dracut-logger.sh

   1 #!/bin/sh
   2 # -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
   3 # ex: ts=8 sw=4 et filetype=sh
   4 #
   5 # logging faciality module for dracut both at build- and boot-time
   6 #
   7 # Copyright 2010 Amadeusz Żołnowski <aidecoe@aidecoe.name>
   8 #
   9 # This program is free software; you can redistribute it and/or modify
  10 # it under the terms of the GNU General Public License as published by
  11 # the Free Software Foundation; either version 2 of the License, or
  12 # (at your option) any later version.
  13 #
  14 # This program is distributed in the hope that it will be useful,
  15 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 # GNU General Public License for more details.
  18 #
  19 # You should have received a copy of the GNU General Public License
  20 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21
  22
  23 __DRACUT_LOGGER__=1
  24
  25
  26 ## @brief Logging facility module for Dracut both at build- and boot-time.
  27 #
  28 # @section intro Introduction
  29 #
  30 # The logger takes a bit from Log4j philosophy. There are defined 6 logging
  31 # levels:
  32 #   - TRACE (6)
  33 #     The TRACE Level designates finer-grained informational events than the
  34 #     DEBUG.
  35 #   - DEBUG (5)
  36 #     The DEBUG Level designates fine-grained informational events that are most
  37 #     useful to debug an application.
  38 #   - INFO (4)
  39 #     The INFO level designates informational messages that highlight the
  40 #     progress of the application at coarse-grained level.
  41 #   - WARN (3)
  42 #     The WARN level designates potentially harmful situations.
  43 #   - ERROR (2)
  44 #     The ERROR level designates error events that might still allow the
  45 #     application to continue running.
  46 #   - FATAL (1)
  47 #     The FATAL level designates very severe error events that will presumably
  48 #     lead the application to abort.
  49 # Descriptions are borrowed from Log4j documentation:
  50 # http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html
  51 #
  52 # @section usage Usage
  53 #
  54 # First of all you have to start with dlog_init() function which initializes
  55 # required variables. Don't call any other logging function before that one!
  56 # If you're ready with this, you can use following functions which corresponds
  57 # clearly to levels listed in @ref intro Introduction. Here they are:
  58 #   - dtrace()
  59 #   - ddebug()
  60 #   - dinfo()
  61 #   - dwarn()
  62 #   - derror()
  63 #   - dfatal()
  64 # They take all arguments given as a single message to be logged. See dlog()
  65 # function for details how it works. Note that you shouldn't use dlog() by
  66 # yourself. It's wrapped with above functions.
  67 #
  68 # @see dlog_init() dlog()
  69 #
  70 # @section conf Configuration
  71 #
  72 # Logging is controlled by following global variables:
  73 #   - @var stdloglvl - logging level to standard error (console output)
  74 #   - @var sysloglvl - logging level to syslog (by logger command)
  75 #   - @var fileloglvl - logging level to file
  76 #   - @var kmsgloglvl - logging level to /dev/kmsg (only for boot-time)
  77 #   - @var logfile - log file which is used when @var fileloglvl is higher
  78 #   than 0
  79 # and two global variables: @var maxloglvl and @var syslogfacility which <b>must
  80 # not</b> be overwritten. Both are set by dlog_init(). @var maxloglvl holds
  81 # maximum logging level of those three and indicates that dlog_init() was run.
  82 # @var syslogfacility is set either to 'user' (when building initramfs) or
  83 # 'daemon' (when booting).
  84 #
  85 # Logging level set by the variable means that messages from this logging level
  86 # and above (FATAL is the highest) will be shown. Logging levels may be set
  87 # independently for each destination (stderr, syslog, file, kmsg).
  88 #
  89 # @see dlog_init()
  90
  91
  92 ## @brief Initializes Dracut Logger.
  93 #
  94 # @retval 1 if something has gone wrong
  95 # @retval 0 on success.
  96 #
  97 # @note This function need to be called before any other from this file.
  98 #
  99 # If any of the variables is not set, this function set it to default:
 100 #   - @var stdloglvl = 4 (info)
 101 #   - @var sysloglvl = 0 (no logging)
 102 #   - @var fileloglvl is set to 4 when @var logfile is set too, otherwise it's
 103 #   - @var kmsgloglvl = 0 (no logging)
 104 #   set to 0
 105 #
 106 # @warning Function sets global variables @var maxloglvl and @syslogfacility.
 107 # See file doc comment for details.
 108 dlog_init() {
 109     local __oldumask
 110     local ret=0; local errmsg
 111     [ -z "$stdloglvl" ] && stdloglvl=4
 112     [ -z "$sysloglvl" ] && sysloglvl=0
 113     [ -z "$kmsgloglvl" ] && kmsgloglvl=0
 114     # Skip initialization if it's already done.
 115     [ -n "$maxloglvl" ] && return 0
 116
 117     if [ -z "$fileloglvl" ]; then
 118         [ -w "$logfile" ] && fileloglvl=4 || fileloglvl=0
 119     elif (( $fileloglvl >= 0 )); then
 120         __oldumask=$(umask)
 121         umask 0377
 122         ! [ -e "$logfile" ] && >"$logfile"
 123         umask $__oldumask
 124         if [ -w "$logfile" -a -f "$logfile" ]; then
 125             # Mark new run in the log file
 126             echo >>"$logfile"
 127             if command -v date >/dev/null; then
 128                 echo "=== $(date) ===" >>"$logfile"
 129             else
 130                 echo "===============================================" >>"$logfile"
 131             fi
 132             echo >>"$logfile"
 133         else
 134             # We cannot log to file, so turn this facility off.
 135             fileloglvl=0
 136             ret=1
 137             errmsg="'$logfile' is not a writable file"
 138         fi
 139     fi
 140
 141     if (( $sysloglvl >= 0 )); then
 142         if ! [ -S /dev/log -a -w /dev/log ] || ! command -v logger >/dev/null
 143         then
 144             # We cannot log to syslog, so turn this facility off.
 145             sysloglvl=0
 146             ret=1
 147             errmsg="No '/dev/log' or 'logger' included for syslog logging"
 148         fi
 149     fi
 150
 151     if (($sysloglvl >= 0)) || (($kmsgloglvl >= 0 )); then
 152         if [ -n "$dracutbasedir" ]; then
 153             readonly syslogfacility=user
 154         else
 155             readonly syslogfacility=daemon
 156         fi
 157         export syslogfacility
 158     fi
 159
 160     local lvl; local maxloglvl_l=0
 161     for lvl in $stdloglvl $sysloglvl $fileloglvl $kmsgloglvl; do
 162         (( $lvl > $maxloglvl_l )) && maxloglvl_l=$lvl
 163     done
 164     readonly maxloglvl=$maxloglvl_l
 165     export maxloglvl
 166
 167
 168     if (($stdloglvl < 6)) && (($kmsgloglvl < 6)) && (($fileloglvl < 6)); then
 169         unset dtrace
 170         dtrace() { :; };
 171     fi
 172
 173     if (($stdloglvl < 5)) && (($kmsgloglvl < 5)) && (($fileloglvl < 5)); then
 174         unset ddebug
 175         ddebug() { :; };
 176     fi
 177
 178     if (($stdloglvl < 4)) && (($kmsgloglvl < 4)) && (($fileloglvl < 4)); then
 179         unset dinfo
 180         dinfo() { :; };
 181     fi
 182
 183     if (($stdloglvl < 3)) && (($kmsgloglvl < 3)) && (($fileloglvl < 3)); then
 184         unset dwarn
 185         dwarn() { :; };
 186         unset dwarning
 187         dwarning() { :; };
 188     fi
 189
 190     if (($stdloglvl < 2)) && (($kmsgloglvl < 2)) && (($fileloglvl < 2)); then
 191         unset derror
 192         derror() { :; };
 193     fi
 194
 195     if (($stdloglvl < 1)) && (($kmsgloglvl < 1)) && (($fileloglvl < 1)); then
 196         unset dfatal
 197         dfatal() { :; };
 198     fi
 199
 200     [ -n "$errmsg" ] && derror "$errmsg"
 201
 202     return $ret
 203 }
 204
 205 ## @brief Converts numeric logging level to the first letter of level name.
 206 #
 207 # @param lvl Numeric logging level in range from 1 to 6.
 208 # @retval 1 if @a lvl is out of range.
 209 # @retval 0 if @a lvl is correct.
 210 # @result Echoes first letter of level name.
 211 _lvl2char() {
 212     case "$1" in
 213         1) echo F;;
 214         2) echo E;;
 215         3) echo W;;
 216         4) echo I;;
 217         5) echo D;;
 218         6) echo T;;
 219         *) return 1;;
 220     esac
 221 }
 222
 223 ## @brief Converts numeric level to logger priority defined by POSIX.2.
 224 #
 225 # @param lvl Numeric logging level in range from 1 to 6.
 226 # @retval 1 if @a lvl is out of range.
 227 # @retval 0 if @a lvl is correct.
 228 # @result Echoes logger priority.
 229 _lvl2syspri() {
 230     printf $syslogfacility.
 231     case "$1" in
 232         1) echo crit;;
 233         2) echo error;;
 234         3) echo warning;;
 235         4) echo info;;
 236         5) echo debug;;
 237         6) echo debug;;
 238         *) return 1;;
 239     esac
 240 }
 241
 242 ## @brief Converts dracut-logger numeric level to syslog log level
 243 #
 244 # @param lvl Numeric logging level in range from 1 to 6.
 245 # @retval 1 if @a lvl is out of range.
 246 # @retval 0 if @a lvl is correct.
 247 # @result Echoes kernel console numeric log level
 248 #
 249 # Conversion is done as follows:
 250 #
 251 # <tt>
 252 #   FATAL(1) -> LOG_EMERG (0)
 253 #   none     -> LOG_ALERT (1)
 254 #   none     -> LOG_CRIT (2)
 255 #   ERROR(2) -> LOG_ERR (3)
 256 #   WARN(3)  -> LOG_WARNING (4)
 257 #   none     -> LOG_NOTICE (5)
 258 #   INFO(4)  -> LOG_INFO (6)
 259 #   DEBUG(5) -> LOG_DEBUG (7)
 260 #   TRACE(6) /
 261 # </tt>
 262 #
 263 # @see /usr/include/sys/syslog.h
 264 _dlvl2syslvl() {
 265     local lvl
 266
 267     case "$1" in
 268         1) lvl=0;;
 269         2) lvl=3;;
 270         3) lvl=4;;
 271         4) lvl=6;;
 272         5) lvl=7;;
 273         6) lvl=7;;
 274         *) return 1;;
 275     esac
 276
 277     [ "$syslogfacility" = user ] && echo $((8+$lvl)) || echo $((24+$lvl))
 278 }
 279
 280 ## @brief Prints to stderr and/or writes to file, to syslog and/or /dev/kmsg
 281 # given message with given level (priority).
 282 #
 283 # @param lvl Numeric logging level.
 284 # @param msg Message.
 285 # @retval 0 It's always returned, even if logging failed.
 286 #
 287 # @note This function is not supposed to be called manually. Please use
 288 # dtrace(), ddebug(), or others instead which wrap this one.
 289 #
 290 # This is core logging function which logs given message to standard error, file
 291 # and/or syslog (with POSIX shell command <tt>logger</tt>) and/or to /dev/kmsg.
 292 # The format is following:
 293 #
 294 # <tt>X: some message</tt>
 295 #
 296 # where @c X is the first letter of logging level. See module description for
 297 # details on that.
 298 #
 299 # Message to syslog is sent with tag @c dracut. Priorities are mapped as
 300 # following:
 301 #   - @c FATAL to @c crit
 302 #   - @c ERROR to @c error
 303 #   - @c WARN to @c warning
 304 #   - @c INFO to @c info
 305 #   - @c DEBUG and @c TRACE both to @c debug
 306 _do_dlog() {
 307     local lvl="$1"; shift
 308     local lvlc=$(_lvl2char "$lvl") || return 0
 309     local msg="$lvlc: $*"
 310
 311     (( $lvl <= $stdloglvl )) && echo "$msg" >&2
 312     if (( $lvl <= $sysloglvl )); then
 313         logger -t "dracut[$$]" -p $(_lvl2syspri $lvl) "$msg"
 314     fi
 315     if (( $lvl <= $fileloglvl )) && [[ -w "$logfile" ]] && [[ -f "$logfile" ]]; then
 316         echo "$msg" >>"$logfile"
 317     fi
 318     (( $lvl <= $kmsgloglvl )) && \
 319         echo "<$(_dlvl2syslvl $lvl)>dracut[$$] $msg" >/dev/kmsg
 320 }
 321
 322 ## @brief Internal helper function for _do_dlog()
 323 #
 324 # @param lvl Numeric logging level.
 325 # @param msg Message.
 326 # @retval 0 It's always returned, even if logging failed.
 327 #
 328 # @note This function is not supposed to be called manually. Please use
 329 # dtrace(), ddebug(), or others instead which wrap this one.
 330 #
 331 # This function calls _do_dlog() either with parameter msg, or if
 332 # none is given, it will read standard input and will use every line as
 333 # a message.
 334 #
 335 # This enables:
 336 # dwarn "This is a warning"
 337 # echo "This is a warning" | dwarn
 338 dlog() {
 339     [ -z "$maxloglvl" ] && return 0
 340     (( $1 <= $maxloglvl )) || return 0
 341
 342     if (( $# > 1 )); then
 343         _do_dlog "$@"
 344     else
 345         while read line; do
 346             _do_dlog "$1" "$line"
 347         done
 348     fi
 349 }
 350
 351 ## @brief Logs message at TRACE level (6)
 352 #
 353 # @param msg Message.
 354 # @retval 0 It's always returned, even if logging failed.
 355 dtrace() {
 356     set +x
 357     dlog 6 "$@"
 358     [ -n "$debug" ] && set -x || :
 359 }
 360
 361 ## @brief Logs message at DEBUG level (5)
 362 #
 363 # @param msg Message.
 364 # @retval 0 It's always returned, even if logging failed.
 365 ddebug() {
 366     set +x
 367     dlog 5 "$@"
 368     [ -n "$debug" ] && set -x || :
 369 }
 370
 371 ## @brief Logs message at INFO level (4)
 372 #
 373 # @param msg Message.
 374 # @retval 0 It's always returned, even if logging failed.
 375 dinfo() {
 376     set +x
 377     dlog 4 "$@"
 378     [ -n "$debug" ] && set -x || :
 379 }
 380
 381 ## @brief Logs message at WARN level (3)
 382 #
 383 # @param msg Message.
 384 # @retval 0 It's always returned, even if logging failed.
 385 dwarn() {
 386     set +x
 387     dlog 3 "$@"
 388     [ -n "$debug" ] && set -x || :
 389 }
 390
 391 ## @brief It's an alias to dwarn() function.
 392 #
 393 # @param msg Message.
 394 # @retval 0 It's always returned, even if logging failed.
 395 dwarning() {
 396     set +x
 397     dwarn "$@"
 398     [ -n "$debug" ] && set -x || :
 399 }
 400
 401 ## @brief Logs message at ERROR level (2)
 402 #
 403 # @param msg Message.
 404 # @retval 0 It's always returned, even if logging failed.
 405 derror() {
 406     set +x
 407     dlog 2 "$@"
 408     [ -n "$debug" ] && set -x || :
 409 }
 410
 411 ## @brief Logs message at FATAL level (1)
 412 #
 413 # @param msg Message.
 414 # @retval 0 It's always returned, even if logging failed.
 415 dfatal() {
 416     set +x
 417     dlog 1 "$@"
 418     [ -n "$debug" ] && set -x || :
 419 }