inetd,mount: add comment with example of flags to build with libtirpc

[oweals/busybox.git] / util-linux / dmesg.c

diff --git a/util-linux/dmesg.c b/util-linux/dmesg.c
index 840358c85771173052a9d2de171291ac8b6a7557..6da9d9f4e8bf006d025dbb0a437786da165ca027 100644 (file)
--- a/util-linux/dmesg.c
+++ b/util-linux/dmesg.c
@@ -4,10 +4,56 @@
  * dmesg - display/control kernel ring buffer.
  *
  * Copyright 2006 Rob Landley <rob@landley.net>
- * Copyright 2006 Bernhard Fischer <rep.nop@aon.at>
+ * Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
  *
- * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
+//config:config DMESG
+//config:      bool "dmesg (3.5 kb)"
+//config:      default y
+//config:      select PLATFORM_LINUX
+//config:      help
+//config:      dmesg is used to examine or control the kernel ring buffer. When the
+//config:      Linux kernel prints messages to the system log, they are stored in
+//config:      the kernel ring buffer. You can use dmesg to print the kernel's ring
+//config:      buffer, clear the kernel ring buffer, change the size of the kernel
+//config:      ring buffer, and change the priority level at which kernel messages
+//config:      are also logged to the system console. Enable this option if you
+//config:      wish to enable the 'dmesg' utility.
+//config:
+//config:config FEATURE_DMESG_PRETTY
+//config:      bool "Pretty output"
+//config:      default y
+//config:      depends on DMESG
+//config:      help
+//config:      If you wish to scrub the syslog level from the output, say 'Y' here.
+//config:      The syslog level is a string prefixed to every line with the form
+//config:      "<#>".
+//config:
+//config:      With this option you will see:
+//config:              # dmesg
+//config:              Linux version 2.6.17.4 .....
+//config:              BIOS-provided physical RAM map:
+//config:               BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
+//config:
+//config:      Without this option you will see:
+//config:              # dmesg
+//config:              <5>Linux version 2.6.17.4 .....
+//config:              <6>BIOS-provided physical RAM map:
+//config:              <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
+
+//applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_DMESG) += dmesg.o
+
+//usage:#define dmesg_trivial_usage
+//usage:       "[-c] [-n LEVEL] [-s SIZE]"
+//usage:#define dmesg_full_usage "\n\n"
+//usage:       "Print or control the kernel ring buffer\n"
+//usage:     "\n       -c              Clear ring buffer after printing"
+//usage:     "\n       -n LEVEL        Set console logging level"
+//usage:     "\n       -s SIZE         Buffer size"
+//usage:     "\n       -r              Print raw message buffer"
 
 #include <sys/klog.h>
 #include "libbb.h"
@@ -15,44 +61,55 @@
 int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int dmesg_main(int argc UNUSED_PARAM, char **argv)
 {
-       int len;
+       int len, level;
        char *buf;
-       char *size, *level;
-       unsigned flags = getopt32(argv, "cs:n:", &size, &level);
+       unsigned opts;
        enum {
-               OPT_c = 1<<0,
-               OPT_s = 1<<1,
-               OPT_n = 1<<2
+               OPT_c = 1 << 0,
+               OPT_s = 1 << 1,
+               OPT_n = 1 << 2,
+               OPT_r = 1 << 3
        };
 
-       if (flags & OPT_n) {
-               if (klogctl(8, NULL, xatoul_range(level, 0, 10)))
+       opts = getopt32(argv, "cs:+n:+r", &len, &level);
+       if (opts & OPT_n) {
+               if (klogctl(8, NULL, (long) level))
                        bb_perror_msg_and_die("klogctl");
                return EXIT_SUCCESS;
        }
 
-       len = (flags & OPT_s) ? xatoul_range(size, 2, INT_MAX) : 16384;
+       if (!(opts & OPT_s))
+               len = klogctl(10, NULL, 0); /* read ring buffer size */
+       if (len < 16*1024)
+               len = 16*1024;
+       if (len > 16*1024*1024)
+               len = 16*1024*1024;
+
        buf = xmalloc(len);
-       len = klogctl(3 + (flags & OPT_c), buf, len);
+       len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
        if (len < 0)
                bb_perror_msg_and_die("klogctl");
        if (len == 0)
                return EXIT_SUCCESS;
 
-       /* Skip <#> at the start of lines, and make sure we end with a newline. */
 
-       if (ENABLE_FEATURE_DMESG_PRETTY) {
+       if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
                int last = '\n';
                int in = 0;
 
-               do {
-                       if (last == '\n' && buf[in] == '<')
-                               in += 3;
-                       else {
+               /* Skip <[0-9]+> at the start of lines */
+               while (1) {
+                       if (last == '\n' && buf[in] == '<') {
+                               while (buf[in++] != '>' && in < len)
+                                       ;
+                       } else {
                                last = buf[in++];
-                               bb_putchar(last);
+                               putchar(last);
                        }
-               } while (in < len);
+                       if (in >= len)
+                               break;
+               }
+               /* Make sure we end with a newline */
                if (last != '\n')
                        bb_putchar('\n');
        } else {