send-at-retry: add script

src/send-at-retry/README.md

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+Send AT commands multiple times until an expected string is in the reply.
+
+This hack is a PoC for sending AT commands through the same pseudo TTY that
+mtkfusionrild is using.
+
+Preparation:
+- Ubuntu touch with ssh enabled and writable rootfs

src/send-at-retry/data/lxc_attach.sh

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+#!/bin/sh -ex
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+# Related: https://github.com/ubports/ubuntu-touch/issues/1836
+
+LD_PRELOAD= LD_LIBRARY_PATH= lxc-attach -n android -e -- "$@"

src/send-at-retry/data/send_at_retry_android.sh

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+#!/bin/sh -e
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+
+DEV="/dev/radio/ptty2cmd2"
+RET="/data/local/tmp/ims_apn"
+
+# $1: AT command to send
+# $2: retry until finding this string in reply
+send() {
+	echo "---"
+	echo "> $1"
+
+	rm -rf "$RET"
+	cat "$DEV" > "$RET" &
+	pid="$!"
+
+	for i in $(seq 1 5); do
+		printf .
+		echo "$1" > "$DEV"
+		sleep 0.1
+
+		if grep -q "$2" "$RET"; then
+			cat "$RET"
+			kill "$pid"
+			return
+		fi
+	done
+
+	kill "$pid"
+	echo
+	echo "ERROR: could not find '$2' in response:"
+	cat "$RET"
+	exit 1
+}
+
+# Query firmware information
+send 'AT+CGMI' '+CGMI:'
+send 'AT+CGMM' '+CGMM:'
+send 'AT+CGMR' '+CGMR:'
+
+# Add your at commands below
+
+echo
+echo "---"
+echo "done"

src/send-at-retry/data/send_at_retry_ut.sh

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+#!/bin/sh -ex
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+set -x
+dump_name="$1"
+
+chmod +x /mnt/tmp/android_run.sh
+chmod +x /tmp/lxc_attach.sh
+
+sudo /tmp/lxc_attach.sh /mnt/tmp/android_run.sh "$1" 2>&1 \
+	| tee /tmp/"$dump_name"

src/send-at-retry/send_at_retry.sh

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+#!/bin/sh -ex
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Author: Oliver Smith
+# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+dump_name="$(date "+%Y-%m-%d_%H%M%S")"
+
+adb push data/send_at_retry_ut.sh /tmp/run.sh
+adb push data/lxc_attach.sh /tmp/lxc_attach.sh
+adb push data/send_at_retry_android.sh /mnt/tmp/android_run.sh
+
+adb forward tcp:8023 tcp:22
+ssh -t -p 8023 phablet@localhost \
+	sh -e /tmp/run.sh "$dump_name"
+
+mkdir -p dump/"${dump_name}_at"
+adb pull /tmp/"$dump_name" "dump/${dump_name}_at/${dump_name}.txt"
+
+ln -sf "$PWD/dump/${dump_name}_at/${dump_name}.txt" /tmp/latest.txt