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scripts/local脚本mount_root脚本文件分析

2024-11-20 04:32:39   203人阅读

# Local filesystem mounting            -*- shell-script -*-

pre_mountroot()
{
    [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-top"
    run_scripts /scripts/local-top
    [ "$quiet" != "y" ] && log_end_msg

    # Don‘t wait for a root device that doesn‘t have a corresponding
    # device in /dev (ie, mtd0)
    if [ "${ROOT#/dev}" = "${ROOT}" ]; then
        return
    fi

    while [ -z "${FSTYPE}" ]; do
        case $DPKG_ARCH in
            powerpc|ppc64|ppc64el)
                ARCHDELAY=180
                ;;
            *)
                ARCHDELAY=30
                ;;
        esac
        FSTYPE=$(wait-for-root "${ROOT}" ${ROOTDELAY:-$ARCHDELAY})

        # Load ubi with the correct MTD partition and return since
        # fstype doesn‘t work with a char device like ubi.
        if [ -n "$UBIMTD" ]; then
            modprobe ubi mtd=$UBIMTD
            return
        fi

        # Run failure hooks, hoping one of them can fix up the system
        # and we can restart the wait loop.  If they all fail, abort
        # and move on to the panic handler and shell.
        if [ -z "${FSTYPE}" ] && ! try_failure_hooks; then
            break
        fi
    done

    # We‘ve given up, but we‘ll let the user fix matters if they can
    while [ -z "${FSTYPE}" -a ! -e "${ROOT}" ]; do
        # give hint about renamed root
        case "${ROOT}" in
        /dev/hd*)
            suffix="${ROOT#/dev/hd}"
            major="${suffix%[[:digit:]]}"
            major="${major%[[:digit:]]}"
            if [ -d "/sys/block/sd${major}" ]; then
                echo "WARNING bootdevice may be renamed. Try root=/dev/sd${suffix}"
            fi
            ;;
        /dev/sd*)
            suffix="${ROOT#/dev/sd}"
            major="${suffix%[[:digit:]]}"
            major="${major%[[:digit:]]}"
            if [ -d "/sys/block/hd${major}" ]; then
                echo "WARNING bootdevice may be renamed. Try root=/dev/hd${suffix}"
            fi
            ;;
        esac
        echo "Gave up waiting for root device.  Common problems:"
        echo " - Boot args (cat /proc/cmdline)"
        echo "   - Check rootdelay= (did the system wait long enough?)"
        echo "   - Check root= (did the system wait for the right device?)"
        echo " - Missing modules (cat /proc/modules; ls /dev)"
        panic "ALERT!  ${ROOT} does not exist.  Dropping to a shell!"
    done
}

mountroot()
{
    pre_mountroot

    # Get the root filesystem type if not set
    if [ -z "${ROOTFSTYPE}" ]; then
        [ -n "${FSTYPE}" ] || FSTYPE=$(blkid -s TYPE -o value "${ROOT}")
        ROOTFSTYPE="${FSTYPE}"
    else
        FSTYPE=${ROOTFSTYPE}
    fi

    [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-premount"
    run_scripts /scripts/local-premount
    [ "$quiet" != "y" ] && log_end_msg

    if [ "${readonly}" = "y" ] && \
       [ -z "$LOOP" ]; then
        roflag=-r
    else
        roflag=-w
    fi

    # FIXME This has no error checking
    [ -n "${FSTYPE}" ] && modprobe ${FSTYPE}

    # FIXME This has no error checking
    # Mount root
    mount ${roflag} ${FSTYPE:+-t ${FSTYPE} }${ROOTFLAGS} ${ROOT} ${rootmnt}
    mountroot_status="$?"
    if [ "$LOOP" ]; then
        if [ "$mountroot_status" != 0 ]; then
            if [ ${FSTYPE} = ntfs ] || [ ${FSTYPE} = vfat ]; then
                panic "
Could not mount the partition ${ROOT}.
This could also happen if the file system is not clean because of an operating
system crash, an interrupted boot process, an improper shutdown, or unplugging
of a removable device without first unmounting or ejecting it.  To fix this,
simply reboot into Windows, let it fully start, log in, run ‘chkdsk /r‘, then
gracefully shut down and reboot back into Windows. After this you should be
able to reboot again and resume the installation.
(filesystem = ${FSTYPE}, error code = $mountroot_status)
"
            fi
        fi
    
        mkdir -p /host
        mount -o move ${rootmnt} /host

        while [ ! -e "/host/${LOOP#/}" ]; do
            panic "ALERT!  /host/${LOOP#/} does not exist.  Dropping to a shell!"
        done

        # Get the loop filesystem type if not set
        if [ -z "${LOOPFSTYPE}" ]; then
            eval $(fstype < "/host/${LOOP#/}")
        else
            FSTYPE="${LOOPFSTYPE}"
        fi
        if [ "$FSTYPE" = "unknown" ] && [ -x /sbin/blkid ]; then
            FSTYPE=$(/sbin/blkid -s TYPE -o value "/host/${LOOP#/}")
            [ -z "$FSTYPE" ] && FSTYPE="unknown"
        fi

        if [ ${readonly} = y ]; then
            roflag=-r
        else
            roflag=-w
        fi

        # FIXME This has no error checking
        modprobe loop
        modprobe ${FSTYPE}

        # FIXME This has no error checking
        mount ${roflag} -o loop -t ${FSTYPE} ${LOOPFLAGS} "/host/${LOOP#/}" ${rootmnt}

        if [ -d ${rootmnt}/host ]; then
            mount -o move /host ${rootmnt}/host
        fi
    fi

    [ "$quiet" != "y" ] && log_begin_msg "Running /scripts/local-bottom"
    run_scripts /scripts/local-bottom
    [ "$quiet" != "y" ] && log_end_msg
}

scripts/local脚本mount_root脚本文件分析


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