; ring-0 file io
; release 2.50
; (x) 2000 Z0MBiE

; subroutines:
; ~~~~~~~~~~~
; r0_fopen_rw(EDX=filename):CF,EAX=handle/errorcode
; r0_fopen_ro(EDX=filename):CF,EAX=handle/errorcode
; r0_fclose(EBX=handle)
; r0_fread (EDX=buf,ECX=size,ESI=filepos,EBX=handle):CF,EAX=numread/error
; r0_fwrite(EDX=buf,ECX=size,ESI=filepos,EBX=handle):CF,EAX=numwritten/error
; r0_fgetsize(EBX=handle):CF,eax=filesize/error
; r0_make_handle_rw(EBX=handle)
; r0_make_handle_ro(EBX=handle)
; r0_getattr(EDX=filename):CF, ECX=attribs
; r0_setattr(EDX=filename,ECX=attribs):CF

                        ; i: edx=filename
                        ; o: cf, eax=handle

r0_fopen_rw:            pusha
                        mov     bx, 2042h       ; no i24, denynone, r/w
                        jmp     r0_fopen_any

r0_fopen_ro:            pusha
                        mov     bx, 2044h       ; no i24, denynone, r/o

r0_fopen_any:           mov     eax, R0_OPENCREATFILE
                        mov     esi, edx
                        mov     cx, 32          ; archive (unused here)
                        mov     dx, 01h         ; fail | open
                        VxDcall IFSMGR, Ring0_FileIO
                        mov     [esp+7*4], eax
                        popa
                        ret

                        ; i: ebx=handle
r0_fclose:              pusha
                        mov     eax, R0_CLOSEFILE
                        VxDcall IFSMGR, Ring0_FileIO
                        popa
                        ret

                        ; i: ebx=handle
                        ;    edx=buffer
                        ;    ecx=size
                        ;    esi=file pos
                        ; o: eax=bytes read
r0_fread:               pusha
                        mov     eax, R0_READFILE
                        xchg    edx, esi
                        VxDcall IFSMGR, Ring0_FileIO
                        mov     [esp+7*4], ecx
                        popa
                        ret

                        ; i: ebx=handle
                        ;    edx=buffer
                        ;    ecx=size
                        ;    esi=file pos
                        ; o: eax=bytes written
r0_fwrite:              pusha
                        mov     eax, R0_WRITEFILE
                        xchg    edx, esi
                        VxDcall IFSMGR, Ring0_FileIO
                        mov     [esp+7*4], ecx
                        popa
                        ret

                        ; input: EBX=handle
                        ; output: EAX=size
r0_fgetsize:            pusha
                        mov     eax, R0_GETFILESIZE
                        VxDcall IFSMGR, Ring0_FileIO
                        mov     [esp+7*4], eax
                        popa
                        ret

                        ; input: EBX=handle
r0_make_handle_rw:      pusha
                        mov     eax, [ebx+0Ch]
                        mov     byte ptr [eax+0Ch], 42h ; denynone, r/w
                        ; 42h=SHARE_DENYNONE+ACCESS_READWRITE
                        popa
                        ret

r0_make_handle_ro:      pusha
                        mov     eax, [ebx+0Ch]
                        mov     byte ptr [eax+0Ch], 44h ; denynone, r/o
                        popa
                        ret

                        ; input:  EDX=filename
                        ; output: ECX=attribs
r0_fgetattr:            pusha
                        mov     eax, R0_FILEATTRIBUTES+GET_ATTRIBUTES
                        mov     esi, edx
                        VxDcall IFSMGR, Ring0_FileIO
                        mov     [esp+6*4], eax       ; popa.ecx
                        popa
                        ret

                        ; input:  EDX=filename, ECX=attribs
r0_fsetattr:            pusha
                        mov     eax, R0_FILEATTRIBUTES+SET_ATTRIBUTES
                        mov     esi, edx
                        VxDcall IFSMGR, Ring0_FileIO
                        popa
                        ret