isolinux: getfssec now outputs bytes read

ISOLINUX support for the API changes needed to handle unknown file
sizes.

diff --git a/isolinux.asm b/isolinux.asm
index bc5eff8..cee100f 100644 (file)
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -76,7 +76,9 @@ comboot_seg   equ real_mode_seg       ; COMBOOT image loading zone
 ;
                struc open_file_t
 file_sector    resd 1                  ; Sector pointer (0 = structure free)
+file_bytesleft resd 1                  ; Number of bytes left
 file_left      resd 1                  ; Number of sectors left
+               resd 1                  ; Unused
                endstruc
 
 %ifndef DEPEND
@@ -105,7 +107,7 @@ trackbuf    resb trackbufsize       ; Track buffer goes here
 
                ; Some of these are touched before the whole image
                ; is loaded.  DO NOT move this to .uibss.
-               section .bss1
+               section .bss2
                alignb 4
 ISOFileName    resb 64                 ; ISO filename canonicalization buffer
 ISOFileNameEnd equ $
@@ -1263,6 +1265,7 @@ searchdir_iso:
                mov eax,[si+2]                  ; Location of extent
                mov [bx+file_sector],eax
                mov eax,[si+10]                 ; Data length
+               mov [bx+file_bytesleft],eax
                push eax
                add eax,SECTOR_SIZE-1
                shr eax,SECTOR_SHIFT
@@ -1429,6 +1432,7 @@ unmangle_name:    call strcpy
 ;  On exit:
 ;      SI      -> File pointer (or 0 on EOF)
 ;      CF = 1  -> Hit EOF
+;      ECX     -> Bytes actually read
 ;
 getfssec:
                TRACER 'F'
@@ -1441,8 +1445,8 @@ getfssec:
                cmp ecx,[si+file_left]
                jna .ok_size
                mov ecx,[si+file_left]
-.ok_size:
 
+.ok_size:
                mov bp,cx
                push cx
                push si
@@ -1456,13 +1460,24 @@ getfssec:
                add [si+file_sector],ecx
                sub [si+file_left],ecx
                ja .not_eof                     ; CF = 0
-
-               xor ecx,ecx
-               mov [si+file_sector],ecx        ; Mark as unused
-               xor si,si
                stc
 
 .not_eof:
+               pushf
+               shl ecx,SECTOR_SHIFT            ; Convert to bytes
+               cmp ecx,[si+file_bytesleft]
+               jb .not_all
+               mov ecx,[si+file_bytesleft]
+.not_all:      sub [si+file_bytesleft],ecx
+               popf
+               jnc .ret
+               push eax
+               xor eax,eax
+               mov [si+file_sector],eax        ; Unused
+               mov si,ax
+               pop eax
+               stc
+.ret:
                pop ds
                TRACER 'f'
                ret