[1.0] 9pfs: improve portability to older systems

Small requirements on "new" features have percolated to virtio-9p-local.c.
In particular, the utimensat wrapper actually only supports dirfd = AT_FDCWD
and flags = AT_SYMLINK_NOFOLLOW in the fallback code.  Remove the arguments
so that virtio-9p-local.c will not use AT_* constants.

At the same time, fail local_ioc_getversion if the ioctl is not supported
by the host.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/9pfs/virtio-9p-local.c |    7 +++++--
 oslib-posix.c             |    5 ++---
 qemu-os-posix.h           |    3 +--
 3 files changed, 8 insertions(+), 7 deletions(-)

On 11/21/2011 02:29 AM, Paolo Bonzini wrote:
> Small requirements on "new" features have percolated to virtio-9p-local.c.
> In particular, the utimensat wrapper actually only supports dirfd = AT_FDCWD
> and flags = AT_SYMLINK_NOFOLLOW in the fallback code.  Remove the arguments
> so that virtio-9p-local.c will not use AT_* constants.
>
> At the same time, fail local_ioc_getversion if the ioctl is not supported
> by the host.
>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
>   hw/9pfs/virtio-9p-local.c |    7 +++++--
>   oslib-posix.c             |    5 ++---
>   qemu-os-posix.h           |    3 +--
>   3 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
> index 7f1c089..cbd07e8 100644
> --- a/hw/9pfs/virtio-9p-local.c
> +++ b/hw/9pfs/virtio-9p-local.c
> @@ -583,8 +583,7 @@ static int local_utimensat(FsContext *s, V9fsPath *fs_path,
>       char buffer[PATH_MAX];
>       char *path = fs_path->data;
>
> -    return qemu_utimensat(AT_FDCWD, rpath(s, path, buffer), buf,
> -                          AT_SYMLINK_NOFOLLOW);
> +    return qemu_utimens(rpath(s, path, buffer), buf);

Hrm, I thought the SYMLINK_NOFOLLOW was critical in enforcing security?

Regards,

Anthony Liguori

>   }
>
>   static int local_remove(FsContext *ctx, const char *path)
> @@ -694,6 +693,7 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
>                                   mode_t st_mode, uint64_t *st_gen)
>   {
>       int err;
> +#ifdef FS_IOC_GETVERSION
>       V9fsFidOpenState fid_open;
>
>       /*
> @@ -709,6 +709,9 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
>       }
>       err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
>       local_close(ctx,&fid_open);
> +#else
> +    err = -ENOTTY;
> +#endif
>       return err;
>   }
>
> diff --git a/oslib-posix.c b/oslib-posix.c
> index 6f29762..ce75549 100644
> --- a/oslib-posix.c
> +++ b/oslib-posix.c
> @@ -162,8 +162,7 @@ int qemu_pipe(int pipefd[2])
>       return ret;
>   }
>
> -int qemu_utimensat(int dirfd, const char *path, const struct timespec *times,
> -                   int flags)
> +int qemu_utimens(const char *path, const struct timespec *times)
>   {
>       struct timeval tv[2], tv_now;
>       struct stat st;
> @@ -171,7 +170,7 @@ int qemu_utimensat(int dirfd, const char *path, const struct timespec *times,
>   #ifdef CONFIG_UTIMENSAT
>       int ret;
>
> -    ret = utimensat(dirfd, path, times, flags);
> +    ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
>       if (ret != -1 || errno != ENOSYS) {
>           return ret;
>       }
> diff --git a/qemu-os-posix.h b/qemu-os-posix.h
> index 920499d..8e1149d 100644
> --- a/qemu-os-posix.h
> +++ b/qemu-os-posix.h
> @@ -44,7 +44,6 @@ typedef struct timeval qemu_timeval;
>   #endif
>   #endif
>   typedef struct timespec qemu_timespec;
> -int qemu_utimensat(int dirfd, const char *path, const qemu_timespec *times,
> -    int flags);
> +int qemu_utimens(const char *path, const qemu_timespec *times);
>
>   #endif

On 11/21/2011 10:01 PM, Anthony Liguori wrote:
>>
>> -    return qemu_utimensat(AT_FDCWD, rpath(s, path, buffer), buf,
>> -                          AT_SYMLINK_NOFOLLOW);
>> +    return qemu_utimens(rpath(s, path, buffer), buf);
>
> Hrm, I thought the SYMLINK_NOFOLLOW was critical in enforcing security?

Yes, and it is applied by qemu_utimens automatically (but the constant 
only appears in a section where we know it is defined).

Paolo