dracut-logger

   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 one global internal variable @var _maxloglvl which <b>must not</b> be
  80 # overwritten. @_maxloglvl is set by dlog_init() and holds maximum logging level
  81 # of those three and indicates that dlog_init() was run.
  82 #
  83 # Logging level set by the variable means that messages from this logging level
  84 # and above (FATAL is the highest) will be shown. Logging levels may be set
  85 # independently for each destination (stderr, syslog, file, kmsg).
  86 #
  87 # @see dlog_init()
  88
  89
  90 ## @brief Initializes Dracut Logger.
  91 #
  92 # @retval 1 if something has gone wrong
  93 # @retval 0 on success.
  94 #
  95 # @note This function need to be called before any other from this file.
  96 #
  97 # If any of the variables is not set, this function set it to default:
  98 #   - @var stdloglvl = 4 (info)
  99 #   - @var sysloglvl = 0 (no logging)
 100 #   - @var fileloglvl is set to 4 when @var logfile is set too, otherwise it's
 101 #   - @var kmsgloglvl = 0 (no logging)
 102 #   set to 0
 103 #
 104 # @warning Function sets global variable @var _maxloglvl for internal use. Don't
 105 # overwrite it.
 106 dlog_init() {
 107     # Skip initialization if it's already done.
 108     [ -n "$_maxloglvl" ] && return 0
 109
 110     local ret=0; local errmsg
 111
 112     [ -z "$stdloglvl" ] && stdloglvl=4
 113     [ -z "$sysloglvl" ] && sysloglvl=0
 114     [ -z "$kmsgloglvl" ] && kmsgloglvl=0
 115
 116     if [ -z "$fileloglvl" ]; then
 117         [ -w "$logfile" ] && fileloglvl=4 || fileloglvl=0
 118     elif [ $fileloglvl -gt 0 ]; then
 119         ! [ -e "$logfile" ] && >"$logfile"
 120         if [ -w "$logfile" -a -f "$logfile" ]; then
 121             # Mark new run in the log file
 122             echo >>"$logfile"
 123             if command -v date >/dev/null; then
 124                 echo "=== $(date) ===" >>"$logfile"
 125             else
 126                 echo "===============================================" >>"$logfile"
 127             fi
 128             echo >>"$logfile"
 129         else
 130             # We cannot log to file, so turn this facility off.
 131             fileloglvl=0
 132             ret=1
 133             errmsg="'$logfile' is not a writable file"
 134         fi
 135     fi
 136
 137     if [ $sysloglvl -gt 0 ]; then
 138         if ! [ -c /dev/log -a -w /dev/log ] || ! command -v logger >/dev/null
 139         then
 140             # We cannot log to syslog, so turn this facility off.
 141             sysloglvl=0
 142             ret=1
 143             errmsg="No '/dev/log' or 'logger' not included for syslog logging"
 144         fi
 145     fi
 146
 147     local lvl
 148     _maxloglvl=0
 149     for lvl in $stdloglvl $sysloglvl $fileloglvl; do
 150         [ $lvl -gt $_maxloglvl ] && _maxloglvl=$lvl
 151     done
 152     export _maxloglvl
 153
 154     [ -n "$errmsg" ] && derror "$errmsg"
 155
 156     return $ret
 157 }
 158
 159 ## @brief Converts numeric logging level to the first letter of level name.
 160 #
 161 # @param lvl Numeric logging level in range from 1 to 6.
 162 # @retval 1 if @a lvl is out of range.
 163 # @retval 0 if @a lvl is correct.
 164 # @result Echoes first letter of level name.
 165 _lvl2char() {
 166     case "$1" in
 167         1) echo F;;
 168         2) echo E;;
 169         3) echo W;;
 170         4) echo I;;
 171         5) echo D;;
 172         6) echo T;;
 173         *) return 1;;
 174     esac
 175 }
 176
 177 ## @brief Converts numeric level to logger priority defined by POSIX.2.
 178 #
 179 # @param lvl Numeric logging level in range from 1 to 6.
 180 # @retval 1 if @a lvl is out of range.
 181 # @retval 0 if @a lvl is correct.
 182 # @result Echoes logger priority.
 183 _lvl2syslogpri() {
 184     case "$1" in
 185         1) echo crit;;
 186         2) echo error;;
 187         3) echo warning;;
 188         4) echo info;;
 189         5) echo debug;;
 190         6) echo debug;;
 191         *) return 1;;
 192     esac
 193 }
 194
 195 ## @brief Converts dracut-logger numeric level to kernel console log level
 196 #
 197 # @param lvl Numeric logging level in range from 1 to 6.
 198 # @retval 1 if @a lvl is out of range.
 199 # @retval 0 if @a lvl is correct.
 200 # @result Echoes kernel console numeric log level
 201 #
 202 # Conversion is done as follows:
 203 #
 204 # <tt>
 205 #   none     -> KERN_EMERG (0)
 206 #   FATAL(1) -> KERN_ALERT (1)
 207 #   none     -> KERN_CRIT (2)
 208 #   ERROR(2) -> KERN_ERR (3)
 209 #   WARN(3)  -> KERN_WARNING (4)
 210 #   none     -> KERN_NOTICE (5)
 211 #   INFO(4)  -> KERN_INFO (6)
 212 #   DEBUG(5) -> KERN_DEBUG (7)
 213 #   TRACE(6) /
 214 # </tt>
 215 _dlvl2klvl() {
 216     case "$1" in
 217         1) echo 1;;
 218         2) echo 3;;
 219         3) echo 4;;
 220         4) echo 6;;
 221         5) echo 7;;
 222         6) echo 7;;
 223         *) return 1;;
 224     esac
 225 }
 226
 227 ## @brief Prints to stderr and/or writes to file, to syslog and/or /dev/kmsg
 228 # given message with given level (priority).
 229 #
 230 # @param lvl Numeric logging level.
 231 # @param msg Message.
 232 # @retval 0 It's always returned, even if logging failed.
 233 #
 234 # @note This function is not supposed to be called manually. Please use
 235 # dtrace(), ddebug(), or others instead which wrap this one.
 236 #
 237 # This is core logging function which logs given message to standard error, file
 238 # and/or syslog (with POSIX shell command <tt>logger</tt>) and/or to /dev/kmsg.
 239 # The format is following:
 240 #
 241 # <tt>X: some message</tt>
 242 #
 243 # where @c X is the first letter of logging level. See module description for
 244 # details on that.
 245 #
 246 # Message to syslog is sent with tag @c dracut. Priorities are mapped as
 247 # following:
 248 #   - @c FATAL to @c crit
 249 #   - @c ERROR to @c error
 250 #   - @c WARN to @c warning
 251 #   - @c INFO to @c info
 252 #   - @c DEBUG and @c TRACE both to @c debug
 253 _do_dlog() {
 254     [ -z "$_maxloglvl" ] && return 0
 255     local lvl="$1"; shift
 256     local lvlc=$(_lvl2char "$lvl") || return 0
 257
 258     [ $lvl -le $_maxloglvl ] || return 0
 259
 260     local msg="$lvlc: $*"
 261
 262     [ $lvl -le $stdloglvl ] && echo "$msg" >&2
 263     if [ $lvl -le $sysloglvl ]; then
 264         logger -t "dracut[$$]" -p $(_lvl2syslogpri $lvl) "$msg"
 265     fi
 266     if [ $lvl -le $fileloglvl -a -w "$logfile" -a -f "$logfile" ]; then
 267         echo "$msg" >>"$logfile"
 268     fi
 269     [ $lvl -le $kmsgloglvl ] && \
 270         echo "<$(_dlvl2klvl $lvl)>dracut[$$] $msg" >/dev/kmsg
 271 }
 272
 273 ## @brief Internal helper function for _do_dlog()
 274 #
 275 # @param lvl Numeric logging level.
 276 # @param msg Message.
 277 # @retval 0 It's always returned, even if logging failed.
 278 #
 279 # @note This function is not supposed to be called manually. Please use
 280 # dtrace(), ddebug(), or others instead which wrap this one.
 281 #
 282 # This function calls _do_dlog() either with parameter msg, or if
 283 # none is given, it will read standard input and will use every line as
 284 # a message.
 285 #
 286 # This enables:
 287 # dwarn "This is a warning"
 288 # echo "This is a warning" | dwarn
 289 dlog() {
 290     if [ $# -gt 1 ]; then
 291         _do_dlog "$@"
 292     else
 293         while read line; do
 294             _do_dlog "$1" "$line"
 295         done
 296     fi
 297     return 0
 298 }
 299
 300 ## @brief Logs message at TRACE level (6)
 301 #
 302 # @param msg Message.
 303 # @retval 0 It's always returned, even if logging failed.
 304 dtrace() {
 305     dlog 6 "$@"
 306 }
 307
 308 ## @brief Logs message at DEBUG level (5)
 309 #
 310 # @param msg Message.
 311 # @retval 0 It's always returned, even if logging failed.
 312 ddebug() {
 313     dlog 5 "$@"
 314 }
 315
 316 ## @brief Logs message at INFO level (4)
 317 #
 318 # @param msg Message.
 319 # @retval 0 It's always returned, even if logging failed.
 320 dinfo() {
 321     dlog 4 "$@"
 322 }
 323
 324 ## @brief Logs message at WARN level (3)
 325 #
 326 # @param msg Message.
 327 # @retval 0 It's always returned, even if logging failed.
 328 dwarn() {
 329     dlog 3 "$@"
 330 }
 331
 332 ## @brief It's an alias to dwarn() function.
 333 #
 334 # @param msg Message.
 335 # @retval 0 It's always returned, even if logging failed.
 336 dwarning() {
 337     dwarn "$@"
 338 }
 339
 340 ## @brief Logs message at ERROR level (2)
 341 #
 342 # @param msg Message.
 343 # @retval 0 It's always returned, even if logging failed.
 344 derror() {
 345     dlog 2 "$@"
 346 }
 347
 348 ## @brief Logs message at FATAL level (1)
 349 #
 350 # @param msg Message.
 351 # @retval 0 It's always returned, even if logging failed.
 352 dfatal() {
 353     dlog 1 "$@"
 354 }