#!/system/bin/sh
# USB 读卡器守护脚本 v5 - 仅针对 GL3224 读卡器 (VID:PID 05e3:0747)
# 功能: ①应用稳定性调优 ②掉线自动恢复(3场景)
# 安全: 仅当 USB 端口 2-1 上的设备 VID/PID 匹配时才干预, 其他设备完全不受影响
DEV_PATH="2-1"
TARGET_VID="05e3"
TARGET_PID="0747"
LOGFILE="/data/local/tmp/usb_guard.log"
AUTHORIZED="/sys/bus/usb/devices/${DEV_PATH}/authorized"
BLKDEV=""
LAST_HEALTH=0
TUNED=0

log() { echo "[$(date '+%F %T')] $1" >> "$LOGFILE"; }

# 校验当前 2-1 口上的设备是否为目标读卡器
is_target() {
    [ "$(cat /sys/bus/usb/devices/${DEV_PATH}/idVendor 2>/dev/null)" = "$TARGET_VID" ] && \
    [ "$(cat /sys/bus/usb/devices/${DEV_PATH}/idProduct 2>/dev/null)" = "$TARGET_PID" ]
}

# 动态解析该 USB 设备对应的块设备名 (如 sdg), 避免硬编码
find_blkdev() {
    for b in /sys/class/block/sd[a-z]; do
        target=$(readlink -f "$b" 2>/dev/null)
        case "$target" in
            *"${DEV_PATH}:1.0"*) echo "${b##*/}"; return 0 ;;
        esac
    done
    return 1
}

apply_tuning() {
    [ -n "$BLKDEV" ] && [ -e "/sys/block/$BLKDEV" ] || return
    echo 120 > /sys/block/$BLKDEV/device/timeout 2>/dev/null
    echo 256 > /sys/block/$BLKDEV/queue/max_sectors_kb 2>/dev/null
    echo none > /sys/block/$BLKDEV/queue/scheduler 2>/dev/null
    TUNED=1
    log "已应用调优参数 ($BLKDEV: timeout=120s, max_sectors=256KB, scheduler=none)"
}

recover() {
    log "$1 -> 执行重枚举..."
    echo 0 > "$AUTHORIZED" 2>/dev/null
    sleep 3
    echo 1 > "$AUTHORIZED" 2>/dev/null
    sleep 7
    if [ -f "$AUTHORIZED" ] && [ "$(cat "$AUTHORIZED" 2>/dev/null)" = "1" ]; then
        log "重枚举成功，设备恢复"
        TUNED=0
        BLKDEV=""
    else
        log "重枚举失败，请手动检查"
    fi
    dmesg -c > /dev/null 2>&1
}

log "守护脚本启动 v5 (目标: GL3224 05e3:0747)"

while true; do
    if [ -f "$AUTHORIZED" ] && is_target; then
        # 解析块设备名
        [ -z "$BLKDEV" ] && BLKDEV=$(find_blkdev)
        # 场景B: 异常断开
        if [ "$(cat "$AUTHORIZED" 2>/dev/null)" = "0" ]; then
            recover "场景B: 设备异常断开"
            continue
        fi
        # 健康时确保调优参数
        if [ "$TUNED" = "0" ] && [ -n "$BLKDEV" ]; then
            apply_tuning
        fi
        # 场景A: SCSI offline 日志
        if dmesg 2>/dev/null | tail -30 | grep -q "device offline or changed"; then
            recover "场景A: 检测到设备假死"
            continue
        fi
        # 场景C: 健康探测 (每12秒, 读扇区0, 5秒超时)
        now=$(date +%s)
        if [ $((now - LAST_HEALTH)) -ge 12 ] && [ -n "$BLKDEV" ]; then
            LAST_HEALTH=$now
            if ! timeout 5 dd if="/dev/block/$BLKDEV" bs=512 count=1 of=/dev/null 2>/dev/null; then
                recover "场景C: 健康探测超时(静默假死)"
                continue
            fi
        fi
    else
        # 非目标设备: 完全旁观, 不做任何操作
        sleep 10
    fi
    sleep 2
done