Re: [Qemu-devel] [PATCH 6/6] hw/nvram/fw_cfg: Add fw_cfg_add_file_from_host()

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Dec 07, 2018 at 06:04:00PM +0100, Philippe Mathieu-Daudé wrote:
> Add a function to read the full content of file on the host, and add
> a new 'file' name item to the fw_cfg device.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Need to be careful with options that let users play with firmware.
Way too easy to create conflicts.
Anyway, I'd rather have this included with whatever is using it.

> ---
>  hw/nvram/fw_cfg.c         | 22 ++++++++++++++++++++++
>  include/hw/nvram/fw_cfg.h | 22 ++++++++++++++++++++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 50525ec1dd..f3232fcb16 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -842,6 +842,28 @@ void fw_cfg_add_file(FWCfgState *s,  const char *filename,
>      fw_cfg_add_file_callback(s, filename, NULL, NULL, NULL, data, len, true);
>  }
>  
> +void *fw_cfg_add_file_from_host(FWCfgState *s, const char *filename,
> +                                const char *host_path, size_t *len)
> +{
> +    GError *gerr = NULL;
> +    gchar *ptr = NULL;
> +    gsize contents_len = 0;
> +
> +
> +    if (g_file_get_contents(host_path, &ptr, &contents_len, &gerr)) {
> +        fw_cfg_add_file(s, filename, ptr, contents_len);
> +    } else {
> +        error_report("failed to read file %s, %s", host_path, gerr->message);
> +        g_error_free(gerr);
> +        return NULL;
> +    }
> +    if (len) {
> +        *len = contents_len;
> +    }
> +
> +    return ptr;
> +}
> +
>  void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
>                          void *data, size_t len)
>  {
> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
> index 28630b2f26..8de8d63433 100644
> --- a/include/hw/nvram/fw_cfg.h
> +++ b/include/hw/nvram/fw_cfg.h
> @@ -166,6 +166,28 @@ void fw_cfg_add_i64(FWCfgState *s, uint16_t key, uint64_t value);
>  void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
>                       size_t len);
>  
> +/**
> + * fw_cfg_add_file_from_host:
> + * @s: fw_cfg device being modified
> + * @filename: name of new fw_cfg file item
> + * @host_path: path of the host file to read the data from
> + * @len: pointer to hold the length of the host file (optional)
> + *
> + * Read the content of a host file as a raw "blob" then add a new NAMED
> + * fw_cfg item of the file size. If @len is provided, it will contains the
> + * total length read from the host file. The data referenced by the starting
> + * pointer is only linked, NOT copied, into the data structure of the fw_cfg
> + * device.
> + * The next available (unused) selector key starting at FW_CFG_FILE_FIRST
> + * will be used; also, a new entry will be added to the file directory
> + * structure residing at key value FW_CFG_FILE_DIR, containing the item name,
> + * data size, and assigned selector key value.
> + *
> + * Returns: pointer to the file content, or NULL if an error occured.
> + */
> +void *fw_cfg_add_file_from_host(FWCfgState *s, const char *filename,
> +                                const char *host_path, size_t *len);
> +
>  /**
>   * fw_cfg_add_file_callback:
>   * @s: fw_cfg device being modified
> -- 
> 2.17.2