https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88745
--- Comment #5 from Iain Sandoe <iains at gcc dot gnu.org> --- (In reply to Eric Gallager from comment #4) > (In reply to Ian Lance Taylor from comment #3) > > filetype.awk is just an AWK script. See > > https://www.gnu.org/software/gawk/manual/gawk.html. A Mach-O file starts > > with 0xfeedface (32-bit Mach-O) or 0xfeedfacf (64-bit Mach-O) in either > > big-endian or little-endian order. > > Does the endianness actually matter? Neither the elf nor pecoff cases seem > to be duplicated for their opposite endiannesses... Also are the octal > escape sequences necessary? Mach-O files have 4 different magic numbers that indicate bit size and endianness. The file format and layout is described in /usr/include/mach-o/loader.h (and the other roles in that directory add information on symbols etc.) You can also look at libiberty/simple-object-mach-o.* (not quite sure why we are not re-using stuff from there instead of inventing yet another binary file reader). ** I have a significant (yet unposted) update to the libiberty/simple-object-mach-o code to handle the LTO debug section copying - which I can send to you if you like. The values are not ascii - so some form of escape sequence will be needed. endianness matters if: (a) we would like to continue for things to work with powerpc (which I continue to support and test) (b) you don't want things to crash or misbehave if a PPC impl. is presented with X86 or vice-versa. If you write the code knowing this support is needed, the endianness and size will not matter [much, at least] (since swapping and the size of a pointer can be abstracted away).
