Re: [Qemu-devel] [PATCH v7 1/2] loader: Add load_image_gzipped function.

[Peter Crosthwaite]

On Sat, Aug 9, 2014 at 5:17 AM, Richard W.M. Jones <address@hidden> wrote:
> As the name suggests this lets you load a ROM/disk image that is
> gzipped.  It is uncompressed before storing it in guest memory.
>
> Signed-off-by: Richard W.M. Jones <address@hidden>
> Reviewed-by: Alex Bennée <address@hidden>

Reviewed-by: Peter Crosthwaite <address@hidden>

> ---
>  hw/core/loader.c    | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/loader.h |  1 +
>  2 files changed, 49 insertions(+)
>
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index 2bf6b8f..83136e8 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -577,6 +577,54 @@ int load_ramdisk(const char *filename, hwaddr addr, 
> uint64_t max_sz)
>      return load_uboot_image(filename, NULL, &addr, NULL, IH_TYPE_RAMDISK);
>  }
>
> +/* This simply prevents g_malloc in the function below from allocating
> + * a huge amount of memory, by placing a limit on the maximum
> + * uncompressed image size that load_image_gzipped will read.
> + */
> +#define LOAD_IMAGE_MAX_GUNZIP_BYTES (256 << 20)
> +
> +/* Load a gzip-compressed kernel. */
> +int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz)
> +{
> +    uint8_t *compressed_data = NULL;
> +    uint8_t *data = NULL;
> +    gsize len;
> +    ssize_t bytes;
> +    int ret = -1;
> +
> +    if (!g_file_get_contents(filename, (char **) &compressed_data, &len,
> +                             NULL)) {
> +        goto out;
> +    }
> +
> +    /* Is it a gzip-compressed file? */
> +    if (len < 2 ||
> +        compressed_data[0] != 0x1f ||
> +        compressed_data[1] != 0x8b ) {
> +        goto out;
> +    }
> +
> +    if (max_sz > LOAD_IMAGE_MAX_GUNZIP_BYTES) {
> +        max_sz = LOAD_IMAGE_MAX_GUNZIP_BYTES;
> +    }
> +
> +    data = g_malloc(max_sz);
> +    bytes = gunzip(data, max_sz, compressed_data, len);
> +    if (bytes < 0) {
> +        fprintf(stderr, "%s: unable to decompress gzipped kernel file\n",
> +                filename);
> +        goto out;
> +    }
> +
> +    rom_add_blob_fixed(filename, data, bytes, addr);
> +    ret = bytes;
> +
> + out:
> +    g_free(compressed_data);
> +    g_free(data);
> +    return ret;
> +}
> +
>  /*
>   * Functions for reboot-persistent memory regions.
>   *  - used for vga bios and option roms.
> diff --git a/include/hw/loader.h b/include/hw/loader.h
> index 796cbf9..00c9117 100644
> --- a/include/hw/loader.h
> +++ b/include/hw/loader.h
> @@ -15,6 +15,7 @@ int get_image_size(const char *filename);
>  int load_image(const char *filename, uint8_t *addr); /* deprecated */
>  int load_image_targphys(const char *filename, hwaddr,
>                          uint64_t max_sz);
> +int load_image_gzipped(const char *filename, hwaddr addr, uint64_t max_sz);
>
>  #define ELF_LOAD_FAILED       -1
>  #define ELF_LOAD_NOT_ELF      -2
> --
> 2.0.4
>
>