factor out C++ ABI exception handling

2026-09-24 02:00:05 +00:00 · 2025-10-07 20:28:06 -07:00
parent 3560c7d3e7
commit 401d7b47df
6 changed files with 297 additions and 255 deletions
@@ -0,0 +1,74 @@
+// Copyright (c) Epic Games Tools
+// Licensed under the MIT license (https://opensource.org/license/mit/)
+
+#ifndef EH_FRAME_H
+#define EH_FRAME_H
+
+typedef U8 EH_PtrEnc;
+enum
+{
+  EH_PtrEnc_Ptr     = 0x00, // Pointer sized unsigned value
+  EH_PtrEnc_ULEB128 = 0x01, // Unsigned LE base-128 value
+  EH_PtrEnc_UData2  = 0x02, // Unsigned 16-bit value
+  EH_PtrEnc_UData4  = 0x03, // Unsigned 32-bit value
+  EH_PtrEnc_UData8  = 0x04, // Unsigned 64-bit value
+  EH_PtrEnc_Signed  = 0x08, // Signed pointer
+  EH_PtrEnc_SLEB128 = 0x09, // Signed LE base-128 value
+  EH_PtrEnc_SData2  = 0x0A, // Signed 16-bit value
+  EH_PtrEnc_SData4  = 0x0B, // Signed 32-bit value
+  EH_PtrEnc_SData8  = 0x0C, // Signed 64-bit value
+ 
+  EH_PtrEnc_TypeMask = 0x0F,
+};
+
+enum
+{
+  EH_PtrEnc_PcRel   = 0x10, // Value is relative to the current program counter.
+  EH_PtrEnc_TextRel = 0x20, // Value is relative to the .text section.
+  EH_PtrEnc_DataRel = 0x30, // Value is relative to the .got or .eh_frame_hdr section.
+  EH_PtrEnc_FuncRel = 0x40, // Value is relative to the function.
+  EH_PtrEnc_Aligned = 0x50, // Value is aligned to an address unit sized boundary.
+                                 
+  EH_PtrEnc_ModifierMask = 0x70,
+};
+
+enum
+{
+  EH_PtrEnc_Indirect = 0x80, // Value is stored in virtual memory.
+  EH_PtrEnc_Omit     = 0xFF,
+};
+
+typedef struct EH_PtrCtx
+{
+  U64 raw_base_vaddr; // address where pointer is being read
+  U64 text_vaddr;     // base address of section with instructions (used for encoding pointer on SH and IA64)
+  U64 data_vaddr;     // base address of data section (used for encoding pointer on x86-64)
+  U64 func_vaddr;     // base address of function where IP is located
+  U64 ptr_align;
+} EH_PtrCtx;
+
+typedef U8 EH_AugFlags;
+enum
+{
+  EH_AugFlag_HasLSDA    = (1 << 0),
+  EH_AugFlag_HasHandler = (1 << 1),
+  EH_AugFlag_HasAddrEnc = (1 << 2),
+};
+
+typedef struct EH_Augmentation
+{
+  EH_AugFlags flags;
+  U64         handler_ip;
+  EH_PtrEnc   handler_encoding;
+  EH_PtrEnc   lsda_encoding;
+  EH_PtrEnc   addr_encoding;
+} EH_Augmentation;
+
+////////////////////////////////
+
+internal U64 eh_read_ptr(String8 frame_base, U64 off, EH_PtrCtx *ptr_ctx, EH_PtrEnc encoding, U64 *ptr_out);
+internal U64 eh_parse_aug_data(String8 aug_string, String8 aug_data, EH_PtrCtx *ptr_ctx, EH_Augmentation *aug_out);
+internal U64 eh_size_from_aug_data(String8 aug_string, String8 data, EH_PtrCtx *ptr_ctx);
+
+#endif // EH_FRAME_H
+