Le 26/04/2022 à 21:24, John Paul Adrian Glaubitz a écrit :
Hi!
...
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=974004
Normally, since qemu v6.0.0 you can preserve argv[0]:
commit 6e1c0d7b951e19c53b8467e8bc4b71ee73a394ea
Author: Laurent Vivier <laur...@vivier.eu>
Date: Mon Feb 22 11:50:04 2021 +0100
linux-user: manage binfmt-misc preserve-arg[0] flag
Add --preserve-argv0 in qemu-binfmt-conf.sh to configure the preserve-argv0
flag.
This patch allows to use new flag in AT_FLAGS to detect if
preserve-argv0 is configured for this interpreter:
argv[0] (the full pathname provided by binfmt-misc) is removed and
replaced by argv[1] (the original argv[0] provided by binfmt-misc when
'P'/preserve-arg[0] is set)
For instance with this patch and kernel support for AT_FLAGS:
$ sudo chroot m68k-chroot sh -c 'echo $0'
sh
without this patch:
$ sudo chroot m68k-chroot sh -c 'echo $0'
/usr/bin/sh
The new flag is available in kernel (v5.12) since:
2347961b11d4 ("binfmt_misc: pass binfmt_misc flags to the interpreter")
This can be tested with something like:
# cp ..../qemu-ppc /chroot/powerpc/jessie
# qemu-binfmt-conf.sh --qemu-path / --systemd ppc --credential yes \
--persistent no --preserve-argv0 yes
# systemctl restart systemd-binfmt.service
# cat /proc/sys/fs/binfmt_misc/qemu-ppc
enabled
interpreter //qemu-ppc
flags: POC
offset 0
magic 7f454c4601020100000000000000000000020014
mask ffffffffffffff00fffffffffffffffffffeffff
# chroot /chroot/powerpc/jessie sh -c 'echo $0'
sh
# qemu-binfmt-conf.sh --qemu-path / --systemd ppc --credential yes \
--persistent no --preserve-argv0 no
# systemctl restart systemd-binfmt.service
# cat /proc/sys/fs/binfmt_misc/qemu-ppc
enabled
interpreter //qemu-ppc
flags: OC
offset 0
magic 7f454c4601020100000000000000000000020014
mask ffffffffffffff00fffffffffffffffffffeffff
# chroot /chroot/powerpc/jessie sh -c 'echo $0'
/bin/sh
Signed-off-by: Laurent Vivier <laur...@vivier.eu>
Message-Id: <20210222105004.1642234-1-laur...@vivier.eu>
You need also kernel v5.12:
commit 2347961b11d4079deace3c81dceed460c08a8fc1
Author: Laurent Vivier <laur...@vivier.eu>
Date: Tue Jan 28 14:25:39 2020 +0100
binfmt_misc: pass binfmt_misc flags to the interpreter
It can be useful to the interpreter to know which flags are in use.
For instance, knowing if the preserve-argv[0] is in use would
allow to skip the pathname argument.
This patch uses an unused auxiliary vector, AT_FLAGS, to add a
flag to inform interpreter if the preserve-argv[0] is enabled.
Note by Helge Deller:
The real-world user of this patch is qemu-user, which needs to know
if it has to preserve the argv[0]. See Debian bug #970460.
Signed-off-by: Laurent Vivier <laur...@vivier.eu>
Reviewed-by: YunQiang Su <y...@wavecomp.com>
URL: http://bugs.debian.org/970460
Signed-off-by: Helge Deller <del...@gmx.de>
Thanks,
Laurent
