tool to read and fix relocs

check_fix_relocs.py

@@ -0,0 +1,63 @@
+import struct
+import sys
+
+"""
+Offset	Type	Name	Description and remarks
+0	byte[2]	e_magic	Signature - ASCII "MZ" or "ZM"
+2	uint16	e_cblp	If nonzero, the number of bytes in the last page
+4	uint16	e_cp	Number of 512-byte pages in the file, not counting the "overlay" segment
+6	uint16	e_crlc	Number of relocations
+8	uint16	e_cparhdr	Header size, in 16-byte paragraphs
+10	uint16	e_minalloc	Minimum allocation
+12	uint16	e_maxalloc	Maximum allocation
+14	int16	e_ss	Initial SS register
+16	uint16	e_sp	Initial SP register
+18	uint16	e_csum	Checksum - Usually unused and set to 0
+20	uint16	e_ip	Initial IP register
+22	int16	e_cs	Initial CS register
+24	uint16	e_lfarlc	Relocation table offset, in bytes from the start of the file
+26	uint16	e_ovno	Overlay number (or other custom data) - Usually unused
+"""
+# Open the executable file in binary mode
+with open(sys.argv[1], 'r+b') as f:
+    # Read the MZ header
+    mz_header = f.read(26)
+
+    # Unpack the values from the MZ header
+    signature, last_page_size, num_pages, num_relocations, header_size, min_alloc, max_alloc, ss, sp, checksum, ip, cs, reloc_table_offset = struct.unpack(
+        "<2sHHHHHHHHHHHH", mz_header)
+
+    print(f"cs:{cs:x} ip:{ip:x} relocs:{num_relocations}")
+    # Read the relocation table
+    f.seek(reloc_table_offset)
+    reloc_table_size = num_relocations * 4
+    reloc_table = f.read(reloc_table_size)
+
+    new_list = []
+    # Iterate over the relocations
+    for i in range(num_relocations):
+        # Get the relocation offset
+        reloc_offset, reloc_seg = struct.unpack("<HH", reloc_table[i * 4:i * 4 + 4])
+
+        # Calculate the relocated address
+        relocated_address = reloc_offset + reloc_seg * 16 + header_size * 16
+
+        f.seek(relocated_address)
+        value = struct.unpack("<H", f.read(2))[0]
+
+        # Print the relocated address
+        print(f"{relocated_address:x} {reloc_seg:x}:{reloc_offset:x} {value:x}")
+
+        if value < 0xf000:
+            new_list.extend([reloc_offset, reloc_seg])
+
+    reloc_table = struct.pack("<" + ("H" * len(new_list)), *new_list)
+    num_relocations = len(reloc_table) // 4
+
+    f.seek(6)
+    f.write(struct.pack("<H", num_relocations))
+
+    f.seek(reloc_table_offset)
+    f.write(reloc_table)
+
+

src/custom/custom.cpp

@@ -28,7 +28,7 @@ bool trace_instructions = false; //m2c::debug >= 1;
 bool trace_instructions_to_stdout = false; //m2c::debug >= 1;
 bool compare_instructions = false; //m2c::debug >= 1;// 1 || m2c::debug == 2 || m2c::debug == 3;
 bool complex_self_modifications = false;
-bool collect_rt_info = false;
+bool collect_rt_info = true;
 bool collect_rt_info_vars = true;
 
 static const size_t