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1 | =head1 NAME |
2 | ||
8e07c86e | 3 | perlxs - XS language reference manual |
a0d0e21e LW |
4 | |
5 | =head1 DESCRIPTION | |
6 | ||
7 | =head2 Introduction | |
8 | ||
9 | XS is a language used to create an extension interface | |
10 | between Perl and some C library which one wishes to use with | |
11 | Perl. The XS interface is combined with the library to | |
12 | create a new library which can be linked to Perl. An B<XSUB> | |
13 | is a function in the XS language and is the core component | |
14 | of the Perl application interface. | |
15 | ||
16 | The XS compiler is called B<xsubpp>. This compiler will embed | |
17 | the constructs necessary to let an XSUB, which is really a C | |
18 | function in disguise, manipulate Perl values and creates the | |
19 | glue necessary to let Perl access the XSUB. The compiler | |
20 | uses B<typemaps> to determine how to map C function parameters | |
21 | and variables to Perl values. The default typemap handles | |
22 | many common C types. A supplement typemap must be created | |
23 | to handle special structures and types for the library being | |
24 | linked. | |
25 | ||
cb1a09d0 | 26 | See L<perlxstut> for a tutorial on the whole extension creation process. |
8e07c86e AD |
27 | |
28 | =head2 On The Road | |
29 | ||
a5f75d66 AD |
30 | Many of the examples which follow will concentrate on creating an interface |
31 | between Perl and the ONC+ RPC bind library functions. The rpcb_gettime() | |
32 | function is used to demonstrate many features of the XS language. This | |
33 | function has two parameters; the first is an input parameter and the second | |
34 | is an output parameter. The function also returns a status value. | |
a0d0e21e LW |
35 | |
36 | bool_t rpcb_gettime(const char *host, time_t *timep); | |
37 | ||
38 | From C this function will be called with the following | |
39 | statements. | |
40 | ||
41 | #include <rpc/rpc.h> | |
42 | bool_t status; | |
43 | time_t timep; | |
44 | status = rpcb_gettime( "localhost", &timep ); | |
45 | ||
46 | If an XSUB is created to offer a direct translation between this function | |
47 | and Perl, then this XSUB will be used from Perl with the following code. | |
48 | The $status and $timep variables will contain the output of the function. | |
49 | ||
50 | use RPC; | |
51 | $status = rpcb_gettime( "localhost", $timep ); | |
52 | ||
53 | The following XS file shows an XS subroutine, or XSUB, which | |
54 | demonstrates one possible interface to the rpcb_gettime() | |
55 | function. This XSUB represents a direct translation between | |
56 | C and Perl and so preserves the interface even from Perl. | |
57 | This XSUB will be invoked from Perl with the usage shown | |
58 | above. Note that the first three #include statements, for | |
59 | C<EXTERN.h>, C<perl.h>, and C<XSUB.h>, will always be present at the | |
60 | beginning of an XS file. This approach and others will be | |
61 | expanded later in this document. | |
62 | ||
63 | #include "EXTERN.h" | |
64 | #include "perl.h" | |
65 | #include "XSUB.h" | |
66 | #include <rpc/rpc.h> | |
67 | ||
68 | MODULE = RPC PACKAGE = RPC | |
69 | ||
70 | bool_t | |
71 | rpcb_gettime(host,timep) | |
8e07c86e AD |
72 | char *host |
73 | time_t &timep | |
a0d0e21e LW |
74 | OUTPUT: |
75 | timep | |
76 | ||
77 | Any extension to Perl, including those containing XSUBs, | |
78 | should have a Perl module to serve as the bootstrap which | |
79 | pulls the extension into Perl. This module will export the | |
80 | extension's functions and variables to the Perl program and | |
81 | will cause the extension's XSUBs to be linked into Perl. | |
82 | The following module will be used for most of the examples | |
83 | in this document and should be used from Perl with the C<use> | |
84 | command as shown earlier. Perl modules are explained in | |
85 | more detail later in this document. | |
86 | ||
87 | package RPC; | |
88 | ||
89 | require Exporter; | |
90 | require DynaLoader; | |
91 | @ISA = qw(Exporter DynaLoader); | |
92 | @EXPORT = qw( rpcb_gettime ); | |
93 | ||
94 | bootstrap RPC; | |
95 | 1; | |
96 | ||
97 | Throughout this document a variety of interfaces to the rpcb_gettime() | |
98 | XSUB will be explored. The XSUBs will take their parameters in different | |
99 | orders or will take different numbers of parameters. In each case the | |
100 | XSUB is an abstraction between Perl and the real C rpcb_gettime() | |
101 | function, and the XSUB must always ensure that the real rpcb_gettime() | |
102 | function is called with the correct parameters. This abstraction will | |
103 | allow the programmer to create a more Perl-like interface to the C | |
104 | function. | |
105 | ||
106 | =head2 The Anatomy of an XSUB | |
107 | ||
8e07c86e AD |
108 | The following XSUB allows a Perl program to access a C library function |
109 | called sin(). The XSUB will imitate the C function which takes a single | |
110 | argument and returns a single value. | |
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111 | |
112 | double | |
113 | sin(x) | |
8e07c86e | 114 | double x |
a0d0e21e | 115 | |
8e07c86e AD |
116 | When using C pointers the indirection operator C<*> should be considered |
117 | part of the type and the address operator C<&> should be considered part of | |
118 | the variable, as is demonstrated in the rpcb_gettime() function above. See | |
119 | the section on typemaps for more about handling qualifiers and unary | |
120 | operators in C types. | |
a0d0e21e | 121 | |
a0d0e21e LW |
122 | The function name and the return type must be placed on |
123 | separate lines. | |
124 | ||
125 | INCORRECT CORRECT | |
126 | ||
127 | double sin(x) double | |
8e07c86e AD |
128 | double x sin(x) |
129 | double x | |
a0d0e21e | 130 | |
c07a80fd | 131 | The function body may be indented or left-adjusted. The following example |
132 | shows a function with its body left-adjusted. Most examples in this | |
133 | document will indent the body. | |
134 | ||
135 | CORRECT | |
136 | ||
137 | double | |
138 | sin(x) | |
139 | double x | |
140 | ||
a0d0e21e LW |
141 | =head2 The Argument Stack |
142 | ||
143 | The argument stack is used to store the values which are | |
144 | sent as parameters to the XSUB and to store the XSUB's | |
145 | return value. In reality all Perl functions keep their | |
146 | values on this stack at the same time, each limited to its | |
147 | own range of positions on the stack. In this document the | |
148 | first position on that stack which belongs to the active | |
149 | function will be referred to as position 0 for that function. | |
150 | ||
8e07c86e AD |
151 | XSUBs refer to their stack arguments with the macro B<ST(x)>, where I<x> |
152 | refers to a position in this XSUB's part of the stack. Position 0 for that | |
a0d0e21e LW |
153 | function would be known to the XSUB as ST(0). The XSUB's incoming |
154 | parameters and outgoing return values always begin at ST(0). For many | |
155 | simple cases the B<xsubpp> compiler will generate the code necessary to | |
156 | handle the argument stack by embedding code fragments found in the | |
157 | typemaps. In more complex cases the programmer must supply the code. | |
158 | ||
159 | =head2 The RETVAL Variable | |
160 | ||
161 | The RETVAL variable is a magic variable which always matches | |
162 | the return type of the C library function. The B<xsubpp> compiler will | |
163 | supply this variable in each XSUB and by default will use it to hold the | |
164 | return value of the C library function being called. In simple cases the | |
165 | value of RETVAL will be placed in ST(0) of the argument stack where it can | |
166 | be received by Perl as the return value of the XSUB. | |
167 | ||
168 | If the XSUB has a return type of C<void> then the compiler will | |
169 | not supply a RETVAL variable for that function. When using | |
170 | the PPCODE: directive the RETVAL variable may not be needed. | |
171 | ||
172 | =head2 The MODULE Keyword | |
173 | ||
174 | The MODULE keyword is used to start the XS code and to | |
175 | specify the package of the functions which are being | |
176 | defined. All text preceding the first MODULE keyword is | |
177 | considered C code and is passed through to the output | |
178 | untouched. Every XS module will have a bootstrap function | |
179 | which is used to hook the XSUBs into Perl. The package name | |
180 | of this bootstrap function will match the value of the last | |
181 | MODULE statement in the XS source files. The value of | |
182 | MODULE should always remain constant within the same XS | |
183 | file, though this is not required. | |
184 | ||
185 | The following example will start the XS code and will place | |
186 | all functions in a package named RPC. | |
187 | ||
188 | MODULE = RPC | |
189 | ||
190 | =head2 The PACKAGE Keyword | |
191 | ||
192 | When functions within an XS source file must be separated into packages | |
193 | the PACKAGE keyword should be used. This keyword is used with the MODULE | |
194 | keyword and must follow immediately after it when used. | |
195 | ||
196 | MODULE = RPC PACKAGE = RPC | |
197 | ||
198 | [ XS code in package RPC ] | |
199 | ||
200 | MODULE = RPC PACKAGE = RPCB | |
201 | ||
202 | [ XS code in package RPCB ] | |
203 | ||
204 | MODULE = RPC PACKAGE = RPC | |
205 | ||
206 | [ XS code in package RPC ] | |
207 | ||
208 | Although this keyword is optional and in some cases provides redundant | |
209 | information it should always be used. This keyword will ensure that the | |
210 | XSUBs appear in the desired package. | |
211 | ||
212 | =head2 The PREFIX Keyword | |
213 | ||
214 | The PREFIX keyword designates prefixes which should be | |
215 | removed from the Perl function names. If the C function is | |
216 | C<rpcb_gettime()> and the PREFIX value is C<rpcb_> then Perl will | |
217 | see this function as C<gettime()>. | |
218 | ||
219 | This keyword should follow the PACKAGE keyword when used. | |
220 | If PACKAGE is not used then PREFIX should follow the MODULE | |
221 | keyword. | |
222 | ||
223 | MODULE = RPC PREFIX = rpc_ | |
224 | ||
225 | MODULE = RPC PACKAGE = RPCB PREFIX = rpcb_ | |
226 | ||
227 | =head2 The OUTPUT: Keyword | |
228 | ||
229 | The OUTPUT: keyword indicates that certain function parameters should be | |
230 | updated (new values made visible to Perl) when the XSUB terminates or that | |
231 | certain values should be returned to the calling Perl function. For | |
232 | simple functions, such as the sin() function above, the RETVAL variable is | |
233 | automatically designated as an output value. In more complex functions | |
234 | the B<xsubpp> compiler will need help to determine which variables are output | |
235 | variables. | |
236 | ||
237 | This keyword will normally be used to complement the CODE: keyword. | |
238 | The RETVAL variable is not recognized as an output variable when the | |
239 | CODE: keyword is present. The OUTPUT: keyword is used in this | |
240 | situation to tell the compiler that RETVAL really is an output | |
241 | variable. | |
242 | ||
243 | The OUTPUT: keyword can also be used to indicate that function parameters | |
244 | are output variables. This may be necessary when a parameter has been | |
245 | modified within the function and the programmer would like the update to | |
8e07c86e | 246 | be seen by Perl. |
a0d0e21e LW |
247 | |
248 | bool_t | |
249 | rpcb_gettime(host,timep) | |
8e07c86e AD |
250 | char *host |
251 | time_t &timep | |
a0d0e21e LW |
252 | OUTPUT: |
253 | timep | |
254 | ||
255 | The OUTPUT: keyword will also allow an output parameter to | |
256 | be mapped to a matching piece of code rather than to a | |
257 | typemap. | |
258 | ||
259 | bool_t | |
260 | rpcb_gettime(host,timep) | |
8e07c86e AD |
261 | char *host |
262 | time_t &timep | |
a0d0e21e | 263 | OUTPUT: |
8e07c86e | 264 | timep sv_setnv(ST(1), (double)timep); |
a0d0e21e LW |
265 | |
266 | =head2 The CODE: Keyword | |
267 | ||
268 | This keyword is used in more complicated XSUBs which require | |
269 | special handling for the C function. The RETVAL variable is | |
270 | available but will not be returned unless it is specified | |
271 | under the OUTPUT: keyword. | |
272 | ||
273 | The following XSUB is for a C function which requires special handling of | |
274 | its parameters. The Perl usage is given first. | |
275 | ||
276 | $status = rpcb_gettime( "localhost", $timep ); | |
277 | ||
278 | The XSUB follows. | |
279 | ||
d1b91892 AD |
280 | bool_t |
281 | rpcb_gettime(host,timep) | |
8e07c86e AD |
282 | char *host |
283 | time_t timep | |
a0d0e21e LW |
284 | CODE: |
285 | RETVAL = rpcb_gettime( host, &timep ); | |
286 | OUTPUT: | |
287 | timep | |
288 | RETVAL | |
289 | ||
c07a80fd | 290 | =head2 The INIT: Keyword |
291 | ||
292 | The INIT: keyword allows initialization to be inserted into the XSUB before | |
293 | the compiler generates the call to the C function. Unlike the CODE: keyword | |
294 | above, this keyword does not affect the way the compiler handles RETVAL. | |
295 | ||
296 | bool_t | |
297 | rpcb_gettime(host,timep) | |
298 | char *host | |
299 | time_t &timep | |
300 | INIT: | |
301 | printf("# Host is %s\n", host ); | |
302 | OUTPUT: | |
303 | timep | |
a0d0e21e LW |
304 | |
305 | =head2 The NO_INIT Keyword | |
306 | ||
307 | The NO_INIT keyword is used to indicate that a function | |
d1b91892 | 308 | parameter is being used as only an output value. The B<xsubpp> |
a0d0e21e LW |
309 | compiler will normally generate code to read the values of |
310 | all function parameters from the argument stack and assign | |
311 | them to C variables upon entry to the function. NO_INIT | |
312 | will tell the compiler that some parameters will be used for | |
313 | output rather than for input and that they will be handled | |
314 | before the function terminates. | |
315 | ||
316 | The following example shows a variation of the rpcb_gettime() function. | |
d1b91892 | 317 | This function uses the timep variable as only an output variable and does |
a0d0e21e LW |
318 | not care about its initial contents. |
319 | ||
320 | bool_t | |
321 | rpcb_gettime(host,timep) | |
8e07c86e AD |
322 | char *host |
323 | time_t &timep = NO_INIT | |
a0d0e21e LW |
324 | OUTPUT: |
325 | timep | |
326 | ||
327 | =head2 Initializing Function Parameters | |
328 | ||
329 | Function parameters are normally initialized with their | |
330 | values from the argument stack. The typemaps contain the | |
331 | code segments which are used to transfer the Perl values to | |
332 | the C parameters. The programmer, however, is allowed to | |
333 | override the typemaps and supply alternate initialization | |
334 | code. | |
335 | ||
336 | The following code demonstrates how to supply initialization code for | |
337 | function parameters. The initialization code is eval'd by the compiler | |
338 | before it is added to the output so anything which should be interpreted | |
339 | literally, such as double quotes, must be protected with backslashes. | |
340 | ||
341 | bool_t | |
342 | rpcb_gettime(host,timep) | |
8e07c86e AD |
343 | char *host = (char *)SvPV(ST(0),na); |
344 | time_t &timep = 0; | |
a0d0e21e LW |
345 | OUTPUT: |
346 | timep | |
347 | ||
348 | This should not be used to supply default values for parameters. One | |
349 | would normally use this when a function parameter must be processed by | |
350 | another library function before it can be used. Default parameters are | |
351 | covered in the next section. | |
352 | ||
353 | =head2 Default Parameter Values | |
354 | ||
355 | Default values can be specified for function parameters by | |
356 | placing an assignment statement in the parameter list. The | |
357 | default value may be a number or a string. Defaults should | |
358 | always be used on the right-most parameters only. | |
359 | ||
360 | To allow the XSUB for rpcb_gettime() to have a default host | |
361 | value the parameters to the XSUB could be rearranged. The | |
362 | XSUB will then call the real rpcb_gettime() function with | |
363 | the parameters in the correct order. Perl will call this | |
364 | XSUB with either of the following statements. | |
365 | ||
366 | $status = rpcb_gettime( $timep, $host ); | |
367 | ||
368 | $status = rpcb_gettime( $timep ); | |
369 | ||
370 | The XSUB will look like the code which follows. A CODE: | |
371 | block is used to call the real rpcb_gettime() function with | |
372 | the parameters in the correct order for that function. | |
373 | ||
374 | bool_t | |
375 | rpcb_gettime(timep,host="localhost") | |
8e07c86e AD |
376 | char *host |
377 | time_t timep = NO_INIT | |
a0d0e21e LW |
378 | CODE: |
379 | RETVAL = rpcb_gettime( host, &timep ); | |
380 | OUTPUT: | |
381 | timep | |
382 | RETVAL | |
383 | ||
c07a80fd | 384 | =head2 The PREINIT: Keyword |
385 | ||
386 | The PREINIT: keyword allows extra variables to be declared before the | |
387 | typemaps are expanded. If a variable is declared in a CODE: block then that | |
388 | variable will follow any typemap code. This may result in a C syntax | |
389 | error. To force the variable to be declared before the typemap code, place | |
390 | it into a PREINIT: block. The PREINIT: keyword may be used one or more | |
391 | times within an XSUB. | |
392 | ||
393 | The following examples are equivalent, but if the code is using complex | |
394 | typemaps then the first example is safer. | |
395 | ||
396 | bool_t | |
397 | rpcb_gettime(timep) | |
398 | time_t timep = NO_INIT | |
399 | PREINIT: | |
400 | char *host = "localhost"; | |
401 | CODE: | |
402 | RETVAL = rpcb_gettime( host, &timep ); | |
403 | OUTPUT: | |
404 | timep | |
405 | RETVAL | |
406 | ||
407 | A correct, but error-prone example. | |
408 | ||
409 | bool_t | |
410 | rpcb_gettime(timep) | |
411 | time_t timep = NO_INIT | |
412 | CODE: | |
413 | char *host = "localhost"; | |
414 | RETVAL = rpcb_gettime( host, &timep ); | |
415 | OUTPUT: | |
416 | timep | |
417 | RETVAL | |
418 | ||
84287afe | 419 | =head2 The SCOPE: Keyword |
420 | ||
421 | The SCOPE: keyword allows scoping to be enabled for a particular XSUB. If | |
422 | enabled, the XSUB will invoke ENTER and LEAVE automatically. | |
423 | ||
424 | To support potentially complex type mappings, if a typemap entry used | |
425 | by this XSUB contains a comment like C</*scope*/> then scoping will | |
426 | automatically be enabled for that XSUB. | |
427 | ||
428 | To enable scoping: | |
429 | ||
430 | SCOPE: ENABLE | |
431 | ||
432 | To disable scoping: | |
433 | ||
434 | SCOPE: DISABLE | |
435 | ||
c07a80fd | 436 | =head2 The INPUT: Keyword |
437 | ||
438 | The XSUB's parameters are usually evaluated immediately after entering the | |
439 | XSUB. The INPUT: keyword can be used to force those parameters to be | |
440 | evaluated a little later. The INPUT: keyword can be used multiple times | |
441 | within an XSUB and can be used to list one or more input variables. This | |
442 | keyword is used with the PREINIT: keyword. | |
443 | ||
444 | The following example shows how the input parameter C<timep> can be | |
445 | evaluated late, after a PREINIT. | |
446 | ||
447 | bool_t | |
448 | rpcb_gettime(host,timep) | |
449 | char *host | |
450 | PREINIT: | |
451 | time_t tt; | |
452 | INPUT: | |
453 | time_t timep | |
454 | CODE: | |
455 | RETVAL = rpcb_gettime( host, &tt ); | |
456 | timep = tt; | |
457 | OUTPUT: | |
458 | timep | |
459 | RETVAL | |
460 | ||
461 | The next example shows each input parameter evaluated late. | |
462 | ||
463 | bool_t | |
464 | rpcb_gettime(host,timep) | |
465 | PREINIT: | |
466 | time_t tt; | |
467 | INPUT: | |
468 | char *host | |
469 | PREINIT: | |
470 | char *h; | |
471 | INPUT: | |
472 | time_t timep | |
473 | CODE: | |
474 | h = host; | |
475 | RETVAL = rpcb_gettime( h, &tt ); | |
476 | timep = tt; | |
477 | OUTPUT: | |
478 | timep | |
479 | RETVAL | |
480 | ||
a0d0e21e LW |
481 | =head2 Variable-length Parameter Lists |
482 | ||
483 | XSUBs can have variable-length parameter lists by specifying an ellipsis | |
484 | C<(...)> in the parameter list. This use of the ellipsis is similar to that | |
485 | found in ANSI C. The programmer is able to determine the number of | |
486 | arguments passed to the XSUB by examining the C<items> variable which the | |
487 | B<xsubpp> compiler supplies for all XSUBs. By using this mechanism one can | |
488 | create an XSUB which accepts a list of parameters of unknown length. | |
489 | ||
490 | The I<host> parameter for the rpcb_gettime() XSUB can be | |
491 | optional so the ellipsis can be used to indicate that the | |
492 | XSUB will take a variable number of parameters. Perl should | |
d1b91892 | 493 | be able to call this XSUB with either of the following statements. |
a0d0e21e LW |
494 | |
495 | $status = rpcb_gettime( $timep, $host ); | |
496 | ||
497 | $status = rpcb_gettime( $timep ); | |
498 | ||
499 | The XS code, with ellipsis, follows. | |
500 | ||
501 | bool_t | |
502 | rpcb_gettime(timep, ...) | |
8e07c86e | 503 | time_t timep = NO_INIT |
c07a80fd | 504 | PREINIT: |
a0d0e21e | 505 | char *host = "localhost"; |
c07a80fd | 506 | CODE: |
507 | if( items > 1 ) | |
508 | host = (char *)SvPV(ST(1), na); | |
509 | RETVAL = rpcb_gettime( host, &timep ); | |
a0d0e21e LW |
510 | OUTPUT: |
511 | timep | |
512 | RETVAL | |
513 | ||
514 | =head2 The PPCODE: Keyword | |
515 | ||
516 | The PPCODE: keyword is an alternate form of the CODE: keyword and is used | |
517 | to tell the B<xsubpp> compiler that the programmer is supplying the code to | |
d1b91892 | 518 | control the argument stack for the XSUBs return values. Occasionally one |
a0d0e21e LW |
519 | will want an XSUB to return a list of values rather than a single value. |
520 | In these cases one must use PPCODE: and then explicitly push the list of | |
521 | values on the stack. The PPCODE: and CODE: keywords are not used | |
522 | together within the same XSUB. | |
523 | ||
524 | The following XSUB will call the C rpcb_gettime() function | |
525 | and will return its two output values, timep and status, to | |
526 | Perl as a single list. | |
527 | ||
d1b91892 AD |
528 | void |
529 | rpcb_gettime(host) | |
8e07c86e | 530 | char *host |
c07a80fd | 531 | PREINIT: |
a0d0e21e LW |
532 | time_t timep; |
533 | bool_t status; | |
c07a80fd | 534 | PPCODE: |
a0d0e21e LW |
535 | status = rpcb_gettime( host, &timep ); |
536 | EXTEND(sp, 2); | |
cb1a09d0 AD |
537 | PUSHs(sv_2mortal(newSViv(status))); |
538 | PUSHs(sv_2mortal(newSViv(timep))); | |
a0d0e21e LW |
539 | |
540 | Notice that the programmer must supply the C code necessary | |
541 | to have the real rpcb_gettime() function called and to have | |
542 | the return values properly placed on the argument stack. | |
543 | ||
544 | The C<void> return type for this function tells the B<xsubpp> compiler that | |
545 | the RETVAL variable is not needed or used and that it should not be created. | |
546 | In most scenarios the void return type should be used with the PPCODE: | |
547 | directive. | |
548 | ||
549 | The EXTEND() macro is used to make room on the argument | |
550 | stack for 2 return values. The PPCODE: directive causes the | |
551 | B<xsubpp> compiler to create a stack pointer called C<sp>, and it | |
552 | is this pointer which is being used in the EXTEND() macro. | |
553 | The values are then pushed onto the stack with the PUSHs() | |
554 | macro. | |
555 | ||
556 | Now the rpcb_gettime() function can be used from Perl with | |
557 | the following statement. | |
558 | ||
559 | ($status, $timep) = rpcb_gettime("localhost"); | |
560 | ||
561 | =head2 Returning Undef And Empty Lists | |
562 | ||
5f05dabc | 563 | Occasionally the programmer will want to return simply |
a0d0e21e LW |
564 | C<undef> or an empty list if a function fails rather than a |
565 | separate status value. The rpcb_gettime() function offers | |
566 | just this situation. If the function succeeds we would like | |
567 | to have it return the time and if it fails we would like to | |
568 | have undef returned. In the following Perl code the value | |
569 | of $timep will either be undef or it will be a valid time. | |
570 | ||
571 | $timep = rpcb_gettime( "localhost" ); | |
572 | ||
573 | The following XSUB uses the C<void> return type to disable the generation of | |
574 | the RETVAL variable and uses a CODE: block to indicate to the compiler | |
575 | that the programmer has supplied all the necessary code. The | |
576 | sv_newmortal() call will initialize the return value to undef, making that | |
577 | the default return value. | |
578 | ||
579 | void | |
580 | rpcb_gettime(host) | |
581 | char * host | |
c07a80fd | 582 | PREINIT: |
a0d0e21e LW |
583 | time_t timep; |
584 | bool_t x; | |
c07a80fd | 585 | CODE: |
a0d0e21e LW |
586 | ST(0) = sv_newmortal(); |
587 | if( rpcb_gettime( host, &timep ) ) | |
588 | sv_setnv( ST(0), (double)timep); | |
a0d0e21e LW |
589 | |
590 | The next example demonstrates how one would place an explicit undef in the | |
591 | return value, should the need arise. | |
592 | ||
593 | void | |
594 | rpcb_gettime(host) | |
595 | char * host | |
c07a80fd | 596 | PREINIT: |
a0d0e21e LW |
597 | time_t timep; |
598 | bool_t x; | |
c07a80fd | 599 | CODE: |
a0d0e21e LW |
600 | ST(0) = sv_newmortal(); |
601 | if( rpcb_gettime( host, &timep ) ){ | |
602 | sv_setnv( ST(0), (double)timep); | |
603 | } | |
604 | else{ | |
605 | ST(0) = &sv_undef; | |
606 | } | |
a0d0e21e LW |
607 | |
608 | To return an empty list one must use a PPCODE: block and | |
609 | then not push return values on the stack. | |
610 | ||
611 | void | |
612 | rpcb_gettime(host) | |
8e07c86e | 613 | char *host |
c07a80fd | 614 | PREINIT: |
a0d0e21e | 615 | time_t timep; |
c07a80fd | 616 | PPCODE: |
a0d0e21e | 617 | if( rpcb_gettime( host, &timep ) ) |
cb1a09d0 | 618 | PUSHs(sv_2mortal(newSViv(timep))); |
a0d0e21e LW |
619 | else{ |
620 | /* Nothing pushed on stack, so an empty */ | |
621 | /* list is implicitly returned. */ | |
622 | } | |
a0d0e21e | 623 | |
f27cfbbe | 624 | Some people may be inclined to include an explicit C<return> in the above |
625 | XSUB, rather than letting control fall through to the end. In those | |
626 | situations C<XSRETURN_EMPTY> should be used, instead. This will ensure that | |
627 | the XSUB stack is properly adjusted. Consult L<perlguts/"API LISTING"> for | |
628 | other C<XSRETURN> macros. | |
629 | ||
4633a7c4 LW |
630 | =head2 The REQUIRE: Keyword |
631 | ||
632 | The REQUIRE: keyword is used to indicate the minimum version of the | |
633 | B<xsubpp> compiler needed to compile the XS module. An XS module which | |
5f05dabc | 634 | contains the following statement will compile with only B<xsubpp> version |
4633a7c4 LW |
635 | 1.922 or greater: |
636 | ||
637 | REQUIRE: 1.922 | |
638 | ||
a0d0e21e LW |
639 | =head2 The CLEANUP: Keyword |
640 | ||
641 | This keyword can be used when an XSUB requires special cleanup procedures | |
642 | before it terminates. When the CLEANUP: keyword is used it must follow | |
643 | any CODE:, PPCODE:, or OUTPUT: blocks which are present in the XSUB. The | |
644 | code specified for the cleanup block will be added as the last statements | |
645 | in the XSUB. | |
646 | ||
647 | =head2 The BOOT: Keyword | |
648 | ||
649 | The BOOT: keyword is used to add code to the extension's bootstrap | |
650 | function. The bootstrap function is generated by the B<xsubpp> compiler and | |
651 | normally holds the statements necessary to register any XSUBs with Perl. | |
652 | With the BOOT: keyword the programmer can tell the compiler to add extra | |
653 | statements to the bootstrap function. | |
654 | ||
655 | This keyword may be used any time after the first MODULE keyword and should | |
656 | appear on a line by itself. The first blank line after the keyword will | |
657 | terminate the code block. | |
658 | ||
659 | BOOT: | |
660 | # The following message will be printed when the | |
661 | # bootstrap function executes. | |
662 | printf("Hello from the bootstrap!\n"); | |
663 | ||
c07a80fd | 664 | =head2 The VERSIONCHECK: Keyword |
665 | ||
666 | The VERSIONCHECK: keyword corresponds to B<xsubpp>'s C<-versioncheck> and | |
5f05dabc | 667 | C<-noversioncheck> options. This keyword overrides the command line |
c07a80fd | 668 | options. Version checking is enabled by default. When version checking is |
669 | enabled the XS module will attempt to verify that its version matches the | |
670 | version of the PM module. | |
671 | ||
672 | To enable version checking: | |
673 | ||
674 | VERSIONCHECK: ENABLE | |
675 | ||
676 | To disable version checking: | |
677 | ||
678 | VERSIONCHECK: DISABLE | |
679 | ||
680 | =head2 The PROTOTYPES: Keyword | |
681 | ||
682 | The PROTOTYPES: keyword corresponds to B<xsubpp>'s C<-prototypes> and | |
5f05dabc | 683 | C<-noprototypes> options. This keyword overrides the command-line options. |
c07a80fd | 684 | Prototypes are enabled by default. When prototypes are enabled XSUBs will |
685 | be given Perl prototypes. This keyword may be used multiple times in an XS | |
686 | module to enable and disable prototypes for different parts of the module. | |
687 | ||
688 | To enable prototypes: | |
689 | ||
690 | PROTOTYPES: ENABLE | |
691 | ||
692 | To disable prototypes: | |
693 | ||
694 | PROTOTYPES: DISABLE | |
695 | ||
696 | =head2 The PROTOTYPE: Keyword | |
697 | ||
698 | This keyword is similar to the PROTOTYPES: keyword above but can be used to | |
699 | force B<xsubpp> to use a specific prototype for the XSUB. This keyword | |
700 | overrides all other prototype options and keywords but affects only the | |
701 | current XSUB. Consult L<perlsub/Prototypes> for information about Perl | |
702 | prototypes. | |
703 | ||
704 | bool_t | |
705 | rpcb_gettime(timep, ...) | |
706 | time_t timep = NO_INIT | |
707 | PROTOTYPE: $;$ | |
708 | PREINIT: | |
709 | char *host = "localhost"; | |
710 | CODE: | |
711 | if( items > 1 ) | |
712 | host = (char *)SvPV(ST(1), na); | |
713 | RETVAL = rpcb_gettime( host, &timep ); | |
714 | OUTPUT: | |
715 | timep | |
716 | RETVAL | |
717 | ||
718 | =head2 The ALIAS: Keyword | |
719 | ||
720 | The ALIAS: keyword allows an XSUB to have two more more unique Perl names | |
721 | and to know which of those names was used when it was invoked. The Perl | |
722 | names may be fully-qualified with package names. Each alias is given an | |
723 | index. The compiler will setup a variable called C<ix> which contain the | |
724 | index of the alias which was used. When the XSUB is called with its | |
725 | declared name C<ix> will be 0. | |
726 | ||
727 | The following example will create aliases C<FOO::gettime()> and | |
728 | C<BAR::getit()> for this function. | |
729 | ||
730 | bool_t | |
731 | rpcb_gettime(host,timep) | |
732 | char *host | |
733 | time_t &timep | |
734 | ALIAS: | |
735 | FOO::gettime = 1 | |
736 | BAR::getit = 2 | |
737 | INIT: | |
738 | printf("# ix = %d\n", ix ); | |
739 | OUTPUT: | |
740 | timep | |
741 | ||
742 | =head2 The INCLUDE: Keyword | |
743 | ||
744 | This keyword can be used to pull other files into the XS module. The other | |
745 | files may have XS code. INCLUDE: can also be used to run a command to | |
746 | generate the XS code to be pulled into the module. | |
747 | ||
748 | The file F<Rpcb1.xsh> contains our C<rpcb_gettime()> function: | |
749 | ||
750 | bool_t | |
751 | rpcb_gettime(host,timep) | |
752 | char *host | |
753 | time_t &timep | |
754 | OUTPUT: | |
755 | timep | |
756 | ||
757 | The XS module can use INCLUDE: to pull that file into it. | |
758 | ||
759 | INCLUDE: Rpcb1.xsh | |
760 | ||
761 | If the parameters to the INCLUDE: keyword are followed by a pipe (C<|>) then | |
762 | the compiler will interpret the parameters as a command. | |
763 | ||
764 | INCLUDE: cat Rpcb1.xsh | | |
765 | ||
766 | =head2 The CASE: Keyword | |
767 | ||
768 | The CASE: keyword allows an XSUB to have multiple distinct parts with each | |
769 | part acting as a virtual XSUB. CASE: is greedy and if it is used then all | |
770 | other XS keywords must be contained within a CASE:. This means nothing may | |
771 | precede the first CASE: in the XSUB and anything following the last CASE: is | |
772 | included in that case. | |
773 | ||
774 | A CASE: might switch via a parameter of the XSUB, via the C<ix> ALIAS: | |
775 | variable (see L<"The ALIAS: Keyword">), or maybe via the C<items> variable | |
776 | (see L<"Variable-length Parameter Lists">). The last CASE: becomes the | |
777 | B<default> case if it is not associated with a conditional. The following | |
778 | example shows CASE switched via C<ix> with a function C<rpcb_gettime()> | |
779 | having an alias C<x_gettime()>. When the function is called as | |
b772cb6e | 780 | C<rpcb_gettime()> its parameters are the usual C<(char *host, time_t *timep)>, |
781 | but when the function is called as C<x_gettime()> its parameters are | |
c07a80fd | 782 | reversed, C<(time_t *timep, char *host)>. |
783 | ||
784 | long | |
785 | rpcb_gettime(a,b) | |
786 | CASE: ix == 1 | |
787 | ALIAS: | |
788 | x_gettime = 1 | |
789 | INPUT: | |
790 | # 'a' is timep, 'b' is host | |
791 | char *b | |
792 | time_t a = NO_INIT | |
793 | CODE: | |
794 | RETVAL = rpcb_gettime( b, &a ); | |
795 | OUTPUT: | |
796 | a | |
797 | RETVAL | |
798 | CASE: | |
799 | # 'a' is host, 'b' is timep | |
800 | char *a | |
801 | time_t &b = NO_INIT | |
802 | OUTPUT: | |
803 | b | |
804 | RETVAL | |
805 | ||
806 | That function can be called with either of the following statements. Note | |
807 | the different argument lists. | |
808 | ||
809 | $status = rpcb_gettime( $host, $timep ); | |
810 | ||
811 | $status = x_gettime( $timep, $host ); | |
812 | ||
813 | =head2 The & Unary Operator | |
814 | ||
815 | The & unary operator is used to tell the compiler that it should dereference | |
816 | the object when it calls the C function. This is used when a CODE: block is | |
817 | not used and the object is a not a pointer type (the object is an C<int> or | |
818 | C<long> but not a C<int*> or C<long*>). | |
819 | ||
820 | The following XSUB will generate incorrect C code. The xsubpp compiler will | |
821 | turn this into code which calls C<rpcb_gettime()> with parameters C<(char | |
822 | *host, time_t timep)>, but the real C<rpcb_gettime()> wants the C<timep> | |
823 | parameter to be of type C<time_t*> rather than C<time_t>. | |
824 | ||
825 | bool_t | |
826 | rpcb_gettime(host,timep) | |
827 | char *host | |
828 | time_t timep | |
829 | OUTPUT: | |
830 | timep | |
831 | ||
832 | That problem is corrected by using the C<&> operator. The xsubpp compiler | |
833 | will now turn this into code which calls C<rpcb_gettime()> correctly with | |
834 | parameters C<(char *host, time_t *timep)>. It does this by carrying the | |
835 | C<&> through, so the function call looks like C<rpcb_gettime(host, &timep)>. | |
836 | ||
837 | bool_t | |
838 | rpcb_gettime(host,timep) | |
839 | char *host | |
840 | time_t &timep | |
841 | OUTPUT: | |
842 | timep | |
843 | ||
a0d0e21e LW |
844 | =head2 Inserting Comments and C Preprocessor Directives |
845 | ||
f27cfbbe | 846 | C preprocessor directives are allowed within BOOT:, PREINIT: INIT:, |
5f05dabc | 847 | CODE:, PPCODE:, and CLEANUP: blocks, as well as outside the functions. |
f27cfbbe | 848 | Comments are allowed anywhere after the MODULE keyword. The compiler |
849 | will pass the preprocessor directives through untouched and will remove | |
850 | the commented lines. | |
b772cb6e | 851 | |
f27cfbbe | 852 | Comments can be added to XSUBs by placing a C<#> as the first |
853 | non-whitespace of a line. Care should be taken to avoid making the | |
854 | comment look like a C preprocessor directive, lest it be interpreted as | |
855 | such. The simplest way to prevent this is to put whitespace in front of | |
856 | the C<#>. | |
857 | ||
f27cfbbe | 858 | If you use preprocessor directives to choose one of two |
859 | versions of a function, use | |
860 | ||
861 | #if ... version1 | |
862 | #else /* ... version2 */ | |
863 | #endif | |
864 | ||
865 | and not | |
866 | ||
867 | #if ... version1 | |
868 | #endif | |
869 | #if ... version2 | |
870 | #endif | |
871 | ||
872 | because otherwise xsubpp will believe that you made a duplicate | |
873 | definition of the function. Also, put a blank line before the | |
874 | #else/#endif so it will not be seen as part of the function body. | |
a0d0e21e LW |
875 | |
876 | =head2 Using XS With C++ | |
877 | ||
878 | If a function is defined as a C++ method then it will assume | |
879 | its first argument is an object pointer. The object pointer | |
880 | will be stored in a variable called THIS. The object should | |
881 | have been created by C++ with the new() function and should | |
cb1a09d0 AD |
882 | be blessed by Perl with the sv_setref_pv() macro. The |
883 | blessing of the object by Perl can be handled by a typemap. An example | |
884 | typemap is shown at the end of this section. | |
a0d0e21e LW |
885 | |
886 | If the method is defined as static it will call the C++ | |
887 | function using the class::method() syntax. If the method is not static | |
f27cfbbe | 888 | the function will be called using the THIS-E<gt>method() syntax. |
a0d0e21e | 889 | |
cb1a09d0 | 890 | The next examples will use the following C++ class. |
a0d0e21e | 891 | |
a5f75d66 | 892 | class color { |
cb1a09d0 | 893 | public: |
a5f75d66 AD |
894 | color(); |
895 | ~color(); | |
cb1a09d0 AD |
896 | int blue(); |
897 | void set_blue( int ); | |
898 | ||
899 | private: | |
900 | int c_blue; | |
901 | }; | |
902 | ||
903 | The XSUBs for the blue() and set_blue() methods are defined with the class | |
904 | name but the parameter for the object (THIS, or "self") is implicit and is | |
905 | not listed. | |
906 | ||
907 | int | |
908 | color::blue() | |
a0d0e21e LW |
909 | |
910 | void | |
cb1a09d0 AD |
911 | color::set_blue( val ) |
912 | int val | |
a0d0e21e | 913 | |
cb1a09d0 AD |
914 | Both functions will expect an object as the first parameter. The xsubpp |
915 | compiler will call that object C<THIS> and will use it to call the specified | |
916 | method. So in the C++ code the blue() and set_blue() methods will be called | |
917 | in the following manner. | |
a0d0e21e | 918 | |
cb1a09d0 | 919 | RETVAL = THIS->blue(); |
a0d0e21e | 920 | |
cb1a09d0 | 921 | THIS->set_blue( val ); |
a0d0e21e | 922 | |
cb1a09d0 AD |
923 | If the function's name is B<DESTROY> then the C++ C<delete> function will be |
924 | called and C<THIS> will be given as its parameter. | |
a0d0e21e | 925 | |
d1b91892 | 926 | void |
cb1a09d0 AD |
927 | color::DESTROY() |
928 | ||
929 | The C++ code will call C<delete>. | |
930 | ||
931 | delete THIS; | |
a0d0e21e | 932 | |
cb1a09d0 AD |
933 | If the function's name is B<new> then the C++ C<new> function will be called |
934 | to create a dynamic C++ object. The XSUB will expect the class name, which | |
935 | will be kept in a variable called C<CLASS>, to be given as the first | |
936 | argument. | |
a0d0e21e | 937 | |
cb1a09d0 AD |
938 | color * |
939 | color::new() | |
a0d0e21e | 940 | |
cb1a09d0 | 941 | The C++ code will call C<new>. |
a0d0e21e | 942 | |
cb1a09d0 AD |
943 | RETVAL = new color(); |
944 | ||
945 | The following is an example of a typemap that could be used for this C++ | |
946 | example. | |
947 | ||
948 | TYPEMAP | |
949 | color * O_OBJECT | |
950 | ||
951 | OUTPUT | |
952 | # The Perl object is blessed into 'CLASS', which should be a | |
953 | # char* having the name of the package for the blessing. | |
954 | O_OBJECT | |
955 | sv_setref_pv( $arg, CLASS, (void*)$var ); | |
a6006777 | 956 | |
cb1a09d0 AD |
957 | INPUT |
958 | O_OBJECT | |
959 | if( sv_isobject($arg) && (SvTYPE(SvRV($arg)) == SVt_PVMG) ) | |
960 | $var = ($type)SvIV((SV*)SvRV( $arg )); | |
961 | else{ | |
962 | warn( \"${Package}::$func_name() -- $var is not a blessed SV reference\" ); | |
963 | XSRETURN_UNDEF; | |
964 | } | |
a0d0e21e | 965 | |
d1b91892 | 966 | =head2 Interface Strategy |
a0d0e21e LW |
967 | |
968 | When designing an interface between Perl and a C library a straight | |
969 | translation from C to XS is often sufficient. The interface will often be | |
970 | very C-like and occasionally nonintuitive, especially when the C function | |
971 | modifies one of its parameters. In cases where the programmer wishes to | |
972 | create a more Perl-like interface the following strategy may help to | |
973 | identify the more critical parts of the interface. | |
974 | ||
975 | Identify the C functions which modify their parameters. The XSUBs for | |
976 | these functions may be able to return lists to Perl, or may be | |
977 | candidates to return undef or an empty list in case of failure. | |
978 | ||
d1b91892 | 979 | Identify which values are used by only the C and XSUB functions |
a0d0e21e LW |
980 | themselves. If Perl does not need to access the contents of the value |
981 | then it may not be necessary to provide a translation for that value | |
982 | from C to Perl. | |
983 | ||
984 | Identify the pointers in the C function parameter lists and return | |
985 | values. Some pointers can be handled in XS with the & unary operator on | |
986 | the variable name while others will require the use of the * operator on | |
987 | the type name. In general it is easier to work with the & operator. | |
988 | ||
989 | Identify the structures used by the C functions. In many | |
990 | cases it may be helpful to use the T_PTROBJ typemap for | |
991 | these structures so they can be manipulated by Perl as | |
992 | blessed objects. | |
993 | ||
a0d0e21e LW |
994 | =head2 Perl Objects And C Structures |
995 | ||
996 | When dealing with C structures one should select either | |
997 | B<T_PTROBJ> or B<T_PTRREF> for the XS type. Both types are | |
998 | designed to handle pointers to complex objects. The | |
999 | T_PTRREF type will allow the Perl object to be unblessed | |
1000 | while the T_PTROBJ type requires that the object be blessed. | |
1001 | By using T_PTROBJ one can achieve a form of type-checking | |
d1b91892 | 1002 | because the XSUB will attempt to verify that the Perl object |
a0d0e21e LW |
1003 | is of the expected type. |
1004 | ||
1005 | The following XS code shows the getnetconfigent() function which is used | |
8e07c86e | 1006 | with ONC+ TIRPC. The getnetconfigent() function will return a pointer to a |
a0d0e21e LW |
1007 | C structure and has the C prototype shown below. The example will |
1008 | demonstrate how the C pointer will become a Perl reference. Perl will | |
1009 | consider this reference to be a pointer to a blessed object and will | |
1010 | attempt to call a destructor for the object. A destructor will be | |
1011 | provided in the XS source to free the memory used by getnetconfigent(). | |
1012 | Destructors in XS can be created by specifying an XSUB function whose name | |
1013 | ends with the word B<DESTROY>. XS destructors can be used to free memory | |
1014 | which may have been malloc'd by another XSUB. | |
1015 | ||
1016 | struct netconfig *getnetconfigent(const char *netid); | |
1017 | ||
1018 | A C<typedef> will be created for C<struct netconfig>. The Perl | |
1019 | object will be blessed in a class matching the name of the C | |
1020 | type, with the tag C<Ptr> appended, and the name should not | |
1021 | have embedded spaces if it will be a Perl package name. The | |
1022 | destructor will be placed in a class corresponding to the | |
1023 | class of the object and the PREFIX keyword will be used to | |
1024 | trim the name to the word DESTROY as Perl will expect. | |
1025 | ||
1026 | typedef struct netconfig Netconfig; | |
1027 | ||
1028 | MODULE = RPC PACKAGE = RPC | |
1029 | ||
1030 | Netconfig * | |
1031 | getnetconfigent(netid) | |
8e07c86e | 1032 | char *netid |
a0d0e21e LW |
1033 | |
1034 | MODULE = RPC PACKAGE = NetconfigPtr PREFIX = rpcb_ | |
1035 | ||
1036 | void | |
1037 | rpcb_DESTROY(netconf) | |
8e07c86e | 1038 | Netconfig *netconf |
a0d0e21e LW |
1039 | CODE: |
1040 | printf("Now in NetconfigPtr::DESTROY\n"); | |
1041 | free( netconf ); | |
1042 | ||
1043 | This example requires the following typemap entry. Consult the typemap | |
1044 | section for more information about adding new typemaps for an extension. | |
1045 | ||
1046 | TYPEMAP | |
1047 | Netconfig * T_PTROBJ | |
1048 | ||
1049 | This example will be used with the following Perl statements. | |
1050 | ||
1051 | use RPC; | |
1052 | $netconf = getnetconfigent("udp"); | |
1053 | ||
1054 | When Perl destroys the object referenced by $netconf it will send the | |
1055 | object to the supplied XSUB DESTROY function. Perl cannot determine, and | |
1056 | does not care, that this object is a C struct and not a Perl object. In | |
1057 | this sense, there is no difference between the object created by the | |
1058 | getnetconfigent() XSUB and an object created by a normal Perl subroutine. | |
1059 | ||
a0d0e21e LW |
1060 | =head2 The Typemap |
1061 | ||
1062 | The typemap is a collection of code fragments which are used by the B<xsubpp> | |
1063 | compiler to map C function parameters and values to Perl values. The | |
1064 | typemap file may consist of three sections labeled C<TYPEMAP>, C<INPUT>, and | |
1065 | C<OUTPUT>. The INPUT section tells the compiler how to translate Perl values | |
1066 | into variables of certain C types. The OUTPUT section tells the compiler | |
1067 | how to translate the values from certain C types into values Perl can | |
1068 | understand. The TYPEMAP section tells the compiler which of the INPUT and | |
1069 | OUTPUT code fragments should be used to map a given C type to a Perl value. | |
1070 | Each of the sections of the typemap must be preceded by one of the TYPEMAP, | |
1071 | INPUT, or OUTPUT keywords. | |
1072 | ||
1073 | The default typemap in the C<ext> directory of the Perl source contains many | |
1074 | useful types which can be used by Perl extensions. Some extensions define | |
1075 | additional typemaps which they keep in their own directory. These | |
1076 | additional typemaps may reference INPUT and OUTPUT maps in the main | |
1077 | typemap. The B<xsubpp> compiler will allow the extension's own typemap to | |
1078 | override any mappings which are in the default typemap. | |
1079 | ||
1080 | Most extensions which require a custom typemap will need only the TYPEMAP | |
1081 | section of the typemap file. The custom typemap used in the | |
1082 | getnetconfigent() example shown earlier demonstrates what may be the typical | |
1083 | use of extension typemaps. That typemap is used to equate a C structure | |
1084 | with the T_PTROBJ typemap. The typemap used by getnetconfigent() is shown | |
1085 | here. Note that the C type is separated from the XS type with a tab and | |
1086 | that the C unary operator C<*> is considered to be a part of the C type name. | |
1087 | ||
1088 | TYPEMAP | |
1089 | Netconfig *<tab>T_PTROBJ | |
1090 | ||
1091 | =head1 EXAMPLES | |
1092 | ||
1093 | File C<RPC.xs>: Interface to some ONC+ RPC bind library functions. | |
1094 | ||
1095 | #include "EXTERN.h" | |
1096 | #include "perl.h" | |
1097 | #include "XSUB.h" | |
1098 | ||
1099 | #include <rpc/rpc.h> | |
1100 | ||
1101 | typedef struct netconfig Netconfig; | |
1102 | ||
1103 | MODULE = RPC PACKAGE = RPC | |
1104 | ||
1105 | void | |
1106 | rpcb_gettime(host="localhost") | |
8e07c86e | 1107 | char *host |
c07a80fd | 1108 | PREINIT: |
a0d0e21e | 1109 | time_t timep; |
c07a80fd | 1110 | CODE: |
a0d0e21e LW |
1111 | ST(0) = sv_newmortal(); |
1112 | if( rpcb_gettime( host, &timep ) ) | |
1113 | sv_setnv( ST(0), (double)timep ); | |
a0d0e21e LW |
1114 | |
1115 | Netconfig * | |
1116 | getnetconfigent(netid="udp") | |
8e07c86e | 1117 | char *netid |
a0d0e21e LW |
1118 | |
1119 | MODULE = RPC PACKAGE = NetconfigPtr PREFIX = rpcb_ | |
1120 | ||
1121 | void | |
1122 | rpcb_DESTROY(netconf) | |
8e07c86e | 1123 | Netconfig *netconf |
a0d0e21e LW |
1124 | CODE: |
1125 | printf("NetconfigPtr::DESTROY\n"); | |
1126 | free( netconf ); | |
1127 | ||
1128 | File C<typemap>: Custom typemap for RPC.xs. | |
1129 | ||
1130 | TYPEMAP | |
1131 | Netconfig * T_PTROBJ | |
1132 | ||
1133 | File C<RPC.pm>: Perl module for the RPC extension. | |
1134 | ||
1135 | package RPC; | |
1136 | ||
1137 | require Exporter; | |
1138 | require DynaLoader; | |
1139 | @ISA = qw(Exporter DynaLoader); | |
1140 | @EXPORT = qw(rpcb_gettime getnetconfigent); | |
1141 | ||
1142 | bootstrap RPC; | |
1143 | 1; | |
1144 | ||
1145 | File C<rpctest.pl>: Perl test program for the RPC extension. | |
1146 | ||
1147 | use RPC; | |
1148 | ||
1149 | $netconf = getnetconfigent(); | |
1150 | $a = rpcb_gettime(); | |
1151 | print "time = $a\n"; | |
1152 | print "netconf = $netconf\n"; | |
1153 | ||
1154 | $netconf = getnetconfigent("tcp"); | |
1155 | $a = rpcb_gettime("poplar"); | |
1156 | print "time = $a\n"; | |
1157 | print "netconf = $netconf\n"; | |
1158 | ||
1159 | ||
c07a80fd | 1160 | =head1 XS VERSION |
1161 | ||
f27cfbbe | 1162 | This document covers features supported by C<xsubpp> 1.935. |
c07a80fd | 1163 | |
a0d0e21e LW |
1164 | =head1 AUTHOR |
1165 | ||
d1b91892 | 1166 | Dean Roehrich F<E<lt>roehrich@cray.comE<gt>> |
b772cb6e | 1167 | Jul 8, 1996 |