blob: b7b2c69241894f44741a814450e59793d013a85d
| 1 | /* vi: set sw=4 ts=4: */ |
| 2 | /* |
| 3 | * |
| 4 | * dmesg - display/control kernel ring buffer. |
| 5 | * |
| 6 | * Copyright 2006 Rob Landley <rob@landley.net> |
| 7 | * Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at> |
| 8 | * |
| 9 | * Licensed under GPLv2, see file LICENSE in this source tree. |
| 10 | */ |
| 11 | //config:config DMESG |
| 12 | //config: bool "dmesg" |
| 13 | //config: default y |
| 14 | //config: select PLATFORM_LINUX |
| 15 | //config: help |
| 16 | //config: dmesg is used to examine or control the kernel ring buffer. When the |
| 17 | //config: Linux kernel prints messages to the system log, they are stored in |
| 18 | //config: the kernel ring buffer. You can use dmesg to print the kernel's ring |
| 19 | //config: buffer, clear the kernel ring buffer, change the size of the kernel |
| 20 | //config: ring buffer, and change the priority level at which kernel messages |
| 21 | //config: are also logged to the system console. Enable this option if you |
| 22 | //config: wish to enable the 'dmesg' utility. |
| 23 | //config: |
| 24 | //config:config FEATURE_DMESG_PRETTY |
| 25 | //config: bool "Pretty dmesg output" |
| 26 | //config: default y |
| 27 | //config: depends on DMESG |
| 28 | //config: help |
| 29 | //config: If you wish to scrub the syslog level from the output, say 'Y' here. |
| 30 | //config: The syslog level is a string prefixed to every line with the form |
| 31 | //config: "<#>". |
| 32 | //config: |
| 33 | //config: With this option you will see: |
| 34 | //config: # dmesg |
| 35 | //config: Linux version 2.6.17.4 ..... |
| 36 | //config: BIOS-provided physical RAM map: |
| 37 | //config: BIOS-e820: 0000000000000000 - 000000000009f000 (usable) |
| 38 | //config: |
| 39 | //config: Without this option you will see: |
| 40 | //config: # dmesg |
| 41 | //config: <5>Linux version 2.6.17.4 ..... |
| 42 | //config: <6>BIOS-provided physical RAM map: |
| 43 | //config: <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable) |
| 44 | |
| 45 | //applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP)) |
| 46 | |
| 47 | //kbuild:lib-$(CONFIG_DMESG) += dmesg.o |
| 48 | |
| 49 | //usage:#define dmesg_trivial_usage |
| 50 | //usage: "[-c] [-n LEVEL] [-s SIZE]" |
| 51 | //usage:#define dmesg_full_usage "\n\n" |
| 52 | //usage: "Print or control the kernel ring buffer\n" |
| 53 | //usage: "\n -c Clear ring buffer after printing" |
| 54 | //usage: "\n -n LEVEL Set console logging level" |
| 55 | //usage: "\n -s SIZE Buffer size" |
| 56 | //usage: "\n -r Print raw message buffer" |
| 57 | |
| 58 | #include <sys/klog.h> |
| 59 | #include "libbb.h" |
| 60 | |
| 61 | int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 62 | int dmesg_main(int argc UNUSED_PARAM, char **argv) |
| 63 | { |
| 64 | int len, level; |
| 65 | char *buf; |
| 66 | unsigned opts; |
| 67 | enum { |
| 68 | OPT_c = 1 << 0, |
| 69 | OPT_s = 1 << 1, |
| 70 | OPT_n = 1 << 2, |
| 71 | OPT_r = 1 << 3 |
| 72 | }; |
| 73 | |
| 74 | opts = getopt32(argv, "cs:+n:+r", &len, &level); |
| 75 | if (opts & OPT_n) { |
| 76 | if (klogctl(8, NULL, (long) level)) |
| 77 | bb_perror_msg_and_die("klogctl"); |
| 78 | return EXIT_SUCCESS; |
| 79 | } |
| 80 | |
| 81 | if (!(opts & OPT_s)) |
| 82 | len = klogctl(10, NULL, 0); /* read ring buffer size */ |
| 83 | if (len < 16*1024) |
| 84 | len = 16*1024; |
| 85 | if (len > 16*1024*1024) |
| 86 | len = 16*1024*1024; |
| 87 | |
| 88 | buf = xmalloc(len); |
| 89 | len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */ |
| 90 | if (len < 0) |
| 91 | bb_perror_msg_and_die("klogctl"); |
| 92 | if (len == 0) |
| 93 | return EXIT_SUCCESS; |
| 94 | |
| 95 | |
| 96 | if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) { |
| 97 | int last = '\n'; |
| 98 | int in = 0; |
| 99 | |
| 100 | /* Skip <[0-9]+> at the start of lines */ |
| 101 | while (1) { |
| 102 | if (last == '\n' && buf[in] == '<') { |
| 103 | while (buf[in++] != '>' && in < len) |
| 104 | ; |
| 105 | } else { |
| 106 | last = buf[in++]; |
| 107 | putchar(last); |
| 108 | } |
| 109 | if (in >= len) |
| 110 | break; |
| 111 | } |
| 112 | /* Make sure we end with a newline */ |
| 113 | if (last != '\n') |
| 114 | bb_putchar('\n'); |
| 115 | } else { |
| 116 | full_write(STDOUT_FILENO, buf, len); |
| 117 | if (buf[len-1] != '\n') |
| 118 | bb_putchar('\n'); |
| 119 | } |
| 120 | |
| 121 | if (ENABLE_FEATURE_CLEAN_UP) free(buf); |
| 122 | |
| 123 | return EXIT_SUCCESS; |
| 124 | } |
| 125 |