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bin/unpack_initramfs.sh: Add TRACE and DEBUG traces

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Thierry Laurion 2023-09-02 01:51:50 -04:00
parent 0ba10e5174
commit e9dbce2adf
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1 changed files with 8 additions and 0 deletions
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8
initrd/bin/unpack_initramfs.sh
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@ -3,6 +3,7 @@ set -e -o pipefail
. /etc/functions
TRACE "Under unpack_initramfs.sh"
# Unpack a Linux initramfs archive.
#
# In general, the initramfs archive is one or more cpio archives, optionally
@ -30,6 +31,7 @@ CPIO_ARGS=("$@")
# Consume zero bytes, the first nonzero byte read (if any) is repeated on stdout
consume_zeros() {
TRACE "Under unpack_initramfs.sh:consume_zeros"
next_byte='00'
while [ "$next_byte" = "00" ]; do
# if we reach EOF, next_byte becomes empty (dd does not fail)
@ -42,11 +44,13 @@ consume_zeros() {
}
unpack_cpio() {
TRACE "Under unpack_initramfs.sh:unpack_cpio"
(cd "$dest_dir"; cpio -i "${CPIO_ARGS[@]}" 2>/dev/null)
}
# unpack the first segment of an archive, then write the rest to another file
unpack_first_segment() {
TRACE "Under unpack_initramfs.sh:unpack_first_segment"
unpack_archive="$1"
dest_dir="$2"
rest_archive="$3"
@ -62,18 +66,21 @@ unpack_first_segment() {
# lib/decompress.c (gzip)
case "$magic" in
00*)
DEBUG "archive segment $magic: uncompressed cpio"
# Skip zero bytes and copy the first nonzero byte
consume_zeros
# Copy the remaining data
cat
;;
303730373031*|303730373032*) # plain cpio
DEBUG "archive segment $magic: plain cpio"
# Unpack the plain cpio, this stops reading after the trailer
unpack_cpio
# Copy the remaining data
cat
;;
1f8b*|1f9e*) # gzip
DEBUG "archive segment $magic: gzip"
# gunzip won't stop when reaching the end of the gzipped member,
# so we can't read another segment after this. We can't
# reasonably determine the member length either, this requires
@ -81,6 +88,7 @@ unpack_first_segment() {
gunzip | unpack_cpio
;;
28b5*) # zstd
DEBUG "archive segment $magic: zstd"
# Like gunzip, this will not stop when reaching the end of the
# frame, and determining the frame length requires walking all
# of its blocks.