Add --preserve-arg0 in qemu-binfmt-conf.sh to configure the preserve-arg0
flag.
Now, if QEMU is started with -0 or QEMU_ARGV0 and an empty parameter
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:
$ sudo QEMU_ARGV0= chroot m68k-chroot sh -c 'echo $0'
sh
without this patch:
$ sudo chroot m68k-chroot sh -c 'echo $0'
/usr/bin/sh
Signed-off-by: Laurent Vivier <laur...@vivier.eu>
---
linux-user/main.c | 18 ++++++++++++++-
scripts/qemu-binfmt-conf.sh | 44 +++++++++++++++++++++++--------------
2 files changed, 44 insertions(+), 18 deletions(-)
diff --git a/linux-user/main.c b/linux-user/main.c
index ef8e8cb10eba..eeaba4a7b914 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -647,6 +647,9 @@ int main(int argc, char **argv, char **envp)
init_qemu_uname_release();
+ /*
+ * Manage binfmt-misc open-binary flag
+ */
execfd = qemu_getauxval(AT_EXECFD);
if (execfd == 0) {
execfd = open(exec_path, O_RDONLY);
@@ -656,6 +659,19 @@ int main(int argc, char **argv, char **envp)
}
}
+ /*
+ * Manage binfmt-misc preserve-arg[0] flag
+ * argv[optind] full path to the binary
+ * argv[optind + 1] original argv[0]
+ */
+ if (optind + 1 < argc && argv0 != NULL && argv0[0] == 0) {
+ /*
+ * argv0 with an empty string will set argv[optind + 1]
+ * as target_argv[0]
+ */
+ optind++;
+ }
+
if (cpu_model == NULL) {
cpu_model = cpu_get_model(get_elf_eflags(execfd));
}
@@ -760,7 +776,7 @@ int main(int argc, char **argv, char **envp)
* argv[0] pointer with the given one.
*/
i = 0;
- if (argv0 != NULL) {
+ if (argv0 != NULL && argv0[0] != 0) {
target_argv[i++] = strdup(argv0);
}
for (; i < target_argc; i++) {
diff --git a/scripts/qemu-binfmt-conf.sh b/scripts/qemu-binfmt-conf.sh
index b5a16742a149..7c9a4609c232 100755
--- a/scripts/qemu-binfmt-conf.sh
+++ b/scripts/qemu-binfmt-conf.sh
@@ -170,25 +170,27 @@ usage() {
Usage: qemu-binfmt-conf.sh [--qemu-path PATH][--debian][--systemd CPU]
[--help][--credential yes|no][--exportdir PATH]
[--persistent yes|no][--qemu-suffix SUFFIX]
+ [--preserve-arg0 yes|no]
Configure binfmt_misc to use qemu interpreter
- --help: display this usage
- --qemu-path: set path to qemu interpreter ($QEMU_PATH)
- --qemu-suffix: add a suffix to the default interpreter name
- --debian: don't write into /proc,
- instead generate update-binfmts templates
- --systemd: don't write into /proc,
- instead generate file for systemd-binfmt.service
- for the given CPU. If CPU is "ALL", generate a
- file for all known cpus
- --exportdir: define where to write configuration files
- (default: $SYSTEMDDIR or $DEBIANDIR)
- --credential: if yes, credential and security tokens are
- calculated according to the binary to interpret
- --persistent: if yes, the interpreter is loaded when binfmt is
- configured and remains in memory. All future uses
- are cloned from the open file.
+ --help: display this usage
+ --qemu-path: set path to qemu interpreter ($QEMU_PATH)
+ --qemu-suffix: add a suffix to the default interpreter name
+ --debian: don't write into /proc,
+ instead generate update-binfmts templates
+ --systemd: don't write into /proc,
+ instead generate file for systemd-binfmt.service
+ for the given CPU. If CPU is "ALL", generate a
+ file for all known cpus
+ --exportdir: define where to write configuration files
+ (default: $SYSTEMDDIR or $DEBIANDIR)
+ --credential: if yes, credential and security tokens are
+ calculated according to the binary to interpret
+ --persistent: if yes, the interpreter is loaded when binfmt is
+ configured and remains in memory. All future uses
+ are cloned from the open file.
+ --preserve-arg0 preserve arg[0]
To import templates with update-binfmts, use :
@@ -261,6 +263,9 @@ qemu_generate_register() {
if [ "$PERSISTENT" = "yes" ] ; then
flags="${flags}F"
fi
+ if [ "$PRESERVE_ARG0" = "yes" ] ; then
+ flags="${flags}P"
+ fi
echo ":qemu-$cpu:M::$magic:$mask:$qemu:$flags"
}
@@ -322,9 +327,10 @@ DEBIANDIR="/usr/share/binfmts"
QEMU_PATH=/usr/local/bin
CREDENTIAL=no
PERSISTENT=no
+PRESERVE_ARG0=no
QEMU_SUFFIX=""
-options=$(getopt -o ds:Q:S:e:hc:p: -l
debian,systemd:,qemu-path:,qemu-suffix:,exportdir:,help,credential:,persistent:
-- "$@")
+options=$(getopt -o ds:Q:S:e:hc:p:0: -l
debian,systemd:,qemu-path:,qemu-suffix:,exportdir:,help,credential:,persistent:,preserve-arg0:
-- "$@")
eval set -- "$options"
while true ; do
@@ -380,6 +386,10 @@ while true ; do
shift
PERSISTENT="$1"
;;
+ -0|--preserve-arg0)
+ shift
+ PRESERVE_ARG0="$1"
+ ;;
*)
break
;;
--
2.21.0
