Re: [Qemu-devel] [PATCH v2] linux-user: make binfmt flag O require P

["Andreas Färber" <afaerber@suse.de>]

Am 14.07.2014 20:52, schrieb Joakim Tjernlund:
> Qemu can autodetect if it is started from Linux binfmt loader

"QEMU"

> when binfmt flag O is on.
> Use that and require binfmt flag P as well which will enable QEMU
> to pass in correct argv0 to the application.
> 
> Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
> ---
>  linux-user/main.c           | 13 ++++++++++++-
>  scripts/qemu-binfmt-conf.sh | 36 ++++++++++++++++++------------------
>  2 files changed, 30 insertions(+), 19 deletions(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 71a33c7..9736768 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -3829,6 +3829,18 @@ int main(int argc, char **argv, char **envp)
>      int ret;
>      int execfd;
>  
> +    execfd = qemu_getauxval(AT_EXECFD);
> +    if (execfd > 0 ) {

Still one superfluous trailing space.

> +        if (argc < 3) {
> +            fprintf(stderr, "%s: Please use me through binfmt with P flag\n",
> +                    argv[0]);
> +            exit(1);
> +        }
> +        handle_arg_argv0(argv[2]); /* binfmt wrapper */

We might as well inline this for clarity, to distinguish from -0 /
QEMU_ARGV0 handling:

argv0 = strdup(argv[2]);

Also, what is the "binfmt wrapper" comment supposed to say here? Either
extend it, move it or drop it.

> +        memmove(&argv[2], &argv[3], (argc-2)*sizeof(argv));

Still missing spaces around * and - operators.

Why do we need to modify argv[] here when we are building a
target_argv[] further down anyway?

> +        argc--;
> +    }
> +
>      module_call_init(MODULE_INIT_QOM);
>  
>      if ((envlist = envlist_create()) == NULL) {
> @@ -4003,7 +4015,6 @@ int main(int argc, char **argv, char **envp)
>      cpu->opaque = ts;
>      task_settid(ts);
>  
> -    execfd = qemu_getauxval(AT_EXECFD);
>      if (execfd == 0) {
>          execfd = open(filename, O_RDONLY);
>          if (execfd < 0) {
[snip]

Regards,
Andreas

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