[PATCH] ACPI: improve acpi_extract_package() utility

[al.stone@linaro.org]

From: Al Stone <ahs3@redhat.com>

  The current version requires one to know the size of the package
  a priori; this is almost impossible if the package is composed of
  strings of variable length.  This change allows the utility to
  allocate a buffer of the proper size if asked.

Signed-off-by: Al Stone <al.stone@linaro.org>
---
 drivers/acpi/utils.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 552248b..fc2cd32 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -169,11 +169,20 @@ acpi_extract_package(union acpi_object *package,
 	/*
 	 * Validate output buffer.
 	 */
-	if (buffer->length < size_required) {
+	if (buffer->length == ACPI_ALLOCATE_BUFFER) {
+		buffer->pointer = ACPI_ALLOCATE(size_required);
+		if (!buffer->pointer)
+			return AE_NO_MEMORY;
 		buffer->length = size_required;
-		return AE_BUFFER_OVERFLOW;
-	} else if (buffer->length != size_required || !buffer->pointer) {
-		return AE_BAD_PARAMETER;
+		memset(buffer->pointer, 0, size_required);
+	} else {
+		if (buffer->length < size_required) {
+			buffer->length = size_required;
+			return AE_BUFFER_OVERFLOW;
+		} else if (buffer->length != size_required ||
+			   !buffer->pointer) {
+			return AE_BAD_PARAMETER;
+		}
 	}
 
 	head = buffer->pointer;
-- 
1.8.3.1