Big cleanup in config help and description

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

diff --git a/util-linux/dmesg.c b/util-linux/dmesg.c
index 1adb0fc2fff8445621d60192dfba3f8cbe7081b6..c3574f8f57ca6f773e1670a9c27aa05c83914b92 100644 (file)
--- a/util-linux/dmesg.c
+++ b/util-linux/dmesg.c
@@ -4,50 +4,121 @@
  * 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"
+//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"
 
 int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int dmesg_main(int argc, char **argv)
+int dmesg_main(int argc UNUSED_PARAM, char **argv)
 {
-       char *size, *level;
-       int flags = getopt32(argv, "cs:n:", &size, &level);
+       int len, level;
+       char *buf;
+       unsigned opts;
+       enum {
+               OPT_c = 1 << 0,
+               OPT_s = 1 << 1,
+               OPT_n = 1 << 2,
+               OPT_r = 1 << 3
+       };
 
-       if (flags & 4) {
-               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");
-       } else {
-               int len;
-               char *buf;
+               return EXIT_SUCCESS;
+       }
 
-               len = (flags & 2) ? xatoul_range(size, 2, INT_MAX) : 16384;
-               buf = xmalloc(len);
-               if (0 > (len = klogctl(3 + (flags & 1), buf, len)))
-                       bb_perror_msg_and_die("klogctl");
+       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 + (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) {
-                       int last = '\n';
-                       int in;
+       if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
+               int last = '\n';
+               int in = 0;
 
-                       for (in = 0; in<len;) {
-                               if (last == '\n' && buf[in] == '<') in += 3;
-                               else bb_putchar(last = buf[in++]);
+               /* Skip <[0-9]+> at the start of lines */
+               while (1) {
+                       if (last == '\n' && buf[in] == '<') {
+                               while (buf[in++] != '>' && in < len)
+                                       ;
+                       } else {
+                               last = buf[in++];
+                               putchar(last);
                        }
-                       if (last != '\n') bb_putchar('\n');
-               } else {
-                       write(1,buf,len);
-                       if (len && buf[len-1]!='\n') bb_putchar('\n');
+                       if (in >= len)
+                               break;
                }
-
-               if (ENABLE_FEATURE_CLEAN_UP) free(buf);
+               /* Make sure we end with a newline */
+               if (last != '\n')
+                       bb_putchar('\n');
+       } else {
+               full_write(STDOUT_FILENO, buf, len);
+               if (buf[len-1] != '\n')
+                       bb_putchar('\n');
        }
 
-       return 0;
+       if (ENABLE_FEATURE_CLEAN_UP) free(buf);
+
+       return EXIT_SUCCESS;
 }