It is. Binaries generated by cosmocc have NUL in the middle.

comex · 2024-09-24T20:05:04 1727208304

Ah, indeed. Here are the first 16 bytes of one:

4d 5a 71 46 70 44 3d 27 0a 00 00 10 00 f8 00 00 |MZqFpD='........|

There are already nul bytes here, and there are a lot more before the single quote gets closed at offset 0x200.

eesmith · 2024-09-24T20:54:53 1727211293

And I can confirm a NUL in 11th byte of my hello.c a.out:

  >>> s[:11]
  b"MZqFpD='\n\n\x00"

Looking closer, I missed the content of "BIOS BOOT SECTOR".