/* dmesg.c - display/control kernel ring buffer. * * Copyright 2006, 2007 Rob Landley <rob@landley.net> * * http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/dmesg.html // We care that FLAG_c is 1, so keep c at the end. USE_DMESG(NEWTOY(dmesg, "trs#<1n#c[!tr]", TOYFLAG_BIN)) config DMESG bool "dmesg" default y help usage: dmesg [-c] [-r|-t] [-n LEVEL] [-s SIZE] Print or control the kernel ring buffer. -c Clear the ring buffer after printing -n Set kernel logging LEVEL (1-9) -r Raw output (with <level markers>) -s Show the last SIZE many bytes -t Don't print kernel's timestamps */ #define FOR_dmesg #include "toys.h" #include <sys/klog.h> GLOBALS( long level; long size; ) void dmesg_main(void) { // For -n just tell kernel to which messages to keep. if (toys.optflags & FLAG_n) { if (klogctl(8, NULL, TT.level)) perror_exit("klogctl"); } else { char *data, *to, *from; int size; // Figure out how much data we need, and fetch it. size = TT.size; if (!size && 1>(size = klogctl(10, 0, 0))) perror_exit("klogctl");; data = to = from = xmalloc(size+1); size = klogctl(3 + (toys.optflags & FLAG_c), data, size); if (size < 0) perror_exit("klogctl"); data[size] = 0; // Filter out level markers and optionally time markers if (!(toys.optflags & FLAG_r)) while ((from - data) < size) { if (from == data || from[-1] == '\n') { char *to; if (*from == '<' && (to = strchr(from, '>'))) from = ++to; if ((toys.optflags&FLAG_t) && *from == '[' && (to = strchr(from, ']'))) from = to+1+(to[1]==' '); } *(to++) = *(from++); } else to = data+size; // Write result. The odds of somebody requesting a buffer of size 3 and // getting "<1>" are remote, but don't segfault if they do. if (to != data) { xwrite(1, data, to-data); if (to[-1] != '\n') xputc('\n'); } if (CFG_TOYBOX_FREE) free(data); } }