[V2,4/8] acpi: build_append_nameseg(): add padding if necessary

According to ACPI spec NameSeg shorter than 4 characters
must be padded up to 4 characters with "_" symbol.
ACPI 5.0:  20.2.2 "Name Objects Encoding"

Do it in build_append_nameseg() so that caller shouldn't know
or care about it.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
v2:
  * simplify padding, suggested by: "Michael S. Tsirkin" <mst@redhat.com>
---
 hw/i386/acpi-build.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

On 16.12.2014 11:58, Igor Mammedov wrote:
> According to ACPI spec NameSeg shorter than 4 characters
> must be padded up to 4 characters with "_" symbol.
> ACPI 5.0:  20.2.2 "Name Objects Encoding"
> 
> Do it in build_append_nameseg() so that caller shouldn't know
> or care about it.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v2:
>   * simplify padding, suggested by: "Michael S. Tsirkin" <mst@redhat.com>
> ---
>  hw/i386/acpi-build.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index f5ec66a..2bf9a09 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -292,6 +292,8 @@ static inline void build_append_array(GArray *array, GArray *val)
>      g_array_append_vals(array, val->data, val->len);
>  }
>  
> +#define ACPI_NAMESEG_LEN 4
> +
>  static void GCC_FMT_ATTR(2, 3)
>  build_append_nameseg(GArray *array, const char *format, ...)
>  {
> @@ -304,8 +306,11 @@ build_append_nameseg(GArray *array, const char *format, ...)
>      len = vsnprintf(s, sizeof s, format, args);
>      va_end(args);
>  
> -    assert(len == 4);
> +    assert(len <= ACPI_NAMESEG_LEN);
> +
>      g_array_append_vals(array, s, len);
> +    /* Pad up to ACPI_NAMESEG_LEN characters if necessary. */
> +    g_array_append_vals(array, "____", ACPI_NAMESEG_LEN - len);
>  }
>  
>  /* 5.4 Definition Block Encoding */
> @@ -846,7 +851,7 @@ static void build_pci_bus_end(PCIBus *bus, void *bus_state)
>  
>      if (bus->parent_dev) {
>          op = 0x82; /* DeviceOp */
> -        build_append_nameseg(bus_table, "S%.02X_",
> +        build_append_nameseg(bus_table, "S%.02X",
>                               bus->parent_dev->devfn);
>          build_append_byte(bus_table, 0x08); /* NameOp */
>          build_append_nameseg(bus_table, "_SUN");
> @@ -966,7 +971,7 @@ static void build_pci_bus_end(PCIBus *bus, void *bus_state)
>              build_append_int(notify, 0x1U << i);
>              build_append_byte(notify, 0x00); /* NullName */
>              build_append_byte(notify, 0x86); /* NotifyOp */
> -            build_append_nameseg(notify, "S%.02X_", PCI_DEVFN(i, 0));
> +            build_append_nameseg(notify, "S%.02X", PCI_DEVFN(i, 0));
>              build_append_byte(notify, 0x69); /* Arg1Op */
>  
>              /* Pack it up */
> @@ -1023,7 +1028,7 @@ static void build_pci_bus_end(PCIBus *bus, void *bus_state)
>          if (bus->parent_dev) {
>              build_append_byte(parent->notify_table, '^'); /* ParentPrefixChar */
>              build_append_byte(parent->notify_table, 0x2E); /* DualNamePrefix */
> -            build_append_nameseg(parent->notify_table, "S%.02X_",
> +            build_append_nameseg(parent->notify_table, "S%.02X",
>                                   bus->parent_dev->devfn);
>              build_append_nameseg(parent->notify_table, "PCNT");
>          }
> @@ -1093,7 +1098,7 @@ build_ssdt(GArray *table_data, GArray *linker,
>          GArray *sb_scope = build_alloc_array();
>          uint8_t op = 0x10; /* ScopeOp */
>  
> -        build_append_nameseg(sb_scope, "_SB_");
> +        build_append_nameseg(sb_scope, "_SB");
>  
>          /* build Processor object for each processor */
>          for (i = 0; i < acpi_cpus; i++) {
> 
Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>