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/*
* dmesg.c -- Print out the contents of the kernel ring buffer
*
* Copyright (C) 1993 Theodore Ts'o <tytso@athena.mit.edu>
* Copyright (C) 2011 Karel Zak <kzak@redhat.com>
*
* This program comes with ABSOLUTELY NO WARRANTY.
*/
#include <linux/unistd.h>
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/klog.h>
#include <sys/syslog.h>
#include <sys/time.h>
#include <sys/sysinfo.h>
#include <ctype.h>
#include <time.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include "c.h"
#include "nls.h"
#include "strutils.h"
#include "xalloc.h"
#include "widechar.h"
#include "all-io.h"
#include "bitops.h"
#include "closestream.h"
#include "optutils.h"
#include "mangle.h"
/* Close the log. Currently a NOP. */
#define SYSLOG_ACTION_CLOSE 0
/* Open the log. Currently a NOP. */
#define SYSLOG_ACTION_OPEN 1
/* Read from the log. */
#define SYSLOG_ACTION_READ 2
/* Read all messages remaining in the ring buffer. (allowed for non-root) */
#define SYSLOG_ACTION_READ_ALL 3
/* Read and clear all messages remaining in the ring buffer */
#define SYSLOG_ACTION_READ_CLEAR 4
/* Clear ring buffer. */
#define SYSLOG_ACTION_CLEAR 5
/* Disable printk's to console */
#define SYSLOG_ACTION_CONSOLE_OFF 6
/* Enable printk's to console */
#define SYSLOG_ACTION_CONSOLE_ON 7
/* Set level of messages printed to console */
#define SYSLOG_ACTION_CONSOLE_LEVEL 8
/* Return number of unread characters in the log buffer */
#define SYSLOG_ACTION_SIZE_UNREAD 9
/* Return size of the log buffer */
#define SYSLOG_ACTION_SIZE_BUFFER 10
/*
* Priority and facility names
*/
struct dmesg_name {
const char *name;
const char *help;
};
/*
* Priority names -- based on sys/syslog.h
*/
static const struct dmesg_name level_names[] =
{
[LOG_EMERG] = { "emerg", N_("system is unusable") },
[LOG_ALERT] = { "alert", N_("action must be taken immediately") },
[LOG_CRIT] = { "crit", N_("critical conditions") },
[LOG_ERR] = { "err", N_("error conditions") },
[LOG_WARNING] = { "warn", N_("warning conditions") },
[LOG_NOTICE] = { "notice",N_("normal but significant condition") },
[LOG_INFO] = { "info", N_("informational") },
[LOG_DEBUG] = { "debug", N_("debug-level messages") }
};
/*
* sys/syslog.h uses (f << 3) for all facility codes.
* We want to use the codes as array idexes, so shift back...
*
* Note that libc LOG_FAC() macro returns the base codes, not the
* shifted code :-)
*/
#define FAC_BASE(f) ((f) >> 3)
static const struct dmesg_name facility_names[] =
{
[FAC_BASE(LOG_KERN)] = { "kern", N_("kernel messages") },
[FAC_BASE(LOG_USER)] = { "user", N_("random user-level messages") },
[FAC_BASE(LOG_MAIL)] = { "mail", N_("mail system") },
[FAC_BASE(LOG_DAEMON)] = { "daemon", N_("system daemons") },
[FAC_BASE(LOG_AUTH)] = { "auth", N_("security/authorization messages") },
[FAC_BASE(LOG_SYSLOG)] = { "syslog", N_("messages generated internally by syslogd") },
[FAC_BASE(LOG_LPR)] = { "lpr", N_("line printer subsystem") },
[FAC_BASE(LOG_NEWS)] = { "news", N_("network news subsystem") },
[FAC_BASE(LOG_UUCP)] = { "uucp", N_("UUCP subsystem") },
[FAC_BASE(LOG_CRON)] = { "cron", N_("clock daemon") },
[FAC_BASE(LOG_AUTHPRIV)] = { "authpriv", N_("security/authorization messages (private)") },
[FAC_BASE(LOG_FTP)] = { "ftp", N_("ftp daemon") },
};
/* supported methods to read message buffer
*/
enum {
DMESG_METHOD_KMSG, /* read messages from /dev/kmsg (default) */
DMESG_METHOD_SYSLOG, /* klogctl() buffer */
DMESG_METHOD_MMAP /* mmap file with records (see --file) */
};
struct dmesg_control {
/* bit arrays -- see include/bitops.h */
char levels[ARRAY_SIZE(level_names) / NBBY + 1];
char facilities[ARRAY_SIZE(facility_names) / NBBY + 1];
struct timeval lasttime; /* last printed timestamp */
struct tm lasttm; /* last localtime */
time_t boot_time; /* system boot time */
int action; /* SYSLOG_ACTION_* */
int method; /* DMESG_METHOD_* */
size_t bufsize; /* size of syslog buffer */
int kmsg; /* /dev/kmsg file descriptor */
ssize_t kmsg_first_read;/* initial read() return code */
char kmsg_buf[BUFSIZ];/* buffer to read kmsg data */
/*
* For the --file option we mmap whole file. The unnecessary (already
* printed) pages are always unmapped. The result is that we have in
* memory only the currently used page(s).
*/
char *filename;
char *mmap_buff;
size_t pagesize;
unsigned int follow:1, /* wait for new messages */
raw:1, /* raw mode */
fltr_lev:1, /* filter out by levels[] */
fltr_fac:1, /* filter out by facilities[] */
decode:1, /* use "facility: level: " prefix */
notime:1, /* don't print timestamp */
delta:1, /* show time deltas */
reltime:1, /* show human readable relative times */
ctime:1; /* show human readable time */
};
struct dmesg_record {
const char *mesg;
size_t mesg_size;
int level;
int facility;
struct timeval tv;
const char *next; /* buffer with next unparsed record */
size_t next_size; /* size of the next buffer */
};
#define INIT_DMESG_RECORD(_r) do { \
(_r)->mesg = NULL; \
(_r)->mesg_size = 0; \
(_r)->facility = -1; \
(_r)->level = -1; \
(_r)->tv.tv_sec = 0; \
(_r)->tv.tv_usec = 0; \
} while (0)
static int read_kmsg(struct dmesg_control *ctl);
static void __attribute__((__noreturn__)) usage(FILE *out)
{
size_t i;
fputs(_("\nUsage:\n"), out);
fprintf(out,
_(" %s [options]\n"), program_invocation_short_name);
fputs(_("\nOptions:\n"), out);
fputs(_(" -C, --clear clear the kernel ring buffer\n"
" -c, --read-clear read and clear all messages\n"
" -D, --console-off disable printing messages to console\n"
" -d, --show-delta show time delta between printed messages\n"
" -e, --reltime show local time and time delta in readable format\n"
" -E, --console-on enable printing messages to console\n"
" -F, --file <file> use the file instead of the kernel log buffer\n"
" -f, --facility <list> restrict output to defined facilities\n"
" -h, --help display this help and exit\n"
" -k, --kernel display kernel messages\n"
" -l, --level <list> restrict output to defined levels\n"
" -n, --console-level <level> set level of messages printed to console\n"
" -r, --raw print the raw message buffer\n"
" -S, --syslog force to use syslog(2) rather than /dev/kmsg\n"
" -s, --buffer-size <size> buffer size to query the kernel ring buffer\n"
" -T, --ctime show human readable timestamp (could be \n"
" inaccurate if you have used SUSPEND/RESUME)\n"
" -t, --notime don't print messages timestamp\n"
" -u, --userspace display userspace messages\n"
" -V, --version output version information and exit\n"
" -w, --follow wait for new messages\n"
" -x, --decode decode facility and level to readable string\n"), out);
fputs(_("\nSupported log facilities:\n"), out);
for (i = 0; i < ARRAY_SIZE(level_names); i++) {
fprintf(stderr, " %7s - %s\n",
facility_names[i].name,
_(facility_names[i].help));
}
fputs(_("\nSupported log levels (priorities):\n"), out);
for (i = 0; i < ARRAY_SIZE(level_names); i++) {
fprintf(stderr, " %7s - %s\n",
level_names[i].name,
_(level_names[i].help));
}
fputc('\n', out);
exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}
/*
* LEVEL ::= <number> | <name>
* <number> ::= number in range <0..N>, where N < ARRAY_SIZE(level_names)
* <name> ::= case-insensitive text
*/
static int parse_level(const char *str, size_t len)
{
if (!str)
return -1;
if (!len)
len = strlen(str);
errno = 0;
if (isdigit(*str)) {
char *end = NULL;
long x = strtol(str, &end, 10);
if (!errno && end && end > str && (size_t) (end - str) == len &&
x >= 0 && (size_t) x < ARRAY_SIZE(level_names))
return x;
} else {
size_t i;
for (i = 0; i < ARRAY_SIZE(level_names); i++) {
const char *n = level_names[i].name;
if (strncasecmp(str, n, len) == 0 && *(n + len) == '\0')
return i;
}
}
if (errno)
err(EXIT_FAILURE, _("failed to parse level '%s'"), str);
errx(EXIT_FAILURE, _("unknown level '%s'"), str);
return -1;
}
/*
* FACILITY ::= <number> | <name>
* <number> ::= number in range <0..N>, where N < ARRAY_SIZE(facility_names)
* <name> ::= case-insensitive text
*/
static int parse_facility(const char *str, size_t len)
{
if (!str)
return -1;
if (!len)
len = strlen(str);
errno = 0;
if (isdigit(*str)) {
char *end = NULL;
long x = strtol(str, &end, 10);
if (!errno && end && end > str && (size_t) (end - str) == len &&
x >= 0 && (size_t) x < ARRAY_SIZE(facility_names))
return x;
} else {
size_t i;
for (i = 0; i < ARRAY_SIZE(facility_names); i++) {
const char *n = facility_names[i].name;
if (strncasecmp(str, n, len) == 0 && *(n + len) == '\0')
return i;
}
}
if (errno)
err(EXIT_FAILURE, _("failed to parse facility '%s'"), str);
errx(EXIT_FAILURE, _("unknown facility '%s'"), str);
return -1;
}
/*
* Parses numerical prefix used for all messages in kernel ring buffer.
*
* Priorities/facilities are encoded into a single 32-bit quantity, where the
* bottom 3 bits are the priority (0-7) and the top 28 bits are the facility
* (0-big number).
*
* Note that the number has to end with '>' or ',' char.
*/
static const char *parse_faclev(const char *str, int *fac, int *lev)
{
long num;
char *end = NULL;
if (!str)
return str;
errno = 0;
num = strtol(str, &end, 10);
if (!errno && end && end > str) {
*fac = LOG_FAC(num);
*lev = LOG_PRI(num);
if (*lev < 0 || (size_t) *lev > ARRAY_SIZE(level_names))
*lev = -1;
if (*fac < 0 || (size_t) *fac > ARRAY_SIZE(facility_names))
*fac = -1;
return end + 1; /* skip '<' or ',' */
}
return str;
}
/*
* Parses timestamp from syslog message prefix, expected format:
*
* seconds.microseconds]
*
* the ']' is the timestamp field terminator.
*/
static const char *parse_syslog_timestamp(const char *str0, struct timeval *tv)
{
const char *str = str0;
char *end = NULL;
if (!str0)
return str0;
errno = 0;
tv->tv_sec = strtol(str, &end, 10);
if (!errno && end && *end == '.' && *(end + 1)) {
str = end + 1;
end = NULL;
tv->tv_usec = strtol(str, &end, 10);
}
if (errno || !end || end == str || *end != ']')
return str0;
return end + 1; /* skip ']' */
}
/*
* Parses timestamp from /dev/kmsg, expected formats:
*
* microseconds,
* microseconds;
*
* the ',' is fields separators and ';' items terminator (for the last item)
*/
static const char *parse_kmsg_timestamp(const char *str0, struct timeval *tv)
{
const char *str = str0;
char *end = NULL;
uint64_t usec;
if (!str0)
return str0;
errno = 0;
usec = strtoumax(str, &end, 10);
if (!errno && end && (*end == ';' || *end == ',')) {
tv->tv_usec = usec % 1000000;
tv->tv_sec = usec / 1000000;
} else
return str0;
return end + 1; /* skip separator */
}
static double time_diff(struct timeval *a, struct timeval *b)
{
return (a->tv_sec - b->tv_sec) + (a->tv_usec - b->tv_usec) / 1E6;
}
static int get_syslog_buffer_size(void)
{
int n = klogctl(SYSLOG_ACTION_SIZE_BUFFER, NULL, 0);
return n > 0 ? n : 0;
}
static time_t get_boot_time(void)
{
struct sysinfo info;
struct timeval tv;
if (sysinfo(&info) != 0)
warn(_("sysinfo failed"));
else if (gettimeofday(&tv, NULL) != 0)
warn(_("gettimeofday failed"));
else
return tv.tv_sec -= info.uptime;
return 0;
}
/*
* Reads messages from regular file by mmap
*/
static ssize_t mmap_file_buffer(struct dmesg_control *ctl, char **buf)
{
struct stat st;
int fd;
if (!ctl->filename)
return -1;
fd = open(ctl->filename, O_RDONLY);
if (fd < 0)
err(EXIT_FAILURE, _("cannot open %s"), ctl->filename);
if (fstat(fd, &st))
err(EXIT_FAILURE, _("stat failed %s"), ctl->filename);
*buf = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (*buf == MAP_FAILED)
err(EXIT_FAILURE, _("cannot mmap: %s"), ctl->filename);
ctl->mmap_buff = *buf;
ctl->pagesize = getpagesize();
close(fd);
return st.st_size;
}
/*
* Reads messages from kernel ring buffer by klogctl()
*/
static ssize_t read_syslog_buffer(struct dmesg_control *ctl, char **buf)
{
size_t sz;
int rc = -1;
if (ctl->bufsize) {
sz = ctl->bufsize + 8;
*buf = xmalloc(sz * sizeof(char));
rc = klogctl(ctl->action, *buf, sz);
} else {
sz = 16392;
while (1) {
*buf = xmalloc(sz * sizeof(char));
rc = klogctl(SYSLOG_ACTION_READ_ALL, *buf, sz);
if (rc < 0)
break;
if ((size_t) rc != sz || sz > (1 << 28))
break;
free(*buf);
*buf = NULL;
sz *= 4;
}
if (rc > 0 && ctl->action == SYSLOG_ACTION_READ_CLEAR)
rc = klogctl(SYSLOG_ACTION_READ_CLEAR, *buf, sz);
}
return rc;
}
/*
* Top level function to read messages
*/
static ssize_t read_buffer(struct dmesg_control *ctl, char **buf)
{
ssize_t n = -1;
switch (ctl->method) {
case DMESG_METHOD_MMAP:
n = mmap_file_buffer(ctl, buf);
break;
case DMESG_METHOD_SYSLOG:
if (!ctl->bufsize)
ctl->bufsize = get_syslog_buffer_size();
n = read_syslog_buffer(ctl, buf);
break;
case DMESG_METHOD_KMSG:
/*
* Since kernel 3.5.0
*/
n = read_kmsg(ctl);
if (n == 0 && ctl->action == SYSLOG_ACTION_READ_CLEAR)
n = klogctl(SYSLOG_ACTION_CLEAR, NULL, 0);
break;
}
return n;
}
static int fwrite_hex(const char *buf, size_t size, FILE *out)
{
size_t i;
for (i = 0; i < size; i++) {
int rc = fprintf(out, "\\x%02x", buf[i]);
if (rc < 0)
return rc;
}
return 0;
}
/*
* Prints to 'out' and non-printable chars are replaced with \x<hex> sequences.
*/
static void safe_fwrite(const char *buf, size_t size, FILE *out)
{
size_t i;
#ifdef HAVE_WIDECHAR
mbstate_t s;
memset(&s, 0, sizeof (s));
#endif
for (i = 0; i < size; i++) {
const char *p = buf + i;
int rc, hex = 0;
size_t len = 1;
#ifdef HAVE_WIDECHAR
wchar_t wc;
len = mbrtowc(&wc, p, size - i, &s);
if (len == 0) /* L'\0' */
return;
if (len == (size_t)-1 || len == (size_t)-2) { /* invalid sequence */
memset(&s, 0, sizeof (s));
len = hex = 1;
} else if (len > 1 && !iswprint(wc)) { /* non-printable multibyte */
hex = 1;
}
i += len - 1;
#else
if (!isprint((unsigned int) *p) &&
!isspace((unsigned int) *p)) /* non-printable */
hex = 1;
#endif
if (hex)
rc = fwrite_hex(p, len, out);
else
rc = fwrite(p, 1, len, out) != len;
if (rc != 0)
err(EXIT_FAILURE, _("write failed"));
}
}
static const char *skip_item(const char *begin, const char *end, const char *sep)
{
while (begin < end) {
int c = *begin++;
if (c == '\0' || strchr(sep, c))
break;
}
return begin;
}
/*
* Parses one record from syslog(2) buffer
*/
static int get_next_syslog_record(struct dmesg_control *ctl,
struct dmesg_record *rec)
{
size_t i;
const char *begin = NULL;
if (ctl->method != DMESG_METHOD_MMAP &&
ctl->method != DMESG_METHOD_SYSLOG)
return -1;
if (!rec->next || !rec->next_size)
return 1;
INIT_DMESG_RECORD(rec);
/*
* Unmap already printed file data from memory
*/
if (ctl->mmap_buff && (size_t) (rec->next - ctl->mmap_buff) > ctl->pagesize) {
void *x = ctl->mmap_buff;
ctl->mmap_buff += ctl->pagesize;
munmap(x, ctl->pagesize);
}
for (i = 0; i < rec->next_size; i++) {
const char *p = rec->next + i;
const char *end = NULL;
if (!begin)
begin = p;
if (i + 1 == rec->next_size) {
end = p + 1;
i++;
} else if (*p == '\n' && *(p + 1) == '<')
end = p;
if (begin && !*begin)
begin = NULL; /* zero(s) at the end of the buffer? */
if (!begin || !end)
continue;
if (end <= begin)
continue; /* error or empty line? */
if (*begin == '<') {
if (ctl->fltr_lev || ctl->fltr_fac || ctl->decode)
begin = parse_faclev(begin + 1, &rec->facility,
&rec->level);
else
begin = skip_item(begin, end, ">");
}
if (*begin == '[' && (*(begin + 1) == ' ' ||
isdigit(*(begin + 1)))) {
if (ctl->delta || ctl->ctime || ctl->reltime)
begin = parse_syslog_timestamp(begin + 1, &rec->tv);
else if (ctl->notime)
begin = skip_item(begin, end, "]");
if (begin < end && *begin == ' ')
begin++;
}
rec->mesg = begin;
rec->mesg_size = end - begin;
rec->next_size -= end - rec->next;
rec->next = rec->next_size > 0 ? end + 1 : NULL;
if (rec->next_size > 0)
rec->next_size--;
return 0;
}
return 1;
}
static int accept_record(struct dmesg_control *ctl, struct dmesg_record *rec)
{
if (ctl->fltr_lev && (rec->facility < 0 ||
!isset(ctl->levels, rec->level)))
return 0;
if (ctl->fltr_fac && (rec->facility < 0 ||
!isset(ctl->facilities, rec->facility)))
return 0;
return 1;
}
static void raw_print(struct dmesg_control *ctl, const char *buf, size_t size)
{
int lastc = '\n';
if (!ctl->mmap_buff) {
/*
* Print whole ring buffer
*/
safe_fwrite(buf, size, stdout);
lastc = buf[size - 1];
} else {
/*
* Print file in small chunks to save memory
*/
while (size) {
size_t sz = size > ctl->pagesize ? ctl->pagesize : size;
char *x = ctl->mmap_buff;
safe_fwrite(x, sz, stdout);
lastc = x[sz - 1];
size -= sz;
ctl->mmap_buff += sz;
munmap(x, sz);
}
}
if (lastc != '\n')
putchar('\n');
}
static struct tm *record_localtime(struct dmesg_control *ctl,
struct dmesg_record *rec,
struct tm *tm)
{
time_t t = ctl->boot_time + rec->tv.tv_sec;
return localtime_r(&t, tm);
}
static char *record_ctime(struct dmesg_control *ctl,
struct dmesg_record *rec,
char *buf, size_t bufsiz)
{
struct tm tm;
record_localtime(ctl, rec, &tm);
if (strftime(buf, bufsiz, "%a %b %e %H:%M:%S %Y", &tm) == 0)
*buf = '\0';
return buf;
}
static char *short_ctime(struct tm *tm, char *buf, size_t bufsiz)
{
if (strftime(buf, bufsiz, "%b%e %H:%M", tm) == 0)
*buf = '\0';
return buf;
}
static double record_count_delta(struct dmesg_control *ctl,
struct dmesg_record *rec)
{
double delta = 0;
if (timerisset(&ctl->lasttime))
delta = time_diff(&rec->tv, &ctl->lasttime);
ctl->lasttime = rec->tv;
return delta;
}
static void print_record(struct dmesg_control *ctl,
struct dmesg_record *rec)
{
char buf[256];
if (!accept_record(ctl, rec))
return;
if (!rec->mesg_size) {
putchar('\n');
return;
}
/*
* compose syslog(2) compatible raw output -- used for /dev/kmsg for
* backward compatibility with syslog(2) buffers only
*/
if (ctl->raw) {
printf("<%d>[%5d.%06d] ",
LOG_MAKEPRI(rec->facility, rec->level),
(int) rec->tv.tv_sec,
(int) rec->tv.tv_usec);
goto mesg;
}
/*
* facility : priority :
*/
if (ctl->decode && rec->level >= 0 && rec->facility >= 0)
printf("%-6s:%-6s: ", facility_names[rec->facility].name,
level_names[rec->level].name);
/*
* [sec.usec <delta>] or [ctime <delta>]
*/
if (ctl->delta) {
if (ctl->ctime)
printf("[%s ", record_ctime(ctl, rec, buf, sizeof(buf)));
else if (ctl->notime)
putchar('[');
else
printf("[%5d.%06d ", (int) rec->tv.tv_sec,
(int) rec->tv.tv_usec);
printf("<%12.06f>] ", record_count_delta(ctl, rec));
/*
* [ctime]
*/
} else if (ctl->ctime)
printf("[%s] ", record_ctime(ctl, rec, buf, sizeof(buf)));
/*
* [reltime]
*/
else if (ctl->reltime) {
double delta;
struct tm cur;
record_localtime(ctl, rec, &cur);
delta = record_count_delta(ctl, rec);
if (cur.tm_min != ctl->lasttm.tm_min ||
cur.tm_hour != ctl->lasttm.tm_hour ||
cur.tm_yday != ctl->lasttm.tm_yday)
printf("[%s] ", short_ctime(&cur, buf, sizeof(buf)));
else if (delta < 10)
printf("[ %+8.06f] ", delta);
else
printf("[ %+9.06f] ", delta);
ctl->lasttm = cur;
}
/*
* In syslog output the timestamp is part of the message and we don't
* parse the timestamp by default. We parse the timestamp only if
* --show-delta or --ctime is specified.
*
* In kmsg output we always parse the timesptamp, so we have to compose
* the [sec.usec] string.
*/
if (ctl->method == DMESG_METHOD_KMSG &&
!ctl->notime && !ctl->delta && !ctl->ctime && !ctl->reltime)
printf("[%5d.%06d] ", (int) rec->tv.tv_sec, (int) rec->tv.tv_usec);
mesg:
safe_fwrite(rec->mesg, rec->mesg_size, stdout);
if (*(rec->mesg + rec->mesg_size - 1) != '\n')
putchar('\n');
}
/*
* Prints the 'buf' kernel ring buffer; the messages are filtered out according
* to 'levels' and 'facilities' bitarrays.
*/
static void print_buffer(struct dmesg_control *ctl,
const char *buf, size_t size)
{
struct dmesg_record rec = { .next = buf, .next_size = size };
if (ctl->raw) {
raw_print(ctl, buf, size);
return;
}
while (get_next_syslog_record(ctl, &rec) == 0)
print_record(ctl, &rec);
}
static ssize_t read_kmsg_one(struct dmesg_control *ctl)
{
ssize_t size;
/* kmsg returns EPIPE if record was modified while reading */
do {
size = read(ctl->kmsg, ctl->kmsg_buf,
sizeof(ctl->kmsg_buf) - 1);
} while (size < 0 && errno == EPIPE);
return size;
}
static int init_kmsg(struct dmesg_control *ctl)
{
int mode = O_RDONLY;
if (!ctl->follow)
mode |= O_NONBLOCK;
ctl->kmsg = open("/dev/kmsg", mode);
if (ctl->kmsg < 0)
return -1;
/*
* Seek after the last record available at the time
* the last SYSLOG_ACTION_CLEAR was issued.
*
* ... otherwise SYSLOG_ACTION_CLEAR will have no effect for kmsg.
*/
lseek(ctl->kmsg, 0, SEEK_DATA);
/*
* Old kernels (<3.5) allow to successfully open /dev/kmsg for
* read-only, but read() returns -EINVAL :-(((
*
* Let's try to read the first record. The record is later processed in
* read_kmsg().
*/
ctl->kmsg_first_read = read_kmsg_one(ctl);
if (ctl->kmsg_first_read < 0) {
close(ctl->kmsg);
ctl->kmsg = -1;
return -1;
}
return 0;
}
/*
* /dev/kmsg record format:
*
* faclev,seqnum,timestamp[optional, ...];messgage\n
* TAGNAME=value
* ...
*
* - fields are separated by ','
* - last field is terminated by ';'
*
*/
#define LAST_KMSG_FIELD(s) (!s || !*s || *(s - 1) == ';')
static int parse_kmsg_record(struct dmesg_control *ctl,
struct dmesg_record *rec,
char *buf,
size_t sz)
{
const char *p = buf, *end;
if (sz == 0 || !buf || !*buf)
return -1;
end = buf + (sz - 1);
INIT_DMESG_RECORD(rec);
while (p < end && isspace(*p))
p++;
/* A) priority and facility */
if (ctl->fltr_lev || ctl->fltr_fac || ctl->decode || ctl->raw)
p = parse_faclev(p, &rec->facility, &rec->level);
else
p = skip_item(p, end, ",");
if (LAST_KMSG_FIELD(p))
goto mesg;
/* B) sequence number */
p = skip_item(p, end, ",;");
if (LAST_KMSG_FIELD(p))
goto mesg;
/* C) timestamp */
if (ctl->notime)
p = skip_item(p, end, ",;");
else
p = parse_kmsg_timestamp(p, &rec->tv);
if (LAST_KMSG_FIELD(p))
goto mesg;
/* D) optional fields (ignore) */
p = skip_item(p, end, ";");
if (LAST_KMSG_FIELD(p))
goto mesg;
mesg:
/* E) message text */
rec->mesg = p;
p = skip_item(p, end, "\n");
if (!p)
return -1;
rec->mesg_size = p - rec->mesg;
/*
* Kernel escapes non-printable characters, unfortuately kernel
* definition of "non-printable" is too strict. On UTF8 console we can
* print many chars, so let's decode from kernel.
*/
unhexmangle_to_buffer(rec->mesg, (char *) rec->mesg, rec->mesg_size + 1);
/* F) message tags (ignore) */
return 0;
}
/*
* Note that each read() call for /dev/kmsg returns always one record. It means
* that we don't have to read whole message buffer before the records parsing.
*
* So this function does not compose one huge buffer (like read_syslog_buffer())
* and print_buffer() is unnecessary. All is done in this function.
*
* Returns 0 on success, -1 on error.
*/
static int read_kmsg(struct dmesg_control *ctl)
{
struct dmesg_record rec;
ssize_t sz;
if (ctl->method != DMESG_METHOD_KMSG || ctl->kmsg < 0)
return -1;
/*
* The very first read() call is done in kmsg_init() where we test
* /dev/kmsg usability. The return code from the initial read() is
* stored in ctl->kmsg_first_read;
*/
sz = ctl->kmsg_first_read;
while (sz > 0) {
*(ctl->kmsg_buf + sz) = '\0'; /* for debug messages */
if (parse_kmsg_record(ctl, &rec,
ctl->kmsg_buf, (size_t) sz) == 0)
print_record(ctl, &rec);
sz = read_kmsg_one(ctl);
}
return 0;
}
#define EXCL_ACT_ERR "--{clear,read-clear,console-level,console-on,console-off}"
#define EXCL_SYS_ERR "--{syslog,follow}"
int main(int argc, char *argv[])
{
char *buf = NULL;
int c;
int console_level = 0;
int klog_rc = 0;
ssize_t n;
static struct dmesg_control ctl = {
.filename = NULL,
.action = SYSLOG_ACTION_READ_ALL,
.method = DMESG_METHOD_KMSG,
.kmsg = -1,
};
static const struct option longopts[] = {
{ "buffer-size", required_argument, NULL, 's' },
{ "clear", no_argument, NULL, 'C' },
{ "console-level", required_argument, NULL, 'n' },
{ "console-off", no_argument, NULL, 'D' },
{ "console-on", no_argument, NULL, 'E' },
{ "decode", no_argument, NULL, 'x' },
{ "file", required_argument, NULL, 'F' },
{ "facility", required_argument, NULL, 'f' },
{ "follow", no_argument, NULL, 'w' },
{ "help", no_argument, NULL, 'h' },
{ "kernel", no_argument, NULL, 'k' },
{ "level", required_argument, NULL, 'l' },
{ "syslog", no_argument, NULL, 'S' },
{ "raw", no_argument, NULL, 'r' },
{ "read-clear", no_argument, NULL, 'c' },
{ "reltime", no_argument, NULL, 'e' },
{ "show-delta", no_argument, NULL, 'd' },
{ "ctime", no_argument, NULL, 'T' },
{ "notime", no_argument, NULL, 't' },
{ "userspace", no_argument, NULL, 'u' },
{ "version", no_argument, NULL, 'V' },
{ NULL, 0, NULL, 0 }
};
static const ul_excl_t excl[] = { /* rows and cols in in ASCII order */
{ 'C','D','E','c','n' }, /* clear,off,on,read-clear,level*/
{ 'S','w' }, /* syslog,follow */
{ 0 }
};
int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
atexit(close_stdout);
while ((c = getopt_long(argc, argv, "CcDdEeF:f:hkl:n:rSs:TtuVwx",
longopts, NULL)) != -1) {
err_exclusive_options(c, longopts, excl, excl_st);
switch (c) {
case 'C':
ctl.action = SYSLOG_ACTION_CLEAR;
break;
case 'c':
ctl.action = SYSLOG_ACTION_READ_CLEAR;
break;
case 'D':
ctl.action = SYSLOG_ACTION_CONSOLE_OFF;
break;
case 'd':
ctl.delta = 1;
break;
case 'E':
ctl.action = SYSLOG_ACTION_CONSOLE_ON;
break;
case 'e':
ctl.boot_time = get_boot_time();
if (ctl.boot_time)
ctl.reltime = 1;
break;
case 'F':
ctl.filename = optarg;
ctl.method = DMESG_METHOD_MMAP;
break;
case 'f':
ctl.fltr_fac = 1;
if (string_to_bitarray(optarg,
ctl.facilities, parse_facility) < 0)
return EXIT_FAILURE;
break;
case 'h':
usage(stdout);
break;
case 'k':
ctl.fltr_fac = 1;
setbit(ctl.facilities, FAC_BASE(LOG_KERN));
break;
case 'l':
ctl.fltr_lev= 1;
if (string_to_bitarray(optarg,
ctl.levels, parse_level) < 0)
return EXIT_FAILURE;
break;
case 'n':
ctl.action = SYSLOG_ACTION_CONSOLE_LEVEL;
console_level = parse_level(optarg, 0);
break;
case 'r':
ctl.raw = 1;
break;
case 'S':
ctl.method = DMESG_METHOD_SYSLOG;
break;
case 's':
ctl.bufsize = strtou32_or_err(optarg,
_("invalid buffer size argument"));
if (ctl.bufsize < 4096)
ctl.bufsize = 4096;
break;
case 'T':
ctl.boot_time = get_boot_time();
if (ctl.boot_time)
ctl.ctime = 1;
break;
case 't':
ctl.notime = 1;
break;
case 'u':
ctl.fltr_fac = 1;
for (n = 1; (size_t) n < ARRAY_SIZE(facility_names); n++)
setbit(ctl.facilities, n);
break;
case 'V':
printf(_("%s from %s\n"), program_invocation_short_name,
PACKAGE_STRING);
return EXIT_SUCCESS;
case 'w':
ctl.follow = 1;
break;
case 'x':
ctl.decode = 1;
break;
case '?':
default:
usage(stderr);
}
}
argc -= optind;
argv += optind;
if (argc > 1)
usage(stderr);
if (ctl.raw && (ctl.fltr_lev || ctl.fltr_fac || ctl.delta ||
ctl.notime || ctl.ctime || ctl.decode))
errx(EXIT_FAILURE, _("--raw can't be used together with level, "
"facility, decode, delta, ctime or notime options"));
if (ctl.notime && (ctl.ctime || ctl.reltime))
errx(EXIT_FAILURE, _("--notime can't be used together with --ctime or --reltime"));
if (ctl.reltime && ctl.ctime)
errx(EXIT_FAILURE, _("--reltime can't be used together with --ctime "));
switch (ctl.action) {
case SYSLOG_ACTION_READ_ALL:
case SYSLOG_ACTION_READ_CLEAR:
if (ctl.method == DMESG_METHOD_KMSG && init_kmsg(&ctl) != 0)
ctl.method = DMESG_METHOD_SYSLOG;
n = read_buffer(&ctl, &buf);
if (n > 0)
print_buffer(&ctl, buf, n);
if (!ctl.mmap_buff)
free(buf);
if (n < 0)
err(EXIT_FAILURE, _("read kernel buffer failed"));
if (ctl.kmsg >= 0)
close(ctl.kmsg);
break;
case SYSLOG_ACTION_CLEAR:
case SYSLOG_ACTION_CONSOLE_OFF:
case SYSLOG_ACTION_CONSOLE_ON:
klog_rc = klogctl(ctl.action, NULL, 0);
break;
case SYSLOG_ACTION_CONSOLE_LEVEL:
klog_rc = klogctl(ctl.action, NULL, console_level);
break;
default:
errx(EXIT_FAILURE, _("unsupported command"));
break;
}
if (klog_rc)
err(EXIT_FAILURE, _("klogctl failed"));
return EXIT_SUCCESS;
}
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