Le 22/01/2016 11:01, Petros Angelatos a écrit : >>> 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
linux-user works only on linux. qemu uses glib-2.0, so you can use g_find_program_in_path(). >>> 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. if we have less than 2 bytes, we can guess it is not executable... >>> + /* 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 http://wiki.qemu.org/Contribute/SubmitAPatch > 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 Generally, it's better to not delete parts. So, someone tacking the mail thread at a moment can read the whole history in the last mail. > 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? Do as you want, but more you send versions, more you (can) have reviews. BTW, I'm not the linux-user maintainer (Riku is), so I can just review and comment, no more. > > Thanks, > Petros Laurent