hw/i386: Replace magic number with field length calculation
Replce the literal magic number 48 with length calculation (32 bytes at
the end of the firmware after the table footer + 16 bytes of the OVMF
table footer GUID).
No functional change intended.
Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Message-Id: <20220222071906.2632426-3-dovmurik@linux.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
diff --git a/hw/i386/pc_sysfw_ovmf.c b/hw/i386/pc_sysfw_ovmf.c
index df15c97..07a4c26 100644
--- a/hw/i386/pc_sysfw_ovmf.c
+++ b/hw/i386/pc_sysfw_ovmf.c
@@ -30,6 +30,8 @@
#define OVMF_TABLE_FOOTER_GUID "96b582de-1fb2-45f7-baea-a366c55a082d"
+static const int bytes_after_table_footer = 32;
+
static bool ovmf_flash_parsed;
static uint8_t *ovmf_table;
static int ovmf_table_len;
@@ -53,12 +55,13 @@
/*
* if this is OVMF there will be a table footer
- * guid 48 bytes before the end of the flash file. If it's
- * not found, silently abort the flash parsing.
+ * guid 48 bytes before the end of the flash file
+ * (= 32 bytes after the table + 16 bytes the GUID itself).
+ * If it's not found, silently abort the flash parsing.
*/
qemu_uuid_parse(OVMF_TABLE_FOOTER_GUID, &guid);
guid = qemu_uuid_bswap(guid); /* guids are LE */
- ptr = flash_ptr + flash_size - 48;
+ ptr = flash_ptr + flash_size - (bytes_after_table_footer + sizeof(guid));
if (!qemu_uuid_is_equal((QemuUUID *)ptr, &guid)) {
return;
}
