Improve the ISO filename comparison algorithm; should now always handle

trailing dots correctly (i.e. ignore them.)

diff --git a/isolinux.asm b/isolinux.asm
index a771760..bb4cd13 100644 (file)
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -275,13 +275,11 @@ VKernelBuf:       resb vk_size            ; "Current" vkernel
                alignb 4
 AppendBuf       resb max_cmd_len+1     ; append=
 KbdMap         resb 256                ; Keyboard map
-BootFile       resb 256                ; Boot file from DHCP packet
-PathPrefix     resb 256                ; Path prefix derived from the above
 FKeyName       resb 10*FILENAME_MAX    ; File names for F-key help
 NumBuf         resb 15                 ; Buffer to load number
 NumBufEnd      resb 1                  ; Last byte in NumBuf
-DotQuadBuf     resb 16                 ; Buffer for dotted-quad IP address
-IPOption       resb 80                 ; ip= option buffer
+ISOFileName    resb 64                 ; ISO filename canonicalization buffer
+ISOFileNameEnd equ $
                alignb 32
 KernelName      resb FILENAME_MAX       ; Mangled name for kernel
 KernelCName     resb FILENAME_MAX      ; Unmangled kernel name
@@ -335,7 +333,6 @@ KbdFlags    resb 1                  ; Check for keyboard escapes
 LoadFlags      resb 1                  ; Loadflags from kernel
 A20Tries       resb 1                  ; Times until giving up on A20
 FuncFlag       resb 1                  ; == 1 if <Ctrl-F> pressed
-OverLoad       resb 1                  ; Set if DHCP packet uses "overloading"
 TextColorReg   resb 17                 ; VGA color registers for text mode
 VGAFileBuf     resb FILENAME_MAX       ; Unmangled VGA image name
 VGAFileBufEnd  equ $
@@ -2787,29 +2784,48 @@ allocate_file:
 ;      the filesystem; CX indicates its length, and ';' terminates.
 ;      DI is expected to end with a null.
 ;
-;      Note: clobbers AX, CX, SI, DI
+;      Note: clobbers AX, CX, SI, DI; assumes DS == ES == base segment
 ;
 iso_compare_names:
-.loop:         jcxz .si_end
+               ; First, terminate and canonicalize input filename
+               push di
+               mov di,ISOFileName
+.canon_loop:   jcxz .canon_end
                lodsb
                dec cx
+               cmp al,';'
+               je .canon_end
+               and al,al
+               je .canon_end
+               stosb
+               cmp di,ISOFileNameEnd-1         ; Guard against buffer overrun
+               jb .canon_loop
+.canon_end:
+               cmp di,ISOFileName
+               jbe .canon_done
+               cmp byte [di-1],'.'             ; Remove terminal dots
+               jne .canon_done
+               dec di
+               jmp short .canon_end
+.canon_done:
+               mov [di],byte 0                 ; Null-terminate string
+               pop di
+               mov si,ISOFileName
+.compare:
+               lodsb
                mov ah,[di]
                inc di
-               and al,al
-               jz .si_end_dec_di
-               cmp al,';'
-               je .si_end_dec_di
-               or ax,2020h                     ; Convert both to lowercase
-               cmp ah,al
-               je .loop
-               ret                             ; Failure, ZF = 0
-.si_end_dec_di:
-               dec di                          ; Re-read "current" character
-.si_end:
-               cmp [di], byte 0
-               ; Now ZF is set according to the final result
-.done:
-               ret
+               and ax,ax
+               jz .success                     ; End of string for both
+               and al,al                       ; Is either one end of string?
+               jz .failure                     ; If so, failure
+               and ah,ah
+               jz .failure
+               or ax,2020h                     ; Convert to lower case
+               cmp al,ah
+               je .compare
+.failure:      and ax,ax                       ; ZF = 0 (at least one will be nonzero)
+.success:      ret
 
 ;
 ; strcpy: Copy DS:SI -> ES:DI up to and including a null byte
@@ -3562,31 +3578,30 @@ gl_xret:        popf
 ;             and doesn't contain whitespace, and zero-pads the output buffer,
 ;             so "repe cmpsb" can do a compare.
 ;
-; ISOLINUX:: This probably should capitalize the filename?
-;
 mangle_name:
-               mov cx,FILENAME_MAX-2
-               mov ah,'.'                      ; No dot encountered
+               push bx
+               mov cx,FILENAME_MAX-1
+               mov bx,di
 
 .mn_loop:
                lodsb
                cmp al,' '                      ; If control or space, end
                jna .mn_end
-               cmp al,ah
-               jne .mn_normal
-               xor ah,ah                       ; Found dot
-               inc cx                          ; We're now allowed one more char
-.mn_normal:    stosb
+               stosb
                loop .mn_loop
 .mn_end:
-               and ah,ah                       ; Did we find the dot?
-               jz .mn_nodot
-               mov al,ah                       ; No, need to append dot
-               stosb
-               dec cx
-.mn_nodot:     inc cx                          ; At least one null byte
+               cmp bx,di                       ; At the beginning of the buffer?
+               jbe .mn_zero
+               cmp byte [di-1], '.'            ; Terminal dot?
+               jne .mn_zero
+               dec di                          ; If so, remove it
+               inc cx
+               jmp short .mn_end
+.mn_zero:
+               inc cx                          ; At least one null byte
                xor ax,ax                       ; Zero-fill name
                rep stosb
+               pop bx
                ret                             ; Done
 
 ;
@@ -3602,8 +3617,6 @@ mangle_name:
 ;                On return, DI points to the first byte after the output name,
 ;                which is set to a null byte.
 ;
-; ISOLINUX:: This needs to strip the trailing dot, if there is one.
-;
 unmangle_name: call strcpy
                dec di                          ; Point to final null byte
                ret