Re: [Qemu-devel] [V3 PATCH 6/8] virtio-9p: Support for creating special files

[Blue Swirl]

On Tue, Jan 18, 2011 at 6:26 AM, M. Mohan Kumar <address@hidden> wrote:
> Add both server and client side interfaces to create special files
> (directory, device nodes, links and symbolic links)
>
> Signed-off-by: M. Mohan Kumar <address@hidden>
> ---
>  hw/9pfs/virtio-9p-chroot.c |   84 ++++++++++++++++++++++++++-
>  hw/9pfs/virtio-9p-chroot.h |    2 +
>  hw/9pfs/virtio-9p-local.c  |  141 
> ++++++++++++++++++++++++++++++++++----------
>  3 files changed, 195 insertions(+), 32 deletions(-)
>
> diff --git a/hw/9pfs/virtio-9p-chroot.c b/hw/9pfs/virtio-9p-chroot.c
> index e7f85e2..92a4917 100644
> --- a/hw/9pfs/virtio-9p-chroot.c
> +++ b/hw/9pfs/virtio-9p-chroot.c
> @@ -193,6 +193,29 @@ static void chroot_do_open(V9fsFileObjectRequest 
> *request, FdInfo *fd_info)
>     }
>  }
>
> +int v9fs_create_special(FsContext *fs_ctx,
> +                V9fsFileObjectRequest *request, int *error)
> +{
> +    int retval;
> +
> +    pthread_mutex_lock(&fs_ctx->chroot_mutex);
> +
> +    *error = 0;
> +    v9fs_write_request(fs_ctx->chroot_socket, request);
> +    retval = qemu_read_full(fs_ctx->chroot_socket, error, sizeof(*error));
> +    if (retval != sizeof(*error)) {
> +        error_report("reading from socket failed: %s", strerror(errno));
> +        exit(1);
> +    }
> +
> +    pthread_mutex_unlock(&fs_ctx->chroot_mutex);
> +    if (*error) {
> +        return -1;
> +    } else {
> +        return 0;
> +    }
> +}
> +
>  /*
>  * Helper routine to create a file and return the file descriptor and
>  * error status in FdInfo structure.
> @@ -229,6 +252,56 @@ unset_uid:
>     setfsuid(cur_uid);
>  }
>
> +/*
> + * Create directory, symbolic link, link, device node and regular files
> + * Similar to create, but it does not return the fd of created object
> + * Returns 0 on success, returns errno on failure
> + */
> +static int chroot_do_create_special(V9fsFileObjectRequest *request)
> +{
> +    int cur_uid, cur_gid;

uid_t cur_uid;
gid_t cur_gid;

> +    int retval, error;
> +
> +    cur_uid = geteuid();
> +    cur_gid = getegid();
> +
> +    if (setfsuid(request->data.uid) < 0) {
> +        return errno;
> +    }
> +    if (setfsgid(request->data.gid) < 0) {
> +        error = errno;
> +        goto unset_uid;
> +    }
> +
> +    switch (request->data.type) {
> +    case T_MKDIR:
> +        retval = mkdir(request->path.path, request->data.mode);
> +        break;
> +    case T_SYMLINK:
> +        retval = symlink(request->path.old_path, request->path.path);
> +        break;
> +    case T_LINK:
> +        retval = link(request->path.old_path, request->path.path);
> +        break;
> +    default:
> +        retval = mknod(request->path.path, request->data.mode,
> +                        request->data.dev);
> +        break;
> +    }
> +
> +    if (retval < 0) {
> +        error = errno;
> +    } else {
> +        error = 0;
> +    }
> +
> +    setfsgid(cur_gid);
> +unset_uid:
> +    setfsuid(cur_uid);
> +
> +    return error;
> +}
> +
>  static int chroot_daemonize(int chroot_sock)
>  {
>     sigset_t sigset;
> @@ -263,7 +336,7 @@ static int chroot_daemonize(int chroot_sock)
>  */
>  int v9fs_chroot(FsContext *fs_ctx)
>  {
> -    int fd_pair[2], pid, chroot_sock, error;
> +    int fd_pair[2], pid, chroot_sock, error, retval;
>     V9fsFileObjectRequest request;
>     FdInfo fd_info;
>
> @@ -318,6 +391,15 @@ int v9fs_chroot(FsContext *fs_ctx)
>                 error = -2;
>             }
>             break;
> +        case T_MKDIR:
> +        case T_SYMLINK:
> +        case T_LINK:
> +        case T_MKNOD:
> +            retval = chroot_do_create_special(&request);
> +            if (qemu_write_full(chroot_sock, &retval, sizeof(retval)) < 0) {
> +                error = -2;
> +            }
> +            break;
>         default:
>             break;
>         }
> diff --git a/hw/9pfs/virtio-9p-chroot.h b/hw/9pfs/virtio-9p-chroot.h
> index f5a2ca0..9a0ba88 100644
> --- a/hw/9pfs/virtio-9p-chroot.h
> +++ b/hw/9pfs/virtio-9p-chroot.h
> @@ -36,5 +36,7 @@ typedef struct V9fsFileObjectRequest
>
>  int v9fs_chroot(FsContext *fs_ctx);
>  int v9fs_request(FsContext *fs_ctx, V9fsFileObjectRequest *or, int *error);
> +int v9fs_create_special(FsContext *fs_ctx,
> +                V9fsFileObjectRequest *request, int *error);
>
>  #endif /* _QEMU_VIRTIO_9P_CHROOT_H */
> diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
> index 7f39b40..08fd67f 100644
> --- a/hw/9pfs/virtio-9p-local.c
> +++ b/hw/9pfs/virtio-9p-local.c
> @@ -69,6 +69,78 @@ static int __create(FsContext *fs_ctx, const char *path, 
> int flags,
>     return fd;
>  }
>
> +static int __mknod(FsContext *fs_ctx, const char *path, FsCred *credp)

underscores