tests/tools/condwait

#!/bin/bash

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#  or more contributor license agreements.  See the NOTICE file
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#  to you under the Apache License, Version 2.0 (the
#  "License"); you may not use this file except in compliance
#  with the License.  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

# A bash script to wait for a condition to be true.
#
# usage:
#  condwait [ MAX-WAIT [ POST-WAIT ] ] CONDITION
#
# CONDITION is the ('test' command) condition to wait for.  (It may contain white space.)
# For file existence tests (-f, -e, -d), glob patterns are supported (e.g., -f /path/crash-*.log).
# Use "--contains FILE PATTERN COUNT" to wait until FILE contains PATTERN in at least COUNT lines.
#
# MAX-WAIT is the maximum number of seconds to wait for the condition.  If it is omitted, it defaults to 60.
#
# POST-WAIT is the number of seconds to wait after the condition is true.  If it is omitted, it defaults to 0.
#
# The script exits with status 0 when the condition is seen to be true.  It exits with status 1 if the condition
# is not seen to be true and the maximum wait has expired.

WAIT=60
POST_WAIT=0

usage() {
    echo "usage: condwait [ MAX-WAIT [ POST-WAIT ] ] TEST-CONDITION" >&2
    echo "       condwait [ MAX-WAIT [ POST-WAIT ] ] --contains FILE PATTERN COUNT" >&2
}

if [[ "$1" = "" ]] ; then
    usage
    exit 1
fi

X=$( echo "$1" | sed 's/x/yy/g' | sed 's/[^0-9]/x/g' )
if [[ "$X" = "$1" ]] ; then
    WAIT=$1
    shift
    if [[ "$1" = "" ]] ; then
        usage
        exit 1
    fi
    X=$( echo "$1" | sed 's/x/yy/g' | sed 's/[^0-9]/x/g' )
    if [[ "$X" = "$1" ]] ; then
        POST_WAIT=$1
        shift
    fi
fi

if [[ "$1" = "" ]] ; then
    usage
    exit 1
fi

if [[ "$1" = "--contains" ]]; then
    if [[ $# -ne 4 ]] || ! [[ "$4" =~ ^[0-9]+$ ]]; then
        usage
        exit 1
    fi
fi

# Check simple file existence tests (-f, -e, -d) specially so literal paths with
# whitespace work while glob patterns remain supported.
check_condition() {
    if [[ "$1" = "--contains" ]]; then
        [[ -f "$2" ]] || return 1
        local matches
        matches=$(awk -v pattern="$3" -v expected="$4" '
            BEGIN {
                if (expected == 0) {
                    print 0
                    found = 1
                    exit
                }
            }
            index($0, pattern) {
                count++
                if (count >= expected) {
                    print count
                    found = 1
                    exit
                }
            }
            END {
                if (!found) {
                    print count + 0
                }
            }
        ' "$2")
        (( matches >= $4 ))
    elif [[ "$1" = "-f" || "$1" = "-e" || "$1" = "-d" ]] && [[ $# -eq 2 ]]; then
        if [[ "$2" = *[\*\?\[]* ]]; then
            # Use compgen for file existence tests to support glob patterns.
            local match
            while IFS= read -r match; do
                test "$1" "$match" && return 0
            done < <(compgen -G "$2")
            return 1
        fi
        test "$1" "$2"
    else
        test "$@"
    fi
}

while (( WAIT > 0 ))
do
    if check_condition "$@"
    then
        if (( POST_WAIT > 0 ))
        then
            sleep $POST_WAIT
        fi
        exit 0
    fi
    sleep 1
    let WAIT=WAIT-1
done
exit 1