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Merge pull request #1860 from tlaurion/fix_initrd_unpack_for_repacking
initrd/bin/unpack_initramfs.sh: add xz unpacking support.
This commit is contained in:
Thierry Laurion
GitHub
commit
45696a4c8a
@ -31,78 +31,105 @@ CPIO_ARGS=("$@")
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# Consume zero bytes, the first nonzero byte read (if any) is repeated on stdout
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consume_zeros() {
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TRACE_FUNC
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next_byte='00'
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while [ "$next_byte" = "00" ]; do
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# if we reach EOF, next_byte becomes empty (dd does not fail)
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next_byte="$(dd bs=1 count=1 status=none | xxd -p | tr -d ' ')"
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done
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# if we finished due to nonzero byte (not EOF), then carry that byte
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if [ -n "$next_byte" ]; then
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echo -n "$next_byte" | xxd -p -r
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fi
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TRACE_FUNC
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next_byte='00'
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while [ "$next_byte" = "00" ]; do
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# if we reach EOF, next_byte becomes empty (dd does not fail)
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next_byte="$(dd bs=1 count=1 status=none | xxd -p | tr -d ' ')"
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done
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# if we finished due to nonzero byte (not EOF), then carry that byte
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if [ -n "$next_byte" ]; then
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echo -n "$next_byte" | xxd -p -r
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fi
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}
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unpack_cpio() {
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TRACE_FUNC
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(cd "$dest_dir"; cpio -i "${CPIO_ARGS[@]}" 2>/dev/null)
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TRACE_FUNC
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(
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cd "$dest_dir"
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cpio -i "${CPIO_ARGS[@]}" 2>/dev/null
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)
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}
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# unpack the first segment of an archive, then write the rest to another file
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unpack_first_segment() {
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TRACE_FUNC
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unpack_archive="$1"
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dest_dir="$2"
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rest_archive="$3"
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TRACE_FUNC
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unpack_archive="$1"
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dest_dir="$2"
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rest_archive="$3"
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mkdir -p "$dest_dir"
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mkdir -p "$dest_dir"
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# peek the beginning of the file to determine what type of content is next
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magic="$(dd if="$unpack_archive" bs=6 count=1 status=none | xxd -p)"
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# peek the beginning of the file to determine what type of content is next
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magic="$(dd if="$unpack_archive" bs=6 count=1 status=none | xxd -p)"
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# read this segment of the archive, then write the rest to the next file
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(
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# Magic values correspond to Linux init/initramfs.c (zero, cpio) and
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# lib/decompress.c (gzip)
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case "$magic" in
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00*)
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DEBUG "archive segment $magic: uncompressed cpio"
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# Skip zero bytes and copy the first nonzero byte
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consume_zeros
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# Copy the remaining data
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cat
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;;
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303730373031*|303730373032*) # plain cpio
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DEBUG "archive segment $magic: plain cpio"
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# Unpack the plain cpio, this stops reading after the trailer
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unpack_cpio
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# Copy the remaining data
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cat
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;;
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1f8b*|1f9e*) # gzip
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DEBUG "archive segment $magic: gzip"
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# gunzip won't stop when reaching the end of the gzipped member,
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# so we can't read another segment after this. We can't
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# reasonably determine the member length either, this requires
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# walking all the compressed blocks.
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gunzip | unpack_cpio
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;;
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28b5*) # zstd
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DEBUG "archive segment $magic: zstd"
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# Like gunzip, this will not stop when reaching the end of the
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# frame, and determining the frame length requires walking all
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# of its blocks.
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(zstd-decompress -d || true) | unpack_cpio
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;;
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*) # unknown
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die "Can't decompress initramfs archive, unknown type: $magic"
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;;
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esac
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) <"$unpack_archive" >"$rest_archive"
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# read this segment of the archive, then write the rest to the next file
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(
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# Magic values correspond to Linux init/initramfs.c (zero, cpio) and
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# lib/decompress.c (gzip)
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case "$magic" in
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00*)
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DEBUG "archive segment $magic: uncompressed cpio"
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# Skip zero bytes and copy the first nonzero byte
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consume_zeros
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# Copy the remaining data
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cat
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;;
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303730373031* | 303730373032*) # plain cpio
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DEBUG "archive segment $magic: plain cpio"
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# Unpack the plain cpio, this stops reading after the trailer
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unpack_cpio
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# Copy the remaining data
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cat
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;;
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1f8b* | 1f9e*) # gzip
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DEBUG "archive segment $magic: gzip"
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# gunzip won't stop when reaching the end of the gzipped member,
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# so we can't read another segment after this. We can't
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# reasonably determine the member length either, this requires
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# walking all the compressed blocks.
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gunzip | unpack_cpio
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;;
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fd37*) # xz
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DEBUG "archive segment $magic: xz"
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unxz | unpack_cpio
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;;
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28b5*) # zstd
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DEBUG "archive segment $magic: zstd"
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# Like gunzip, this will not stop when reaching the end of the
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# frame, and determining the frame length requires walking all
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# of its blocks.
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(zstd-decompress -d || true) | unpack_cpio
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;;
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*) # unknown
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die "Can't decompress initramfs archive, unknown type: $magic"
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# The following are magic values for other compression formats
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# but not added because not tested.
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# TODO: open an issue for unsupported magic number reported on die.
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#
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#425a*) # bzip2
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# DEBUG "archive segment $magic: bzip2"
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# bunzip2 | unpack_cpio
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#;;
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#5d00*) # lzma
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# DEBUG "archive segment $magic: lzma"
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# unlzma | unpack_cpio
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#;;
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#894c*) # lzo
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# DEBUG "archive segment $magic: lzo"
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# lzop -d | unpack_cpio
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#;;
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#0221*) # lz4
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# DEBUG "archive segment $magic: lz4"
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# lz4 -d | unpack_cpio
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# ;;
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;;
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esac
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) <"$unpack_archive" >"$rest_archive"
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orig_size="$(stat -c %s "$unpack_archive")"
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rest_size="$(stat -c %s "$rest_archive")"
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DEBUG "archive segment $magic: $((orig_size - rest_size)) bytes"
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orig_size="$(stat -c %s "$unpack_archive")"
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rest_size="$(stat -c %s "$rest_archive")"
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DEBUG "archive segment $magic: $((orig_size - rest_size)) bytes"
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}
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DEBUG "Unpacking $INITRAMFS_ARCHIVE to $DEST_DIR"
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@ -112,7 +139,7 @@ rest_archive="/tmp/unpack_initramfs_rest"
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# Break when there is no remaining data
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while [ -s "$next_archive" ]; do
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unpack_first_segment "$next_archive" "$DEST_DIR" "$rest_archive"
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next_archive="/tmp/unpack_initramfs_next"
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mv "$rest_archive" "$next_archive"
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unpack_first_segment "$next_archive" "$DEST_DIR" "$rest_archive"
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next_archive="/tmp/unpack_initramfs_next"
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mv "$rest_archive" "$next_archive"
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done
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