Le 22/02/2021 à 15:45, Michael Tokarev a écrit : > 22.02.2021 13:50, Laurent Vivier wrote: >> 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) > > A few days ago I sent an RFC patch which fixes this issue without kernel > patch, by registering special binary name in binfmt (note: that patch had > argv[1] & argv[2] swapped by mistake). > > Here it is: > https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg04639.html > In this case, we don't want to modify QEMU to manage special case based on the binary name but instead use a wrapper:
- add a proper parameter to manage the argv0 case [like this one https://patchew.org/QEMU/20191024153847.31815-1-laur...@vivier.eu/ but I think now it would be better to use a new flag rather than using -0 ""] - write a wrapper and name it "/usr/libexec/qemu-binfmt/foo-binfmt-P" - the wrapper will call qemu-foo with the new parameter: something like (with the example patch above): #include <stdio.h> #include <unistd.h> #include <string.h> static const char *baseargv[] = { "-0", "", }; int main(int argc, char **argv, char **envp) { char *newargv[argc + sizeof(baseargv) / sizeof(char *) + 1]; int current = 0; newargv[current] = argv[0]; current++; memcpy(&newargv[current], baseargv, sizeof(baseargv)); current += sizeof(baseargv) / sizeof(char *); memcpy(&newargv[current], &argv[1], sizeof(*argv) * (argc - 1)); current += argc - 1; newargv[current] = NULL; return execve("/qemu-foo", newargv, envp); } Thanks, Laurent
