v4.0/src/CMD/COMMAND/PATH2.ASM

   1  page 80,132
   2 ;       SCCSID = @(#)path2.asm  1.1 85/05/14
   3 ;       SCCSID = @(#)path2.asm  1.1 85/05/14
   4 .sall
   5 .xlist
   6 .xcref
   7 INCLUDE DOSSYM.INC
   8     include comsw.asm
   9     include comseg.asm
  10     include comequ.asm
  11 .list
  12 .cref
  13
  14
  15 DATARES SEGMENT PUBLIC BYTE
  16         EXTRN   FORFLAG:BYTE
  17 DATARES ENDS
  18
  19
  20 break <Path.Asm>
  21 ;----------------------------------------------------------------------------
  22 ;    PATH.ASM contains the routines to perform pathname incovation.  Path and
  23 ;    Parse share a temporary buffer and argv[] definitions.  <Path_Search>,
  24 ;    given a pathname, attempts to find a corresponding executable or batch
  25 ;    file on disk.  Directories specified in the user's search path will be
  26 ;    searched for a matching file, if a match is not found in the current
  27 ;    directory and if the pathname is actually only an MSDOS filename.
  28 ;    <Path_Search> assumes that the parsed command name can be found in
  29 ;    argv[0] -- in other words, <Parseline> should be executed prior to
  30 ;    <Path_Search>.  Alternatively, the command name and appropriate
  31 ;    information could be placed in argv[0], or <Path_Search> could be
  32 ;    (easily) modified to make no assumptions about where its input is found.
  33 ;    Please find enclosed yet another important routine, <Save_Args>, which
  34 ;    places the entire arg/argv[]/argbuf structure on a piece of newly
  35 ;    allocated memory.  This is handy for for-loop processing, and anything
  36 ;    else that wants to save the whole shebang and then process other command
  37 ;    lines.
  38 ;
  39 ; Alan L, OS/MSDOS                                  August 15, 1983
  40 ;
  41 ; ENTRY:
  42 ;   <Path_Search>:          argv[0].
  43 ;   <Save_Args>:            bytes to allocate in addition to arg structure
  44 ; EXIT:
  45 ;   <Path_Search>:          success flag, best pathname match in EXECPATH.
  46 ;   <Save_Args>:            success flag, segment address of new memory
  47 ; NOTE(S):
  48 ;   *   <Argv_calc> handily turns an array index into an absolute pointer.
  49 ;       The computation depends on the size of an argv[] element (arg_ele).
  50 ;   *   <Parseline> calls <cparse> for chunks of the command line.  <Cparse>
  51 ;       does not function as specified; see <Parseline> for more details.
  52 ;   *   <Parseline> now knows about the flags the internals of COMMAND.COM
  53 ;       need to know about.  This extra information is stored in a switch_flag
  54 ;       word with each command-line argument; the switches themselves will not
  55 ;       appear in the resulting arg structure.
  56 ;   *   With the exception of CARRY, flags are generally preserved across calls.
  57 ;---------------
  58 ; CONSTANTS:
  59 ;---------------
  60     DEBUGx      equ         FALSE       ; prints out debug info
  61 ;---------------
  62 ; DATA:
  63 ;---------------
  64
  65 TRANSPACE       SEGMENT PUBLIC BYTE     ;AC000;
  66         EXTRN   arg:byte
  67         EXTRN   BADPMES_ptr:word
  68         EXTRN   curdrv:byte
  69         EXTRN   EXECPATH:byte
  70         EXTRN   ext_entered:byte        ;AN005;
  71         EXTRN   fbuf:byte
  72         EXTRN   pathinfo:word
  73         EXTRN   psep_char:byte
  74         EXTRN   string_ptr_2:word
  75         EXTRN   tpbuf:byte
  76 TRANSPACE       ENDS
  77
  78 TRANCODE        SEGMENT PUBLIC BYTE     ;AC000;
  79
  80 assume cs:trangroup, ds:trangroup, es:trangroup, ss:nothing
  81
  82
  83 break <Search>
  84 ;----------------------------------------------------------------------------
  85 ;   SEARCH, when given a pathname, attempts to find a file with
  86 ; one of the following extensions:  .com, .exe, .bat (highest to
  87 ; lowest priority).  Where conflicts arise, the extension with
  88 ; the highest priority is favored.
  89 ; ENTRY:
  90 ;   DX          --      pointer to null-terminated pathname
  91 ;   fbuf        --      dma buffer for findfirst/next
  92 ; EXIT:
  93 ;   AX          --      8)  file found with .com extension
  94 ;                       4)  file found with .exe extension
  95 ;                       2)  file found with .bat extension
  96 ;                       0)  no such file to be found
  97 ;   (if AX is non-zero:)
  98 ;   [search_best]       identical to AX
  99 ;   [search_best_buf]   null-terminated filename
 100 ; NOTES:
 101 ;   1)  Requires caller to have allocated a dma buffer and executed a setdma.
 102 ;---------------
 103 ; CONSTANTS:
 104 ;---------------
 105 search_file_not_found       equ         0
 106 search_com                  equ         8
 107 search_exe                  equ         4
 108 search_bat                  equ         2
 109 fname_len                   equ         8
 110 fname_max_len               equ         13
 111 dot                         equ         '.'
 112 wildchar                    equ         '?'
 113
 114 ;---------------
 115 ; DATA:
 116 ;---------------
 117 TRANSPACE       SEGMENT PUBLIC BYTE     ;AC000;
 118         EXTRN   search_best:byte
 119         EXTRN   search_best_buf:byte
 120         EXTRN   search_curdir_buf:byte
 121         EXTRN   search_error:word
 122 TRANSPACE       ENDS
 123
 124 ;---------------
 125 Procedure   Search,NEAR
 126 ;---------------
 127         push    CX
 128         push    DX
 129         push    DI
 130         push    SI
 131         pushf
 132
 133         push    DX                              ; check drivespec (save pname ptr)
 134         mov     DI, DX                          ; working copy of pathname
 135         mov     SI, OFFSET TRANGROUP:search_curdir_buf
 136         xor     DX, DX                          ; zero means current drive
 137         cmp     BYTE PTR [DI+1],':'             ; is there a drive spec?
 138         jne     search_dir_check
 139         mov     DL, [DI]                        ; get the drive byte
 140         and     DL, NOT 20H                     ; uppercase the sucker
 141         sub     DL, '@'                         ; and convert to drive number
 142
 143 search_dir_check:
 144         trap    Current_Dir                     ; can we get the drive's current
 145         pop     DX                              ; directory?  If we can't we'll
 146         jc      search_invalid_drive            ; assume it's a bad drive...
 147
 148         mov     CX, search_attr                 ; filetypes to search for
 149         trap    Find_First                      ; request first match, if any
 150         jc      search_no_file
 151         mov     search_best, search_file_not_found
 152         mov     [search_best_buf], ANULL        ; nothing's been found, yet
 153
 154 search_loop:
 155         call    search_ftype                    ; determine if .com, &c...
 156         cmp     AL, search_best                 ; better than what we've found so far?
 157         jle     search_next                     ; no, look for another
 158         mov     search_best, AL                 ; found something... save its code
 159         mov     SI, OFFSET TRANGROUP:fbuf.find_buf_pname
 160         mov     DI, OFFSET TRANGROUP:search_best_buf
 161         mov     CX, fname_max_len
 162         cld
 163         rep     movsb                           ; save complete pathname representation
 164         cmp     AL, search_com                  ; have we found the best of all?
 165         je      search_done
 166
 167 search_next:                                    ; keep on looking
 168         mov     CX, search_attr
 169         trap    Find_Next                       ; next match
 170         jnc     search_loop
 171
 172 search_done:                                    ; it's all over with...
 173         mov     AL, search_best                 ; pick best to return with
 174         cmp     ext_entered,1                   ;AN005; Did user request a specific ext?
 175         jz      search_exit                     ;AN005; no - exit
 176         mov     al,ext_entered                  ;AN005; yes - get the real file type back
 177         mov     search_best,al                  ;AN005; save the real file type
 178         jmp     short search_exit
 179
 180 search_invalid_drive:                           ; Tell the user path/drive
 181         mov     DX, [search_error]              ; appropriate error message
 182         invoke  std_printf                      ; and pretend no file found
 183
 184 search_no_file:                                 ; couldn't find a match
 185         mov     AX, search_file_not_found
 186
 187 search_exit:
 188         popf
 189         pop     SI
 190         pop     DI
 191         pop     DX
 192         pop     CX
 193         ret
 194 ;---------------
 195 EndProc Search
 196 ;----------------------------------------------------------------------------
 197
 198
 199 break <Search_Ftype>
 200 ;----------------------------------------------------------------------------
 201 ;   SEARCH_FTYPE determines the type of a file by examining its extension.
 202 ; ENTRY:
 203 ;   fbuf    --      dma buffer containing filename
 204 ; EXIT:
 205 ;   AX      --      file code, as given in search header
 206 ; NOTE(S):
 207 ;   *   Implicit assumption that NULL == search_file_not_found
 208 ;---------------
 209 ; DATA:
 210 ;---------------
 211 TRANDATA        SEGMENT PUBLIC BYTE             ;AC000;
 212         extrn   comext:byte,exeext:byte,batext:byte
 213 trandata     ends
 214 ;---------------
 215 Procedure   Search_Ftype,NEAR
 216 ;---------------
 217         push    DI
 218         push    si
 219         mov     AX, ANULL                       ; find the end of the filename
 220         mov     DI, OFFSET TRANGROUP:fbuf.find_buf_pname
 221         mov     CX, fname_max_len
 222         cld
 223         repnz   scasb                           ; search for the terminating null
 224         jnz     ftype_exit                      ; weird... no null byte at end
 225         sub     di,5                            ; . + E + X + T + NULL
 226 ;
 227 ; Compare .COM
 228 ;
 229         mov     si,offset trangroup:comext
 230         mov     ax,di
 231         cmpsw
 232         jnz     ftype_exe
 233         cmpsw
 234         jnz     ftype_exe
 235         mov     AX, search_com                  ; success!
 236         jmp     short ftype_exit
 237 ;
 238 ; Compare .EXE
 239 ;
 240
 241 ftype_exe:                                      ; still looking... now for '.exe'
 242         mov     di,ax
 243         mov     si,offset trangroup:exeext
 244         cmpsw
 245         jnz     ftype_bat
 246         cmpsw
 247         jnz     ftype_bat
 248         mov     AX, search_exe                  ; success!
 249         jmp     short ftype_exit
 250 ;
 251 ; Compare .BAT
 252 ;
 253
 254 ftype_bat:                                      ; still looking... now for '.bat'
 255         mov     di,ax
 256         mov     si,offset trangroup:batext
 257         cmpsw
 258         jnz     ftype_fail
 259         cmpsw
 260         jnz     ftype_fail
 261         mov     AX, search_bat                  ; success!
 262         jmp     short ftype_exit
 263
 264 ftype_fail:                                     ; file doesn't match what we need
 265         mov     ax,ANULL
 266
 267 ftype_exit:
 268         cmp     ext_entered,1                   ;AN005; was an extension entered?
 269         jz      ftype_done                      ;AN005; no - exit
 270         cmp     ax,ANULL                        ;AN005; was any match found
 271         jz      ftype_done                      ;AN005; no - exit
 272         mov     ext_entered,al                  ;AN005; save the match type found
 273         mov     AX, search_com                  ;AN005; send back best was found to stop search
 274
 275 ftype_done:                                     ;AN005;
 276         pop     SI
 277         pop     DI
 278         ret
 279
 280 ;---------------
 281 EndProc Search_Ftype
 282 ;----------------------------------------------------------------------------
 283
 284
 285 break <Strip>
 286 ;----------------------------------------------------------------------------
 287 ;    STRIP copies the source string (argv[0]) into the destination buffer,
 288 ; replacing any extension with wildcards.
 289 ; ENTRY:
 290 ;       BX              --              maximum length of destination buffer
 291 ;       DS:SI           --              address of destination buffer
 292 ;       argv[0]         --              command name to be stripped
 293 ; EXIT:
 294 ;       CF              --              set if failure, clear if successful
 295 ; NOTE(S):
 296 ;---------------
 297 Procedure   Strip,NEAR
 298 ;---------------
 299         push    AX
 300         push    BX
 301         push    CX
 302         push    DX
 303         push    DI
 304         push    SI
 305         pushf
 306
 307         mov     ext_entered,1                   ;AN005; assume no extension on file name
 308         mov     DX, DS:arg.argv[0].argpointer   ; save pointer to beginning of argstring
 309         mov     DI, DS:arg.argv[0].argstartel   ; beginning of last pathname element
 310         cmp     BYTE PTR [DI], 0                ; *STARTEL == NULL means no command
 311         jz      strip_error
 312         mov     CX, DX                          ; compute where end of argstring lies
 313         add     CX, DS:arg.argv[0].arglen
 314         sub     CX, DI                          ; and then find length of last element
 315         inc     CX                              ; include null as well
 316         mov     AL, dot                         ; let's find the filetype extension
 317         cld
 318         repnz   scasb                           ; wind up pointing to either null or dot
 319         jcxz    process_ext                     ;AN005; if no extension found, just continue
 320         mov     ext_entered,0                   ;AN005; we found an extension
 321         mov     al,ANULL                        ;AN005; continue scanning until the
 322         repnz   scasb                           ;AN005;    end of line is reached.
 323
 324 process_ext:                                    ;AN005;
 325         mov     CX, DI                          ; pointer to end of argstring yields
 326         sub     CX, DX                          ; number of bytes to be copied
 327         sub     BX, 4                           ; can argstring fit into dest. buffer?
 328         cmp     CX, BX
 329         jg      strip_error                     ; if not, we must have a bad pathname
 330         mov     DI, SI                          ; destination buffer
 331         mov     SI, DX                          ; source is beginning of pathname
 332         cld
 333         rep     movsb                           ; SI=arg,DI=buffer,CX=argend-argbeg
 334         cmp     ext_entered,1                   ;AN005; if an extension was entered
 335         jnz     skip_wilds                      ;AN005;    don't set up wildcard ext.
 336
 337         dec     DI                              ; overwrite null or dot
 338         stosb                                   ; with a dot
 339         mov     AL, wildchar                    ; now add wildcards
 340         stosb
 341         stosb
 342         stosb
 343         mov     AL, ANULL                       ; and a terminating null
 344         stosb
 345
 346 skip_wilds:                                     ;AN005;
 347         popf
 348         clc                                     ; chill out...
 349         jmp     short strip_exit
 350
 351 strip_error:
 352         popf
 353         stc
 354
 355 strip_exit:
 356         pop     SI
 357         pop     DI
 358         pop     DX
 359         pop     CX
 360         pop     BX
 361         pop     AX
 362         ret
 363 ;---------------
 364 EndProc Strip
 365 ;----------------------------------------------------------------------------
 366
 367
 368 break <Save_Args>
 369 ;----------------------------------------------------------------------------
 370 ;   SAVE_ARGS attempts to preserve the existing argv[]/argvcnt/argbuffer
 371 ; structure in newly allocated memory.  The argv[] structure is found at the
 372 ; beginning of this area.  The caller indicates how much extra space is
 373 ; needed in the resulting structure; Save_Args returns a segment number and
 374 ; an offset into that area, indicating where the caller may preserve its own
 375 ; data.  Note that <argvcnt> can be found at <offset-2>.
 376 ; ENTRY:
 377 ;   BX      --      size (in bytes) of extra area to allocate
 378 ; EXIT:
 379 ;   AX      --      segment of new area.
 380 ;   CF      --      set if unable to save a copy.
 381 ; NOTE(S):
 382 ;   1)  The allocated area will be AT LEAST the size requested -- since
 383 ;       the underlying MSDOS call, <alloc> returns an integral number of
 384 ;       paragraphs.
 385 ;   2)  It is an error if MSDOS can't allocate AT LEAST as much memory
 386 ;       as the caller of Save_Args requests.
 387 ;   3)  AX is undefined if CF indicates an error.
 388 ;---------------
 389 Procedure   Save_Args,NEAR
 390 ;---------------
 391         push    BX
 392         push    CX
 393         push    DX
 394         push    DI
 395         push    SI
 396         push    BP
 397         pushf
 398         add     BX, SIZE arg_unit + 0FH         ; space for arg structure, round up
 399         mov     CL, 4                           ; to paragraph size and convert
 400         shr     BX, CL                          ; size in bytes to size in paragraphs
 401         trap    Alloc
 402         jc      save_error
 403         mov     BP, AX                          ; save segment id
 404         push    ES                              ; save TRANGROUP address
 405         mov     ES, AX                          ; switch to new memory segment
 406 assume  ES:nothing
 407         mov     CX, SIZE arg_unit               ; get back structure size
 408         xor     DI, DI                          ; destination is new memory area
 409         mov     SI, OFFSET TRANGROUP:arg        ; source is arg structure
 410         rep     movsb                           ; move that sucker!
 411         mov     CX, arg.argvcnt                 ; adjust argv pointers
 412         xor     AX, AX                          ; base address for argv_calc
 413         mov     SI, OFFSET TRANGROUP:arg.argbuf - OFFSET arg_unit.argbuf
 414
 415 save_ptr_loop:
 416         dec     CX                              ; exhausted all args?
 417         jl      save_done
 418         mov     BX, CX                          ; get arg index and
 419         invoke  argv_calc                       ; convert to a pointer
 420         mov     DX, DS:arg.argv[BX].argpointer
 421         sub     DX, SI                          ; adjust argpointer
 422         mov     ES:argv[BX].argpointer, DX
 423         mov     DX, DS:arg.argv[BX].argstartel
 424         sub     DX, SI                          ; and adjust argstartel
 425         mov     ES:argv[BX].argstartel, DX
 426         mov     DX, DS:arg.argv[BX].arg_ocomptr
 427         sub     DX, SI                          ; and adjust arg_ocomptr
 428         mov     ES:argv[BX].arg_ocomptr, DX
 429         jmp     save_ptr_loop
 430
 431 save_done:
 432         pop     ES                              ; back we go to TRANGROUP
 433 assume  ES:trangroup
 434         mov     AX, BP                          ; restore segment id
 435         jmp     short save_ok
 436
 437 save_error:
 438         popf
 439         stc
 440         jmp     short save_exit
 441
 442 save_ok:
 443         popf
 444         clc
 445 save_exit:
 446         pop     BP
 447         pop     SI
 448         pop     DI
 449         pop     DX
 450         pop     CX
 451         pop     BX
 452         ret
 453 ;---------------
 454 EndProc Save_Args
 455 ;----------------------------------------------------------------------------
 456
 457 trancode    ends
 458 END