Re: [Xen-devel] [PATCH v4 12/12] livepatch: Add python bindings for livepatch operations

[Ross Lagerwall <ross.lagerwall@citrix.com>]

On 9/28/19 4:13 PM, Pawel Wieczorkiewicz wrote:
> Extend the XC python bindings library to support also all common
> livepatch operations and actions.
> 
> Add the python bindings for the following operations:
> - status (pyxc_livepatch_status):
>    Requires a payload name as an input.
>    Returns a status dict containing a state string and a return code
>    integer.
> - action (pyxc_livepatch_action):
>    Requires a payload name and an action id as an input. Timeout and
>    flags are optional parameters.
>    Returns None or throws an exception.
> - upload (pyxc_livepatch_upload):
>    Requires a payload name and a module's filename as an input.
>    Returns None or throws an exception.
> - list (pyxc_livepatch_list):
>    Takes no parameters.
>    Returns a list of dicts containing each payload's:
>    * name as a string
>    * state as a string
>    * return code as an integer
>    * list of metadata key=value strings
> 
> Each functions throws an exception error based on the errno value
> received from its corresponding libxc function call.
> 
snip> +static PyObject *pyxc_livepatch_upload(XcObject *self,
> +                                       PyObject *args,
> +                                       PyObject *kwds)
> +{
> +    unsigned char *fbuf = MAP_FAILED;
> +    char *name, *filename;
> +    struct stat buf;
> +    int fd = 0, rc = -1, saved_errno;
> +    ssize_t len;
> +
> +    static char *kwd_list[] = { "name", "filename", NULL };
> +
> +    if ( !PyArg_ParseTupleAndKeywords(args, kwds, "ss", kwd_list,
> +                                      &name, &filename))
> +        goto error;
> +
> +    fd = open(filename, O_RDONLY);
> +    if ( fd < 0 )
> +        goto error;
> +
> +    if ( fstat(fd, &buf) != 0 )
> +        goto error;
> +
> +    len = buf.st_size;
> +    fbuf = mmap(0, len, PROT_READ, MAP_PRIVATE, fd, 0);
> +    if ( fbuf == MAP_FAILED )
> +        goto error;
> +
> +    rc = xc_livepatch_upload(self->xc_handle, name, fbuf, len);
> +
> +    saved_errno = errno;
> +    munmap(fbuf, len);
> +    close(fd);
> +    errno = saved_errno;
> +
> +error:
> +    return rc ? pyxc_error_to_exception(self->xc_handle) : Py_None;
> +}
> +
The fstat() and mmap() error paths leak fd on error.

Regards,
-- 
Ross Lagerwall

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