>> diff --git a/linux-user/main.c b/linux-user/main.c >> index ee12035..5951279 100644 >> --- a/linux-user/main.c >> +++ b/linux-user/main.c >> @@ -79,6 +79,7 @@ static void usage(int exitcode); >> >> static const char *interp_prefix = CONFIG_QEMU_INTERP_PREFIX; >> const char *qemu_uname_release; >> +const char *qemu_execve_path; >> >> /* XXX: on x86 MAP_GROWSDOWN only works if ESP <= address + 32, so >> we allocate a bigger stack. Need a better solution, for example >> @@ -3828,6 +3829,11 @@ static void handle_arg_guest_base(const char *arg) >> have_guest_base = 1; >> } >> >> +static void handle_arg_execve(const char *arg) >> +{ >> + qemu_execve_path = strdup(arg); > > I think you can use the parameter just as an on/off switch and > realpath(argv[0]) as qemu_execve_path. > > I don't see any reason to use other binary than the one in use.
This was my initial approach too, but argv[0] can be just the filename like "qemu-arm-static". And while I could add extra logic to look this up in the PATH, someone could run it from a completely different location. Then I looked for a way to get the path of the current executable but every platform has its own way of doing that and I didn't want to add all these cases. https://stackoverflow.com/questions/1023306/finding-current-executables-path-without-proc-self-exe >> diff --git a/linux-user/syscall.c b/linux-user/syscall.c >> index 0cbace4..d0b5442 100644 >> --- a/linux-user/syscall.c >> +++ b/linux-user/syscall.c >> @@ -5854,6 +5854,109 @@ static target_timer_t get_timer_id(abi_long arg) >> return timerid; >> } >> >> +#define BINPRM_BUF_SIZE 128 > > This is defined in <linux/binfmts.h> Got it, I'll add this header and remove the definition. > >> +/* qemu_execve() Must return target values and target errnos. */ >> +static abi_long qemu_execve(char *filename, char *argv[], >> + char *envp[]) >> +{ >> + char *i_arg = NULL, *i_name = NULL; >> + char **new_argp; >> + int argc, fd, ret, i, offset = 3; >> + char *cp; >> + char buf[BINPRM_BUF_SIZE]; >> + >> + for (argc = 0; argv[argc] != NULL; argc++) { >> + /* nothing */ ; >> + } >> + >> + fd = open(filename, O_RDONLY); >> + if (fd == -1) { >> + return -ENOENT; > > return -errno; ? Will fix in v2 >> + ret = read(fd, buf, BINPRM_BUF_SIZE); >> + if (ret == -1) { >> + close(fd); >> + return -ENOENT; > > return -errno; ? Will fix in v2 >> + } >> + >> + close(fd); >> + >> + /* adapted from the kernel >> + * >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/binfmt_script.c >> + */ >> + if ((buf[0] == '#') && (buf[1] == '!')) { > > what happens if read() < 2 ? Hm, the easy option is for qemu_execve to return ENOEXEC or EIO. Otherwise I could retry the read N times? I'm not sure how to handle this if we don't want to return an error. >> + /* Copy the original arguments with offset */ >> + for (i = 0; i < argc; i++) { >> + new_argp[i + offset] = argv[i]; >> + } >> + >> + new_argp[0] = strdup(qemu_execve_path); >> + new_argp[1] = strdup("-0"); >> + new_argp[offset] = filename; >> + new_argp[argc + offset] = NULL; >> + >> + if (i_name) { >> + new_argp[2] = i_name; >> + new_argp[3] = i_name; >> + >> + if (i_arg) { >> + new_argp[4] = i_arg; >> + } >> + } else { >> + new_argp[2] = argv[0]; >> + } >> + >> + return get_errno(execve(qemu_execve_path, new_argp, envp)); > > duplicate get_errno() with the caller. I'll add the logic proposed bellow in this function and remove the duplicate get_errno() from the caller. >> /* do_syscall() should always have a single exit point at the end so >> that actions, such as logging of syscall results, can be performed. >> All errnos that do_syscall() returns must be -TARGET_<errcode>. */ >> @@ -6113,7 +6216,13 @@ abi_long do_syscall(void *cpu_env, int num, abi_long >> arg1, >> >> if (!(p = lock_user_string(arg1))) >> goto execve_efault; >> - ret = get_errno(execve(p, argp, envp)); >> + >> + if (qemu_execve_path && *qemu_execve_path) { >> + ret = get_errno(qemu_execve(p, argp, envp)); >> + } else { >> + ret = get_errno(execve(p, argp, envp)); >> + } >> + > > what do you think of: > > ret = qemu_execve(p, argp, envp); > > and in qemu_execve(): > > if (qemu_execve_path == NULL || *qemu_execve_path == 0) { > return get_errno(execve(p, argp, envp)); > } > > so all the logic is in the function. Sounds good, I'll include this in v2 Since I'm new to this style of contribution I have a couple of questions. Is it ok that I deleted part of the patch for my reply to code review, or should I have replied inline without deleting anything? Should I send v2 after we resolve all the issues here or should I send a v2 with proposed fixes but lacking the ones pending replies? Thanks, Petros