ACPICA: Add support for zero-length buffer-to-string conversions

Allow zero length strings during interpreter buffer-to-string
conversions. For example, during the ToDecimalString and
ToHexString operaters, as well as implicit conversions. Fiodor
Suietov.  ACPICA BZ 585.

http://www.acpica.org/bugzilla/show_bug.cgi?id=585

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/acpi/executer/exconvrt.c b/drivers/acpi/executer/exconvrt.c
index 890378e789a4..1d1f35adddde 100644
--- a/drivers/acpi/executer/exconvrt.c
+++ b/drivers/acpi/executer/exconvrt.c
@@ -512,9 +512,14 @@ acpi_ex_convert_to_string(union acpi_operand_object * obj_desc,
                 /*
                  * Create a new string object and string buffer
                  * (-1 because of extra separator included in string_length from above)
+                 * Allow creation of zero-length strings from zero-length buffers.
                  */
+                if (string_length) {
+                        string_length--;
+                }
+
                 return_desc = acpi_ut_create_string_object((acpi_size)
-                                                           (string_length - 1));
+                                                           string_length);
                 if (!return_desc) {
                         return_ACPI_STATUS(AE_NO_MEMORY);
                 }
@@ -537,7 +542,9 @@ acpi_ex_convert_to_string(union acpi_operand_object * obj_desc,
                  * Null terminate the string
                  * (overwrites final comma/space from above)
                  */
-                new_buf--;
+                if (obj_desc->buffer.length) {
+                        new_buf--;
+                }
                 *new_buf = 0;
                 break;