1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/* dmesg.c - display/control kernel ring buffer.
*
* Copyright 2006, 2007 Rob Landley <rob@landley.net>
*
* See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/dmesg.html
*
* Don't ask me why the horrible new dmesg API is still in "testing":
* http://kernel.org/doc/Documentation/ABI/testing/dev-kmsg
// We care that FLAG_c is 1, so keep c at the end.
USE_DMESG(NEWTOY(dmesg, "w(follow)CSTtrs#<1n#c[!Ttr][!Cc][!Sw]", TOYFLAG_BIN))
config DMESG
bool "dmesg"
default y
help
usage: dmesg [-Cc] [-r|-t|-T] [-n LEVEL] [-s SIZE] [-w]
Print or control the kernel ring buffer.
-C Clear ring buffer without printing
-c Clear ring buffer after printing
-n Set kernel logging LEVEL (1-9)
-r Raw output (with <level markers>)
-S Use syslog(2) rather than /dev/kmsg
-s Show the last SIZE many bytes
-T Show human-readable timestamps
-t Don't print timestamps
-w Keep waiting for more output (aka --follow)
*/
#define FOR_dmesg
#include "toys.h"
#include <sys/klog.h>
GLOBALS(
long n, s;
int use_color;
time_t tea;
)
static void color(int c)
{
if (TT.use_color) printf("\033[%dm", c);
}
static void format_message(char *msg, int new)
{
unsigned long long time_s, time_us;
int facpri, subsystem, pos;
char *p, *text;
// The new /dev/kmsg and the old syslog(2) formats differ slightly.
if (new) {
if (sscanf(msg, "%u,%*u,%llu,%*[^;]; %n", &facpri, &time_us, &pos) != 2)
return;
time_s = time_us/1000000;
time_us %= 1000000;
} else if (sscanf(msg, "<%u>[%llu.%llu] %n",
&facpri, &time_s, &time_us, &pos) != 3) return;
// Drop extras after end of message text.
if ((p = strchr(text = msg+pos, '\n'))) *p = 0;
// Is there a subsystem? (The ": " is just a convention.)
p = strstr(text, ": ");
subsystem = p ? (p-text) : 0;
// To get "raw" output for /dev/kmsg we need to add priority to each line
if (toys.optflags&FLAG_r) {
color(0);
printf("<%d>", facpri);
}
// Format the time.
if (!(toys.optflags&FLAG_t)) {
color(32);
if (toys.optflags&FLAG_T) {
time_t t = TT.tea+time_s;
char *ts = ctime(&t);
printf("[%.*s] ", (int)(strlen(ts)-1), ts);
} else printf("[%5lld.%06lld] ", time_s, time_us);
}
// Errors (or worse) are shown in red, subsystems are shown in yellow.
if (subsystem) {
color(33);
printf("%.*s", subsystem, text);
text += subsystem;
}
color(31*((facpri&7)<=3));
xputs(text);
}
static int xklogctl(int type, char *buf, int len)
{
int rc = klogctl(type, buf, len);
if (rc<0) perror_exit("klogctl");
return rc;
}
static void dmesg_cleanup(void)
{
color(0);
}
void dmesg_main(void)
{
TT.use_color = isatty(1);
if (TT.use_color) sigatexit(dmesg_cleanup);
// If we're displaying output, is it klogctl or /dev/kmsg?
if (toys.optflags & (FLAG_C|FLAG_n)) goto no_output;
if (toys.optflags&FLAG_T) {
struct sysinfo info;
sysinfo(&info);
TT.tea = time(0)-info.uptime;
}
if (!(toys.optflags&FLAG_S)) {
char msg[8193]; // CONSOLE_EXT_LOG_MAX+1
ssize_t len;
int fd;
// Each read returns one message. By default, we block when there are no
// more messages (--follow); O_NONBLOCK is needed for for usual behavior.
fd = open("/dev/kmsg", O_RDONLY|(O_NONBLOCK*!(toys.optflags&FLAG_w)));
if (fd == -1) goto klogctl_mode;
// SYSLOG_ACTION_CLEAR(5) doesn't actually remove anything from /dev/kmsg,
// you need to seek to the last clear point.
lseek(fd, 0, SEEK_DATA);
for (;;) {
// why does /dev/kmesg return EPIPE instead of EAGAIN if oldest message
// expires as we read it?
if (-1==(len = read(fd, msg, sizeof(msg))) && errno==EPIPE) continue;
// read() from kmsg always fails on a pre-3.5 kernel.
if (len==-1 && errno==EINVAL) goto klogctl_mode;
if (len<1) break;
msg[len] = 0;
format_message(msg, 1);
}
close(fd);
} else {
char *data, *to, *from, *end;
int size;
klogctl_mode:
// Figure out how much data we need, and fetch it.
if (!(size = TT.s)) size = xklogctl(10, 0, 0);
data = from = xmalloc(size+1);
data[size = xklogctl(3+(toys.optflags&FLAG_c), data, size)] = 0;
// Send each line to format_message.
to = data + size;
while (from < to) {
if (!(end = memchr(from, '\n', to-from))) break;
*end = 0;
format_message(from, 0);
from = end + 1;
}
if (CFG_TOYBOX_FREE) free(data);
}
no_output:
// Set the log level?
if (toys.optflags & FLAG_n) xklogctl(8, 0, TT.n);
// Clear the buffer?
if (toys.optflags & (FLAG_C|FLAG_c)) xklogctl(5, 0, 0);
}
|
