Re: [Qemu-devel] [PATCH v7 05/10] linux-user: Add support for ustat() syscall

[Riku Voipio <riku.voipio@iki.fi>]

On Thu, Sep 22, 2016 at 06:56:54PM +0200, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
> 
> This patch implements Qemu user mode ustat() syscall support.
> 
> Syscall ustat() returns information about a mounted filesystem.
> 
> Its declaration is:
> 
> int ustat(dev_t dev, struct ustat *ubuf);
> 
> Its Linux kernel implementation is at fs/compat.c, line 334.
> 
> The Qemu implementation proposed in this patch is similar to the
> Qemu implementations of statfs(), fstatfs() and other related syscalls.
> It is based on invocation of host's ustat(), and its key part is in the
> correspondent case segment of the main switch statement of the function
> do_syscall(), in file linux-user/syscalls.c. All necessary conversions
> of data structures from target to host and from host to target are
> covered. Support for target_ustat is included. Sufficient support for
> "-strace" option for this syscall is already present, and this patch
> does not change it.
> 
> This patch also fixes failures of LTP tests ustat01, and ustat02, if
> executed on Qemu-emulated systems.

Had to drop this patch from my series. Not all platforms implement
ustat anymore. As Peter suggested, it is probably better implement ustat
with calling statvfs or statfs.
 
> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
> ---
>  linux-user/syscall.c      | 23 +++++++++++++++++++++--
>  linux-user/syscall_defs.h |  6 ++++++
>  2 files changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 563796a..d28f3e6 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -48,6 +48,7 @@ int __clone2(int (*fn)(void *), void *child_stack_base,
>  #include <sys/shm.h>
>  #include <sys/sem.h>
>  #include <sys/statfs.h>
> +#include <ustat.h>
>  #include <utime.h>
>  #include <sys/sysinfo.h>
>  #include <sys/signalfd.h>
> @@ -8226,9 +8227,27 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>          ret = get_errno(chroot(p));
>          unlock_user(p, arg1, 0);
>          break;
> -#ifdef TARGET_NR_ustat
> +#if defined(TARGET_NR_ustat)
>      case TARGET_NR_ustat:
> -        goto unimplemented;
> +        {
> +            struct ustat ust;
> +
> +            ret = get_errno(ustat(arg1, &ust));
> +            if (!is_error(ret)) {
> +                struct target_ustat *target_ust;
> +
> +                if (!lock_user_struct(VERIFY_WRITE, target_ust, arg2, 0)) {
> +                    goto efault;
> +                }
> +                __put_user(ust.f_tfree, &target_ust->f_tfree);
> +                __put_user(ust.f_tinode, &target_ust->f_tinode);
> +                memcpy(target_ust->f_fname, ust.f_fname, 6);
> +                memcpy(target_ust->f_fpack, ust.f_fpack, 6);
> +                unlock_user_struct(target_ust, arg2, 1);
> +            }
> +        }
> +        break;
> +
>  #endif
>  #ifdef TARGET_NR_dup2
>      case TARGET_NR_dup2:
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index e47a61a..2c183d1 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -2164,6 +2164,12 @@ struct target_statfs64 {
>  };
>  #endif
>  
> +struct target_ustat {
> +        abi_ulong f_tfree;
> +        abi_int f_tinode;
> +        char f_fname[6];
> +        char f_fpack[6];
> +};
>  
>  #define TARGET_F_DUPFD         0       /* dup */
>  #define TARGET_F_GETFD         1       /* get close_on_exec */
> -- 
> 2.9.3
>