Benji Smith wrote:
Just out of curiosity... Why is a linker so hard to write?
Linkers are actually rather simple programs. The hard part is all the
undocumented, semi-documented, and flat out wrong documentation on
esoterica of the various file formats involved.
A linker that's been around for a while gets all this "lore" embedded
into the code. Discarding it and not using it for a reference means
you're in for years of debugging.
(Caveat: I don't know much about Windows PE, or any of the many other
object file formats. Still, though... it doesn't seem like it could be
THAT difficult. The compiler has already done most of the tricky stuff.)
Here's a list of the file formats optlink deals with:
Intel OMF with Pharlap, Microsoft, and Digital Mars (!) extensions
Codeview (various versions of)
COM
EXE
New EXE
Portable EXE
16 bit Windows
16 bit DLLs
DOS Overlays
OS/2 executables
DOS extender executables
Stub executables
16 and 32 bit resource files
library file format
module definition file
map files
linker command files
For just one example, PE formats are only semi-documented. Write a file
dumper for them and you'll see <g>.
Granted, these days one can cross about half of that off the list. But
there's still a lot left.
