I have a CPIO archive with the Linux image on it. With binwalk I can see that there are the following chunks:
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
0 0x0 ASCII cpio archive (SVR4 with no CRC), file name: "kernel", file name length: "0x00000007", file size: "0x00000000"
120 0x78 ASCII cpio archive (SVR4 with no CRC), file name: "kernel/x86", file name length: "0x0000000B", file size: "0x00000000"
244 0xF4 ASCII cpio archive (SVR4 with no CRC), file name: "kernel/x86/microcode", file name length: "0x00000015", file size: "0x00000000"
376 0x178 ASCII cpio archive (SVR4 with no CRC), file name: "kernel/x86/microcode/.enuineIntel.align.0123456789abc", file name length: "0x00000036", file size: "0x00000000"
540 0x21C ASCII cpio archive (SVR4 with no CRC), file name: "kernel/x86/microcode/GenuineIntel.bin", file name length: "0x00000026", file size: "0x001A3800"
1718960 0x1A3AB0 ASCII cpio archive (SVR4 with no CRC), file name: "TRAILER!!!", file name length: "0x0000000B", file size: "0x00000000"
1719296 0x1A3C00 gzip compressed data, NULL date (1970-01-01 00:00:00)
32277012 0x1EC8214 Zlib compressed data, default compression
70217888 0x42F70A0 Unix path: /usr/local/go/src/runtime/runtime-gdb.py
85577309 0x519CE5D MySQL MISAM compressed data file Version 3
96044561 0x5B98611 Unix path: /usr/local/go/src/runtime/runtime-gdb.py
100702073 0x6009779 Zlib compressed data, default compression
106454594 0x6585E42 MySQL MISAM compressed data file Version 7
110250207 0x69248DF Unix path: /usr/local/go/src/runtime/runtime-gdb.py
115809787 0x6E71DFB Unix path: /usr/local/go/src/runtime/runtime-gdb.py
I need to extract the the gzipped one:
1719296 0x1A3C00 gzip compressed data, NULL date (1970-01-01 00:00:00)
and replace a single binary file within it, then repack the image.
That gzipped content is another CPIO image.
What is the best/easiest way of doing that?
