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      1 /*	$NetBSD: field.c,v 1.32 2021/04/13 13:13:03 christos Exp $	*/
      2 /*-
      3  * Copyright (c) 1998-1999 Brett Lymn
      4  *                         (blymn (at) baea.com.au, brett_lymn (at) yahoo.com.au)
      5  * All rights reserved.
      6  *
      7  * This code has been donated to The NetBSD Foundation by the Author.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  *
     28  *
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __RCSID("$NetBSD: field.c,v 1.32 2021/04/13 13:13:03 christos Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <stdlib.h>
     36 #include <strings.h>
     37 #include <stdarg.h>
     38 #include <form.h>
     39 #include "internals.h"
     40 
     41 extern FORM _formi_default_form;
     42 
     43 FIELD _formi_default_field = {
     44 	0, /* rows in the field */
     45 	0, /* columns in the field */
     46 	0, /* dynamic rows */
     47 	0, /* dynamic columns */
     48 	0, /* maximum growth */
     49 	0, /* starting row in the form subwindow */
     50 	0, /* starting column in the form subwindow */
     51 	0, /* number of off screen rows */
     52 	0, /* index of this field in form fields array. */
     53 	0, /* number of buffers associated with this field */
     54 	FALSE, /* set to true if buffer 0 has changed. */
     55 	NO_JUSTIFICATION, /* justification style of the field */
     56 	FALSE, /* set to true if field is in overlay mode */
     57 	NULL, /* pointer to the current line cursor is on */
     58 	0, /* starting char in string (horiz scroll) */
     59 	NULL, /* starting line in field (vert scroll) */
     60 	0, /* number of rows actually used in field */
     61 	0, /* actual pos of cursor in row, not same as x pos due to tabs */
     62 	0, /* x pos of cursor in field */
     63 	0, /* y pos of cursor in field */
     64 	0, /* start of a new page on the form if 1 */
     65 	0, /* number of the page this field is on */
     66 	A_NORMAL, /* character attributes for the foreground */
     67 	A_NORMAL, /* character attributes for the background */
     68 	' ', /* padding character */
     69 	DEFAULT_FORM_OPTS, /* options for the field */
     70 	NULL, /* the form this field is bound to, if any */
     71 	NULL, /* field above this one */
     72 	NULL, /* field below this one */
     73 	NULL, /* field to the left of this one */
     74 	NULL, /* field to the right of this one */
     75 	NULL,  /* user defined pointer. */
     76 	NULL, /* used if fields are linked */
     77 	NULL, /* type struct for the field */
     78 	{NULL, NULL}, /* circle queue glue for sorting fields */
     79 	NULL, /* args for field type. */
     80 	NULL, /* pointer to the array of lines structures. */
     81 	NULL, /* list of lines available for reuse */
     82 	NULL, /* array of buffers for the field */
     83 };
     84 
     85 /* internal function prototypes */
     86 static int
     87 field_buffer_init(FIELD *field, int buffer, unsigned int len);
     88 static FIELD *
     89 _formi_create_field(FIELD *, int, int, int, int, int, int);
     90 
     91 
     92 /*
     93  * Set the userptr for the field
     94  */
     95 int
     96 set_field_userptr(FIELD *field, void *ptr)
     97 {
     98 	FIELD *fp = (field == NULL) ? &_formi_default_field : field;
     99 
    100 	fp->userptr = ptr;
    101 
    102 	return E_OK;
    103 }
    104 
    105 /*
    106  * Return the userptr for the field.
    107  */
    108 
    109 void *
    110 field_userptr(FIELD *field)
    111 {
    112 	if (field == NULL)
    113 		return _formi_default_field.userptr;
    114 	else
    115 		return field->userptr;
    116 }
    117 
    118 /*
    119  * Set the options for the designated field.
    120  */
    121 int
    122 set_field_opts(FIELD *field, Form_Options options)
    123 {
    124 	int i;
    125 
    126 	FIELD *fp = (field == NULL) ? &_formi_default_field : field;
    127 
    128 	  /* not allowed to set opts if the field is the current one */
    129 	if ((field != NULL) && (field->parent != NULL) &&
    130 	    (field->parent->cur_field == field->index))
    131 		return E_CURRENT;
    132 
    133 	if ((options & O_STATIC) == O_STATIC) {
    134 		for (i = 0; i < fp->nbuf; i++) {
    135 			if (fp->buffers[i].length > fp->cols)
    136 				fp->buffers[i].string[fp->cols] = '\0';
    137 		}
    138 	}
    139 
    140 	fp->opts = options;
    141 
    142 	  /* if appropriate, redraw the field */
    143 	if ((field != NULL) && (field->parent != NULL)
    144 	    && (field->parent->posted == 1)) {
    145 		_formi_redraw_field(field->parent, field->index);
    146 		pos_form_cursor(field->parent);
    147 		wrefresh(field->parent->scrwin);
    148 	}
    149 
    150 	return E_OK;
    151 }
    152 
    153 /*
    154  * Turn on the passed field options.
    155  */
    156 int
    157 field_opts_on(FIELD *field, Form_Options options)
    158 {
    159 	int i;
    160 
    161 	FIELD *fp = (field == NULL) ? &_formi_default_field : field;
    162 
    163 	  /* not allowed to set opts if the field is the current one */
    164 	if ((field != NULL) && (field->parent != NULL) &&
    165 	    (field->parent->cur_field == field->index))
    166 		return E_CURRENT;
    167 
    168 	if ((options & O_STATIC) == O_STATIC) {
    169 		for (i = 0; i < fp->nbuf; i++) {
    170 			if (fp->buffers[i].length > fp->cols)
    171 				fp->buffers[i].string[fp->cols] = '\0';
    172 		}
    173 	}
    174 
    175 	fp->opts |= options;
    176 
    177 	  /* if appropriate, redraw the field */
    178 	if ((field != NULL) && (field->parent != NULL)
    179 	    && (field->parent->posted == 1)) {
    180 		_formi_redraw_field(field->parent, field->index);
    181 		pos_form_cursor(field->parent);
    182 		wrefresh(field->parent->scrwin);
    183 	}
    184 
    185 	return E_OK;
    186 }
    187 
    188 /*
    189  * Turn off the passed field options.
    190  */
    191 int
    192 field_opts_off(FIELD *field, Form_Options options)
    193 {
    194 	FIELD *fp = (field == NULL) ? &_formi_default_field : field;
    195 
    196 	  /* not allowed to set opts if the field is the current one */
    197 	if ((field != NULL) && (field->parent != NULL) &&
    198 	    (field->parent->cur_field == field->index))
    199 		return E_CURRENT;
    200 
    201 	fp->opts &= ~options;
    202 
    203 	  /* if appropriate, redraw the field */
    204 	if ((field != NULL) && (field->parent != NULL)
    205 	    && (field->parent->posted == 1)) {
    206 		_formi_redraw_field(field->parent, field->index);
    207 		pos_form_cursor(field->parent);
    208 		wrefresh(field->parent->scrwin);
    209 	}
    210 
    211 	return E_OK;
    212 }
    213 
    214 /*
    215  * Return the field options associated with the passed field.
    216  */
    217 Form_Options
    218 field_opts(FIELD *field)
    219 {
    220 	if (field == NULL)
    221 		return _formi_default_field.opts;
    222 	else
    223 		return field->opts;
    224 }
    225 
    226 /*
    227  * Set the justification for the passed field.
    228  */
    229 int
    230 set_field_just(FIELD *field, int justification)
    231 {
    232 	FIELD *fp = (field == NULL) ? &_formi_default_field : field;
    233 
    234 	  /*
    235 	   * not allowed to set justification if the field is
    236 	   * the current one
    237 	   */
    238 	if ((field != NULL) && (field->parent != NULL) &&
    239 	    (field->parent->cur_field == field->index))
    240 		return E_CURRENT;
    241 
    242 	if ((justification < MIN_JUST_STYLE) /* check justification valid */
    243 	    || (justification > MAX_JUST_STYLE))
    244 		return E_BAD_ARGUMENT;
    245 
    246 	  /* only allow justification on static, single row fields */
    247 	if (((fp->opts & O_STATIC) != O_STATIC) ||
    248 	    ((fp->rows + fp->nrows) > 1))
    249 		return E_BAD_ARGUMENT;
    250 
    251 	fp->justification = justification;
    252 
    253 	_formi_init_field_xpos(fp);
    254 
    255 	return E_OK;
    256 }
    257 
    258 /*
    259  * Return the justification style of the field passed.
    260  */
    261 int
    262 field_just(FIELD *field)
    263 {
    264 	if (field == NULL)
    265 		return _formi_default_field.justification;
    266 	else
    267 		return field->justification;
    268 }
    269 
    270 /*
    271  * Return information about the field passed.
    272  */
    273 int
    274 field_info(FIELD *field, int *rows, int *cols, int *frow, int *fcol,
    275 	   int *nrow, int *nbuf)
    276 {
    277 	if (field == NULL)
    278 		return E_BAD_ARGUMENT;
    279 
    280 	*rows = field->rows;
    281 	*cols = field->cols;
    282 	*frow = field->form_row;
    283 	*fcol = field->form_col;
    284 	*nrow = field->nrows;
    285 	*nbuf = field->nbuf;
    286 
    287 	return E_OK;
    288 }
    289 
    290 /*
    291  * Report the dynamic field information.
    292  */
    293 int
    294 dynamic_field_info(FIELD *field, int *drows, int *dcols, int *max)
    295 {
    296 	if (field == NULL)
    297 		return E_BAD_ARGUMENT;
    298 
    299 	if ((field->opts & O_STATIC) == O_STATIC) {
    300 		*drows = field->rows;
    301 		*dcols = field->cols;
    302 	} else {
    303 		*drows = field->drows;
    304 		*dcols = field->dcols;
    305 	}
    306 
    307 	*max = field->max;
    308 
    309 	return E_OK;
    310 }
    311 
    312 /*
    313  * Init all the field variables, perform wrapping and other tasks
    314  * after the field buffer is set.
    315  */
    316 static int
    317 field_buffer_init(FIELD *field, int buffer, unsigned int len)
    318 {
    319 	int status;
    320 	char *newp;
    321 
    322 	if (buffer == 0) {
    323 		field->start_char = 0;
    324 		field->start_line = 0;
    325 		field->row_xpos = 0;
    326 		field->cursor_xpos = 0;
    327 		field->cursor_ypos = 0;
    328 		field->row_count = 1; /* must be at least one row  XXX need to shift old rows (if any) to free list??? */
    329 		field->alines->length = len;
    330 		if ((newp = realloc(field->alines->string,
    331 				    (size_t) len + 1)) == NULL)
    332 			return E_SYSTEM_ERROR;
    333 		field->alines->string = newp;
    334 		field->alines->allocated = len + 1;
    335 		strlcpy(field->alines->string, field->buffers[buffer].string,
    336 			(size_t) len + 1);
    337 		field->alines->expanded =
    338 			_formi_tab_expanded_length(field->alines->string,
    339 						   0, field->alines->length);
    340 
    341 		field->start_line = field->alines;
    342 		field->cur_line = field->alines;
    343 
    344 		  /* we have to hope the wrap works - if it does not then the
    345 		     buffer is pretty much borked */
    346 		status = _formi_wrap_field(field, field->cur_line);
    347 		if (status != E_OK)
    348 			return status;
    349 
    350 		  /*
    351 		   * calculate the tabs for a single row field, the
    352 		   * multiline case is handled when the wrap is done.
    353 		   */
    354 		if (field->row_count == 1)
    355 			_formi_calculate_tabs(field->alines);
    356 
    357 		  /* redraw the field to reflect the new contents. If the field
    358 		   * is attached....
    359 		   */
    360 		if ((field->parent != NULL) && (field->parent->posted == 1)) {
    361 			_formi_redraw_field(field->parent, field->index);
    362 			  /* make sure cursor goes back to current field */
    363 			pos_form_cursor(field->parent);
    364 		}
    365 	}
    366 
    367 	return E_OK;
    368 }
    369 
    370 
    371 /*
    372  * Set the field buffer to the string that results from processing
    373  * the given format (fmt) using sprintf.
    374  */
    375 int
    376 set_field_printf(FIELD *field, int buffer, char *fmt, ...)
    377 {
    378 	int len;
    379 	va_list args;
    380 
    381 	if (field == NULL)
    382 		return E_BAD_ARGUMENT;
    383 
    384 	if (buffer >= field->nbuf)
    385 		return E_BAD_ARGUMENT;
    386 
    387 	va_start(args, fmt);
    388 	  /* check for buffer already existing, free the storage */
    389 	if (field->buffers[buffer].allocated != 0)
    390 		free(field->buffers[buffer].string);
    391 
    392 	len = vasprintf(&field->buffers[buffer].string, fmt, args);
    393 	va_end(args);
    394 	if (len < 0)
    395 		return E_SYSTEM_ERROR;
    396 
    397 	field->buffers[buffer].length = len;
    398 	field->buffers[buffer].allocated = len + 1;
    399 	if (((field->opts & O_STATIC) == O_STATIC) && (len > field->cols)
    400 	    && ((field->rows + field->nrows) == 1))
    401 		len = field->cols;
    402 
    403 	field->buffers[buffer].string[len] = '\0';
    404 	return field_buffer_init(field, buffer, (unsigned int) len);
    405 }
    406 
    407 /*
    408  * Set the value of the field buffer to the value given.
    409  */
    410 
    411 int
    412 set_field_buffer(FIELD *field, int buffer, const char *value)
    413 {
    414 	unsigned int len;
    415 	int status;
    416 
    417 	if (field == NULL)
    418 		return E_BAD_ARGUMENT;
    419 
    420 	if (buffer >= field->nbuf) /* make sure buffer is valid */
    421 		return E_BAD_ARGUMENT;
    422 
    423 	len = (unsigned int) strlen(value);
    424 	if (((field->opts & O_STATIC) == O_STATIC) && (len > field->cols)
    425 	    && ((field->rows + field->nrows) == 1))
    426 		len = field->cols;
    427 
    428 	_formi_dbg_printf( "%s: len = %d, value = %s, buffer=%d\n", __func__,
    429 	    len, value, buffer);
    430 	if (field->buffers[buffer].string != NULL)
    431 		_formi_dbg_printf("%s: string=%s, len = %d\n", __func__,
    432 		    field->buffers[buffer].string,
    433 		    field->buffers[buffer].length);
    434 	else
    435 		_formi_dbg_printf("%s: string=(null), len = 0\n", __func__);
    436 	_formi_dbg_printf("%s: lines.len = %d\n", __func__,
    437 	    field->alines[0].length);
    438 
    439 	if ((field->buffers[buffer].string = realloc(
    440 	    field->buffers[buffer].string, (size_t) len + 1)) == NULL)
    441 		return E_SYSTEM_ERROR;
    442 
    443 	strlcpy(field->buffers[buffer].string, value, (size_t) len + 1);
    444 	field->buffers[buffer].length = len;
    445 	field->buffers[buffer].allocated = len + 1;
    446 	status = field_buffer_init(field, buffer, len);
    447 
    448 	_formi_dbg_printf("%s: len = %d, value = %s\n", __func__, len, value);
    449 	_formi_dbg_printf("%s: string = %s, len = %d\n", __func__,
    450 	    field->buffers[buffer].string, field->buffers[buffer].length);
    451 	_formi_dbg_printf("%s: lines.len = %d\n", __func__,
    452 		field->alines[0].length);
    453 
    454 	return status;
    455 }
    456 
    457 /*
    458  * Return the requested field buffer to the caller.
    459  */
    460 char *
    461 field_buffer(FIELD *field, int buffer)
    462 {
    463 
    464 	char *reformat, *p;
    465 	_FORMI_FIELD_LINES *linep;
    466 	size_t bufsize, pos;
    467 
    468 	if (field == NULL)
    469 		return NULL;
    470 
    471 	if (buffer >= field->nbuf)
    472 		return NULL;
    473 
    474 	  /*
    475 	   * We force a sync from the line structs to the buffer here.
    476 	   * Traditional libform say we don't need to because it is
    477 	   * done on a REQ_VALIDATE but NetBSD libform previously did
    478 	   * not enforce this because the buffer contents were always
    479 	   * current.  Changes to line handling make this no longer so
    480 	   * - the line structs may contain different data to the
    481 	   * buffer if unsynced.
    482 	   */
    483 	if (_formi_sync_buffer(field) != E_OK)
    484 		return NULL;
    485 
    486 	if ((field->opts & O_REFORMAT) != O_REFORMAT)
    487 		return field->buffers[buffer].string;
    488 
    489 	if (field->row_count <= 1)
    490 		return strdup(field->buffers[buffer].string);
    491 
    492 	/*
    493 	 * create a single string containing each line,
    494 	 * separated by newline, last line having no
    495 	 * newline, but NUL terminated.
    496 	 */
    497 	bufsize = pos = 0;
    498 	reformat = NULL;
    499 	for (linep = field->alines; linep; linep = linep->next) {
    500 		size_t len = strlen(linep->string);
    501 		if (len + 1 >= bufsize - pos) {
    502 			bufsize += MAX(1024, 2 * len);
    503 			p = realloc(reformat, bufsize);
    504 			if (p == NULL) {
    505 				free(reformat);
    506 				return NULL;
    507 			}
    508 			reformat = p;
    509 		}
    510 		memcpy(reformat + pos, linep->string, len);
    511 		pos += len;
    512 		reformat[pos++] = linep->next ? '\n' : '\0';
    513 	}
    514 	return reformat;
    515 }
    516 
    517 /*
    518  * Set the buffer 0 field status.
    519  */
    520 int
    521 set_field_status(FIELD *field, int status)
    522 {
    523 
    524 	if (field == NULL)
    525 		return E_BAD_ARGUMENT;
    526 
    527 	if (status != FALSE)
    528 		field->buf0_status = TRUE;
    529 	else
    530 		field->buf0_status = FALSE;
    531 
    532 	return E_OK;
    533 }
    534 
    535 /*
    536  * Return the buffer 0 status flag for the given field.
    537  */
    538 int
    539 field_status(FIELD *field)
    540 {
    541 
    542 	if (field == NULL) /* the default buffer 0 never changes :-) */
    543 		return FALSE;
    544 
    545 	return field->buf0_status;
    546 }
    547 
    548 /*
    549  * Set the maximum growth for a dynamic field.
    550  */
    551 int
    552 set_max_field(FIELD *fptr, int max)
    553 {
    554 	FIELD *field = (fptr == NULL)? &_formi_default_field : fptr;
    555 
    556 	if ((field->opts & O_STATIC) == O_STATIC) /* check if field dynamic */
    557 		return E_BAD_ARGUMENT;
    558 
    559 	if (max < 0) /* negative numbers are bad.... */
    560 		return E_BAD_ARGUMENT;
    561 
    562 	field->max = max;
    563 	return E_OK;
    564 }
    565 
    566 /*
    567  * Set the field foreground character attributes.
    568  */
    569 int
    570 set_field_fore(FIELD *fptr, chtype attribute)
    571 {
    572 	FIELD *field = (fptr == NULL)? &_formi_default_field : fptr;
    573 
    574 	field->fore = attribute;
    575 	return E_OK;
    576 }
    577 
    578 /*
    579  * Return the foreground character attribute for the given field.
    580  */
    581 chtype
    582 field_fore(FIELD *field)
    583 {
    584 	if (field == NULL)
    585 		return _formi_default_field.fore;
    586 	else
    587 		return field->fore;
    588 }
    589 
    590 /*
    591  * Set the background character attribute for the given field.
    592  */
    593 int
    594 set_field_back(FIELD *field, chtype attribute)
    595 {
    596 	if (field == NULL)
    597 		_formi_default_field.back = attribute;
    598 	else
    599 		field->back = attribute;
    600 
    601 	return E_OK;
    602 }
    603 
    604 /*
    605  * Get the background character attribute for the given field.
    606  */
    607 chtype
    608 field_back(FIELD *field)
    609 {
    610 	if (field == NULL)
    611 		return _formi_default_field.back;
    612 	else
    613 		return field->back;
    614 }
    615 
    616 /*
    617  * Set the pad character for the given field.
    618  */
    619 int
    620 set_field_pad(FIELD *field, int pad)
    621 {
    622 	if (field == NULL)
    623 		_formi_default_field.pad = pad;
    624 	else
    625 		field->pad = pad;
    626 
    627 	return E_OK;
    628 }
    629 
    630 /*
    631  * Return the padding character for the given field.
    632  */
    633 int
    634 field_pad(FIELD *field)
    635 {
    636 	if (field == NULL)
    637 		return _formi_default_field.pad;
    638 	else
    639 		return field->pad;
    640 }
    641 
    642 /*
    643  * Set the field initialisation function hook.
    644  */
    645 int
    646 set_field_init(FORM *form, Form_Hook function)
    647 {
    648 	if (form == NULL)
    649 		_formi_default_form.field_init = function;
    650 	else
    651 		form->field_init = function;
    652 
    653 	return E_OK;
    654 }
    655 
    656 /*
    657  * Return the function hook for the field initialisation.
    658  */
    659 Form_Hook
    660 field_init(FORM *form)
    661 {
    662 	if (form == NULL)
    663 		return _formi_default_form.field_init;
    664 	else
    665 		return form->field_init;
    666 }
    667 
    668 /*
    669  * Set the field termination function hook.
    670  */
    671 int
    672 set_field_term(FORM *form, Form_Hook function)
    673 {
    674 	if (form == NULL)
    675 		_formi_default_form.field_term = function;
    676 	else
    677 		form->field_term = function;
    678 
    679 	return E_OK;
    680 }
    681 
    682 /*
    683  * Return the function hook defined for the field termination.
    684  */
    685 Form_Hook
    686 field_term(FORM *form)
    687 {
    688 	if (form == NULL)
    689 		return _formi_default_form.field_term;
    690 	else
    691 		return form->field_term;
    692 }
    693 
    694 /*
    695  * Set the page flag on the given field to indicate it is the start of a
    696  * new page.
    697  */
    698 int
    699 set_new_page(FIELD *fptr, int page)
    700 {
    701 	FIELD *field = (fptr == NULL)? &_formi_default_field : fptr;
    702 
    703 	if (field->parent != NULL) /* check if field is connected to a form */
    704 		return E_CONNECTED;
    705 
    706 	field->page_break = (page != FALSE);
    707 	return E_OK;
    708 }
    709 
    710 /*
    711  * Return the page status for the given field.  TRUE is returned if the
    712  * field is the start of a new page.
    713  */
    714 int
    715 new_page(FIELD *field)
    716 {
    717 	if (field == NULL)
    718 		return _formi_default_field.page_break;
    719 	else
    720 		return field->page_break;
    721 }
    722 
    723 /*
    724  * Return the index of the field in the form fields array.
    725  */
    726 int
    727 field_index(FIELD *field)
    728 {
    729 	if (field == NULL)
    730 		return E_BAD_ARGUMENT;
    731 
    732 	if (field->parent == NULL)
    733 		return E_NOT_CONNECTED;
    734 
    735 	return field->index;
    736 }
    737 
    738 /*
    739  * Internal function that does most of the work to create a new field.
    740  * The new field is initialised from the information in the prototype
    741  * field passed.
    742  * Returns NULL on error.
    743  */
    744 static FIELD *
    745 _formi_create_field(FIELD *prototype, int rows, int cols, int frow,
    746 		    int fcol, int nrows, int nbuf)
    747 {
    748 	FIELD *new;
    749 
    750 	if ((rows <= 0) || (cols <= 0) || (frow < 0) || (fcol < 0) ||
    751 	    (nrows < 0) || (nbuf < 0))
    752 		return NULL;
    753 
    754 	if ((new = malloc(sizeof(*new))) == NULL) {
    755 		return NULL;
    756 	}
    757 
    758 	  /* copy in the default field info */
    759 	memcpy(new, prototype, sizeof(*new));
    760 
    761 	new->nbuf = nbuf + 1;
    762 	new->rows = rows;
    763 	new->cols = cols;
    764 	new->form_row = frow;
    765 	new->form_col = fcol;
    766 	new->nrows = nrows;
    767 	new->link = new;
    768 	return new;
    769 }
    770 
    771 /*
    772  * Create a new field structure.
    773  */
    774 FIELD *
    775 new_field(int rows, int cols, int frow, int fcol, int nrows, int nbuf)
    776 {
    777 	FIELD *new;
    778 	int i;
    779 
    780 
    781 	if ((new = _formi_create_field(&_formi_default_field, rows, cols,
    782 				       frow, fcol, nrows, nbuf)) == NULL)
    783 		return NULL;
    784 
    785 	if ((new->buffers = calloc(nbuf + 1, sizeof(*new->buffers))) == NULL) {
    786 		free(new);
    787 		return NULL;
    788 	}
    789 
    790 	/* Initialise the strings to a zero length string */
    791 	for (i = 0; i < nbuf + 1; i++) {
    792 		if ((new->buffers[i].string =
    793 		    malloc(sizeof(*new->buffers[i].string))) == NULL) {
    794 			goto out;
    795 		}
    796 		new->buffers[i].string[0] = '\0';
    797 		new->buffers[i].length = 0;
    798 		new->buffers[i].allocated = 1;
    799 	}
    800 
    801 	if ((new->alines = malloc(sizeof(*new->alines))) == NULL) {
    802 		goto out;
    803 	}
    804 
    805 	new->alines->prev = NULL;
    806 	new->alines->next = NULL;
    807 	new->alines->allocated = 0;
    808 	new->alines->length = 0;
    809 	new->alines->expanded = 0;
    810 	new->alines->string = NULL;
    811 	new->alines->hard_ret = FALSE;
    812 	new->alines->tabs = NULL;
    813 	new->start_line = new->alines;
    814 	new->cur_line = new->alines;
    815 
    816 	return new;
    817 out:
    818 	while (--i >= 0) {
    819 		free(new->buffers[i].string);
    820 	}
    821 	free(new->buffers);
    822 	free(new);
    823 	return NULL;
    824 }
    825 
    826 /*
    827  * Duplicate the given field, including its buffers.
    828  */
    829 FIELD *
    830 dup_field(FIELD *field, int frow, int fcol)
    831 {
    832 	FIELD *new;
    833 	size_t row_len, buf_len;
    834 
    835 	if (field == NULL)
    836 		return NULL;
    837 
    838 	/* XXX: this right???? */
    839 	if ((new = _formi_create_field(field, (int) field->rows,
    840 				       (int) field->cols,
    841 				       frow, fcol, (int) field->nrows,
    842 				       field->nbuf - 1)) == NULL)
    843 		return NULL;
    844 
    845 	row_len = (field->rows + field->nrows + 1) * field->cols;
    846 	buf_len = (field->nbuf + 1) * row_len * sizeof(*new->buffers);
    847 
    848 	/* XXX: dups buffers but not their strings? */
    849 	if ((new->buffers = malloc(buf_len)) == NULL) {
    850 		free(new);
    851 		return NULL;
    852 	}
    853 
    854 	  /* copy the buffers from the source field into the new copy */
    855 	memcpy(new->buffers, field->buffers, buf_len);
    856 
    857 	return new;
    858 }
    859 
    860 /*
    861  * Create a new field at the specified location by duplicating the given
    862  * field.  The buffers are shared with the parent field.
    863  */
    864 FIELD *
    865 link_field(FIELD *field, int frow, int fcol)
    866 {
    867 	FIELD *new;
    868 
    869 	if (field == NULL)
    870 		return NULL;
    871 
    872 	if ((new = _formi_create_field(field, (int) field->rows,
    873 				       (int) field->cols,
    874 				       frow, fcol, (int) field->nrows,
    875 				       field->nbuf - 1)) == NULL)
    876 		return NULL;
    877 
    878 	new->link = field->link;
    879 	field->link = new;
    880 
    881 	  /* we are done.  The buffer pointer was copied during the field
    882 	     creation. */
    883 	return new;
    884 }
    885 
    886 /*
    887  * Release all storage allocated to the field
    888  */
    889 int
    890 free_field(FIELD *field)
    891 {
    892 	FIELD *flink;
    893 	unsigned int i;
    894 	_formi_tab_t *ts, *nts;
    895 
    896 	if (field == NULL)
    897 		return E_BAD_ARGUMENT;
    898 
    899 	if (field->parent != NULL)
    900 		return E_CONNECTED;
    901 
    902 	if (field->link == field) { /* check if field linked */
    903 		  /* no it is not - release the buffers */
    904 		free(field->buffers);
    905 		  /* free the tab structures */
    906 		for (i = 0; i + 1 < field->row_count; i++) {
    907 			if (field->alines[i].tabs != NULL) {
    908 				ts = field->alines[i].tabs;
    909 				while (ts != NULL) {
    910 					nts = ts->fwd;
    911 					free(ts);
    912 					ts = nts;
    913 				}
    914 			}
    915 		}
    916 	} else {
    917 		  /* is linked, traverse the links to find the field referring
    918 		   * to the one to be freed.
    919 		   */
    920 		for (flink = field->link; flink != field; flink = flink->link);
    921 		flink->link = field->link;
    922 	}
    923 
    924 	free(field);
    925 	return E_OK;
    926 }
    927 
    928 
    929