patterns: add UEFI Boot Entry pattern (#183)

add uefi_boot_entry pattern

patterns/uefi_boot_entry.hexpat

@@ -0,0 +1,74 @@
+// subsections in this pattern refer to subsections in the
+// UEFI Specification Release 2.10 from Aug 29 2022
+
+#pragma author iTrooz
+#pragma description UEFI Boot Entry (Load option)
+
+#include <std/io.pat>
+#include <type/guid.pat>
+
+// subsection 10.3.5.1
+struct HARD_DRIVE {
+    u32 partitionNumber;
+    u64 partitionStart;
+    u64 partitionSize;
+    type::GUID partitionSig;
+    u8 format;
+    u8 sigType;
+};
+
+// subsection 10.3.5.4
+struct FILE_PATH {
+    char16 path[];
+};
+
+// subsection 10.3.1
+enum MEDIA_DEVICE_PATH_SUBTYPE : u8 {
+  HARD_DRIVE = 0x01,
+  FILE_PATH = 0x04,  
+};
+
+enum DEVICE_PATH_TYPE : u8 {
+    MEDIA_DEVICE_PATH = 0x04,
+};
+
+// subsection 10.2
+// EFI_DEVICE_PATH_PROTOCOL
+struct DEVICE_PATH {
+    u8 type;
+    u8 subtype;
+    // length of this DEVICE_PATH structure
+    u16 length;
+    // the size of the data is the size of the structure minus the fields we know.
+    // not always used
+    u16 dataSize = length-1-1-2;
+    
+    match (type, subtype) {
+        (DEVICE_PATH_TYPE::MEDIA_DEVICE_PATH, MEDIA_DEVICE_PATH_SUBTYPE::HARD_DRIVE): HARD_DRIVE data;
+        (DEVICE_PATH_TYPE::MEDIA_DEVICE_PATH, MEDIA_DEVICE_PATH_SUBTYPE::FILE_PATH): FILE_PATH data;                              
+        (_, _): u8 data[dataSize];
+    }
+};
+
+// subsections 3.1.3
+// EFI_LOAD_OPTION
+struct LOAD_OPTION {
+    u32 attributes;
+    // length of the filePathList data
+    u16 filePathLength;
+    char16 description[];
+
+    u64 startOffset = $;
+    DEVICE_PATH filePathList[while($ - startOffset < filePathLength)];
+    u8 optionalData;
+};
+
+// on Linux, variables are found in /sys/firmware/efi/efivars,
+// and will be prefixed by their attributes
+struct EFI_VAR {
+    u32 attributes;
+    LOAD_OPTION loadOption;
+};
+
+
+EFI_VAR data @0x0;