Add --preserve-argv0 in qemu-binfmt-conf.sh to configure the preserve-argv0 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 QEMU can be forced to always use preserve-argv[0] at configuration time with --force-preserve-argv0 Signed-off-by: Laurent Vivier <laur...@vivier.eu> --- configure | 8 +++++++ linux-user/main.c | 24 +++++++++++++++++++- scripts/qemu-binfmt-conf.sh | 44 +++++++++++++++++++++++-------------- 3 files changed, 58 insertions(+), 18 deletions(-) diff --git a/configure b/configure index 145fcabbb3c3..94c41f0a068a 100755 --- a/configure +++ b/configure @@ -497,6 +497,7 @@ sheepdog="yes" libxml2="" debug_mutex="no" libpmem="" +force_preserve_argv0="no" default_devices="yes" supported_cpu="no" @@ -1529,6 +1530,8 @@ for opt do ;; --disable-xkbcommon) xkbcommon=no ;; + --force-preserve-argv0) force_preserve_argv0=yes + ;; *) echo "ERROR: unknown option $opt" echo "Try '$0 --help' for more information" @@ -1710,6 +1713,8 @@ Advanced options (experts only): --enable-profiler profiler support --enable-debug-stack-usage track the maximum stack usage of stacks created by qemu_alloc_stack + --force-preserve-argv0 for linux-user only, force the use of binfmt_misc 'P' + flag (preserve-argv[0]) Optional features, enabled with --enable-FEATURE and disabled with --disable-FEATURE, default is enabled if available: @@ -7633,6 +7638,9 @@ if test "$target_user_only" = "yes" ; then fi if test "$target_linux_user" = "yes" ; then echo "CONFIG_LINUX_USER=y" >> $config_target_mak + if test "$force_preserve_argv0" = "yes" ; then + echo "CONFIG_FORCE_PRESERVE_ARGV0=y" >> $config_target_mak + fi fi list="" if test ! -z "$gdb_xml_files" ; then diff --git a/linux-user/main.c b/linux-user/main.c index 560d053f7249..1b4df24ef483 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -616,6 +616,7 @@ int main(int argc, char **argv, char **envp) int ret; int execfd; unsigned long max_reserved_va; + bool preserve_argv0; error_init(argv[0]); module_call_init(MODULE_INIT_TRACE); @@ -664,6 +665,9 @@ 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); @@ -673,6 +677,24 @@ int main(int argc, char **argv, char **envp) } } + /* + * argv0 with an empty string will set argv[optind + 1] + * as target_argv[0] + */ +#ifdef CONFIG_FORCE_PRESERVE_ARGV0 + preserve_argv0 = true; +#else + preserve_argv0 = (argv0 != NULL && argv0[0] == 0); +#endif + /* + * Manage binfmt-misc preserve-arg[0] flag + * argv[optind] full path to the binary + * argv[optind + 1] original argv[0] + */ + if (optind + 1 < argc && preserve_argv0) { + optind++; + } + if (cpu_model == NULL) { cpu_model = cpu_get_model(get_elf_eflags(execfd)); } @@ -777,7 +799,7 @@ 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..275d3cf57e83 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-argv0 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 $DEBIANDIR) + --credential: if yes, credential and security tokens are + calculated according to the binary to interpret + --persistent: if yes, the interpreter is loaded when binfmt is + configured and remains in memory. All future uses + are cloned from the open file. + --preserve-argv0 preserve argv[0] To import templates with update-binfmts, use : @@ -261,6 +263,9 @@ qemu_generate_register() { if [ "$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=$(getopt -o ds:Q:S:e:hc:p:0: -l debian,systemd:,qemu-path:,qemu-suffix:,exportdir:,help,credential:,persistent:,preserve-argv0: -- "$@") eval set -- "$options" while true ; do @@ -380,6 +386,10 @@ while true ; do shift PERSISTENT="$1" ;; + -0|--preserve-argv0) + shift + PRESERVE_ARG0="$1" + ;; *) break ;; -- 2.21.0