[PATCH] linux-user: report ENOTTY for unknown ioctls

[PATCH] linux-user: report ENOTTY for unknown ioctls

[Thomas Weißschuh]

The correct error number for unknown ioctls is ENOTTY.

ENOSYS would mean that the ioctl() syscall itself is not implemented,
which is very improbable and unexpected for userspace.

ENOTTY means "Inappropriate ioctl for device". This is what the kernel
returns on unknown ioctls, what qemu is trying to express and what
userspace is prepared to handle.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 linux-user/syscall.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 69f740ff98c8..c5955313a063 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5747,7 +5747,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
         if (ie->target_cmd == 0) {
             qemu_log_mask(
                 LOG_UNIMP, "Unsupported ioctl: cmd=0x%04lx\n", (long)cmd);
-            return -TARGET_ENOSYS;
+            return -TARGET_ENOTTY;
         }
         if (ie->target_cmd == cmd)
             break;
@@ -5759,7 +5759,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
     } else if (!ie->host_cmd) {
         /* Some architectures define BSD ioctls in their headers
            that are not implemented in Linux.  */
-        return -TARGET_ENOSYS;
+        return -TARGET_ENOTTY;
     }
 
     switch(arg_type[0]) {
@@ -5817,7 +5817,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
         qemu_log_mask(LOG_UNIMP,
                       "Unsupported ioctl type: cmd=0x%04lx type=%d\n",
                       (long)cmd, arg_type[0]);
-        ret = -TARGET_ENOSYS;
+        ret = -TARGET_ENOTTY;
         break;
     }
     return ret;

base-commit: a14b8206c5edcbbad1c71256ea9b44c3b382a9f5
-- 
2.40.1

Re: [PATCH] linux-user: report ENOTTY for unknown ioctls

[Philippe Mathieu-Daudé]

On 26/4/23 09:06, Thomas Weißschuh wrote:
> The correct error number for unknown ioctls is ENOTTY.
> 
> ENOSYS would mean that the ioctl() syscall itself is not implemented,
> which is very improbable and unexpected for userspace.
> 
> ENOTTY means "Inappropriate ioctl for device". This is what the kernel
> returns on unknown ioctls, what qemu is trying to express and what
> userspace is prepared to handle.
> 
> Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
> ---
>   linux-user/syscall.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH] linux-user: report ENOTTY for unknown ioctls

[Laurent Vivier]

Le 26/04/2023 à 09:06, Thomas Weißschuh a écrit :
> The correct error number for unknown ioctls is ENOTTY.
> 
> ENOSYS would mean that the ioctl() syscall itself is not implemented,
> which is very improbable and unexpected for userspace.
> 
> ENOTTY means "Inappropriate ioctl for device". This is what the kernel
> returns on unknown ioctls, what qemu is trying to express and what
> userspace is prepared to handle.
> 
> Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
> ---
>   linux-user/syscall.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 69f740ff98c8..c5955313a063 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -5747,7 +5747,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
>           if (ie->target_cmd == 0) {
>               qemu_log_mask(
>                   LOG_UNIMP, "Unsupported ioctl: cmd=0x%04lx\n", (long)cmd);
> -            return -TARGET_ENOSYS;
> +            return -TARGET_ENOTTY;
>           }
>           if (ie->target_cmd == cmd)
>               break;
> @@ -5759,7 +5759,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
>       } else if (!ie->host_cmd) {
>           /* Some architectures define BSD ioctls in their headers
>              that are not implemented in Linux.  */
> -        return -TARGET_ENOSYS;
> +        return -TARGET_ENOTTY;
>       }
>   
>       switch(arg_type[0]) {
> @@ -5817,7 +5817,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
>           qemu_log_mask(LOG_UNIMP,
>                         "Unsupported ioctl type: cmd=0x%04lx type=%d\n",
>                         (long)cmd, arg_type[0]);
> -        ret = -TARGET_ENOSYS;
> +        ret = -TARGET_ENOTTY;
>           break;
>       }
>       return ret;
> 
> base-commit: a14b8206c5edcbbad1c71256ea9b44c3b382a9f5

Applied to my linux-user-for-8.1 branch.

Thanks,
Laurent