v4.0/src/DOS/EXEC.ASM

   1 ;       SCCSID = @(#)exec.asm   1.3 85/08/13
   2 ;       SCCSID = @(#)exec.asm   1.3 85/08/13
   3 ;    AN000 version 4.0 jan. 1988
   4 ;    A007  PTM 3957 - fake vesrion for IBMCACHE.COM
   5 ;    A008  PTM 4070 - fake version for MS WINDOWS
   6
   7 SUBTTL $exec - load/go a program
   8 PAGE
   9 ;
  10 ; Assembler usage:
  11 ;           LDS     DX, name
  12 ;           LES     BX, blk
  13 ;           MOV     AH, Exec
  14 ;           MOV     AL, func
  15 ;           INT     int_command
  16 ;
  17 ;       AL  Function
  18 ;       --  --------
  19 ;        0  Load and execute the program.
  20 ;        1  Load, create  the  program  header  but  do  not
  21 ;           begin execution.
  22 ;        3  Load overlay. No header created.
  23 ;
  24 ;           AL = 0 -> load/execute program
  25 ;
  26 ;           +---------------------------+
  27 ;           | WORD segment address of   |
  28 ;           | environment.              |
  29 ;           +---------------------------+
  30 ;           | DWORD pointer to ASCIZ    |
  31 ;           | command line at 80h       |
  32 ;           +---------------------------+
  33 ;           | DWORD pointer to default  |
  34 ;           | FCB to be passed at 5Ch   |
  35 ;           +---------------------------+
  36 ;           | DWORD pointer to default  |
  37 ;           | FCB to be passed at 6Ch   |
  38 ;           +---------------------------+
  39 ;
  40 ;           AL = 1 -> load program
  41 ;
  42 ;           +---------------------------+
  43 ;           | WORD segment address of   |
  44 ;           | environment.              |
  45 ;           +---------------------------+
  46 ;           | DWORD pointer to ASCIZ    |
  47 ;           | command line at 80h       |
  48 ;           +---------------------------+
  49 ;           | DWORD pointer to default  |
  50 ;           | FCB to be passed at 5Ch   |
  51 ;           +---------------------------+
  52 ;           | DWORD pointer to default  |
  53 ;           | FCB to be passed at 6Ch   |
  54 ;           +---------------------------+
  55 ;           | DWORD returned value of   |
  56 ;           | CS:IP                     |
  57 ;           +---------------------------+
  58 ;           | DWORD returned value of   |
  59 ;           | SS:IP                     |
  60 ;           +---------------------------+
  61 ;
  62 ;           AL = 3 -> load overlay
  63 ;
  64 ;           +---------------------------+
  65 ;           | WORD segment address where|
  66 ;           | file will be loaded.      |
  67 ;           +---------------------------+
  68 ;           | WORD relocation factor to |
  69 ;           | be applied to the image.  |
  70 ;           +---------------------------+
  71 ;
  72 ; Returns:
  73 ;           AX = error_invalid_function
  74 ;              = error_bad_format
  75 ;              = error_bad_environment
  76 ;              = error_not_enough_memory
  77 ;              = error_file_not_found
  78 ;
  79 ;   Revision history:
  80 ;
  81 ;        A000   version 4.00  Jan. 1988
  82 ;
  83 include EA.INC
  84 include version.inc
  85
  86         I_Need     Temp_Var2,WORD            ;AN000;file type from $open
  87         I_Need     Special_Entries,WORD      ;AN007;address of special entries
  88         I_Need     Special_Version,WORD      ;AN007;special version number
  89         I_Need     Fake_Count,BYTE           ;AN008;fake version count
  90
  91 IF      BUFFERFLAG
  92         extrn   restore_user_map:near
  93 ENDIF
  94
  95 TABLE   SEGMENT
  96
  97 exec_init_SP        DW  ?
  98 exec_init_SS        DW  ?
  99 exec_init_IP        DW  ?
 100 exec_init_CS        DW  ?
 101
 102 exec_internal_buffer    EQU OpenBuf
 103
 104 exec_signature      DW  ?               ; must contain 4D5A  (yay zibo!)
 105 exec_len_mod_512    DW  ?               ; low 9 bits of length
 106 exec_pages          DW  ?               ; number of 512b pages in file
 107 exec_rle_count      DW  ?               ; count of reloc entries
 108 exec_par_dir        DW  ?               ; number of paragraphs before image
 109 exec_min_BSS        DW  ?               ; minimum number of para of BSS
 110 exec_max_BSS        DW  ?               ; max number of para of BSS
 111 exec_SS             DW  ?               ; stack of image
 112 exec_SP             DW  ?               ; SP of image
 113 exec_chksum         DW  ?               ; checksum  of file (ignored)
 114 exec_IP             DW  ?               ; IP of entry
 115 exec_CS             DW  ?               ; CS of entry
 116 exec_rle_table      DW  ?               ; byte offset of reloc table
 117 Exec_header_len     EQU $-Exec_Signature
 118
 119 exec_internal_buffer_size   EQU (128+128+53+curdirLEN)
 120 %out    Please make sure that the following are contiguous and of the
 121 %out    following sizes:
 122 %out
 123 %out    OpenBuf     128
 124 %out    RenBuf      128
 125 %out    SearchBuf    53
 126 %out    DummyCDS    CurDirLen
 127
 128 TABLE   ENDS
 129
 130 .sall
 131
 132 procedure   $Exec,NEAR
 133         ASSUME  DS:NOTHING, ES:NOTHING
 134 PUBLIC EXEC001S,EXEC001E
 135 EXEC001S:
 136         LocalVar    exec_blk,DWORD
 137         LocalVar    exec_func,BYTE
 138         LocalVar    exec_load_high,BYTE
 139         LocalVar    exec_fh,WORD
 140         LocalVar    exec_rel_fac,WORD
 141         LocalVar    exec_res_len_para,WORD
 142         LocalVar    exec_environ,WORD
 143         LocalVar    exec_size,WORD
 144         LocalVar    exec_load_block,WORD
 145         LocalVar    exec_dma,WORD
 146         LocalVar    execNameLen,WORD
 147         LocalVar    execName,DWORD
 148 EXEC001E:
 149         Enter
 150 ;
 151 ; validate function
 152 ;
 153
 154         CMP     AL,3                    ; only 0, 1 or 3 are allowed
 155         JNA     exec_check_2
 156
 157 exec_bad_fun:
 158         MOV     EXTERR_LOCUS,errLOC_Unk ; Extended Error Locus
 159         mov     al,error_invalid_function
 160
 161 exec_ret_err:
 162         Leave
 163         transfer    SYS_RET_ERR
 164
 165 exec_check_2:
 166         CMP     AL,2
 167         JZ      exec_bad_fun
 168
 169         MOV     exec_blkL,BX            ; stash args
 170         MOV     exec_blkH,ES
 171         MOV     exec_func,AL
 172         MOV     exec_load_high,0
 173 ;
 174 ; set up length of exec name
 175 ;
 176         MOV     execNameL,DX
 177         MOV     execNameH,DS
 178         MOV     SI,DX                   ; move pointer to convenient place
 179         invoke  DStrLen
 180         MOV     ExecNameLen,CX          ; save length
 181
 182         XOR     AL,AL                   ; open for reading
 183         PUSH    BP
 184         invoke  $OPEN                   ; is the file there?
 185         POP     BP
 186         JC      exec_ret_err
 187 ;File Type Checking
 188 ;       CMP     BYTE PTR [Temp_Var2],EAEXISTING      ;AN000;;FT.  old file ?
 189 ;       JZ      oldexf                               ;AN000;;FT.  yes
 190 ;       TEST    BYTE PTR EXEC_FUNC,EXEC_FUNC_OVERLAY ;AN000;;FT.  exec overlay?
 191 ;       JNZ     exovrly                              ;AN000;;FT.  yes
 192 ;       CMP     BYTE PTR [Temp_Var2],EAEXECUTABLE    ;AN000;;FT.  only file type
 193 ;       JZ      oldexf                               ;AN000;;FT.  3 & 4 will pass
 194 ;       CMP     BYTE PTR [Temp_Var2],EAINSTALLABLE   ;AN000;;FT.
 195 ;       JZ      oldexf                               ;AN000;;FT.
 196 ;exerr:                                               ;AN000;;FT.
 197 ;       MOV     AL,error_access_denied               ;AN000;;FT.  error
 198 ;       JMP     exec_ret_err                         ;AN000;;FT.
 199 ;exovrly:                                             ;AN000;;FT.
 200 ;       CMP     BYTE PTR [Temp_Var2],EAOVERLAY       ;AN000;;FT.  only 5,6,7  pass
 201 ;       JZ      oldexf                               ;AN000;;FT.
 202 ;       CMP     BYTE PTR [Temp_Var2],EADEV_DRIVER    ;AN000;;FT.
 203 ;       JZ      oldexf                               ;AN000;;FT.
 204 ;       CMP     BYTE PTR [Temp_Var2],EAIFS_DRIVER    ;AN000;;FT.
 205 ;       JNZ     exerr                                ;AN000;;FT.
 206 ;
 207 ;oldexf:                                              ;AN000;
 208 ;File Type Checking
 209
 210         MOV     exec_fh,AX
 211         MOV     BX,AX
 212         XOR     AL,AL
 213         invoke  $IOCTL
 214         JC      Exec_bombJ
 215         TEST    DL,devid_ISDEV
 216         JZ      exec_check_environ
 217         MOV     AL,error_file_not_found
 218 Exec_bombJ:
 219         JMP     Exec_Bomb
 220
 221 BadEnv:
 222         MOV     AL,error_bad_environment
 223         JMP     exec_bomb
 224
 225 exec_check_environ:
 226         MOV     exec_load_block,0
 227         MOV     exec_environ,0
 228
 229         TEST    BYTE PTR exec_func,exec_func_overlay    ; overlays... no environment
 230         JNZ     exec_read_header
 231         LDS     SI,exec_blk             ; get block
 232         MOV     AX,[SI].Exec1_environ   ; address of environ
 233         OR      AX,AX
 234         JNZ     exec_scan_env
 235         MOV     DS,CurrentPDB
 236         MOV     AX,DS:[PDB_environ]
 237         MOV     exec_environ,AX
 238         OR      AX,AX
 239         JZ      exec_read_header
 240
 241 exec_scan_env:
 242         MOV     ES,AX
 243         XOR     DI,DI
 244         MOV     CX,07FFFh               ; at most 32k of environment
 245         XOR     AL,AL
 246
 247 exec_get_environ_len:
 248         REPNZ   SCASB                   ; find that nul byte
 249         JNZ     BadEnv
 250         DEC     CX                      ; Dec CX for the next nul byte test
 251         JB      BadEnv                  ; gone beyond the end of the environment
 252         SCASB                           ; is there another nul byte?
 253         JNZ     exec_get_environ_len    ; no, scan some more
 254         PUSH    DI
 255         LEA     BX,[DI+0Fh+2]
 256         ADD     BX,ExecNameLen          ; BX <- length of environment
 257                                         ; remember argv[0] length
 258                                         ; round up and remember argc
 259         MOV     CL,4
 260         SHR     BX,CL                   ; number of paragraphs needed
 261         PUSH    ES
 262         invoke  $ALLOC                  ; can we get the space?
 263         POP     DS
 264         POP     CX
 265         JNC     exec_save_environ
 266         JMP     exec_no_mem             ; nope... cry and sob
 267
 268 exec_save_environ:
 269         MOV     ES,AX
 270         MOV     exec_environ,AX         ; save him for a rainy day
 271         XOR     SI,SI
 272         MOV     DI,SI
 273         REP     MOVSB                   ; copy the environment
 274         MOV     AX,1
 275         STOSW
 276         LDS     SI,execName
 277         MOV     CX,execNameLen
 278         REP     MOVSB
 279
 280 exec_read_header:
 281 ;
 282 ; We read in the program header into the above data area and determine
 283 ; where in this memory the image will be located.
 284 ;
 285         Context DS
 286         MOV     CX,exec_header_len      ; header size
 287         MOV     DX,OFFSET DOSGROUP:exec_signature
 288         PUSH    ES
 289         PUSH    DS
 290         CALL    ExecRead
 291         POP     DS
 292         POP     ES
 293         JC      exec_bad_file
 294         OR      AX,AX
 295         JZ      exec_bad_file
 296         CMP     AX,exec_header_len      ; did we read the right number?
 297         JNZ     exec_com_filej          ; yep... continue
 298         TEST    exec_max_BSS,-1         ; indicate load high?
 299         JNZ     exec_check_sig
 300         MOV     exec_load_high,-1
 301 exec_check_sig:
 302         MOV     AX,exec_signature
 303         CMP     AX,exe_valid_signature  ; zibo arises!
 304         JZ      exec_save_start         ; assume com file if no signature
 305         CMP     AX,exe_valid_old_signature  ; zibo arises!
 306         JZ      exec_save_start         ; assume com file if no signature
 307
 308 exec_com_filej:
 309         JMP     exec_com_file
 310
 311 ;
 312 ; We have the program header... determine memory requirements
 313 ;
 314 exec_save_start:
 315         MOV     AX,exec_pages           ; get 512-byte pages
 316         MOV     CL,5                    ; convert to paragraphs
 317         SHL     AX,CL
 318         SUB     AX,exec_par_dir         ; AX = size in paragraphs
 319         MOV     exec_res_len_para,AX
 320
 321 ;
 322 ; Do we need to allocate memory?  Yes if function is not load-overlay
 323 ;
 324         TEST    BYTE PTR exec_func,exec_func_overlay
 325         JZ      exec_allocate           ; allocation of space
 326 ;
 327 ; get load address from block
 328 ;
 329         LES     DI,exec_blk
 330         MOV     AX,ES:[DI].exec3_load_addr
 331         MOV     exec_dma,AX
 332         MOV     AX,ES:[DI].exec3_reloc_fac
 333         MOV     exec_rel_fac,AX
 334 IF DEBUG
 335         JMP     exec_find_res
 336 ELSE
 337         JMP     SHORT exec_find_res
 338 ENDIF
 339
 340 exec_no_mem:
 341         MOV     AL,error_not_enough_memory
 342         JMP     SHORT exec_bomb
 343
 344 exec_bad_file:
 345         MOV     AL,error_bad_format
 346
 347 exec_bomb:
 348         ASSUME  DS:NOTHING,ES:NOTHING
 349         MOV     BX,exec_fh
 350         CALL    exec_dealloc
 351         LeaveCrit   CritMem
 352         SaveReg <AX,BP>
 353         invoke  $CLOSE
 354         RestoreReg  <BP,AX>
 355         JMP     Exec_Ret_Err
 356
 357 exec_allocate:
 358         DOSAssume   CS,<DS>,"EXEC/exec_allocate"
 359         PUSH    AX
 360         MOV     BX,0FFFFh               ; see how much room in arena
 361         PUSH    DS
 362         invoke  $ALLOC                  ; should have carry set and BX has max
 363         POP     DS
 364         POP     AX
 365         ADD     AX,10h                  ; room for header
 366         CMP     BX,11h                  ; enough room for a header
 367         JB      exec_no_mem
 368         CMP     AX,BX                   ; is there enough for bare image?
 369         JA      exec_no_mem
 370         TEST    exec_load_high,-1       ; if load high, use max
 371         JNZ     exec_BX_max             ; use max
 372         ADD     AX,exec_min_BSS         ; go for min allocation
 373         JC      exec_no_mem             ; oops! carry
 374         CMP     AX,BX                   ; enough space?
 375         JA      exec_no_mem             ; nope...
 376         SUB     AX,exec_min_BSS
 377         ADD     AX,exec_max_BSS         ; go for the MAX
 378         JC      exec_BX_max
 379         CMP     AX,BX
 380         JBE     exec_got_block
 381
 382 exec_BX_max:
 383         MOV     AX,BX
 384
 385 exec_got_block:
 386         PUSH    DS
 387         MOV     BX,AX
 388         MOV     exec_size,BX
 389         invoke  $ALLOC                  ; get the space
 390         POP     DS
 391         JC      exec_no_mem
 392         MOV     exec_load_block,AX
 393         ADD     AX,10h
 394         TEST    exec_load_high,-1
 395         JZ      exec_use_ax             ; use ax for load info
 396         ADD     AX,exec_size            ; go to end
 397         SUB     AX,exec_res_len_para    ; drop off header
 398         SUB     AX,10h                  ; drop off pdb
 399 exec_use_ax:
 400         MOV     exec_rel_fac,AX         ; new segment
 401         MOV     exec_dma,AX             ; beginning of dma
 402
 403 ;
 404 ; Determine the location in the file of the beginning of the resident
 405 ;
 406 exec_find_res:
 407         MOV     DX,exec_par_dir
 408         PUSH    DX
 409         MOV     CL,4
 410         SHL     DX,CL                   ; low word of location
 411         POP     AX
 412         MOV     CL,12
 413         SHR     AX,CL                   ; high word of location
 414         MOV     CX,AX                   ; CX <- high
 415
 416 ;
 417 ; Read in the resident image (first, seek to it)
 418 ;
 419         MOV     BX,exec_fh
 420         PUSH    DS
 421         XOR     AL,AL
 422         invoke  $LSEEK                  ; seek to resident
 423         POP     DS
 424         jnc     exec_big_read
 425         jmp     exec_bomb
 426
 427 exec_big_read:                          ; Read resident into memory
 428         MOV     BX,exec_res_len_para
 429         CMP     BX,1000h                ; too many bytes to read?
 430         JB      exec_read_ok
 431         MOV     BX,0FE0h                ; max in one chunk FE00 bytes
 432
 433 exec_read_ok:
 434         SUB     exec_res_len_para,BX    ; we read (soon) this many
 435         PUSH    BX
 436         MOV     CL,4
 437         SHL     BX,CL                   ; get count in bytes from paras
 438         MOV     CX,BX                   ; count in correct register
 439         PUSH    DS
 440         MOV     DS,exec_dma             ; Set up read buffer
 441         ASSUME  DS:NOTHING
 442         XOR     DX,DX
 443         PUSH    CX                      ; save our count
 444         CALL    ExecRead
 445         POP     CX                      ; get old count to verify
 446         POP     DS
 447         JC      exec_bad_fileJ
 448         DOSAssume   CS,<DS>,"EXEC/exec_read_ok"
 449         CMP     CX,AX                   ; did we read enough?
 450         POP     BX                      ; get paragraph count back
 451         JZ      execCheckEnd            ; and do reloc if no more to read
 452 ;
 453 ; The read did not match the request.  If we are off by 512 bytes or more
 454 ; then the header lied and we have an error.
 455 ;
 456         SUB     CX,AX
 457         CMP     CX,512
 458         JAE     Exec_Bad_fileJ
 459 ;
 460 ; We've read in CX bytes... bump DTA location
 461 ;
 462 ExecCheckEnd:
 463         ADD     exec_dma,BX             ; bump dma address
 464         TEST    exec_res_len_para,-1
 465         JNZ     exec_big_read
 466 ;
 467 ; The image has now been read in.  We must perform relocation to
 468 ; the current location.
 469 ;
 470 exec_do_reloc:
 471         MOV     CX,exec_rel_fac
 472         MOV     AX,exec_SS              ; get initial SS
 473         ADD     AX,CX                   ; and relocate him
 474         MOV     exec_init_SS,AX
 475
 476         MOV     AX,exec_SP              ; initial SP
 477         MOV     exec_init_SP,AX
 478
 479         LES     AX,DWORD PTR exec_IP
 480         MOV     exec_init_IP,AX
 481         MOV     AX,ES
 482         ADD     AX,CX                   ; relocated...
 483         MOV     exec_init_CS,AX
 484
 485         XOR     CX,CX
 486         MOV     DX,exec_rle_table
 487         MOV     BX,exec_fh
 488         PUSH    DS
 489         XOR     AX,AX
 490         invoke  $LSEEK
 491         POP     DS
 492
 493         JNC     exec_get_entries
 494 exec_bad_filej:
 495         JMP     exec_bad_file
 496
 497 exec_get_entries:
 498         MOV     DX,exec_rle_count       ; Number of entries left
 499
 500 exec_read_reloc:
 501         ASSUME  DS:NOTHING
 502         PUSH    DX
 503         MOV     DX,OFFSET DOSGROUP:exec_internal_buffer
 504         MOV     CX,((exec_internal_buffer_size)/4)*4
 505         PUSH    DS
 506         CALL    ExecRead
 507         POP     ES
 508         POP     DX
 509         JC      exec_bad_filej
 510         MOV     CX,(exec_internal_buffer_size)/4
 511         MOV     DI,OFFSET DOSGROUP:exec_internal_buffer ; Pointer to byte location in header
 512 ;
 513 ; Relocate a single address
 514 ;
 515         MOV     SI,exec_rel_fac
 516
 517 exec_reloc_one:
 518         OR      DX,DX                   ; Any more entries?
 519         JE      exec_set_PDBJ
 520
 521 exec_get_addr:
 522         LDS     BX,DWORD PTR ES:[DI]    ; Get ra/sa of entry
 523         MOV     AX,DS                   ; Relocate address of item
 524         ADD     AX,SI
 525         MOV     DS,AX
 526         ADD     [BX],SI
 527         ADD     DI,4
 528         DEC     DX
 529         LOOP    exec_reloc_one          ; End of internal buffer?
 530
 531 ;
 532 ; We've exhausted a single buffer's worth.  Read in the next piece
 533 ; of the relocation table.
 534 ;
 535
 536         PUSH    ES
 537         POP     DS
 538         JMP     exec_read_reloc
 539
 540 exec_set_PDBJ:
 541         JMP     exec_set_PDB
 542
 543 exec_no_memj:
 544         JMP     exec_no_mem
 545
 546 ;
 547 ; we have a .COM file.  First, determine if we are merely loading an overlay.
 548 ;
 549 exec_com_file:
 550         TEST    BYTE PTR exec_func,exec_func_overlay
 551         JZ      exec_alloc_com_file
 552         LDS     SI,exec_blk             ; get arg block
 553         LODSW                           ; get load address
 554         MOV     exec_dma,AX
 555         MOV     AX,0FFFFh
 556         JMP     SHORT exec_read_block   ; read it all!
 557
 558 ; We must allocate the max possible size block (ick!)  and set up
 559 ; CS=DS=ES=SS=PDB pointer, IP=100, SP=max size of block.
 560 ;
 561 exec_alloc_com_file:
 562         MOV     BX,0FFFFh
 563         invoke  $ALLOC                  ; largest piece available as error
 564         OR      BX,BX
 565         JZ      exec_no_memj
 566         MOV     exec_size,BX            ; save size of allocation block
 567         PUSH    BX
 568         invoke  $ALLOC                  ; largest piece available as error
 569         POP     BX                      ; get size of block...
 570         MOV     exec_load_block,AX
 571         ADD     AX,10h                  ; increment for header
 572         MOV     exec_dma,AX
 573         XOR     AX,AX                   ; presume 64K read...
 574         CMP     BX,1000h                ; 64k or more in block?
 575         JAE     exec_read_com           ; yes, read only 64k
 576         MOV     AX,BX                   ; convert size to bytes
 577         MOV     CL,4
 578         SHL     AX,CL
 579 exec_read_com:
 580         SUB     AX,100h                 ; remember size of psp
 581 exec_read_block:
 582         PUSH    AX                      ; save number to read
 583         MOV     BX,exec_fh              ; of com file
 584         XOR     CX,CX                   ; but seek to 0:0
 585         MOV     DX,CX
 586         XOR     AX,AX                   ; seek relative to beginning
 587         invoke  $LSEEK                  ; back to beginning of file
 588         POP     CX                      ; number to read
 589         MOV     DS,exec_dma
 590         XOR     DX,DX
 591         PUSH    CX
 592         CALL    ExecRead
 593         POP     SI                      ; get number of bytes to read
 594         jnc     OkRead
 595         jmp     exec_bad_file
 596 OkRead:
 597         CMP     AX,SI                   ; did we read them all?
 598         JZ      exec_no_memj            ; exactly the wrong number... no memory
 599         TEST    BYTE PTR exec_func,exec_func_overlay
 600         JNZ     exec_set_PDB            ; no starto, chumo!
 601         MOV     AX,exec_DMA
 602         SUB     AX,10h
 603         MOV     exec_init_CS,AX
 604         MOV     exec_init_IP,100h       ; initial IP is 100
 605 ;
 606 ; SI is at most FF00h.  Add FE to account for PSP - word of 0 on stack.
 607 ;
 608         ADD     SI,0FEh                 ; make room for stack
 609         MOV     exec_init_SP,SI         ; max value for read is also SP!
 610         MOV     exec_init_SS,AX
 611         MOV     DS,AX
 612         MOV     WORD PTR [SI],0         ; 0 for return
 613
 614 exec_set_PDB:
 615         MOV     BX,exec_fh              ; we are finished with the file.
 616         CALL    exec_dealloc
 617         PUSH    BP
 618         invoke  $CLOSE                  ; release the jfn
 619         POP     BP
 620         CALL    exec_alloc
 621         TEST    BYTE PTR exec_func,exec_func_overlay
 622         JZ      exec_build_header
 623         CALL    Scan_Execname           ;MS.;AN007;
 624         CALL    Scan_Special_Entries    ;MS.;AN007;
 625         Leave
 626         transfer    SYS_RET_OK          ; overlay load -> done
 627
 628 exec_build_header:
 629         MOV     DX,exec_load_block
 630 ;
 631 ; assign the space to the process
 632 ;
 633
 634         MOV     SI,arena_owner          ; pointer to owner field
 635
 636         MOV     AX,exec_environ         ; get environ pointer
 637         OR      AX,AX
 638         JZ      NO_OWNER                ; no environment
 639         DEC     AX                      ; point to header
 640         MOV     DS,AX
 641         MOV     [SI],DX                 ; assign ownership
 642 NO_OWNER:
 643         MOV     AX,exec_load_block      ; get load block pointer
 644         DEC     AX
 645         MOV     DS,AX                   ; point to header
 646         MOV     [SI],DX                 ; assign ownership
 647
 648         PUSH    DS                      ;AN000;MS. make ES=DS
 649         POP     ES                      ;AN000;MS.
 650         MOV     DI,ARENA_NAME           ;AN000;MS. ES:DI points to destination
 651         CALL    Scan_Execname           ;AN007;MS. parse execname
 652                                         ;          ds:si->name, cx=name length
 653         PUSH    CX                      ;AN007;;MS. save for fake version
 654         PUSH    SI                      ;AN007;;MS. save for fake version
 655
 656 movename:                               ;AN000;
 657         LODSB                           ;AN000;;MS. get char
 658         CMP     AL,'.'                  ;AN000;;MS. is '.' ,may be name.exe
 659         JZ      mem_done                ;AN000;;MS. no, move to header
 660                                         ;AN000;
 661         STOSB                           ;AN000;;MS. move char
 662         LOOP    movename                ;AN000;;MS. continue
 663 mem_done:                               ;AN000;
 664         XOR     AL,AL                   ;AN000;;MS. make ASCIIZ
 665         CMP     DI,SIZE ARENA           ;AN000;MS. if not all filled
 666         JAE     fill8                   ;AN000;MS.
 667         STOSB                           ;AN000;MS.
 668 fill8:                                  ;AN000;
 669         POP    SI                       ;AN007;MS. ds:si -> file name
 670         POP    CX                       ;AN007;MS.
 671
 672         CALL   Scan_Special_Entries     ;AN007;MS.
 673
 674         PUSH    DX
 675         MOV     SI,exec_size
 676         ADD     SI,DX
 677         invoke  $Dup_PDB                ; ES is now PDB
 678         POP     DX
 679
 680         PUSH    exec_environ
 681         POP     ES:[PDB_environ]
 682 ;
 683 ; set up proper command line stuff
 684 ;
 685         LDS     SI,exec_blk             ; get the block
 686         PUSH    DS                      ; save its location
 687         PUSH    SI
 688         LDS     SI,[SI.exec0_5C_FCB]    ; get the 5c fcb
 689 ;
 690 ; DS points to user space 5C FCB
 691 ;
 692         MOV     CX,12                   ; copy drive, name and ext
 693         PUSH    CX
 694         MOV     DI,5Ch
 695         MOV     BL,[SI]
 696         REP     MOVSB
 697 ;
 698 ; DI = 5Ch + 12 = 5Ch + 0Ch = 68h
 699 ;
 700         XOR     AX,AX                   ; zero extent, etc for CPM
 701         STOSW
 702         STOSW
 703 ;
 704 ; DI = 5Ch + 12 + 4 = 5Ch + 10h = 6Ch
 705 ;
 706         POP     CX
 707         POP     SI                      ; get block
 708         POP     DS
 709         PUSH    DS                      ; save (again)
 710         PUSH    SI
 711         LDS     SI,[SI.exec0_6C_FCB]    ; get 6C FCB
 712 ;
 713 ; DS points to user space 6C FCB
 714 ;
 715         MOV     BH,[SI]                 ; do same as above
 716         REP     MOVSB
 717         STOSW
 718         STOSW
 719         POP     SI                      ; get block (last time)
 720         POP     DS
 721         LDS     SI,[SI.exec0_com_line]  ; command line
 722 ;
 723 ; DS points to user space 80 command line
 724 ;
 725         OR      CL,80h
 726         MOV     DI,CX
 727         REP     MOVSB                   ; Wham!
 728 ;
 729 ; Process BX into default AX (validity of drive specs on args).  We no longer
 730 ; care about DS:SI.
 731 ;
 732         DEC     CL                      ; get 0FFh in CL
 733         MOV     AL,BH
 734         XOR     BH,BH
 735         invoke  GetVisDrv
 736         JNC     exec_BL
 737         MOV     BH,CL
 738 exec_BL:
 739         MOV     AL,BL
 740         XOR     BL,BL
 741         invoke  GetVisDrv
 742         JNC     exec_Set_Return
 743         MOV     BL,CL
 744 exec_set_return:
 745         invoke  get_user_stack          ; get his return address
 746         PUSH    [SI.user_CS]            ; suck out the CS and IP
 747         PUSH    [SI.user_IP]
 748         PUSH    [SI.user_CS]            ; suck out the CS and IP
 749         PUSH    [SI.user_IP]
 750         POP     WORD PTR ES:[PDB_Exit]
 751         POP     WORD PTR ES:[PDB_Exit+2]
 752         XOR     AX,AX
 753         MOV     DS,AX
 754         POP     DS:[addr_int_terminate] ; save them where we can get them later
 755         POP     DS:[addr_int_terminate+2]   ; when the child exits.
 756         MOV     WORD PTR DMAADD,80h
 757         MOV     DS,CurrentPDB
 758         MOV     WORD PTR DMAADD+2,DS
 759         TEST    BYTE PTR exec_func,exec_func_no_execute
 760         JZ      exec_go
 761
 762         LDS     SI,DWORD PTR exec_init_SP   ; get stack
 763         LES     DI,exec_blk             ; and block for return
 764         MOV     ES:[DI].exec1_SS,DS     ; return SS
 765
 766         DEC     SI                      ; 'push' default AX
 767         DEC     SI
 768         MOV     [SI],BX                 ; save default AX reg
 769         MOV     ES:[DI].exec1_SP,SI     ; return 'SP'
 770
 771         LDS     AX,DWORD PTR exec_init_IP
 772         MOV     ES:[DI].exec1_CS,DS     ; initial entry stuff
 773
 774         MOV     ES:[DI].exec1_IP,AX
 775         Leave
 776         transfer    SYS_RET_OK
 777
 778 exec_go:
 779         LDS     SI,DWORD PTR exec_init_IP   ; get entry point
 780         LES     DI,DWORD PTR exec_init_SP   ; new stack
 781         MOV     AX,ES
 782 ;
 783 ; DS:SI points to entry point
 784 ; AX:DI points to initial stack
 785 ; DX has PDB pointer
 786 ; BX has initial AX value
 787 ;
 788         CLI
 789         MOV     BYTE PTR INDOS,0
 790         ASSUME  SS:NOTHING
 791         MOV     SS,AX                   ; set up user's stack
 792         MOV     SP,DI                   ; and SP
 793         STI
 794         PUSH    DS                      ; fake long call to entry
 795         PUSH    SI
 796         MOV     ES,DX                   ; set up proper seg registers
 797         MOV     DS,DX
 798         MOV     AX,BX                   ; set up proper AX
 799 procedure   exec_long_ret,FAR
 800
 801 IF      BUFFERFLAG
 802         invoke  restore_user_map
 803 ENDIF
 804
 805         RET
 806 EndProc exec_long_ret
 807
 808 EndProc $Exec
 809
 810 Procedure   ExecRead,NEAR
 811         CALL    exec_dealloc
 812         MOV     bx,exec_fh
 813         PUSH    BP
 814         invoke  $READ
 815         POP     BP
 816         CALL    exec_alloc
 817         return
 818 EndProc ExecRead
 819
 820 procedure   exec_dealloc,near
 821         ASSUME      DS:NOTHING,ES:NOTHING
 822         PUSH        BX
 823         MOV         BX,arena_owner_system
 824         EnterCrit   CritMEM
 825         CALL        ChangeOwners
 826         POP         BX
 827         return
 828 EndProc exec_dealloc
 829
 830 procedure   exec_alloc,near
 831         PUSH        BX
 832         MOV         BX,CurrentPDB
 833         CALL        ChangeOwners
 834         LeaveCrit   CritMEM
 835         POP         BX
 836         return
 837 EndProc exec_alloc
 838
 839 procedure   ChangeOwners,NEAR
 840         pushf
 841         PUSH    AX
 842         MOV     AX,exec_environ
 843         CALL    ChangeOwner
 844         MOV     AX,exec_load_block
 845         Call    ChangeOwner
 846         POP     AX
 847         popf
 848         return
 849 EndProc ChangeOwners
 850
 851 Procedure   ChangeOwner,near
 852         OR      AX,AX                   ; is area allocated?
 853         retz                            ; no, do nothing
 854         DEC     AX
 855         PUSH    DS
 856         MOV     DS,AX
 857         MOV     DS:[arena_owner],BX
 858         POP     DS
 859         return
 860 EndProc ChangeOwner
 861
 862 Procedure    Scan_Execname,near         ;AN000;MS.
 863
 864         LDS     SI,execName             ;AN000;MS. DS:SI points to name
 865 save_begin:                             ;AN000;
 866         MOV     CX,SI                   ;AN000;MS. CX= starting addr
 867 scan0:                                  ;AN000;
 868         LODSB                           ;AN000;MS. get char
 869         CMP     AL,':'                  ;AN000;;MS. is ':' , may be A:name
 870         JZ      save_begin              ;AN000;;MS. yes, save si
 871         CMP     AL,'\'                  ;AN000;;MS. is '\', may be A:\name
 872         JZ      save_begin              ;AN000;;MS. yes, save si
 873         CMP     AL,0                    ;AN000;;MS. is end of name
 874         JNZ     scan0                   ;AN000;;MS. no, continue scanning
 875         SUB     SI,CX                   ;AN000;;MS. get name's length
 876         XCHG    SI,CX                   ;AN000;;MS. cx= length, si= starting addr
 877
 878         return                          ;AN000;;MS.
 879 EndProc Scan_Execname                   ;AN000;;MS.
 880
 881
 882 Procedure    Scan_Special_Entries,near  ;AN000;MS.
 883
 884         DEC    CX                       ;AN007;MS. cx= name length
 885         MOV    DI,CS:[Special_Entries]  ;AN007;MS. es:di -> addr of special entries
 886         CALL   Reset_Version            ;AN008;MS.
 887         PUSH   CS                       ;AN007;MS.
 888         POP    ES                       ;AN007;MS.
 889 Getentries:                             ;AN007;MS.
 890         MOV    AL,ES:[DI]               ;AN007;MS. end of list
 891         OR     AL,AL                    ;AN007;MS.
 892         JZ     end_list                 ;AN007;MS. yes
 893         MOV    CS:[Temp_Var2],DI        ;AN007;MS. save di
 894         CMP    AL,CL                    ;AN007;MS. same length ?
 895         JNZ    skipone                  ;AN007;MS. no
 896         INC    DI                       ;AN007;MS. es:di -> special name
 897         PUSH   CX                       ;AN007;MS. save length and name addr
 898         PUSH   SI                       ;AN007;MS.
 899         REPZ   CMPSB                    ;AN007;MS. same name ?
 900         JNZ    not_matched              ;AN007;MS. no
 901         MOV    AX,ES:[DI]               ;AN007;MS. get special version
 902         MOV    CS:[Special_Version],AX  ;AN007;MS. save it
 903         MOV    AL,ES:[DI+2]             ;AN008;MS. get fake count
 904         MOV    CS:[Fake_Count],AL       ;AN007;MS. save it
 905         POP    SI                       ;AN007;MS.
 906         POP    CX                       ;AN007;MS.
 907         JMP    SHORT end_list           ;AN007;MS.
 908 not_matched:                            ;AN007;MS.
 909         POP    SI                       ;AN007;MS. restore si,cx
 910         POP    CX                       ;AN007;MS.
 911 skipone:                                ;AN007;MS.
 912         MOV    DI,CS:[Temp_Var2]        ;AN007;MS. restore old di
 913         XOR    AH,AH                    ;AN007;MS. position to next entry
 914         ADD    DI,AX                    ;AN007;MS.
 915         ADD    DI,4                     ;AN007;MS.
 916         JMP    Getentries               ;AN007;MS.
 917
 918
 919 end_list:                               ;AN007;MS.
 920         return
 921 EndProc Scan_Special_Entries            ;AN000;;MS.
 922
 923 Procedure    Reset_Version,near         ;AN008;MS.
 924
 925         CMP    CS:[Fake_Count],0FFH     ;AN008;MS.
 926         JNZ    dont_reset               ;AN008;MS.
 927         MOV    CS:[Special_Version],0   ;AN008;MS. reset to current version
 928 dont_reset:
 929         return
 930 EndProc Reset_Version,near              ;AN008;;MS.
 931 \1a