Re: [Qemu-devel] [PATCH] aml-build: don't modify child

[Igor Mammedov <imammedo@redhat.com>]

On Sat, 7 Mar 2015 20:51:33 +0100
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> this code:
>     aml_append(foo, bar);
> 
> might, non-intuitively, modify bar, which means that e.g. the following
> might not DTRT:
> 
>     c = ....;
>     aml_append(a, c);
>     aml_append(b, c);
> 
> to fix, simply allocate an intermediate array,
> and always modify that.
While at it, could 'c' be made 'const Aml*' argument of aml_append() ???

> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/acpi/aml-build.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index 876cada..ff12b28 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -335,26 +335,29 @@ static void build_buffer(GArray *array, uint8_t op)
>  
>  void aml_append(Aml *parent_ctx, Aml *child)
>  {
> +    GArray *buf = build_alloc_array();
> +    build_append_array(buf, child->buf);
> +
>      switch (child->block_flags) {
>      case AML_OPCODE:
>          build_append_byte(parent_ctx->buf, child->op);
>          break;
>      case AML_EXT_PACKAGE:
> -        build_extop_package(child->buf, child->op);
> +        build_extop_package(buf, child->op);
>          break;
>      case AML_PACKAGE:
> -        build_package(child->buf, child->op);
> +        build_package(buf, child->op);
>          break;
>      case AML_RES_TEMPLATE:
> -        build_append_byte(child->buf, 0x79); /* EndTag */
> +        build_append_byte(buf, 0x79); /* EndTag */
>          /*
>           * checksum operations are treated as succeeded if checksum
>           * field is zero. [ACPI Spec 1.0b, 6.4.2.8 End Tag]
>           */
> -        build_append_byte(child->buf, 0);
> +        build_append_byte(buf, 0);
>          /* fall through, to pack resources in buffer */
>      case AML_BUFFER:
> -        build_buffer(child->buf, child->op);
> +        build_buffer(buf, child->op);
>          break;
>      case AML_NO_OPCODE:
>          break;
> @@ -362,7 +365,8 @@ void aml_append(Aml *parent_ctx, Aml *child)
>          assert(0);
>          break;
>      }
> -    build_append_array(parent_ctx->buf, child->buf);
> +    build_append_array(parent_ctx->buf, buf);
> +    build_free_array(buf);
>  }
>  
>  /* ACPI 1.0b: 16.2.5.1 Namespace Modifier Objects Encoding: DefScope */