set o32abi bit patch

tools/set_o32abi_bit.py

@@ -0,0 +1,74 @@
+import argparse
+import sys
+import struct
+
+
+ARCH_MAGIC = b"!<arch>\n"
+ARCH_END = b"`\n"
+ARCH_HEADER_LENGTH = 60
+
+ELF_MAGIC = b"\x7fELF"
+ELF_FLAG_OFFSET = 36
+
+
+def patch_elf(f):
+    patched = None
+    elf_start = f.tell()
+
+    assert (elf_header := f.read(len(ELF_MAGIC))) == ELF_MAGIC
+
+    f.seek(elf_start + ELF_FLAG_OFFSET)
+    flags, = struct.unpack(">I", f.read(4))
+    if flags & 0xF0001000 == 0x20000000:
+        # set EF_MIPS_ABI_O32 flag
+        flags |= 0x00001000
+        # patch in-place
+        f.seek(elf_start + ELF_FLAG_OFFSET)
+        f.write(struct.pack(">I", flags))
+        patched = True
+    elif flags & 0xF0001000 == 0x20001000:
+        patched = False
+
+    # return cursor to start of payload
+    f.seek(elf_start)
+
+    return patched
+
+
+def patch_elf_wrapper(f, name, quiet=False):
+    res = patch_elf(f)
+    if not quiet:
+        if res is True:
+            print("EF_MIPS_ABI_O32 bit successfully patched in %s" % name)
+        elif res is False:
+            print("EF_MIPS_ABI_O32 bit already patched in %s" % name)
+
+
+def patch_ar(f, quiet=False):
+    assert (header := f.read(len(ARCH_MAGIC))) == ARCH_MAGIC
+
+    while obj_header := f.read(ARCH_HEADER_LENGTH):
+        id, _, _, _, _, size, end = struct.unpack(">16s12s6s6s8s10s2s", obj_header)
+
+        assert end == ARCH_END
+
+        id = id.rstrip().decode("utf8").rstrip("/")
+        size = int(size.rstrip().decode("utf8"))
+
+        if id.endswith(".o"):
+            patch_elf_wrapper(f, id, quiet=quiet)
+
+        # skip over payload
+        f.seek(size + size % 2, 1) # 1 means relative to current position
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("file", help="input file", type=argparse.FileType("r+b"))
+    parser.add_argument("--quiet", action="store_true", default=False)
+    args = parser.parse_args()
+
+    if args.file.name.endswith(".a"):
+        patch_ar(args.file, args.quiet)
+    else:
+        patch_elf_wrapper(args.file, args.file.name, args.quiet)