < 0) {

            if (errno != EINTR)

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

        }

    }

}