Bug#894294: Comment in the source of unmkinitramfs is ambiguous
Source: initramfs-tools
Version: 0.130
Severity: wishlist
The line 56-59 of unmkinitramfs goes:
# There may be a prepended uncompressed archive. cpio
# won't tell us the true size of this so we have to
# parse the headers and padding ourselves. This is
# very roughly based on linux/lib/earlycpio.c
The claim "cpio won't tell us the true size of this ..." doesn't have
any explicit reference to substantiate its claim while my uneducated
simple use of cpio telling me the true file size without the tailing
garbage ;-)
For example:
$ cpio -i -t </initrd.img >/dev/null
48 blocks
So the uncompressed cpio file size is 512*48 BYTES. With some simple
experimentation with cpio, I realize cpio always create file size in
multiple of 512 bytes and it treat 512 bytes as a block. I can extract
tailing basic initrd image file as subinitrd.img with:
$ dd if=/initrd.img of=subinitrd.img bs=512 skip=48
At least on my recent Debian system, this subinitrd.img is a nicely
extracted gzipped cpio archive.
I am sure you had a reason why you made extensive binary file tracing
code. If it was previous bug in cpio, it's nice to reference it. If
there are some non-GNU/Linux cpio implementations having such problems,
it's nice to be specific.
It seems GNU version of cpio reports its true file size in blocks
whenever with -i option.
If this block based file size identification is OK, please consider
using it to simplify the code.
== Background ==
I was thinking to update initramfs related Debian wiki pages and
realized simple method I was using seems to be problematic if your
comment has some history behind.
https://wiki.debian.org/initramfs
Osamu
-- Package-specific info:
-- initramfs sizes
-rw-r--r-- 1 root root 27M Mar 28 01:22 /boot/initrd.img-4.14.0-3-amd64
-- /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-4.14.0-3-amd64 root=UUID=fde2800b-8afc-42e0-87b2-d7c8909dcea0 ro
-- resume
RESUME=UUID=4e3bd2a9-a62f-4d3f-9945-0719726af7c5
-- /proc/filesystems
btrfs
ext3
ext2
ext4
fuseblk
-- lsmod
Module Size Used by
fuse 118784 3
snd_hda_codec_hdmi 57344 1
intel_rapl 24576 0
x86_pkg_temp_thermal 16384 0
intel_powerclamp 16384 0
coretemp 16384 0
kvm_intel 225280 0
kvm 700416 1 kvm_intel
irqbypass 16384 1 kvm
crct10dif_pclmul 16384 0
crc32_pclmul 16384 0
iTCO_wdt 16384 0
iTCO_vendor_support 16384 1 iTCO_wdt
snd_hda_codec_realtek 106496 1
i915 1613824 25
snd_hda_codec_generic 86016 1 snd_hda_codec_realtek
ghash_clmulni_intel 16384 0
intel_cstate 16384 0
intel_uncore 131072 0
snd_soc_rt5640 118784 0
intel_rapl_perf 16384 0
drm_kms_helper 192512 1 i915
snd_hda_intel 45056 10
joydev 24576 0
snd_soc_rl6231 16384 1 snd_soc_rt5640
pcspkr 16384 0
serio_raw 16384 0
evdev 28672 12
mei_me 45056 0
snd_hda_codec 151552 4 snd_hda_intel,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek
drm 438272 16 i915,drm_kms_helper
snd_hda_core 90112 5 snd_hda_intel,snd_hda_codec,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek
lpc_ich 28672 0
i2c_algo_bit 16384 1 i915
mei 114688 1 mei_me
sg 36864 0
mfd_core 16384 1 lpc_ich
snd_hwdep 16384 1 snd_hda_codec
shpchp 40960 0
snd_soc_core 258048 1 snd_soc_rt5640
snd_compress 24576 1 snd_soc_core
snd_pcm 118784 6 snd_hda_intel,snd_hda_codec,snd_hda_core,snd_soc_rt5640,snd_hda_codec_hdmi,snd_soc_core
video 45056 1 i915
snd_timer 36864 1 snd_pcm
snd 94208 30 snd_compress,snd_hda_intel,snd_hwdep,snd_hda_codec,snd_timer,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_codec_realtek,snd_soc_core,snd_pcm
soundcore 16384 1 snd
intel_smartconnect 16384 0
acpi_pad 24576 0
button 16384 1 i915
parport_pc 32768 0
ppdev 20480 0
lp 20480 0
parport 57344 3 lp,parport_pc,ppdev
loop 32768 0
dm_crypt 40960 0
ip_tables 28672 0
x_tables 40960 1 ip_tables
autofs4 49152 3
ext4 720896 1
crc16 16384 1 ext4
mbcache 16384 1 ext4
jbd2 118784 1 ext4
fscrypto 32768 1 ext4
ecb 16384 0
btrfs 1339392 0
zstd_decompress 94208 1 btrfs
zstd_compress 188416 1 btrfs
xxhash 16384 2 zstd_compress,zstd_decompress
raid10 57344 0
raid456 163840 0
async_raid6_recov 20480 1 raid456
async_memcpy 16384 2 raid456,async_raid6_recov
async_pq 16384 2 raid456,async_raid6_recov
async_xor 16384 3 async_pq,raid456,async_raid6_recov
async_tx 16384 5 async_xor,async_pq,raid456,async_memcpy,async_raid6_recov
xor 24576 2 async_xor,btrfs
raid6_pq 122880 4 async_pq,btrfs,raid456,async_raid6_recov
libcrc32c 16384 1 raid456
crc32c_generic 16384 0
raid1 45056 0
raid0 20480 0
multipath 16384 0
linear 16384 0
md_mod 159744 6 raid1,raid10,multipath,linear,raid0,raid456
dm_mirror 28672 0
dm_region_hash 20480 1 dm_mirror
dm_log 20480 2 dm_mirror,dm_region_hash
dm_mod 143360 3 dm_mirror,dm_log,dm_crypt
hid_generic 16384 0
usbhid 57344 0
hid 131072 2 hid_generic,usbhid
sr_mod 28672 0
sd_mod 53248 3
cdrom 69632 1 sr_mod
crc32c_intel 24576 4
e1000e 282624 0
ahci 40960 2
ptp 20480 1 e1000e
libahci 40960 1 ahci
aesni_intel 188416 0
psmouse 167936 0
xhci_pci 16384 0
ehci_pci 16384 0
libata 274432 2 ahci,libahci
xhci_hcd 241664 1 xhci_pci
ehci_hcd 94208 1 ehci_pci
aes_x86_64 20480 1 aesni_intel
crypto_simd 16384 1 aesni_intel
pps_core 20480 1 ptp
cryptd 28672 3 crypto_simd,ghash_clmulni_intel,aesni_intel
glue_helper 16384 1 aesni_intel
scsi_mod 253952 4 sd_mod,libata,sr_mod,sg
i2c_i801 28672 0
usbcore 286720 5 usbhid,ehci_hcd,xhci_pci,xhci_hcd,ehci_pci
usb_common 16384 1 usbcore
-- /etc/initramfs-tools/modules
-- /etc/kernel-img.conf
# Kernel image management overrides
# See kernel-img.conf(5) for details
do_symlinks = yes
do_bootloader = no
do_initrd = yes
link_in_boot = no
-- /etc/initramfs-tools/initramfs.conf
MODULES=most
BUSYBOX=auto
KEYMAP=n
COMPRESS=gzip
DEVICE=
NFSROOT=auto
-- /etc/initramfs-tools/update-initramfs.conf
update_initramfs=yes
backup_initramfs=no
-- /etc/crypttab
# <target name> <source device> <key file> <options>
-- /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
unused devices: <none>
-- mkinitramfs hooks
/etc/initramfs-tools/hooks/:
/usr/share/initramfs-tools/hooks:
amd64_microcode
bcache
btrfs
cryptgnupg
cryptkeyctl
cryptopenct
cryptopensc
cryptpassdev
cryptroot
cryptroot-unlock
dmraid
dmsetup
fsck
fuse
intel_microcode
keymap
klibc-utils
kmod
lvm2
mdadm
ntfs_3g
resume
sg3-utils
thermal
udev
zz-busybox
-- System Information:
Debian Release: buster/sid
APT prefers testing
APT policy: (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 4.14.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
-- no debconf information
Reply to: