Subversion Repositories SvarDOS

/* This file is part of the SvarCOM project and is published under the terms

 * of the MIT license.

 *

 * Copyright (C) 2021-2022 Mateusz Viste

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

/*

 * goto label

 *

 * if label does not exist in the currently processed batch file, then a error

 * "Label not found" is displayed and the batch file is aborted. Any parent

 * batches are ALSO aborted. Same behavior if called without any parameter.

 *

 * if called outside of a batch file, this command has no effect (and does not

 * display any error, even when called without any argument).

 *

 * it reacts to /? by outputing its help screen

 *

 * only 1st argument is processed, any extra arguments are ignored (even /?).

 *

 * Labels can be written as:

 * :LABEL

 *    :LABEL

 *   :  LABEL

 *

 * A label can also be followed by one or more space or tabs, followed by

 * anything. The label is parsed only to the first space, tab, end of line or

 * end of file. Hence this would be perfectly ok:

 *

 * :LABEL this is a comment

 *

 * Labels are searched in the batch file from top to bottom and first match

 * is jumped to. Matching labels is case-insensitive (ie. LABEL == LaBeL)

 */

static void goto_close_dos_handle(unsigned short fhandle) {

  _asm {

    push bx

    mov ah, 0x3e

    mov bx, fhandle

    int 0x21

    pop bx

  }

}

static enum cmd_result cmd_goto(struct cmd_funcparam *p) {

  char *buff = NULL;

  const char *label;

  unsigned short bufflen = 0;

  unsigned short fhandle = 0;

  unsigned short doserr = 0;

  unsigned short batname_seg;

  unsigned short batname_off;

  unsigned char eof_reached = 0;

  unsigned short i;

  /* help? reacts only to /? being passed as FIRST argument */

  if ((p->argc > 0) && imatch(p->argv[0], "/?")) {

    nls_outputnl(17,0); /* "Directs batch processing to a labelled line in the batch program." */

    outputnl("");

    nls_outputnl(17,1); /* "GOTO LABEL" */

    outputnl("");

    nls_outputnl(17,2); /* "LABEL specifies a text string used in the batch program as a label." */

    outputnl("");

    nls_outputnl(17,3); /* "A label is on a line by itself and must be preceded by a colon." */

    return(CMD_OK);

  }

  /* not inside a batch file? not given any argument? then do nothing */

  if ((p->rmod->bat == NULL) || (p->argc == 0)) return(CMD_OK);

  /* label is in first arg */

  label = p->argv[0];

  /* open batch file (read-only) */

  batname_seg = FP_SEG(p->rmod->bat->fname);

  batname_off = FP_OFF(p->rmod->bat->fname);

  _asm {

    push bx

    push dx

    mov ax, batname_seg

    push ds /* save ds */

    mov ds, ax

    mov dx, batname_off

    mov ax, 0x3d00

    int 0x21    /* handle in ax on success */

    pop ds

    jnc OPEN_SUCCESS

    mov doserr, ax

    OPEN_SUCCESS:

    mov fhandle, ax /* save file handle */

    pop dx

    pop bx

  }

  /* file open failed? */

  if (doserr != 0) {

    nls_outputnl_doserr(doserr);

    return(CMD_FAIL);

  }

  /* reset the rmod bat counter since I will scan all lines from top to bottom */

  p->rmod->bat->nextline = 0; /* remember this is a byte offset, not a line number */

  /* read bat file line by line until label is found or EOF */

  for (;;) {

    /* move any existing data to the start of the buffer */

    if (bufflen > 0) memmove(p->BUFFER, buff, bufflen);

    buff = p->BUFFER; /* assumption: must be big enough to hold 2 sectors (2 * 512) */

    /* if buffer has less than 512b then load it with another sector (unless eof) */

    if ((eof_reached == 0) && (bufflen < 512)) {

      /* load 512b of data into buffer */

      _asm {

        push ax

        push bx

        push cx

        push dx

        pushf

        mov ah, 0x3f    /* read from file handle */

        mov bx, fhandle /* file handle where to read from */

        mov cx, 512     /* read 512 bytes (one sector) */

        mov dx, buff    /* target buffer */

        add dx, bufflen /* data must follow existing pending data */

        int 0x21        /* CF clear on success and AX=number of bytes read */

        /* error? */

        jnc READ_OK

        mov doserr, ax

        READ_OK:

        add bufflen, ax

        /* set eof if amount of bytes read is shorter than cx */

        cmp ax, cx

        je EOF_NOT_REACHED

        mov eof_reached, byte ptr 1

        EOF_NOT_REACHED:

        popf

        pop dx

        pop cx

        pop bx

        pop ax

      }

      /* on error close the file and quit */

      if (doserr != 0) {

        goto_close_dos_handle(fhandle);

        nls_outputnl_doserr(doserr);

        return(CMD_FAIL);

      }

    }

    /* advance buffer to first non-space/non-tab/non-CR/non-LF */

    while (bufflen > 0) {

      if ((*buff != ' ') && (*buff != '\t') && (*buff != '\r') && (*buff != '\n')) break;

      bufflen--;

      buff++;

      p->rmod->bat->nextline++;

    }

    /* if the line does not start with a colon, then jump to next line */

    if ((bufflen > 0) && (*buff != ':')) {

      while ((bufflen > 0) && (*buff != '\n')) {

        bufflen--;

        buff++;

        p->rmod->bat->nextline++;

      }

    }

    /* refill buffer if needed */

    if ((bufflen < 512) && (eof_reached == 0)) continue;

    /* eof? */

    if (bufflen == 0) break;

    /* skip the colon */

    if (*buff == ':') {

      bufflen--;

      buff++;

      p->rmod->bat->nextline++;

    }

    /* skip any leading white spaces (space or tab) */

    while (bufflen > 0) {

      if ((*buff != ' ') && (*buff != '\t')) break;

      bufflen--;

      buff++;

      p->rmod->bat->nextline++;

    }

    /* read the in-file label and compare it with what's in the label buff */

    for (i = 0;; i++) {

      /* if end of label then check if it is also end of in-file label (ends with space, tab, \r or \n) */

      if ((i == bufflen) || (buff[i] == ' ') || (buff[i] == '\t') || (buff[i] == '\r') || (buff[i] == '\n')) {

        if (label[i] == 0) {

          /* match found -> close file, skip to end of line and quit */

          while (bufflen > 0) {

            bufflen--;

            buff++;

            p->rmod->bat->nextline++;

            if (*buff == '\n') break;

          }

          goto_close_dos_handle(fhandle);

          return(CMD_OK);

        }

        break;

      }

      /* end of label = mismatch */

      if (label[i] == 0) break;

      /* case-insensitive comparison */

      if ((label[i] & 0xDF) != (buff[i] & 0xDF)) break;

    }

    /* no match, move forward to end of line and repeat */

    while ((bufflen > 0) && (*buff != '\n')) {

      bufflen--;

      buff++;

      p->rmod->bat->nextline++;

    }

  }

  /* close the batch file handle */

  goto_close_dos_handle(fhandle);

  /* label not found, display error message and abort all batch scripts */

  nls_outputnl(17, 10); /* "Label not found" */

  rmod_free_bat_llist(p->rmod);

  /* restore echo flag as it was before running the (first) bat file */

  p->rmod->flags &= ~FLAG_ECHOFLAG;

  if (p->rmod->flags & FLAG_ECHO_BEFORE_BAT) p->rmod->flags |= FLAG_ECHOFLAG;

  return(CMD_FAIL);

}