SYSLINUX, EXTLINUX: support the new getfssec API

Support the new getfssec API which returns number of bytes read in
SYSLINUX and EXTLINUX.  Untested so far, but it's a reasonably easy
change.

diff --git a/extlinux.asm b/extlinux.asm
index 61c83d3..afcdb33 100644 (file)
--- a/extlinux.asm
+++ b/extlinux.asm
@@ -85,7 +85,7 @@ comboot_seg   equ real_mode_seg       ; COMBOOT image loading zone
 ; File structure.  This holds the information for each currently open file.
 ;
                struc open_file_t
-file_left      resd 1                  ; Number of sectors left (0 = free)
+file_bytesleft resd 1                  ; Number of bytes left (0 = free)
 file_sector    resd 1                  ; Next linear sector to read
 file_in_sec    resd 1                  ; Sector where inode lives
 file_in_off    resw 1
@@ -987,11 +987,7 @@ open_inode:
                mov ax,[ThisInode+i_mode]
                mov [bx+file_mode],ax
                mov eax,[ThisInode+i_size]
-               push eax
-               add eax,SECTOR_SIZE-1
-               shr eax,SECTOR_SHIFT
-               mov [bx+file_left],eax
-               pop eax
+               mov [bx+file_bytesleft],eax
                mov si,bx
                and eax,eax                     ; ZF clear unless zero-length file
                pop gs
@@ -1013,7 +1009,7 @@ ThisInode resb EXT2_GOOD_OLD_INODE_SIZE   ; The most recently opened inode
 close_file:
                and si,si
                jz .closed
-               mov dword [si],0                ; First dword == file_left
+               mov dword [si],0                ; First dword == file_bytesleft
 .closed:       ret
 
 ;
@@ -1435,6 +1431,7 @@ linsector:
 ;      CX      -> Sector count (0FFFFh = until end of file)
 ;                  Must not exceed the ES segment
 ;      Returns CF=1 on EOF (not necessarily error)
+;      On return ECX = number of bytes read
 ;      All arguments are advanced to reflect data read.
 ;
 getfssec:
@@ -1444,9 +1441,13 @@ getfssec:
                push edi
 
                movzx ecx,cx
-               cmp ecx,[si]                    ; Number of sectors left
+               push ecx                        ; Sectors requested read
+               mov eax,[si+file_bytesleft]
+               add eax,SECTOR_SIZE-1
+               shr eax,SECTOR_SHIFT
+               cmp ecx,eax                     ; Number of sectors left
                jbe .lenok
-               mov cx,[si]
+               mov cx,ax
 .lenok:
 .getfragment:
                mov eax,[si+file_sector]        ; Current start index
@@ -1485,12 +1486,18 @@ getfssec:
                add bx,bp                       ; Adjust buffer pointer
                pop bp
                add [si+file_sector],ebp        ; Next sector index
-               sub [si],ebp                    ; Sectors consumed
                jcxz .done
                jnz .getfragment
                ; Fall through
 .done:
-               cmp dword [si],1                ; Did we run out of file?
+               pop ecx                         ; Sectors requested read
+               shl ecx,SECTOR_SHIFT
+               cmp ecx,[si+file_bytesleft]
+               jb .noteof
+               mov ecx,[si+file_bytesleft]
+.noteof:       sub [si+file_bytesleft],ecx
+               ; Did we run out of file?
+               cmp dword [si+file_bytesleft],1
                ; CF set if [SI] < 1, i.e. == 0
                pop edi
                pop edx

diff --git a/ldlinux.asm b/ldlinux.asm
index c8e4aa8..4df94b7 100644 (file)
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -88,7 +88,9 @@ 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
@@ -1089,6 +1091,7 @@ searchdir:
                jnz .badfile            ; If not a file, it's a bad thing
 
                ; SI and EAX are already set
+               mov [si+file_bytesleft],eax
                and eax,eax             ; EAX != 0
                jz .badfile
                ret                     ; Done!
@@ -1341,20 +1344,30 @@ getfssec_edx:
 ;      CX      -> Sector count (0FFFFh = until end of file)
 ;                  Must not exceed the ES segment
 ;      Returns CF=1 on EOF (not necessarily error)
+;      ECX returns number of bytes read.
 ;      All arguments are advanced to reflect data read.
 ;
 getfssec:
                push edx
                movzx edx,cx
-               cmp edx,[si+4]
+               push edx                ; Zero-extended CX
+               cmp edx,[si+file_left]
                jbe .sizeok
-               mov edx,[si+4]
+               mov edx,[si+file_left]
                mov cx,dx
 .sizeok:
-               sub [si+4],edx
-               mov edx,[si]
+               sub [si+file_left],edx
+               mov edx,[si+file_sector]
                call getfssec_edx
-               mov [si],edx
+               mov [si+file_sector],edx
+               pop ecx                 ; Sectors requested read
+               pushf                   ; Save CF from getfssec_edx
+               shl ecx,SECTOR_SHIFT
+               cmp ecx,[si+file_bytesleft]
+               jna .noteof
+               mov ecx,[si+file_bytesleft]
+.noteof:       sub ecx,[si+file_bytesleft]
+               popf
                pop edx
                ret