Re: [Qemu-devel] [PATCH 1/4] block: adding lzfse decompressing support as a module.

[Kevin Wolf <kwolf@redhat.com>]

Am 10.08.2018 um 06:07 hat Julio Faracco geschrieben:
> QEMU dmg support includes zlib and bzip2, but it does not contains lzfse
> support. This commit adds the source file to extend compression support
> for new DMGs.
> 
> Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
> ---
>  block/dmg-lzfse.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
>  create mode 100644 block/dmg-lzfse.c
> 
> diff --git a/block/dmg-lzfse.c b/block/dmg-lzfse.c
> new file mode 100644
> index 0000000000..d09b544a0a
> --- /dev/null
> +++ b/block/dmg-lzfse.c
> @@ -0,0 +1,54 @@
> +/*
> + * DMG lzfse uncompression
> + *
> + * Copyright (c) 2018 Julio Cesar Faracco
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +#include "dmg.h"
> +#include <lzfse.h>
> +
> +static int dmg_uncompress_lzfse_do(char *next_in, unsigned int avail_in,
> +                                   char *next_out, unsigned int avail_out)
> +{
> +    void *aux;
> +    size_t aux_allocated;
> +    size_t out_size;
> +
> +    aux_allocated = lzfse_decode_scratch_size();
> +    aux = g_malloc(aux_allocated);
> +
> +    if (aux_allocated != 0 && aux == 0) {
> +        return -1;
> +    }
> +
> +    out_size = lzfse_decode_buffer((uint8_t *) next_out, avail_out,
> +                                   (uint8_t *) next_in, avail_in, aux);
> +
> +    return out_size;
> +}

aux is leaked in this function.

Also, I don't think we actually need it. lzfse_decode_buffer() is
documented to just do the necessary allocation internally if NULL is
passed. Unless we do something more sophisticated, doing the memory
allocation ourselves is unnecessary complexity.

Kevin