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 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     # Skip initialization if it's already done.
 110     [ -n "$maxloglvl" ] && return 0
 111
 112     local ret=0; local errmsg
 113
 114     [ -z "$stdloglvl" ] && stdloglvl=4
 115     [ -z "$sysloglvl" ] && sysloglvl=0
 116     [ -z "$kmsgloglvl" ] && kmsgloglvl=0
 117
 118     if [ -z "$fileloglvl" ]; then
 119         [ -w "$logfile" ] && fileloglvl=4 || fileloglvl=0
 120     elif [ $fileloglvl -gt 0 ]; then
 121         ! [ -e "$logfile" ] && >"$logfile"
 122         if [ -w "$logfile" -a -f "$logfile" ]; then
 123             # Mark new run in the log file
 124             echo >>"$logfile"
 125             if command -v date >/dev/null; then
 126                 echo "=== $(date) ===" >>"$logfile"
 127             else
 128                 echo "===============================================" >>"$logfile"
 129             fi
 130             echo >>"$logfile"
 131         else
 132             # We cannot log to file, so turn this facility off.
 133             fileloglvl=0
 134             ret=1
 135             errmsg="'$logfile' is not a writable file"
 136         fi
 137     fi
 138
 139     if [ $sysloglvl -gt 0 ]; then
 140         if ! [ -S /dev/log -a -w /dev/log ] || ! command -v logger >/dev/null
 141         then
 142             # We cannot log to syslog, so turn this facility off.
 143             sysloglvl=0
 144             ret=1
 145             errmsg="No '/dev/log' or 'logger' included for syslog logging"
 146         fi
 147     fi
 148
 149     if [ $sysloglvl -gt 0 -o $kmsgloglvl -gt 0 ]; then
 150         if [ -n "$dracutbasedir" ]; then
 151             readonly syslogfacility=user
 152         else
 153             readonly syslogfacility=daemon
 154         fi
 155         export syslogfacility
 156     fi
 157
 158     local lvl; local maxloglvl_l=0
 159     for lvl in $stdloglvl $sysloglvl $fileloglvl $kmsgloglvl; do
 160         [ $lvl -gt $maxloglvl_l ] && maxloglvl_l=$lvl
 161     done
 162     readonly maxloglvl=$maxloglvl_l
 163     export maxloglvl
 164
 165     [ -n "$errmsg" ] && derror "$errmsg"
 166
 167     return $ret
 168 }
 169
 170 ## @brief Converts numeric logging level to the first letter of level name.
 171 #
 172 # @param lvl Numeric logging level in range from 1 to 6.
 173 # @retval 1 if @a lvl is out of range.
 174 # @retval 0 if @a lvl is correct.
 175 # @result Echoes first letter of level name.
 176 _lvl2char() {
 177     case "$1" in
 178         1) echo F;;
 179         2) echo E;;
 180         3) echo W;;
 181         4) echo I;;
 182         5) echo D;;
 183         6) echo T;;
 184         *) return 1;;
 185     esac
 186 }
 187
 188 ## @brief Converts numeric level to logger priority defined by POSIX.2.
 189 #
 190 # @param lvl Numeric logging level in range from 1 to 6.
 191 # @retval 1 if @a lvl is out of range.
 192 # @retval 0 if @a lvl is correct.
 193 # @result Echoes logger priority.
 194 _lvl2syspri() {
 195     printf $syslogfacility.
 196     case "$1" in
 197         1) echo crit;;
 198         2) echo error;;
 199         3) echo warning;;
 200         4) echo info;;
 201         5) echo debug;;
 202         6) echo debug;;
 203         *) return 1;;
 204     esac
 205 }
 206
 207 ## @brief Converts dracut-logger numeric level to syslog log level
 208 #
 209 # @param lvl Numeric logging level in range from 1 to 6.
 210 # @retval 1 if @a lvl is out of range.
 211 # @retval 0 if @a lvl is correct.
 212 # @result Echoes kernel console numeric log level
 213 #
 214 # Conversion is done as follows:
 215 #
 216 # <tt>
 217 #   FATAL(1) -> LOG_EMERG (0)
 218 #   none     -> LOG_ALERT (1)
 219 #   none     -> LOG_CRIT (2)
 220 #   ERROR(2) -> LOG_ERR (3)
 221 #   WARN(3)  -> LOG_WARNING (4)
 222 #   none     -> LOG_NOTICE (5)
 223 #   INFO(4)  -> LOG_INFO (6)
 224 #   DEBUG(5) -> LOG_DEBUG (7)
 225 #   TRACE(6) /
 226 # </tt>
 227 #
 228 # @see /usr/include/sys/syslog.h
 229 _dlvl2syslvl() {
 230     local lvl
 231
 232     case "$1" in
 233         1) lvl=0;;
 234         2) lvl=3;;
 235         3) lvl=4;;
 236         4) lvl=6;;
 237         5) lvl=7;;
 238         6) lvl=7;;
 239         *) return 1;;
 240     esac
 241
 242     [ "$syslogfacility" = user ] && echo $((8+$lvl)) || echo $((24+$lvl))
 243 }
 244
 245 ## @brief Prints to stderr and/or writes to file, to syslog and/or /dev/kmsg
 246 # given message with given level (priority).
 247 #
 248 # @param lvl Numeric logging level.
 249 # @param msg Message.
 250 # @retval 0 It's always returned, even if logging failed.
 251 #
 252 # @note This function is not supposed to be called manually. Please use
 253 # dtrace(), ddebug(), or others instead which wrap this one.
 254 #
 255 # This is core logging function which logs given message to standard error, file
 256 # and/or syslog (with POSIX shell command <tt>logger</tt>) and/or to /dev/kmsg.
 257 # The format is following:
 258 #
 259 # <tt>X: some message</tt>
 260 #
 261 # where @c X is the first letter of logging level. See module description for
 262 # details on that.
 263 #
 264 # Message to syslog is sent with tag @c dracut. Priorities are mapped as
 265 # following:
 266 #   - @c FATAL to @c crit
 267 #   - @c ERROR to @c error
 268 #   - @c WARN to @c warning
 269 #   - @c INFO to @c info
 270 #   - @c DEBUG and @c TRACE both to @c debug
 271 _do_dlog() {
 272     [ -z "$maxloglvl" ] && return 0
 273     local lvl="$1"; shift
 274     local lvlc=$(_lvl2char "$lvl") || return 0
 275
 276     [ $lvl -le $maxloglvl ] || return 0
 277
 278     local msg="$lvlc: $*"
 279
 280     [ $lvl -le $stdloglvl ] && echo "$msg" >&2
 281     if [ $lvl -le $sysloglvl ]; then
 282         logger -t "dracut[$$]" -p $(_lvl2syspri $lvl) "$msg"
 283     fi
 284     if [ $lvl -le $fileloglvl -a -w "$logfile" -a -f "$logfile" ]; then
 285         echo "$msg" >>"$logfile"
 286     fi
 287     [ $lvl -le $kmsgloglvl ] && \
 288         echo "<$(_dlvl2syslvl $lvl)>dracut[$$] $msg" >/dev/kmsg
 289 }
 290
 291 ## @brief Internal helper function for _do_dlog()
 292 #
 293 # @param lvl Numeric logging level.
 294 # @param msg Message.
 295 # @retval 0 It's always returned, even if logging failed.
 296 #
 297 # @note This function is not supposed to be called manually. Please use
 298 # dtrace(), ddebug(), or others instead which wrap this one.
 299 #
 300 # This function calls _do_dlog() either with parameter msg, or if
 301 # none is given, it will read standard input and will use every line as
 302 # a message.
 303 #
 304 # This enables:
 305 # dwarn "This is a warning"
 306 # echo "This is a warning" | dwarn
 307 dlog() {
 308     if [ $# -gt 1 ]; then
 309         _do_dlog "$@"
 310     else
 311         while read line; do
 312             _do_dlog "$1" "$line"
 313         done
 314     fi
 315     [ -n "$debug" ] && set -x || :
 316 }
 317
 318 ## @brief Logs message at TRACE level (6)
 319 #
 320 # @param msg Message.
 321 # @retval 0 It's always returned, even if logging failed.
 322 dtrace() {
 323     set +x
 324     dlog 6 "$@"
 325 }
 326
 327 ## @brief Logs message at DEBUG level (5)
 328 #
 329 # @param msg Message.
 330 # @retval 0 It's always returned, even if logging failed.
 331 ddebug() {
 332     set +x
 333     dlog 5 "$@"
 334 }
 335
 336 ## @brief Logs message at INFO level (4)
 337 #
 338 # @param msg Message.
 339 # @retval 0 It's always returned, even if logging failed.
 340 dinfo() {
 341     set +x
 342     dlog 4 "$@"
 343 }
 344
 345 ## @brief Logs message at WARN level (3)
 346 #
 347 # @param msg Message.
 348 # @retval 0 It's always returned, even if logging failed.
 349 dwarn() {
 350     set +x
 351     dlog 3 "$@"
 352 }
 353
 354 ## @brief It's an alias to dwarn() function.
 355 #
 356 # @param msg Message.
 357 # @retval 0 It's always returned, even if logging failed.
 358 dwarning() {
 359     set +x
 360     dwarn "$@"
 361 }
 362
 363 ## @brief Logs message at ERROR level (2)
 364 #
 365 # @param msg Message.
 366 # @retval 0 It's always returned, even if logging failed.
 367 derror() {
 368     set +x
 369     dlog 2 "$@"
 370 }
 371
 372 ## @brief Logs message at FATAL level (1)
 373 #
 374 # @param msg Message.
 375 # @retval 0 It's always returned, even if logging failed.
 376 dfatal() {
 377     set +x
 378     dlog 1 "$@"
 379 }