1#include <stdlib.h>
2#include <unistd.h>
3#include <stdio.h>
4#include <errno.h>
5#include <sys/klog.h>
6#include <string.h>
7
8#define FALLBACK_KLOG_BUF_SHIFT	17	/* CONFIG_LOG_BUF_SHIFT from our kernel */
9#define FALLBACK_KLOG_BUF_LEN	(1 << FALLBACK_KLOG_BUF_SHIFT)
10
11int dmesg_main(int argc, char **argv)
12{
13    char *buffer;
14    char *p;
15    ssize_t ret;
16    int n, op, klog_buf_len;
17
18    klog_buf_len = klogctl(KLOG_SIZE_BUFFER, 0, 0);
19
20    if (klog_buf_len <= 0) {
21        klog_buf_len = FALLBACK_KLOG_BUF_LEN;
22    }
23
24    buffer = (char *)malloc(klog_buf_len + 1);
25
26    if (!buffer) {
27        perror("malloc");
28        return EXIT_FAILURE;
29    }
30
31    p = buffer;
32
33    if((argc == 2) && (!strcmp(argv[1],"-c"))) {
34        op = KLOG_READ_CLEAR;
35    } else {
36        op = KLOG_READ_ALL;
37    }
38
39    n = klogctl(op, buffer, klog_buf_len);
40    if (n < 0) {
41        perror("klogctl");
42        return EXIT_FAILURE;
43    }
44    buffer[n] = '\0';
45
46    while((ret = write(STDOUT_FILENO, p, n))) {
47        if (ret == -1) {
48	    if (errno == EINTR)
49                continue;
50	    perror("write");
51	    return EXIT_FAILURE;
52	}
53	p += ret;
54	n -= ret;
55    }
56
57    return 0;
58}
59