| 48,8 → 48,14 |
|---|
| ; Program to execute, preset by SvarCOM (128 bytes, ASCIIZ) ; +6Bh |
| EXECPROG dd 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 |
| |
| skipsig: ; +EBh |
| ; offset within EXECPROG for out and in filenames in case stdin or stdout |
| ; needs to be redirected (0xffff=no redirection) |
| REDIR_OUTFIL dw 0xffff ; +EBh |
| REDIR_INFIL dw 0xffff ; +EDh |
| REDIR_OUTAPPEND dw 0 ; +EFh |
| |
| skipsig: ; +F1h |
| |
| ; set up CS=DS=SS and point SP to my private stack buffer |
| mov ax, cs |
| mov ds, ax |
| 57,6 → 63,12 |
|---|
| mov ss, ax |
| mov sp, STACKPTR |
| |
| ; revert stdin/stdout redirections (if any) to their initial state |
| call REVERT_REDIR_IF_ANY |
| |
| ; redirect stdout if required |
| call REDIR_OUTFILE_IF_REQUIRED |
| |
| ; should I executed command.com or a pre-set application? |
| or [EXECPROG], byte 0 |
| jz EXEC_COMMAND_COM |
| 148,3 → 160,57 |
|---|
| CMDTAIL db 0x01, 0x0A, 0x0D |
| |
| ERRLOAD db "ERR x, FAILED TO LOAD COMMAND.COM", 13, 10, '$' |
| |
| ; variables used to revert stdin/stdout to their initial state |
| OLD_STDOUT dw 0xffff |
| OLD_STDIN dw 0xffff |
| |
| |
| ; *** ROUTINES *************************************************************** |
| |
| |
| ; revert stdin/stdout redirections (if any) to their initial state |
| ; all memory accesses are CS-prefixes because this code may be called at |
| ; times when DS is out of whack. |
| REVERT_REDIR_IF_ANY: |
| ; is stdout redirected? |
| mov bx, [OLD_STDOUT] |
| cmp bx, 0xffff |
| je STDOUT_DONE |
| ; revert the stdout handle (dst in BX alread) |
| mov cx, 1 ; src handle (1=stdout) |
| mov ah, 0x46 ; redirect a handle |
| int 0x21 |
| mov [OLD_STDOUT], word 0xffff ; mark stdout as "not redirected" |
| STDOUT_DONE: |
| ret |
| |
| |
| ; redirect stdout if REDIR_OUTFIL points to something |
| REDIR_OUTFILE_IF_REQUIRED: |
| mov si, [REDIR_OUTFIL] |
| cmp si, 0xffff |
| je NO_STDOUT_REDIR |
| add si, EXECPROG ; si=output file |
| mov ax, 0x6c00 ; Extended Open/Create |
| mov bx, 1 ; access mode (0=read, 1=write, 2=r+w) |
| xor cx, cx ; file attribs when(if) file is created (0=normal) |
| mov dx, [REDIR_OUTAPPEND] ; action if file exist (0x11=open, 0x12=truncate) |
| int 0x21 ; ax=handle on success (CF clear) |
| mov [REDIR_OUTFIL], word 0xffff |
| jc NO_STDOUT_REDIR ; TODO: abort with an error message instead |
| ; duplicate current stdout so I can revert it later |
| push ax ; save my file handle in stack |
| mov ah, 0x45 ; duplicate file handle BX |
| mov bx, 1 ; 1=stdout |
| int 0x21 ; ax=new (duplicated) file handle |
| mov [OLD_STDOUT], ax ; save the old handle in memory |
| ; redirect stdout to my file |
| pop bx ; dst handle |
| mov cx, 1 ; src handle (1=stdout) |
| mov ah, 0x46 ; "redirect a handle" |
| int 0x21 |
| ; close the original file handle, I no longer need it |
| mov ah, 0x3e ; close a file handle (handle in BX) |
| NO_STDOUT_REDIR: |
| ret |