e53af95c93
Allow limit.sh to log its errors to an MW debug log channel, by opening a separate FD for private communication. Ensure that the log FD is always closed (3>&-) before executing a subprocess, so that MW will not hang waiting for background processes to close the log FD. This means using a fixed FD number, since the bash syntax for closing a file requires a literal FD number. The "exec" debug channel is now intended for production monitoring. In addition to errors from limit.sh, it also records when a subprocess is terminated by a signal. The case where stream_select() returns false was tested by patching PHP to inject EINTR or EBADF into errno. When wfShellExec() is used with a memory cgroup, and the cgroup is missing, log and continue with no cgroup instead of immediately exiting. Bug: 55709 Change-Id: Ie40befe9c0d00c9a0ddb01077df4afb774d17e15
119 lines
2.7 KiB
Bash
119 lines
2.7 KiB
Bash
#!/bin/bash
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#
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# Resource limiting wrapper for command execution
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#
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# Why is this in shell script? Because bash has a setrlimit() wrapper
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# and is available on most Linux systems. If Perl was distributed with
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# BSD::Resource included, we would happily use that instead, but it isn't.
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# Clean up cgroup
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cleanup() {
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# First we have to move the current task into a "garbage" group, otherwise
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# the cgroup will not be empty, and attempting to remove it will fail with
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# "Device or resource busy"
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if [ -w "$MW_CGROUP"/tasks ]; then
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GARBAGE="$MW_CGROUP"
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else
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GARBAGE="$MW_CGROUP"/garbage-`id -un`
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if [ ! -e "$GARBAGE" ]; then
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mkdir -m 0700 "$GARBAGE"
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fi
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fi
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echo $BASHPID > "$GARBAGE"/tasks
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# Suppress errors in case the cgroup has disappeared due to a release script
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rmdir "$MW_CGROUP"/$$ 2>/dev/null
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}
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updateTaskCount() {
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# There are lots of ways to count lines in a file in shell script, but this
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# is one of the few that doesn't create another process, which would
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# increase the returned number of tasks.
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readarray < "$MW_CGROUP"/$$/tasks
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NUM_TASKS=${#MAPFILE[*]}
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}
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log() {
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echo limit.sh: "$*" >&3
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echo limit.sh: "$*" >&2
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}
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MW_INCLUDE_STDERR=
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MW_USE_LOG_PIPE=
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MW_CPU_LIMIT=0
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MW_CGROUP=
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MW_MEM_LIMIT=0
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MW_FILE_SIZE_LIMIT=0
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MW_WALL_CLOCK_LIMIT=0
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# Override settings
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eval "$2"
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if [ -n "$MW_INCLUDE_STDERR" ]; then
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exec 2>&1
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fi
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if [ -z "$MW_USE_LOG_PIPE" ]; then
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# Open a dummy log FD
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exec 3>/dev/null
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fi
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if [ "$MW_CPU_LIMIT" -gt 0 ]; then
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ulimit -t "$MW_CPU_LIMIT"
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fi
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if [ "$MW_MEM_LIMIT" -gt 0 ]; then
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if [ -n "$MW_CGROUP" ]; then
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# Create cgroup
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if ! mkdir -m 0700 "$MW_CGROUP"/$$; then
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log "failed to create the cgroup."
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MW_CGROUP=""
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fi
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fi
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if [ -n "$MW_CGROUP" ]; then
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echo $$ > "$MW_CGROUP"/$$/tasks
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if [ -n "$MW_CGROUP_NOTIFY" ]; then
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echo "1" > "$MW_CGROUP"/$$/notify_on_release
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fi
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# Memory
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echo $(($MW_MEM_LIMIT*1024)) > "$MW_CGROUP"/$$/memory.limit_in_bytes
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# Memory+swap
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echo $(($MW_MEM_LIMIT*1024)) > "$MW_CGROUP"/$$/memory.memsw.limit_in_bytes
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else
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ulimit -v "$MW_MEM_LIMIT"
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fi
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else
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MW_CGROUP=""
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fi
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if [ "$MW_FILE_SIZE_LIMIT" -gt 0 ]; then
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ulimit -f "$MW_FILE_SIZE_LIMIT"
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fi
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if [ "$MW_WALL_CLOCK_LIMIT" -gt 0 -a -x "/usr/bin/timeout" ]; then
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/usr/bin/timeout $MW_WALL_CLOCK_LIMIT /bin/bash -c "$1" 3>&-
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STATUS="$?"
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if [ "$STATUS" == 124 ]; then
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log "timed out executing command \"$1\""
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fi
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else
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eval "$1" 3>&-
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STATUS="$?"
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fi
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if [ -n "$MW_CGROUP" ]; then
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updateTaskCount
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if [ $NUM_TASKS -gt 1 ]; then
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# Spawn a monitor process which will continue to poll for completion
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# of all processes in the cgroup after termination of the parent shell
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(
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while [ $NUM_TASKS -gt 1 ]; do
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sleep 10
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updateTaskCount
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done
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cleanup
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) >&/dev/null < /dev/null 3>&- &
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disown -a
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else
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cleanup
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fi
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fi
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exit "$STATUS"
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