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Old 04-11-2012, 03:56 PM   #7
seaniko7
wannabe developer
seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.seaniko7 can grok the meaning of the universe.
 
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Posts: 179
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Join Date: Mar 2011
Device: Kindle: 2xKeyboard, Classic, 2xTouch, 2xPW, PW2; Onyx: Boox M92
@geekmaster, you might consider including this code in your script. It works as expected :
Code:
#!/bin/bash
DEBUG=
TEMP_DIR=/tmp
KERNEL_FILE=kernel
KERNEL_GZIP_FILE=kernel.gz
INITRAMFS_FILE=initramfs.cpio
INITRAMFS_DIR=initramfs_root

# DO NOT MODIFY BELOW THIS LINE
[ -z $1 ] && exit 1 || zImage=$1
[ ! -e $1 ] && exit 1

#GET CURRENT DIR
CURRENT_DIR=`pwd`

function pre_clean()
{
    [ -z $DEBUG ] || echo "-D- Function: pre_clean()"
    [ -e $INITRAMFS_FILE ] && ( [ -z $DEBUG ] || echo "-D- Deleting $INITRAMFS_FILE"; rm -f $INITRAMFS_FILE )
    [ -e $INITRAMFS_DIR ] && ( [ -z $DEBUG ] || echo "-D- Deleting $INITRAMFS_DIR"; rm -rf $INITRAMFS_DIR )
    [ -z $DEBUG ] || echo
}

function ungzip_kernel()
{
    #========================================================
    # find start of gziped kernel object in the zImage file:
    #========================================================
    [ -z $DEBUG ] || echo "-D- Function: ungzip_kernel()"

    pos=`grep -P -a -b -m 1 --only-matching '\x1F\x8B\x08' $zImage | cut -f 1 -d :`
    echo "-I- Extracting gzip'd kernel image from file: $zImage (start = $pos)"

    if [ ! -z $pos ]; then
        dd if=$zImage of=$TEMP_DIR/$KERNEL_GZIP_FILE bs=1 skip=$pos 2>/dev/null >/dev/null
        gunzip -qf $TEMP_DIR/$KERNEL_GZIP_FILE
    else
        echo "-E- Compressed kernel image not found"; exit 1
    fi
    [ -z $DEBUG ] || echo
}

function search_cpio()
{
    #========================================================
    # Determine cpio compression type:
    #========================================================
    [ -z $DEBUG ] || echo "-D- Function: search_cpio()"

    for x in gzip bzip lzma none; do
        case $x in
            bzip)
                csig='\x{31}\x{41}\x{59}\x{26}\x{53}\x{59}'
                ucmd='bunzip2 -q'
                fext='.bz2'
                ;;

            gzip)
                csig='\x1F\x8B\x08'
                ucmd='gunzip -q'
                fext='.gz'
                ;;

            lzma)
                csig='\x{5D}\x{00}\x..\x{FF}\x{FF}\x{FF}\x{FF}\x{FF}\x{FF}'
                ucmd='unlzma -q'
                fext='.lzma'
                ;;

            none)
                csig='070701'
                ucmd=
                fext=
                ;;
        esac

        #========================================================================
        # Search for compressed cpio archive
        #========================================================================
        search=`grep -P -a -b -m 1 --only-matching $csig $TEMP_DIR/$KERNEL_FILE | cut -f 1 -d : | head -1`
        pos=${search:-0}

        if [ ${pos} -gt 0 ]; then
            if [ ${pos} -le ${cpio_compressed_start:-0} ] || [ -z $cpio_compressed_start ];then
                cpio_compressed_start=$pos

                compression_name=$x
                compression_signature=$csig
                uncompress_cmd=$ucmd
                file_ext=$fext

                [ -z $DEBUG ] || echo "-D- Checking for compression type: $compression_name | signature: $compression_signature | in file: $TEMP_DIR/$KERNEL_FILE | offset = $pos"
            fi
        fi
    done 

    [ $compression_name = "bzip" ] && cpio_compressed_start=$((cpio_compressed_start - 4))
    echo "-I- CPIO compression type detected = $compression_name | offset = $cpio_compressed_start"

    [ -z $DEBUG ] || echo
}

function extract_cpio()
{
    [ -z $DEBUG ] || echo "-D- Function: extract_cpio()"

    if [ ! $compression_name = "none" ]; then
        echo "-I- Extracting $compression_name'd compressed CPIO image from kernel image (offset = $cpio_compressed_start)"
        [ -z $DEBUG ] || echo "-D- dd if=$TEMP_DIR/$KERNEL_FILE of=$TEMP_DIR/$INITRAMFS_FILE$file_ext bs=1 skip=$cpio_compressed_start; $uncompress_cmd $TEMP_DIR/$INITRAMFS_FILE$file_ext"
        dd if=$TEMP_DIR/$KERNEL_FILE of=$TEMP_DIR/$INITRAMFS_FILE$file_ext bs=1 skip=$cpio_compressed_start 2>/dev/null >/dev/null
        $uncompress_cmd -q $TEMP_DIR/$INITRAMFS_FILE$file_ext

    else
        echo "-I- Extracting non-compressed CPIO image from kernel image (offset = $cpio_compressed_start)"
        [ -z $DEBUG ] || echo "-D- dd if=$TEMP_DIR/$KERNEL_FILE of=$TEMP_DIR/${INITRAMFS_FILE}${file_ext} bs=1 skip=$cpio_compressed_start 2>/dev/null >/dev/null"
        dd if=$TEMP_DIR/$KERNEL_FILE of=$TEMP_DIR/${INITRAMFS_FILE}${file_ext} bs=1 skip=$cpio_compressed_start 2>/dev/null >/dev/null
    fi

    [ -z $DEBUG ] || echo
}

function uncompress_cpio()
{
    #==========================================================================
    # find start and end of the "cpio" initramfs image inside the kernel object:
    # ASCII cpio header starts with '070701'
    # The end of the cpio archive is marked with an empty file named TRAILER!!!
    #==========================================================================
    [ -z $DEBUG ] || echo "-D- Function: uncompress_cpio()"

    if [ ! $compress_type = "none" ]; then
        start=`grep -a -b -m 1 --only-matching '070701' $TEMP_DIR/$INITRAMFS_FILE | head -1 | cut -f 1 -d :`
        end=`grep -a -b -m 1 --only-matching 'TRAILER!!!' $TEMP_DIR/$INITRAMFS_FILE | head -1 | cut -f 1 -d :`

        if [ ! -z $start ] || [ ! -z $end ]; then
            #11 bytes = length of TRAILER!!! zero terminated string, fixes premature end of file warning in CPIO
            end=$((end + 14))
            [ -z $DEBUG ] || echo "-D- Kernel start = $start"
            [ -z $DEBUG ] || echo "-D- Kernel end = $end"
            count=$((end - start))

            if (($count < 0)); then
                echo "-E- Couldn't match start/end of the initramfs image."
                exit 1
            fi

            echo "-I- Extracting initramfs image from file: $inputfile (start = $start, end = $end)"
            dd if=$TEMP_DIR/$INITRAMFS_FILE of=$CURRENT_DIR/$INITRAMFS_FILE bs=1 skip=$start count=$count 2>/dev/null >/dev/null
            INITRAMFS_FILE=$CURRENT_DIR/$INITRAMFS_FILE
        else
        
            echo "-E- No CPIO image found in $inputfile."
        fi
    else
        echo "-I- CPIO already uncompressed."
    fi
    [ -z $DEBUG ] || echo
}

function expand_cpio_archive()
{
    [ -z $DEBUG ] || echo "-D- Function: expand_cpio_archive()"
    echo "-I- Expanding CPIO archive: $INITRAMFS_FILE to $INITRAMFS_DIR."

    if [ -e $TEMP_DIR/$INITRAMFS_FILE ]; then
        mkdir $INITRAMFS_DIR
        cd $INITRAMFS_DIR
        cpio --quiet -i --make-directories --preserve-modification-time --no-absolute-filenames -F $TEMP_DIR/$INITRAMFS_FILE 2>/dev/null
    fi
    [ -z $DEBUG ] || echo
}

function clean_up()
{
    [ -z $DEBUG ] || echo "-D- Deleting $TEMP_DIR/$KERNEL_FILE"; rm -f $TEMP_DIR/$KERNEL_FILE
    [ -z $DEBUG ] || echo "-D- Deleting $TEMP_DIR/$INITRAMFS_FILE"; rm -f $TEMP_DIR/$INITRAMFS_FILE
    [ -z $DEBUG ] || echo "-D- Deleting $TEMP_DIR/$INITRAMFS_FILE$file_ext"; rm -f $TEMP_DIR/$INITRAMFS_FILE$file_ext
}





reset
pre_clean
ungzip_kernel
search_cpio
extract_cpio
uncompress_cpio
expand_cpio_archive
clean_up
Oh, to make things clear. I'm not the author of this script.

Last edited by seaniko7; 04-11-2012 at 03:59 PM.
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