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Diffstat (limited to 'cmd/zed/zed.d/zed-functions.sh')
| -rw-r--r-- | cmd/zed/zed.d/zed-functions.sh | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/cmd/zed/zed.d/zed-functions.sh b/cmd/zed/zed.d/zed-functions.sh new file mode 100644 index 000000000..b42911b2e --- /dev/null +++ b/cmd/zed/zed.d/zed-functions.sh @@ -0,0 +1,230 @@ +# zed-functions.sh +# +# ZED helper functions for use in ZEDLETs + + +# Variable Defaults +# +: "${ZED_EMAIL_INTERVAL_SECS:=3600}" +: "${ZED_EMAIL_VERBOSE:=0}" +: "${ZED_LOCKDIR:="/var/lock"}" +: "${ZED_RUNDIR:="/var/run"}" +: "${ZED_SYSLOG_PRIORITY:="daemon.notice"}" +: "${ZED_SYSLOG_TAG:="zed"}" + +ZED_FLOCK_FD=8 + + +# zed_check_cmd (cmd, ...) +# +# For each argument given, search PATH for the executable command [cmd]. +# Log a message if [cmd] is not found. +# +# Arguments +# cmd: name of executable command for which to search +# +# Return +# 0 if all commands are found in PATH and are executable +# n for a count of the command executables that are not found +# +zed_check_cmd() +{ + local cmd + local rv=0 + + for cmd; do + if ! command -v "${cmd}" >/dev/null 2>&1; then + zed_log_err "\"${cmd}\" not installed" + rv=$((rv + 1)) + fi + done + return "${rv}" +} + + +# zed_log_msg (msg, ...) +# +# Write all argument strings to the system log. +# +# Globals +# ZED_SYSLOG_PRIORITY +# ZED_SYSLOG_TAG +# +# Return +# nothing +# +zed_log_msg() +{ + logger -p "${ZED_SYSLOG_PRIORITY}" -t "${ZED_SYSLOG_TAG}" -- "$@" +} + + +# zed_log_err (msg, ...) +# +# Write an error message to the system log. This message will contain the +# script name, EID, and all argument strings. +# +# Globals +# ZED_SYSLOG_PRIORITY +# ZED_SYSLOG_TAG +# ZEVENT_EID +# +# Return +# nothing +# +zed_log_err() +{ + logger -p "${ZED_SYSLOG_PRIORITY}" -t "${ZED_SYSLOG_TAG}" -- "error:" \ + "$(basename -- "$0"):" "${ZEVENT_EID:+"eid=${ZEVENT_EID}:"}" "$@" +} + + +# zed_lock (lockfile, [fd]) +# +# Obtain an exclusive (write) lock on [lockfile]. If the lock cannot be +# immediately acquired, wait until it becomes available. +# +# Every zed_lock() must be paired with a corresponding zed_unlock(). +# +# By default, flock-style locks associate the lockfile with file descriptor 8. +# The bash manpage warns that file descriptors >9 should be used with care as +# they may conflict with file descriptors used internally by the shell. File +# descriptor 9 is reserved for zed_rate_limit(). If concurrent locks are held +# within the same process, they must use different file descriptors (preferably +# decrementing from 8); otherwise, obtaining a new lock with a given file +# descriptor will release the previous lock associated with that descriptor. +# +# Arguments +# lockfile: pathname of the lock file; the lock will be stored in +# ZED_LOCKDIR unless the pathname contains a "/". +# fd: integer for the file descriptor used by flock (OPTIONAL unless holding +# concurrent locks) +# +# Globals +# ZED_FLOCK_FD +# ZED_LOCKDIR +# +# Return +# nothing +# +zed_lock() +{ + local lockfile="$1" + local fd="${2:-${ZED_FLOCK_FD}}" + local umask_bak + local err + + [ -n "${lockfile}" ] || return + if ! expr "${lockfile}" : '.*/' >/dev/null 2>&1; then + lockfile="${ZED_LOCKDIR}/${lockfile}" + fi + + umask_bak="$(umask)" + umask 077 + + # Obtain a lock on the file bound to the given file descriptor. + # + eval "exec ${fd}> '${lockfile}'" + err="$(flock --exclusive "${fd}" 2>&1)" + if [ $? -ne 0 ]; then + zed_log_err "failed to lock \"${lockfile}\": ${err}" + fi + + umask "${umask_bak}" +} + + +# zed_unlock (lockfile, [fd]) +# +# Release the lock on [lockfile]. +# +# Arguments +# lockfile: pathname of the lock file +# fd: integer for the file descriptor used by flock (must match the file +# descriptor passed to the zed_lock function call) +# +# Globals +# ZED_FLOCK_FD +# ZED_LOCKDIR +# +# Return +# nothing +# +zed_unlock() +{ + local lockfile="$1" + local fd="${2:-${ZED_FLOCK_FD}}" + local err + + [ -n "${lockfile}" ] || return + if ! expr "${lockfile}" : '.*/' >/dev/null 2>&1; then + lockfile="${ZED_LOCKDIR}/${lockfile}" + fi + + # Release the lock and close the file descriptor. + # + err="$(flock --unlock "${fd}" 2>&1)" + if [ $? -ne 0 ]; then + zed_log_err "failed to unlock \"${lockfile}\": ${err}" + fi + eval "exec ${fd}>&-" +} + + +# zed_rate_limit (tag, [interval]) +# +# Check whether an event of a given type [tag] has already occurred within the +# last [interval] seconds. +# +# This function obtains a lock on the statefile using file descriptor 9. +# +# Arguments +# tag: arbitrary string for grouping related events to rate-limit +# interval: time interval in seconds (OPTIONAL) +# +# Globals +# ZED_EMAIL_INTERVAL_SECS +# ZED_RUNDIR +# +# Return +# 0 if the event should be processed +# 1 if the event should be dropped +# +# State File Format +# time;tag +# +zed_rate_limit() +{ + local tag="$1" + local interval="${2:-${ZED_EMAIL_INTERVAL_SECS}}" + local lockfile="zed.zedlet.state.lock" + local lockfile_fd=9 + local statefile="${ZED_RUNDIR}/zed.zedlet.state" + local time_now + local time_prev + local umask_bak + local rv=0 + + [ -n "${tag}" ] || return 0 + + zed_lock "${lockfile}" "${lockfile_fd}" + time_now="$(date +%s)" + time_prev="$(egrep "^[0-9]+;${tag}\$" "${statefile}" 2>/dev/null \ + | tail -1 | cut -d\; -f1)" + + if [ -n "${time_prev}" ] \ + && [ "$((time_now - time_prev))" -lt "${interval}" ]; then + rv=1 + else + umask_bak="$(umask)" + umask 077 + egrep -v "^[0-9]+;${tag}\$" "${statefile}" 2>/dev/null \ + > "${statefile}.$$" + echo "${time_now};${tag}" >> "${statefile}.$$" + mv -f "${statefile}.$$" "${statefile}" + umask "${umask_bak}" + fi + + zed_unlock "${lockfile}" "${lockfile_fd}" + return "${rv}" +} |