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9ec36e9040
Support sending any signal to background commands, instead of only
supporting properly SIGKILL/SIGTERM/SIGQUIT.
The main issue is figuring out what PID to send the signal to, as the
devlib API allows running a whole snippet of shell script that typically
is wrapped under many layers of sh -c and sudo calls. In order to lift
the ambiguity, the user has access to a "devlib-signal-target" command
that points devlib at what process should be the target of signals:
# Run a "setup" command, then the main command that will receive the
# signals
cmd = 'echo setup; devlib-signal-target echo hello world'
with target.background(cmd) as bg:
bg.communicate()
The devlib-signal-target script can only be used once per background
command, so that it is never ambiguous what process is targeted, and so
that the Python code can cache the target PID. Subsequent invocations
of devlib-signal-target will fail.
21 lines
783 B
Plaintext
21 lines
783 B
Plaintext
(
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# If there is no data dir, it means we are not running as a background
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# command so we just do nothing
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if [ -e "$_DEVLIB_BG_CMD_DATA_DIR" ]; then
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pid_file="$_DEVLIB_BG_CMD_DATA_DIR/pid"
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# Atomically check if the PID file already exist and make the write
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# fail if it already does. This way we don't have any race condition
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# with the Python API, as there is either no PID or the same PID for
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# the duration of the command
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set -o noclobber
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if ! printf "%u\n" $$ > "$pid_file"; then
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echo "$0 was already called for this command" >&2
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exit 1
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fi
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fi
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) || exit $?
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# Use exec so that the PID of the command we run is the same as the current $$
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# PID that we just registered
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exec "$@"
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