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1
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#!/bin/sh
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2
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# Wraps lockfile/dotlockfile
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3
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# Usage: env [interval=...] self lockfile
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4
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5
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selfDir="$(dirname -- "$0")"
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6
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7
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: "${interval=5}" # s
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8
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9
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if test -n "$inner"; then
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10
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"$selfDir/dotlockfile" -l -r 65535 -p "$lockfile" || exit
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11
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echo "$pid" >"$lockfile" # use the outer process's PPID
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exit
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13
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fi
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14
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15
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statFmtFlag="$(test "$(uname)" = Darwin && echo f || echo c)"
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16
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17
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if test "$(uname)" = Darwin; then
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18
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file_group () { stat -f %Sg "$@"; }
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19
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else
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20
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file_group () { stat -c %G "$@"; }
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21
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fi
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22
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23
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export lockfile="$1"
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24
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if test "$(uname)" = Darwin; then
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25
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while ! shlock -p "$PPID" -f "$1"; do sleep "$interval"; done
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26
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else
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27
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# Need to change primary group of the dotlockfile process to the group of
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28
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# the dir to contain the lockfile, because dotlockfile otherwise reports a
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29
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# "permission denied" error (even though the directory is actually writable,
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30
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# dotlockfile thinks it isn't).
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31
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# newgrp, the command that does this, does not pass arguments to the new
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32
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# process, so they must instead be passed via environment variables and a
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33
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# recursive invocation of lockfile (with the $inner recursion flag set).
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34
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# Additionally, exec cannot be used to propagate the PPID (needed by
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35
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# dotlockfile) because newgrp creates a new process rather than using exec,
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36
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# so it must be manually entered into the lockfile after dotlockfile runs.
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37
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export SHELL="$0" inner=1 pid="$PPID"
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38
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newgrp "$(file_group "$(dirname -- "$lockfile")")"
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39
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fi
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