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<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
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<!-- This material may be distributed only subject to the terms      -->
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<!-- and conditions set forth in the Open Publication License, v1.0  -->
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<HTML
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><HEAD
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><TITLE
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>Support Functions and Macros</TITLE
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><meta name="MSSmartTagsPreventParsing" content="TRUE">
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<META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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"><LINK
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REL="HOME"
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TITLE="eCos Reference Manual"
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HREF="ecos-ref.html"><LINK
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REL="UP"
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TITLE="Embedded HTTP Server"
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HREF="net-httpd-chapter.html"><LINK
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REL="PREVIOUS"
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TITLE="Server Configuration"
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HREF="net-httpd-configuration.html"><LINK
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REL="NEXT"
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TITLE="System Monitor"
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HREF="net-httpd-monitor.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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VLINK="#840084"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>eCos Reference Manual</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="net-httpd-configuration.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 48. Embedded HTTP Server</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="net-httpd-monitor.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="NET-HTTPD-HTML">Support Functions and Macros</H1
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><P
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>The emphasis of this server is on dynamically generated content,
88
rather than fetching it from a filesystem. To do this the handler
89
functions make calls to <TT
90
CLASS="FUNCTION"
91
>fprintf()</TT
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> and
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<TT
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CLASS="FUNCTION"
95
>fputs()</TT
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>. Such handler functions would end up a
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mass of print calls, with the actual structure of the HTML page hidden
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in the format strings and arguments, making maintenance and debugging
99
very difficult. Such an approach would also result in the definition
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of many, often only slightly different, format strings, leading to
101
unnecessary bloat.</P
102
><P
103
>In an effort to expose the structure of the HTML in the structure of
104
the C code, and to maximize the sharing of string constants, the
105
<TT
106
CLASS="FILENAME"
107
>cyg/httpd/httpd.h</TT
108
> header file defines a set of
109
helper functions and macros. Most of these are wrappers for predefined
110
print calls on the <TT
111
CLASS="PARAMETER"
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><I
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>client</I
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></TT
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> stream passed to the
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hander function. For examples of their use, see the System Monitor
117
example.</P
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><DIV
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CLASS="NOTE"
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><BLOCKQUOTE
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CLASS="NOTE"
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><P
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><B
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>Note: </B
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>All arguments to macros are pointers to strings, unless otherwise
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stated. In general, wherever a function or macro has an
127
<TT
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CLASS="PARAMETER"
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><I
130
>attr</I
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></TT
132
> or <TT
133
CLASS="PARAMETER"
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><I
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>__attr</I
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></TT
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>
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parameter, then the contents of this string will be inserted into the
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tag being defined as HTML attributes. If it is a NULL or empty string
140
it will be ignored.</P
141
></BLOCKQUOTE
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="AEN15305">HTTP Support</H2
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
155
><PRE
156
CLASS="PROGRAMLISTING"
157
>void cyg_http_start( FILE *client, char *content_type, int content_length );
158
void cyg_http_finish( FILE *client );
159
#define html_begin(__client)
160
#define html_end( __client )</PRE
161
></TD
162
></TR
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></TABLE
164
><P
165
>The function <TT
166
CLASS="FUNCTION"
167
>cyg_http_start()</TT
168
> generates a simple
169
HTTP response header containing the value of
170
<TT
171
CLASS="LITERAL"
172
>CYGDAT_HTTPD_SERVER_ID</TT
173
> in the &quot;Server&quot; field, and the
174
values of <TT
175
CLASS="PARAMETER"
176
><I
177
>content_type</I
178
></TT
179
> and
180
<TT
181
CLASS="PARAMETER"
182
><I
183
>content_length</I
184
></TT
185
> in the &quot;Content-type&quot;
186
and &quot;Content-length&quot; field respectively. The function
187
<TT
188
CLASS="FUNCTION"
189
>cyg_http_finish()</TT
190
> just adds an extra newline to
191
the end of the output and then flushes it to force the data out to the
192
client.</P
193
><P
194
>The macro <TT
195
CLASS="LITERAL"
196
>html_begin()</TT
197
> generates an HTTP header
198
with a &quot;text/html&quot; content type followed by an opening
199
&quot;&lt;html&gt;&quot; tag. <TT
200
CLASS="LITERAL"
201
>html_end()</TT
202
> generates
203
a closing &quot;&lt;/html&gt;&quot; tag and calls
204
<TT
205
CLASS="FUNCTION"
206
>cyg_http_finish()</TT
207
>.</P
208
></DIV
209
><DIV
210
CLASS="SECT2"
211
><H2
212
CLASS="SECT2"
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><A
214
NAME="AEN15318">General HTML Support</H2
215
><TABLE
216
BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
220
><TD
221
><PRE
222
CLASS="PROGRAMLISTING"
223
>void cyg_html_tag_begin( FILE *client, char *tag, char *attr );
224
void cyg_html_tag_end( FILE *client, char *tag );
225
#define html_tag_begin( __client, __tag, __attr )
226
#define html_tag_end( __client, __tag )
227
#define html_head( __client, __title, __meta )
228
#define html_body_begin( __client, __attr )
229
#define html_body_end( __client )
230
#define html_heading( __client, __level, __heading )
231
#define html_para_begin( __client, __attr )
232
#define html_url( __client, __text, __link )
233
#define html_image( __client, __source, __alt, __attr )</PRE
234
></TD
235
></TR
236
></TABLE
237
><P
238
>The function <TT
239
CLASS="FUNCTION"
240
>cyg_html_tag_begin()</TT
241
> generates an
242
opening tag with the given name. The function
243
<TT
244
CLASS="FUNCTION"
245
>cyg_html_tag_end()</TT
246
> generates a closing tag with
247
the given name. The macros <TT
248
CLASS="LITERAL"
249
>html_tag_begin()</TT
250
> and
251
<TT
252
CLASS="LITERAL"
253
>html_tag_end</TT
254
> are just wrappers for these functions.</P
255
><P
256
>The macro <TT
257
CLASS="LITERAL"
258
>html_head()</TT
259
> generates an HTML header
260
section with <TT
261
CLASS="PARAMETER"
262
><I
263
>__title</I
264
></TT
265
> as the title. The
266
<TT
267
CLASS="PARAMETER"
268
><I
269
>__meta</I
270
></TT
271
> argument defines any meta tags that will
272
be inserted into the header. <TT
273
CLASS="LITERAL"
274
>html_body_begin()</TT
275
> and
276
<TT
277
CLASS="LITERAL"
278
>html_body_end</TT
279
> generate HTML body begin and end
280
tags.</P
281
><P
282
><TT
283
CLASS="LITERAL"
284
>html_heading()</TT
285
> generates a complete HTML header
286
where <TT
287
CLASS="PARAMETER"
288
><I
289
>__level</I
290
></TT
291
> is a numerical level, between 1
292
and 6, and <TT
293
CLASS="PARAMETER"
294
><I
295
>__heading</I
296
></TT
297
> is the heading
298
text. <TT
299
CLASS="LITERAL"
300
>html_para_begin()</TT
301
> generates a paragraph
302
break.</P
303
><P
304
><TT
305
CLASS="LITERAL"
306
>html_url()</TT
307
> inserts a URL where
308
<TT
309
CLASS="PARAMETER"
310
><I
311
>__text</I
312
></TT
313
> is the displayed text and
314
<TT
315
CLASS="PARAMETER"
316
><I
317
>__link</I
318
></TT
319
> is the URL of the linked
320
page. <TT
321
CLASS="LITERAL"
322
>html_image()</TT
323
> inserts an image tag where
324
<TT
325
CLASS="PARAMETER"
326
><I
327
>__source</I
328
></TT
329
> is the URL of the image to be
330
included and <TT
331
CLASS="PARAMETER"
332
><I
333
>__alt</I
334
></TT
335
> is the alternative text for
336
when the image is not displayed.</P
337
></DIV
338
><DIV
339
CLASS="SECT2"
340
><H2
341
CLASS="SECT2"
342
><A
343
NAME="AEN15344">Table Support</H2
344
><TABLE
345
BORDER="5"
346
BGCOLOR="#E0E0F0"
347
WIDTH="70%"
348
><TR
349
><TD
350
><PRE
351
CLASS="PROGRAMLISTING"
352
>#define html_table_begin( __client, __attr )
353
#define html_table_end( __client )
354
#define html_table_header( __client, __content, __attr )
355
#define html_table_row_begin( __client, __attr )
356
#define html_table_row_end( __client )
357
#define html_table_data_begin( __client, __attr )
358
#define html_table_data_end( __client )               </PRE
359
></TD
360
></TR
361
></TABLE
362
><P
363
><TT
364
CLASS="LITERAL"
365
>html_table_begin()</TT
366
> starts a table and
367
<TT
368
CLASS="LITERAL"
369
>html_table_end()</TT
370
> end
371
it. <TT
372
CLASS="LITERAL"
373
>html_table_header()</TT
374
> generates a simple table
375
column header containg the string <TT
376
CLASS="PARAMETER"
377
><I
378
>__content</I
379
></TT
380
>. </P
381
><P
382
><TT
383
CLASS="LITERAL"
384
>html_table_row_begin()</TT
385
> and
386
<TT
387
CLASS="LITERAL"
388
>html_table_row_end()</TT
389
> begin and end a table row,
390
and similarly <TT
391
CLASS="LITERAL"
392
>html_table_data_begin()</TT
393
> and
394
<TT
395
CLASS="LITERAL"
396
>html_table_data_end()</TT
397
> begin and end a table
398
entry. </P
399
></DIV
400
><DIV
401
CLASS="SECT2"
402
><H2
403
CLASS="SECT2"
404
><A
405
NAME="AEN15357">Forms Support</H2
406
><TABLE
407
BORDER="5"
408
BGCOLOR="#E0E0F0"
409
WIDTH="70%"
410
><TR
411
><TD
412
><PRE
413
CLASS="PROGRAMLISTING"
414
>#define html_form_begin( __client, __url, __attr )
415
#define html_form_end( __client )
416
#define html_form_input( __client, __type, __name, __value, __attr )
417
#define html_form_input_radio( __client, __name, __value, __checked )
418
#define html_form_input_checkbox( __client, __name, __value, __checked )
419
#define html_form_input_hidden( __client, __name, __value )
420
#define html_form_select_begin( __client, __name, __attr )
421
#define html_form_option( __client, __value, __label, __selected )
422
#define html_form_select_end( __client )
423
void cyg_formdata_parse( char *data, char *list[], int size );
424
char *cyg_formlist_find( char *list[], char *name );</PRE
425
></TD
426
></TR
427
></TABLE
428
><P
429
><TT
430
CLASS="LITERAL"
431
>html_form_begin()</TT
432
> begins a form, the
433
<TT
434
CLASS="PARAMETER"
435
><I
436
>__url</I
437
></TT
438
> argument is the value for the
439
<TT
440
CLASS="LITERAL"
441
>action</TT
442
>
443
attribute. <TT
444
CLASS="LITERAL"
445
>html_form_end()</TT
446
> ends the form.</P
447
><P
448
><TT
449
CLASS="LITERAL"
450
>html_form_input()</TT
451
> defines a general form input
452
element with the given type, name and
453
value. <TT
454
CLASS="LITERAL"
455
>html_form_input_radio</TT
456
> creates a radio button
457
with the given name and value; the <TT
458
CLASS="PARAMETER"
459
><I
460
>__checked</I
461
></TT
462
>
463
argument is a boolean expression that is used to determine whether the
464
<TT
465
CLASS="LITERAL"
466
>checked</TT
467
> attribute is added to the tag. Similarly
468
<TT
469
CLASS="LITERAL"
470
>html_form_input_checkbox()</TT
471
> defines a checkbox
472
element. <TT
473
CLASS="LITERAL"
474
>html_form_input_hidden()</TT
475
> defines a hidden
476
form element with the given name and value.</P
477
><P
478
><TT
479
CLASS="LITERAL"
480
>html_form_select_begin()</TT
481
> begins a multiple choice
482
menu with the given name. <TT
483
CLASS="LITERAL"
484
>html_form_select_end()</TT
485
>
486
end it. <TT
487
CLASS="LITERAL"
488
>html_form_option()</TT
489
> defines a menu entry
490
with the given value and label; the <TT
491
CLASS="PARAMETER"
492
><I
493
>__selected</I
494
></TT
495
>
496
argument is a boolean expression controlling whether the
497
<TT
498
CLASS="LITERAL"
499
>selected</TT
500
> attribute is added to the tag.</P
501
><P
502
><TT
503
CLASS="FUNCTION"
504
>cyg_formdata_parse()</TT
505
> converts a form response
506
string into an <TT
507
CLASS="LITERAL"
508
>NULL</TT
509
>-terminated array of
510
&quot;name=value&quot; entries. The <TT
511
CLASS="PARAMETER"
512
><I
513
>data</I
514
></TT
515
>
516
argument is the string as passed to the handler function; note that
517
this string is not copied and will be updated in place to form the
518
list entries.  <TT
519
CLASS="PARAMETER"
520
><I
521
>list</I
522
></TT
523
> is a pointer to an array of
524
character pointers, and is <TT
525
CLASS="PARAMETER"
526
><I
527
>size</I
528
></TT
529
> elements long.
530
<TT
531
CLASS="FUNCTION"
532
>cyg_formlist_find()</TT
533
> searches a list generated by
534
<TT
535
CLASS="FUNCTION"
536
>cyg_formdata_parse()</TT
537
> and returns a pointer to the
538
value part of the string whose name part matches
539
<TT
540
CLASS="PARAMETER"
541
><I
542
>name</I
543
></TT
544
>; if there is no match it will return
545
<TT
546
CLASS="LITERAL"
547
>NULL</TT
548
>.</P
549
></DIV
550
><DIV
551
CLASS="SECT2"
552
><H2
553
CLASS="SECT2"
554
><A
555
NAME="AEN15388">Predefined Handlers</H2
556
><TABLE
557
BORDER="5"
558
BGCOLOR="#E0E0F0"
559
WIDTH="70%"
560
><TR
561
><TD
562
><PRE
563
CLASS="PROGRAMLISTING"
564
>&#13;int cyg_httpd_send_html( FILE *client, char *filename, char *request, void *arg );
565
 
566
typedef struct
567
{
568
    char        *content_type;
569
    cyg_uint32  content_length;
570
    cyg_uint8   *data;
571
} cyg_httpd_data;
572
#define CYG_HTTPD_DATA( __name, __type, __length, __data )
573
 
574
int cyg_httpd_send_data( FILE *client, char *filename, char *request, void *arg );&#13;</PRE
575
></TD
576
></TR
577
></TABLE
578
><P
579
>The HTTP server defines a couple of predefined handers to make it
580
easier to deliver simple, static content.</P
581
><P
582
><TT
583
CLASS="FUNCTION"
584
>cyg_httpd_send_html()</TT
585
> takes a
586
<TT
587
CLASS="LITERAL"
588
>NULL</TT
589
>-terminated string as the argument and sends it
590
to the client with an HTTP header indicating that it is HTML. The
591
following is an example of its use:</P
592
><TABLE
593
BORDER="5"
594
BGCOLOR="#E0E0F0"
595
WIDTH="70%"
596
><TR
597
><TD
598
><PRE
599
CLASS="PROGRAMLISTING"
600
>&#13;char cyg_html_message[] = "&lt;head&gt;&lt;title&gt;Welcome&lt;/title&gt;&lt;/head&gt;\n"
601
                          "&lt;body&gt;&lt;h2&gt;Welcome to my Web Page&lt;/h2&gt;&lt;/body&gt;\n"
602
 
603
CYG_HTTPD_TABLE_ENTRY( cyg_html_message_entry,
604
                       "/message.html",
605
                       cyg_httpd_send_html,
606
                       cyg_html_message );&#13;</PRE
607
></TD
608
></TR
609
></TABLE
610
><P
611
><TT
612
CLASS="FUNCTION"
613
>cyg_httpd_send_data()</TT
614
> Sends arbitrary data to the
615
client. The argument is a pointer to a <SPAN
616
CLASS="TYPE"
617
>cyg_httpd_data</SPAN
618
>
619
structure that defines the content type and length of the data, and a
620
pointer to the data itself. The <TT
621
CLASS="LITERAL"
622
>CYG_HTTPD_DATA()</TT
623
>
624
macro automates the definition of the structure. Here is a typical
625
example of its use:</P
626
><TABLE
627
BORDER="5"
628
BGCOLOR="#E0E0F0"
629
WIDTH="70%"
630
><TR
631
><TD
632
><PRE
633
CLASS="PROGRAMLISTING"
634
>&#13;static cyg_uint8 ecos_logo_gif[] = {
635
    ...
636
};
637
 
638
CYG_HTTPD_DATA( cyg_monitor_ecos_logo_data,
639
                "image/gif",
640
                sizeof(ecos_logo_gif),
641
                ecos_logo_gif );
642
 
643
CYG_HTTPD_TABLE_ENTRY( cyg_monitor_ecos_logo,
644
                       "/monitor/ecos.gif",
645
                       cyg_httpd_send_data,
646
                       &amp;cyg_monitor_ecos_logo_data );&#13;</PRE
647
></TD
648
></TR
649
></TABLE
650
></DIV
651
></DIV
652
><DIV
653
CLASS="NAVFOOTER"
654
><HR
655
ALIGN="LEFT"
656
WIDTH="100%"><TABLE
657
SUMMARY="Footer navigation table"
658
WIDTH="100%"
659
BORDER="0"
660
CELLPADDING="0"
661
CELLSPACING="0"
662
><TR
663
><TD
664
WIDTH="33%"
665
ALIGN="left"
666
VALIGN="top"
667
><A
668
HREF="net-httpd-configuration.html"
669
ACCESSKEY="P"
670
>Prev</A
671
></TD
672
><TD
673
WIDTH="34%"
674
ALIGN="center"
675
VALIGN="top"
676
><A
677
HREF="ecos-ref.html"
678
ACCESSKEY="H"
679
>Home</A
680
></TD
681
><TD
682
WIDTH="33%"
683
ALIGN="right"
684
VALIGN="top"
685
><A
686
HREF="net-httpd-monitor.html"
687
ACCESSKEY="N"
688
>Next</A
689
></TD
690
></TR
691
><TR
692
><TD
693
WIDTH="33%"
694
ALIGN="left"
695
VALIGN="top"
696
>Server Configuration</TD
697
><TD
698
WIDTH="34%"
699
ALIGN="center"
700
VALIGN="top"
701
><A
702
HREF="net-httpd-chapter.html"
703
ACCESSKEY="U"
704
>Up</A
705
></TD
706
><TD
707
WIDTH="33%"
708
ALIGN="right"
709
VALIGN="top"
710
>System Monitor</TD
711
></TR
712
></TABLE
713
></DIV
714
></BODY
715
></HTML
716
>

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