Introduce "current directory" support for the isolinux directory.

diff --git a/isolinux.asm b/isolinux.asm
index bb4cd13..72ffab4 100644 (file)
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -295,6 +295,9 @@ KernelSize  resd 1                  ; Size of kernel (bytes)
 RootDir                resd 1                  ; Root directory location (LBA)
 RootDirLen     resd 1                  ; Root directory length
 RootDirClust   resd 1                  ; Root directory length in clusters
+CurDir         resd 1                  ; Current directory location (LBA)
+CurDirLen      resd 1                  ; Current directory length
+CurDirClust    resd 1                  ; Current directory length in clusters
 SavedSSSP      resw 1                  ; Our SS:SP while running a COMBOOT image
 FBytes         equ $                   ; Used by open/getc
 FBytes1                resw 1
@@ -333,6 +336,7 @@ 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
+ISOFlags       resb 1                  ; Flags for ISO directory search
 TextColorReg   resb 17                 ; VGA color registers for text mode
 VGAFileBuf     resb FILENAME_MAX       ; Unmangled VGA image name
 VGAFileBufEnd  equ $
@@ -794,29 +798,6 @@ rl_checkpt_off     equ ($-$$)
 
 all_read:
 ;
-; Now, we need to sniff out the actual filesystem data structures.
-; mkisofs gave us a pointer to the primary volume descriptor
-; (which will be at 16 only for a single-session disk!); from the PVD
-; we should be able to find the rest of what we need to know.
-; 
-get_fs_structures:
-               mov eax,[bi_pvd]
-               mov bx,trackbuf
-               call getonesec
-
-               mov si,dbg_rootdir_msg                  ; ***
-               call writemsg                           ; ***
-               mov eax,[trackbuf+156+2]
-               mov [RootDir],eax
-               call writehex8                          ; ***
-               call crlf                               ; ***
-               mov eax,[trackbuf+156+10]
-               mov [RootDirLen],eax            
-               add eax,SECTORSIZE-1
-               shr eax,SECTORSIZE_LG2
-               mov [RootDirClust],eax
-
-;
 ; Initialize screen (if we're using one)
 ;
                ; Get ROM 8x16 font in case we switch to graphics mode
@@ -965,8 +946,54 @@ mkkeymap:  stosb
                loop mkkeymap
 
 ;
+; Now, we need to sniff out the actual filesystem data structures.
+; mkisofs gave us a pointer to the primary volume descriptor
+; (which will be at 16 only for a single-session disk!); from the PVD
+; we should be able to find the rest of what we need to know.
+; 
+get_fs_structures:
+               mov eax,[bi_pvd]
+               mov bx,trackbuf
+               call getonesec
+
+               mov si,dbg_rootdir_msg                  ; ***
+               call writemsg                           ; ***
+               mov eax,[trackbuf+156+2]
+               mov [RootDir],eax
+               mov [CurDir],eax
+               call writehex8                          ; ***
+               call crlf                               ; ***
+               mov eax,[trackbuf+156+10]
+               mov [RootDirLen],eax            
+               mov [CurDirLen],eax
+               add eax,SECTORSIZE-1
+               shr eax,SECTORSIZE_LG2
+               mov [RootDirClust],eax
+               mov [CurDirClust],eax
+
+               ; Look for an "isolinux" directory, and if found,
+               ; make it the current directory instead of the root
+               ; directory.
+               mov di,isolinux_dir
+               mov al,02h                      ; Search for a directory
+               call searchdir_iso
+               jz .no_isolinux_dir
+
+               mov [CurDirLen],eax
+               mov eax,[si+file_sector]
+               mov [CurDir],eax
+               mov eax,[si+file_left]
+               mov [CurDirClust],eax
+
+               xor eax,eax
+               mov [si+file_sector],eax        ; Free this file pointer entry
+
+.no_isolinux_dir:
+
+;
 ; Locate the configuration file
 ;
+load_config:
                mov si,dbg_config_msg           ; ***
                call writemsg                   ; ***
 
@@ -2671,13 +2698,21 @@ kaboom:
 ;              DS:DI   = filename
 ;           If successful:
 ;              ZF clear
-;              SI      = file pointer
-;              DX:AX   = file length in bytes
+;              SI              = file pointer
+;              DX:AX or EAX    = file length in bytes
 ;           If unsuccessful
 ;              ZF set
 ;
 
+;
+; searchdir_iso is a special entry point for ISOLINUX only.  In addition
+; to the above, searchdir_iso passes a file flag mask in AL.  This is useful
+; for searching for directories.
+;
 searchdir:
+               xor al,al
+searchdir_iso:
+               mov [ISOFlags],al
                TRACER 'S'
                push es
                push ds
@@ -2707,7 +2742,9 @@ searchdir:
                cmp al,33
                jb .next_sector
                TRACER 'c'
-               test [si+25], byte 8Eh          ; Unwanted file attributes!
+               mov al,[si+25]
+               xor al,[ISOFlags]
+               test al, byte 8Eh               ; Unwanted file attributes!
                jnz .not_file
                pusha
                movzx cx,byte [si+32]           ; File identifier length
@@ -4028,6 +4065,7 @@ aborted_msg       db ' aborted.'                  ; Fall through to crlf_msg!
 crff_msg       db CR, FF, 0
 default_str    db 'default', 0
 default_len    equ ($-default_str)
+isolinux_dir   db 'isolinux', 0
 isolinux_cfg   db 'isolinux.cfg', 0
 
 dbg_rootdir_msg        db 'Root directory at LBA = ', 0