Hi, Sorry for the long delay.
Chaos Eternal <chaoseter...@shlug.org> skribis: > Proposals to solve this bug: > > Proposal 1. > > Adding a keyword argument to pointer->procedure, if set to true, the > generated wrapper will check 'errno' immediately after ffi_call and > return the errno as second value. > > the proposed pointer->procedure maybe like this: > pointer->procedure return_type func_ptr arg_types #:return-errno > > Proposal 2. > > let pointer->procedure check return_type, if it is a list: > (func_return_type, 'errno) > then return multiple values, as errno be second value. That’s my favorite because it’s both pragmatic and extensible (we can also add support for h_errno, etc.) > Proposal 3. > > introduce another procedure "pointers->procedure", which will pack > multiple function pointer into one procedure, in this procedure, the > packed functions will be called in sequence, and their return value > will be returned as multiple values. > > the interface would be like this: > pointers->procedure (list-of-return-type) (list-of-pointers) (list-of > arg-defs) > > also, we need a simple c-function deref-pointer-to-int, which will > de-reference a pointer and return it's int value. > > using above tools, a proper system call with errno be returned could > be like this: > > ((pointers->procedure > (list int int) > (list pointer-of-inotify-add-watch pointer-of-deref-pointer-to-int) > (list (list int '* int) (list '*))) > (list inotify-fd "path-to-watch" watch-flag) (list pointer-of-errno)) The problem is that POINTER-OF-ERRNO does not necessarily exist and cannot be obtained portably. Also, I find the interface a bit clumsy. So my support goes to #2. Would you like to give it a try? Thanks for your input! Ludo’.
