Tighten close_file, fix SYSLINUX new file API

Define close_file slightly tighter:

       - It is permitted to call close_file with a zero filehandle
       - close_file zeros SI

Fix the handling of the new API in SYSLINUX.  It appears file_left was
never actually initialized; it simply didn't matter since the old code
would either trip on reaching the end of the FAT chain or count the
data it needed.  Now operating according to spec.

diff --git a/comboot.inc b/comboot.inc
index 99a4115..07ec352 100644 (file)
--- a/comboot.inc
+++ b/comboot.inc
@@ -61,10 +61,7 @@
 
 ; Looks like a COMBOOT image but too large
 comboot_too_large:
-               and si,si
-               jnz .closed
                call close_file
-.closed:
                mov si,err_comlarge
                call cwritestr
                jmp enter_command

diff --git a/extlinux.asm b/extlinux.asm
index afcdb33..73c8bed 100644 (file)
--- a/extlinux.asm
+++ b/extlinux.asm
@@ -1010,6 +1010,7 @@ close_file:
                and si,si
                jz .closed
                mov dword [si],0                ; First dword == file_bytesleft
+               xor si,si
 .closed:       ret
 
 ;

diff --git a/isolinux.asm b/isolinux.asm
index cee100f..4293564 100644 (file)
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -1141,6 +1141,7 @@ close_file:
                and si,si
                jz .closed
                mov dword [si],0                ; First dword == file_left
+               xor si,si
 .closed:       ret
 
 ;

diff --git a/ldlinux.asm b/ldlinux.asm
index 4df94b7..b12403e 100644 (file)
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -1034,7 +1034,8 @@ search_dos_dir:
 close_file:
                and si,si
                jz .closed
-               mov dword [si],0                ; First dword == file_left
+               mov dword [si],0                ; First dword == file_sector
+               xor si,si
 .closed:       ret
 
 ;
@@ -1092,6 +1093,11 @@ searchdir:
 
                ; SI and EAX are already set
                mov [si+file_bytesleft],eax
+               push eax
+               add eax,SECTOR_SIZE-1
+               shr eax,SECTOR_SHIFT
+               mov [si+file_left],eax  ; Sectors left
+               pop eax
                and eax,eax             ; EAX != 0
                jz .badfile
                ret                     ; Done!
@@ -1361,14 +1367,18 @@ getfssec:
                call getfssec_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
+               ja .eof
+.noteof:
+               sub [si+file_bytesleft],ecx     ; CF <- 0
+               pop edx
+               ret
+.eof:
                mov ecx,[si+file_bytesleft]
-.noteof:       sub ecx,[si+file_bytesleft]
-               popf
+               call close_file
                pop edx
+               stc
                ret
 
 ;