Commit | Line | Data |
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760ac839 LW |
1 | =head1 NAME |
2 | ||
28757baa | 3 | perlapio - perl's IO abstraction interface. |
760ac839 LW |
4 | |
5 | =head1 SYNOPSIS | |
6 | ||
f185f654 KW |
7 | #define PERLIO_NOT_STDIO 0 /* For co-existence with stdio only */ |
8 | #include <perlio.h> /* Usually via #include <perl.h> */ | |
9 | ||
10 | PerlIO *PerlIO_stdin(void); | |
11 | PerlIO *PerlIO_stdout(void); | |
12 | PerlIO *PerlIO_stderr(void); | |
13 | ||
14 | PerlIO *PerlIO_open(const char *path,const char *mode); | |
15 | PerlIO *PerlIO_fdopen(int fd, const char *mode); | |
16 | PerlIO *PerlIO_reopen(const char *path, /* deprecated */ | |
17 | const char *mode, PerlIO *old); | |
18 | int PerlIO_close(PerlIO *f); | |
19 | ||
20 | int PerlIO_stdoutf(const char *fmt,...) | |
21 | int PerlIO_puts(PerlIO *f,const char *string); | |
22 | int PerlIO_putc(PerlIO *f,int ch); | |
23 | SSize_t PerlIO_write(PerlIO *f,const void *buf,size_t numbytes); | |
24 | int PerlIO_printf(PerlIO *f, const char *fmt,...); | |
25 | int PerlIO_vprintf(PerlIO *f, const char *fmt, va_list args); | |
26 | int PerlIO_flush(PerlIO *f); | |
27 | ||
5aae6663 | 28 | int PerlIO_fill(PerlIO *f); |
f185f654 KW |
29 | int PerlIO_eof(PerlIO *f); |
30 | int PerlIO_error(PerlIO *f); | |
31 | void PerlIO_clearerr(PerlIO *f); | |
32 | ||
33 | int PerlIO_getc(PerlIO *d); | |
34 | int PerlIO_ungetc(PerlIO *f,int ch); | |
35 | SSize_t PerlIO_read(PerlIO *f, void *buf, size_t numbytes); | |
5aae6663 | 36 | Size_t PerlIO_unread(PerlIO *f,const void *vbuf, size_t count |
f185f654 KW |
37 | |
38 | int PerlIO_fileno(PerlIO *f); | |
39 | ||
40 | void PerlIO_setlinebuf(PerlIO *f); | |
41 | ||
42 | Off_t PerlIO_tell(PerlIO *f); | |
43 | int PerlIO_seek(PerlIO *f, Off_t offset, int whence); | |
44 | void PerlIO_rewind(PerlIO *f); | |
45 | ||
46 | int PerlIO_getpos(PerlIO *f, SV *save); /* prototype changed */ | |
47 | int PerlIO_setpos(PerlIO *f, SV *saved); /* prototype changed */ | |
48 | ||
49 | int PerlIO_fast_gets(PerlIO *f); | |
50 | int PerlIO_has_cntptr(PerlIO *f); | |
51 | SSize_t PerlIO_get_cnt(PerlIO *f); | |
52 | char *PerlIO_get_ptr(PerlIO *f); | |
53 | void PerlIO_set_ptrcnt(PerlIO *f, char *ptr, SSize_t count); | |
54 | ||
55 | int PerlIO_canset_cnt(PerlIO *f); /* deprecated */ | |
56 | void PerlIO_set_cnt(PerlIO *f, int count); /* deprecated */ | |
57 | ||
58 | int PerlIO_has_base(PerlIO *f); | |
59 | char *PerlIO_get_base(PerlIO *f); | |
60 | SSize_t PerlIO_get_bufsiz(PerlIO *f); | |
61 | ||
62 | PerlIO *PerlIO_importFILE(FILE *stdio, const char *mode); | |
463029d7 | 63 | FILE *PerlIO_exportFILE(PerlIO *f, const char *mode); |
f185f654 KW |
64 | FILE *PerlIO_findFILE(PerlIO *f); |
65 | void PerlIO_releaseFILE(PerlIO *f,FILE *stdio); | |
66 | ||
3329a50e | 67 | int PerlIO_apply_layers(pTHX_ PerlIO *f, const char *mode, |
f185f654 | 68 | const char *layers); |
3329a50e | 69 | int PerlIO_binmode(pTHX_ PerlIO *f, int ptype, int imode, |
f185f654 | 70 | const char *layers); |
678f21a2 KW |
71 | void PerlIO_debug(const char *fmt,...); |
72 | ||
89222628 | 73 | =for apidoc_section $io |
51b56f5c | 74 | |
fc995cfb KW |
75 | =for apidoc Amh|int |PerlIO_apply_layers|PerlIO *f|const char *mode|const char *layers |
76 | =for apidoc_item |int |PerlIO_binmode|PerlIO *f|int ptype|int imode|const char *layers | |
77 | =for apidoc_item T|int |PerlIO_canset_cnt|PerlIO *f | |
78 | =for apidoc_item | |PerlIO_clearerr | |
79 | =for apidoc_item | |PerlIO_close | |
80 | =for apidoc_item T|void |PerlIO_debug|const char *fmt|... | |
81 | =for apidoc_item | |PerlIO_eof | |
82 | =for apidoc_item | |PerlIO_error | |
83 | =for apidoc_item T|FILE * |PerlIO_exportFILE|PerlIO *f|const char *mode | |
84 | =for apidoc_item T|int |PerlIO_fast_gets|PerlIO *f | |
85 | =for apidoc_item T|PerlIO * |PerlIO_fdopen|int fd|const char *mode | |
86 | =for apidoc_item | |PerlIO_fileno | |
4c7da727 | 87 | =for apidoc_item | |PerlIO_fill |
fc995cfb KW |
88 | =for apidoc_item T|FILE * |PerlIO_findFILE|PerlIO *f |
89 | =for apidoc_item | |PerlIO_flush | |
90 | =for apidoc_item | |PerlIO_get_base | |
91 | =for apidoc_item | |PerlIO_get_bufsiz | |
fc995cfb | 92 | =for apidoc_item | |PerlIO_get_cnt |
fc995cfb | 93 | =for apidoc_item | |PerlIO_get_ptr |
6d21409f KW |
94 | =for apidoc_item T|int |PerlIO_getc|PerlIO *d |
95 | =for apidoc_item T|int |PerlIO_getpos|PerlIO *f|SV *save | |
fc995cfb KW |
96 | =for apidoc_item T|int |PerlIO_has_base|PerlIO *f |
97 | =for apidoc_item T|int |PerlIO_has_cntptr|PerlIO *f | |
98 | =for apidoc_item T|PerlIO * |PerlIO_importFILE|FILE *stdio|const char *mode | |
99 | =for apidoc_item T|PerlIO * |PerlIO_open|const char *path|const char *mode | |
100 | =for apidoc_item T|int |PerlIO_printf|PerlIO *f|const char *fmt|... | |
101 | =for apidoc_item T|int |PerlIO_putc|PerlIO *f|int ch | |
102 | =for apidoc_item T|int |PerlIO_puts|PerlIO *f|const char *string | |
103 | =for apidoc_item | |PerlIO_read | |
104 | =for apidoc_item T|void |PerlIO_releaseFILE|PerlIO *f|FILE *stdio | |
105 | =for apidoc_item T|PerlIO * |PerlIO_reopen|const char *path|const char *mode|PerlIO *old | |
106 | =for apidoc_item T|void |PerlIO_rewind|PerlIO *f | |
107 | =for apidoc_item | |PerlIO_seek | |
108 | =for apidoc_item | |PerlIO_set_cnt | |
6d21409f | 109 | =for apidoc_item | |PerlIO_set_ptrcnt |
fc995cfb KW |
110 | =for apidoc_item | |PerlIO_setlinebuf |
111 | =for apidoc_item T|int |PerlIO_setpos|PerlIO *f|SV *saved | |
fc995cfb KW |
112 | =for apidoc_item | |PerlIO_stderr |
113 | =for apidoc_item | |PerlIO_stdin | |
114 | =for apidoc_item | |PerlIO_stdout | |
115 | =for apidoc_item T|int |PerlIO_stdoutf|const char *fmt|... | |
116 | =for apidoc_item | |PerlIO_tell | |
117 | =for apidoc_item T|int |PerlIO_ungetc|PerlIO *f|int ch | |
4c7da727 | 118 | =for apidoc_item | |PerlIO_unread |
fc995cfb KW |
119 | =for apidoc_item T|int |PerlIO_vprintf|PerlIO *f|const char *fmt|va_list args |
120 | =for apidoc_item | |PerlIO_write | |
760ac839 LW |
121 | |
122 | =head1 DESCRIPTION | |
123 | ||
06936a3c PN |
124 | Perl's source code, and extensions that want maximum portability, |
125 | should use the above functions instead of those defined in ANSI C's | |
126 | I<stdio.h>. The perl headers (in particular "perlio.h") will | |
127 | C<#define> them to the I/O mechanism selected at Configure time. | |
760ac839 LW |
128 | |
129 | The functions are modeled on those in I<stdio.h>, but parameter order | |
130 | has been "tidied up a little". | |
131 | ||
06936a3c PN |
132 | C<PerlIO *> takes the place of FILE *. Like FILE * it should be |
133 | treated as opaque (it is probably safe to assume it is a pointer to | |
134 | something). | |
50b80e25 | 135 | |
1549f383 | 136 | There are currently two implementations: |
50b80e25 | 137 | |
760ac839 LW |
138 | =over 4 |
139 | ||
50b80e25 | 140 | =item 1. USE_STDIO |
760ac839 | 141 | |
06936a3c PN |
142 | All above are #define'd to stdio functions or are trivial wrapper |
143 | functions which call stdio. In this case I<only> PerlIO * is a FILE *. | |
144 | This has been the default implementation since the abstraction was | |
145 | introduced in perl5.003_02. | |
50b80e25 | 146 | |
9a7c5cb7 | 147 | =for apidoc Amnh#||USE_STDIO |
d50808b5 | 148 | |
97cb92d6 | 149 | =item 2. USE_PERLIO |
50b80e25 | 150 | |
06936a3c PN |
151 | Introduced just after perl5.7.0, this is a re-implementation of the |
152 | above abstraction which allows perl more control over how IO is done | |
153 | as it decouples IO from the way the operating system and C library | |
154 | choose to do things. For USE_PERLIO PerlIO * has an extra layer of | |
155 | indirection - it is a pointer-to-a-pointer. This allows the PerlIO * | |
210b36aa | 156 | to remain with a known value while swapping the implementation around |
06936a3c PN |
157 | underneath I<at run time>. In this case all the above are true (but |
158 | very simple) functions which call the underlying implementation. | |
50b80e25 | 159 | |
06936a3c PN |
160 | This is the only implementation for which C<PerlIO_apply_layers()> |
161 | does anything "interesting". | |
50b80e25 NIS |
162 | |
163 | The USE_PERLIO implementation is described in L<perliol>. | |
164 | ||
165 | =back | |
166 | ||
06936a3c | 167 | Because "perlio.h" is a thin layer (for efficiency) the semantics of |
39ac7f1b LS |
168 | these functions are somewhat dependent on the underlying implementation. |
169 | Where these variations are understood they are noted below. | |
50b80e25 | 170 | |
39ac7f1b LS |
171 | Unless otherwise noted, functions return 0 on success, or a negative |
172 | value (usually C<EOF> which is usually -1) and set C<errno> on error. | |
50b80e25 NIS |
173 | |
174 | =over 4 | |
760ac839 LW |
175 | |
176 | =item B<PerlIO_stdin()>, B<PerlIO_stdout()>, B<PerlIO_stderr()> | |
177 | ||
178 | Use these rather than C<stdin>, C<stdout>, C<stderr>. They are written | |
179 | to look like "function calls" rather than variables because this makes | |
54310121 | 180 | it easier to I<make them> function calls if platform cannot export data |
181 | to loaded modules, or if (say) different "threads" might have different | |
760ac839 LW |
182 | values. |
183 | ||
184 | =item B<PerlIO_open(path, mode)>, B<PerlIO_fdopen(fd,mode)> | |
185 | ||
3039a93d | 186 | These correspond to fopen()/fdopen() and the arguments are the same. |
06936a3c PN |
187 | Return C<NULL> and set C<errno> if there is an error. There may be an |
188 | implementation limit on the number of open handles, which may be lower | |
189 | than the limit on the number of open files - C<errno> may not be set | |
210b36aa | 190 | when C<NULL> is returned if this limit is exceeded. |
50b80e25 | 191 | |
11e1c8f2 | 192 | =item B<PerlIO_reopen(path,mode,f)> |
50b80e25 | 193 | |
8cc92bd4 | 194 | While this currently exists in both implementations, perl itself |
50b80e25 NIS |
195 | does not use it. I<As perl does not use it, it is not well tested.> |
196 | ||
06936a3c PN |
197 | Perl prefers to C<dup> the new low-level descriptor to the descriptor |
198 | used by the existing PerlIO. This may become the behaviour of this | |
199 | function in the future. | |
760ac839 LW |
200 | |
201 | =item B<PerlIO_printf(f,fmt,...)>, B<PerlIO_vprintf(f,fmt,a)> | |
202 | ||
7b8d334a | 203 | These are fprintf()/vfprintf() equivalents. |
760ac839 LW |
204 | |
205 | =item B<PerlIO_stdoutf(fmt,...)> | |
206 | ||
207 | This is printf() equivalent. printf is #defined to this function, | |
84dc3c4d | 208 | so it is (currently) legal to use C<printf(fmt,...)> in perl sources. |
760ac839 LW |
209 | |
210 | =item B<PerlIO_read(f,buf,count)>, B<PerlIO_write(f,buf,count)> | |
211 | ||
2c2cb412 GA |
212 | These correspond functionally to fread() and fwrite() but the |
213 | arguments and return values are different. The PerlIO_read() and | |
214 | PerlIO_write() signatures have been modeled on the more sane low level | |
215 | read() and write() functions instead: The "file" argument is passed | |
216 | first, there is only one "count", and the return value can distinguish | |
217 | between error and C<EOF>. | |
218 | ||
219 | Returns a byte count if successful (which may be zero or | |
c0a503cc JH |
220 | positive), returns negative value and sets C<errno> on error. |
221 | Depending on implementation C<errno> may be C<EINTR> if operation was | |
222 | interrupted by a signal. | |
760ac839 | 223 | |
5aae6663 KW |
224 | =item B<PerlIO_fill(f)> |
225 | ||
226 | Fills the buffer associated with C<f> with data from the layer below. | |
227 | C<PerlIO_read> calls this as part of its normal operation. Returns 0 | |
228 | upon success; -1 on failure. | |
229 | ||
760ac839 LW |
230 | =item B<PerlIO_close(f)> |
231 | ||
06936a3c PN |
232 | Depending on implementation C<errno> may be C<EINTR> if operation was |
233 | interrupted by a signal. | |
50b80e25 | 234 | |
21917246 | 235 | =item B<PerlIO_puts(f,s)>, B<PerlIO_putc(f,c)> |
760ac839 | 236 | |
54310121 | 237 | These correspond to fputs() and fputc(). |
760ac839 LW |
238 | Note that arguments have been revised to have "file" first. |
239 | ||
21917246 | 240 | =item B<PerlIO_ungetc(f,c)> |
760ac839 | 241 | |
06936a3c PN |
242 | This corresponds to ungetc(). Note that arguments have been revised |
243 | to have "file" first. Arranges that next read operation will return | |
244 | the byte B<c>. Despite the implied "character" in the name only | |
245 | values in the range 0..0xFF are defined. Returns the byte B<c> on | |
246 | success or -1 (C<EOF>) on error. The number of bytes that can be | |
247 | "pushed back" may vary, only 1 character is certain, and then only if | |
248 | it is the last character that was read from the handle. | |
760ac839 | 249 | |
5aae6663 KW |
250 | =item B<PerlIO_unread(f,buf,count)> |
251 | ||
252 | This allows one to unget more than a single byte. | |
253 | It effectively unshifts C<count> bytes onto the beginning of the buffer | |
254 | C<buf>, so that the next read operation(s) will return them before | |
255 | anything else that was in the buffer. | |
256 | ||
257 | Returns the number of unread bytes. | |
258 | ||
760ac839 LW |
259 | =item B<PerlIO_getc(f)> |
260 | ||
261 | This corresponds to getc(). | |
50b80e25 | 262 | Despite the c in the name only byte range 0..0xFF is supported. |
3039a93d | 263 | Returns the character read or -1 (C<EOF>) on error. |
760ac839 LW |
264 | |
265 | =item B<PerlIO_eof(f)> | |
266 | ||
06936a3c PN |
267 | This corresponds to feof(). Returns a true/false indication of |
268 | whether the handle is at end of file. For terminal devices this may | |
269 | or may not be "sticky" depending on the implementation. The flag is | |
270 | cleared by PerlIO_seek(), or PerlIO_rewind(). | |
760ac839 LW |
271 | |
272 | =item B<PerlIO_error(f)> | |
273 | ||
06936a3c PN |
274 | This corresponds to ferror(). Returns a true/false indication of |
275 | whether there has been an IO error on the handle. | |
760ac839 LW |
276 | |
277 | =item B<PerlIO_fileno(f)> | |
278 | ||
06936a3c PN |
279 | This corresponds to fileno(), note that on some platforms, the meaning |
280 | of "fileno" may not match Unix. Returns -1 if the handle has no open | |
281 | descriptor associated with it. | |
760ac839 LW |
282 | |
283 | =item B<PerlIO_clearerr(f)> | |
284 | ||
06936a3c PN |
285 | This corresponds to clearerr(), i.e., clears 'error' and (usually) |
286 | 'eof' flags for the "stream". Does not return a value. | |
760ac839 LW |
287 | |
288 | =item B<PerlIO_flush(f)> | |
289 | ||
06936a3c PN |
290 | This corresponds to fflush(). Sends any buffered write data to the |
291 | underlying file. If called with C<NULL> this may flush all open | |
fa11829f | 292 | streams (or core dump with some USE_STDIO implementations). Calling |
c0a503cc JH |
293 | on a handle open for read only, or on which last operation was a read |
294 | of some kind may lead to undefined behaviour on some USE_STDIO | |
295 | implementations. The USE_PERLIO (layers) implementation tries to | |
296 | behave better: it flushes all open streams when passed C<NULL>, and | |
297 | attempts to retain data on read streams either in the buffer or by | |
298 | seeking the handle to the current logical position. | |
760ac839 | 299 | |
50b80e25 | 300 | =item B<PerlIO_seek(f,offset,whence)> |
760ac839 | 301 | |
06936a3c PN |
302 | This corresponds to fseek(). Sends buffered write data to the |
303 | underlying file, or discards any buffered read data, then positions | |
d7f8936a | 304 | the file descriptor as specified by B<offset> and B<whence> (sic). |
06936a3c PN |
305 | This is the correct thing to do when switching between read and write |
306 | on the same handle (see issues with PerlIO_flush() above). Offset is | |
307 | of type C<Off_t> which is a perl Configure value which may not be same | |
50b80e25 | 308 | as stdio's C<off_t>. |
760ac839 | 309 | |
50b80e25 | 310 | =item B<PerlIO_tell(f)> |
760ac839 | 311 | |
06936a3c PN |
312 | This corresponds to ftell(). Returns the current file position, or |
313 | (Off_t) -1 on error. May just return value system "knows" without | |
314 | making a system call or checking the underlying file descriptor (so | |
315 | use on shared file descriptors is not safe without a | |
316 | PerlIO_seek()). Return value is of type C<Off_t> which is a perl | |
317 | Configure value which may not be same as stdio's C<off_t>. | |
760ac839 LW |
318 | |
319 | =item B<PerlIO_getpos(f,p)>, B<PerlIO_setpos(f,p)> | |
320 | ||
06936a3c PN |
321 | These correspond (loosely) to fgetpos() and fsetpos(). Rather than |
322 | stdio's Fpos_t they expect a "Perl Scalar Value" to be passed. What is | |
323 | stored there should be considered opaque. The layout of the data may | |
324 | vary from handle to handle. When not using stdio or if platform does | |
325 | not have the stdio calls then they are implemented in terms of | |
326 | PerlIO_tell() and PerlIO_seek(). | |
760ac839 LW |
327 | |
328 | =item B<PerlIO_rewind(f)> | |
329 | ||
50b80e25 NIS |
330 | This corresponds to rewind(). It is usually defined as being |
331 | ||
332 | PerlIO_seek(f,(Off_t)0L, SEEK_SET); | |
333 | PerlIO_clearerr(f); | |
334 | ||
760ac839 LW |
335 | =item B<PerlIO_tmpfile()> |
336 | ||
06936a3c PN |
337 | This corresponds to tmpfile(), i.e., returns an anonymous PerlIO or |
338 | NULL on error. The system will attempt to automatically delete the | |
339 | file when closed. On Unix the file is usually C<unlink>-ed just after | |
340 | it is created so it does not matter how it gets closed. On other | |
341 | systems the file may only be deleted if closed via PerlIO_close() | |
342 | and/or the program exits via C<exit>. Depending on the implementation | |
343 | there may be "race conditions" which allow other processes access to | |
344 | the file, though in general it will be safer in this regard than | |
345 | ad. hoc. schemes. | |
50b80e25 NIS |
346 | |
347 | =item B<PerlIO_setlinebuf(f)> | |
348 | ||
06936a3c PN |
349 | This corresponds to setlinebuf(). Does not return a value. What |
350 | constitutes a "line" is implementation dependent but usually means | |
351 | that writing "\n" flushes the buffer. What happens with things like | |
352 | "this\nthat" is uncertain. (Perl core uses it I<only> when "dumping"; | |
353 | it has nothing to do with $| auto-flush.) | |
760ac839 | 354 | |
54310121 | 355 | =back |
760ac839 | 356 | |
510d21e9 | 357 | =head2 Co-existence with stdio |
760ac839 | 358 | |
510d21e9 | 359 | There is outline support for co-existence of PerlIO with stdio. |
06936a3c PN |
360 | Obviously if PerlIO is implemented in terms of stdio there is no |
361 | problem. However in other cases then mechanisms must exist to create a | |
362 | FILE * which can be passed to library code which is going to use stdio | |
363 | calls. | |
50b80e25 | 364 | |
210b36aa | 365 | The first step is to add this line: |
50b80e25 NIS |
366 | |
367 | #define PERLIO_NOT_STDIO 0 | |
368 | ||
d50808b5 KW |
369 | =for apidoc Amnh ||PERLIO_NOT_STDIO |
370 | ||
06936a3c PN |
371 | I<before> including any perl header files. (This will probably become |
372 | the default at some point). That prevents "perlio.h" from attempting | |
373 | to #define stdio functions onto PerlIO functions. | |
50b80e25 | 374 | |
06936a3c PN |
375 | XS code is probably better using "typemap" if it expects FILE * |
376 | arguments. The standard typemap will be adjusted to comprehend any | |
377 | changes in this area. | |
760ac839 LW |
378 | |
379 | =over 4 | |
380 | ||
4b069b44 | 381 | =item B<PerlIO_importFILE(f,mode)> |
760ac839 | 382 | |
22569500 | 383 | Used to get a PerlIO * from a FILE *. |
760ac839 | 384 | |
c0a503cc JH |
385 | The mode argument should be a string as would be passed to |
386 | fopen/PerlIO_open. If it is NULL then - for legacy support - the code | |
387 | will (depending upon the platform and the implementation) either | |
388 | attempt to empirically determine the mode in which I<f> is open, or | |
389 | use "r+" to indicate a read/write stream. | |
22569500 NIS |
390 | |
391 | Once called the FILE * should I<ONLY> be closed by calling | |
392 | C<PerlIO_close()> on the returned PerlIO *. | |
393 | ||
f504ae08 LC |
394 | The PerlIO is set to textmode. Use PerlIO_binmode if this is |
395 | not the desired mode. | |
396 | ||
b9d6bf13 JH |
397 | This is B<not> the reverse of PerlIO_exportFILE(). |
398 | ||
4b069b44 | 399 | =item B<PerlIO_exportFILE(f,mode)> |
760ac839 | 400 | |
8dcb5783 | 401 | Given a PerlIO * create a 'native' FILE * suitable for passing to code |
c0a503cc JH |
402 | expecting to be compiled and linked with ANSI C I<stdio.h>. The mode |
403 | argument should be a string as would be passed to fopen/PerlIO_open. | |
404 | If it is NULL then - for legacy support - the FILE * is opened in same | |
405 | mode as the PerlIO *. | |
406 | ||
407 | The fact that such a FILE * has been 'exported' is recorded, (normally | |
408 | by pushing a new :stdio "layer" onto the PerlIO *), which may affect | |
409 | future PerlIO operations on the original PerlIO *. You should not | |
410 | call C<fclose()> on the file unless you call C<PerlIO_releaseFILE()> | |
411 | to disassociate it from the PerlIO *. (Do not use PerlIO_importFILE() | |
412 | for doing the disassociation.) | |
760ac839 | 413 | |
22569500 NIS |
414 | Calling this function repeatedly will create a FILE * on each call |
415 | (and will push an :stdio layer each time as well). | |
760ac839 LW |
416 | |
417 | =item B<PerlIO_releaseFILE(p,f)> | |
418 | ||
06936a3c | 419 | Calling PerlIO_releaseFILE informs PerlIO that all use of FILE * is |
65dabbe3 LC |
420 | complete. It is removed from the list of 'exported' FILE *s, and the |
421 | associated PerlIO * should revert to its original behaviour. | |
760ac839 | 422 | |
b9d6bf13 JH |
423 | Use this to disassociate a file from a PerlIO * that was associated |
424 | using PerlIO_exportFILE(). | |
425 | ||
22569500 NIS |
426 | =item B<PerlIO_findFILE(f)> |
427 | ||
428 | Returns a native FILE * used by a stdio layer. If there is none, it | |
429 | will create one with PerlIO_exportFILE. In either case the FILE * | |
65dabbe3 | 430 | should be considered as belonging to PerlIO subsystem and should |
22569500 NIS |
431 | only be closed by calling C<PerlIO_close()>. |
432 | ||
8dcb5783 | 433 | |
760ac839 LW |
434 | =back |
435 | ||
50b80e25 NIS |
436 | =head2 "Fast gets" Functions |
437 | ||
06936a3c PN |
438 | In addition to standard-like API defined so far above there is an |
439 | "implementation" interface which allows perl to get at internals of | |
440 | PerlIO. The following calls correspond to the various FILE_xxx macros | |
441 | determined by Configure - or their equivalent in other | |
442 | implementations. This section is really of interest to only those | |
443 | concerned with detailed perl-core behaviour, implementing a PerlIO | |
444 | mapping or writing code which can make use of the "read ahead" that | |
445 | has been done by the IO system in the same way perl does. Note that | |
446 | any code that uses these interfaces must be prepared to do things the | |
447 | traditional way if a handle does not support them. | |
760ac839 LW |
448 | |
449 | =over 4 | |
450 | ||
50b80e25 | 451 | =item B<PerlIO_fast_gets(f)> |
760ac839 | 452 | |
50b80e25 | 453 | Returns true if implementation has all the interfaces required to |
c0a503cc JH |
454 | allow perl's C<sv_gets> to "bypass" normal IO mechanism. This can |
455 | vary from handle to handle. | |
760ac839 | 456 | |
50b80e25 NIS |
457 | PerlIO_fast_gets(f) = PerlIO_has_cntptr(f) && \ |
458 | PerlIO_canset_cnt(f) && \ | |
ccf3535a | 459 | 'Can set pointer into buffer' |
760ac839 | 460 | |
50b80e25 | 461 | =item B<PerlIO_has_cntptr(f)> |
760ac839 | 462 | |
06936a3c PN |
463 | Implementation can return pointer to current position in the "buffer" |
464 | and a count of bytes available in the buffer. Do not use this - use | |
465 | PerlIO_fast_gets. | |
760ac839 | 466 | |
50b80e25 | 467 | =item B<PerlIO_get_cnt(f)> |
760ac839 | 468 | |
06936a3c PN |
469 | Return count of readable bytes in the buffer. Zero or negative return |
470 | means no more bytes available. | |
760ac839 | 471 | |
50b80e25 | 472 | =item B<PerlIO_get_ptr(f)> |
760ac839 | 473 | |
06936a3c PN |
474 | Return pointer to next readable byte in buffer, accessing via the |
475 | pointer (dereferencing) is only safe if PerlIO_get_cnt() has returned | |
476 | a positive value. Only positive offsets up to value returned by | |
477 | PerlIO_get_cnt() are allowed. | |
760ac839 LW |
478 | |
479 | =item B<PerlIO_set_ptrcnt(f,p,c)> | |
480 | ||
54310121 | 481 | Set pointer into buffer, and a count of bytes still in the |
06936a3c PN |
482 | buffer. Should be used only to set pointer to within range implied by |
483 | previous calls to C<PerlIO_get_ptr> and C<PerlIO_get_cnt>. The two | |
484 | values I<must> be consistent with each other (implementation may only | |
485 | use one or the other or may require both). | |
50b80e25 NIS |
486 | |
487 | =item B<PerlIO_canset_cnt(f)> | |
488 | ||
489 | Implementation can adjust its idea of number of bytes in the buffer. | |
490 | Do not use this - use PerlIO_fast_gets. | |
760ac839 LW |
491 | |
492 | =item B<PerlIO_set_cnt(f,c)> | |
493 | ||
06936a3c PN |
494 | Obscure - set count of bytes in the buffer. Deprecated. Only usable |
495 | if PerlIO_canset_cnt() returns true. Currently used in only doio.c to | |
496 | force count less than -1 to -1. Perhaps should be PerlIO_set_empty or | |
497 | similar. This call may actually do nothing if "count" is deduced from | |
498 | pointer and a "limit". Do not use this - use PerlIO_set_ptrcnt(). | |
760ac839 LW |
499 | |
500 | =item B<PerlIO_has_base(f)> | |
501 | ||
50b80e25 | 502 | Returns true if implementation has a buffer, and can return pointer |
760ac839 LW |
503 | to whole buffer and its size. Used by perl for B<-T> / B<-B> tests. |
504 | Other uses would be very obscure... | |
505 | ||
506 | =item B<PerlIO_get_base(f)> | |
507 | ||
50b80e25 NIS |
508 | Return I<start> of buffer. Access only positive offsets in the buffer |
509 | up to the value returned by PerlIO_get_bufsiz(). | |
760ac839 LW |
510 | |
511 | =item B<PerlIO_get_bufsiz(f)> | |
512 | ||
06936a3c PN |
513 | Return the I<total number of bytes> in the buffer, this is neither the |
514 | number that can be read, nor the amount of memory allocated to the | |
515 | buffer. Rather it is what the operating system and/or implementation | |
516 | happened to C<read()> (or whatever) last time IO was requested. | |
50b80e25 NIS |
517 | |
518 | =back | |
519 | ||
520 | =head2 Other Functions | |
521 | ||
522 | =over 4 | |
523 | ||
3329a50e | 524 | =item PerlIO_apply_layers(aTHX_ f,mode,layers) |
50b80e25 NIS |
525 | |
526 | The new interface to the USE_PERLIO implementation. The layers ":crlf" | |
56c919a0 | 527 | and ":raw" are the only ones allowed for other implementations and those |
c0a503cc JH |
528 | are silently ignored. (As of perl5.8 ":raw" is deprecated.) Use |
529 | PerlIO_binmode() below for the portable case. | |
50b80e25 | 530 | |
3329a50e | 531 | =item PerlIO_binmode(aTHX_ f,ptype,imode,layers) |
50b80e25 NIS |
532 | |
533 | The hook used by perl's C<binmode> operator. | |
210b36aa | 534 | B<ptype> is perl's character for the kind of IO: |
50b80e25 NIS |
535 | |
536 | =over 8 | |
537 | ||
11e1c8f2 | 538 | =item 'E<lt>' read |
50b80e25 | 539 | |
11e1c8f2 | 540 | =item 'E<gt>' write |
50b80e25 NIS |
541 | |
542 | =item '+' read/write | |
543 | ||
544 | =back | |
545 | ||
546 | B<imode> is C<O_BINARY> or C<O_TEXT>. | |
547 | ||
56c919a0 KW |
548 | B<layers> is a string of layers to apply; only ":crlf" makes sense in |
549 | the non-USE_PERLIO case. (As of perl5.8 ":raw" is deprecated in favour | |
c0a503cc | 550 | of passing NULL.) |
50b80e25 NIS |
551 | |
552 | Portable cases are: | |
553 | ||
3329a50e | 554 | PerlIO_binmode(aTHX_ f,ptype,O_BINARY,NULL); |
50b80e25 | 555 | and |
3329a50e | 556 | PerlIO_binmode(aTHX_ f,ptype,O_TEXT,":crlf"); |
50b80e25 | 557 | |
06936a3c PN |
558 | On Unix these calls probably have no effect whatsoever. Elsewhere |
559 | they alter "\n" to CR,LF translation and possibly cause a special text | |
560 | "end of file" indicator to be written or honoured on read. The effect | |
561 | of making the call after doing any IO to the handle depends on the | |
562 | implementation. (It may be ignored, affect any data which is already | |
563 | buffered as well, or only apply to subsequent data.) | |
50b80e25 NIS |
564 | |
565 | =item PerlIO_debug(fmt,...) | |
566 | ||
06936a3c PN |
567 | PerlIO_debug is a printf()-like function which can be used for |
568 | debugging. No return value. Its main use is inside PerlIO where using | |
569 | real printf, warn() etc. would recursively call PerlIO and be a | |
570 | problem. | |
50b80e25 | 571 | |
2104c695 CB |
572 | PerlIO_debug writes to the file named by $ENV{'PERLIO_DEBUG'} or defaults |
573 | to stderr if the environment variable is not defined. Typical | |
06936a3c | 574 | use might be |
50b80e25 | 575 | |
ada498b9 | 576 | Bourne shells (sh, ksh, bash, zsh, ash, ...): |
2104c695 | 577 | PERLIO_DEBUG=/tmp/perliodebug.log ./perl -Di somescript some args |
50b80e25 | 578 | |
ada498b9 | 579 | Csh/Tcsh: |
2104c695 CB |
580 | setenv PERLIO_DEBUG /tmp/perliodebug.log |
581 | ./perl -Di somescript some args | |
50b80e25 | 582 | |
ada498b9 | 583 | If you have the "env" utility: |
2104c695 | 584 | env PERLIO_DEBUG=/tmp/perliodebug.log ./perl -Di somescript args |
ada498b9 | 585 | |
50b80e25 | 586 | Win32: |
2104c695 CB |
587 | set PERLIO_DEBUG=perliodebug.log |
588 | perl -Di somescript some args | |
50b80e25 | 589 | |
2104c695 CB |
590 | On a Perl built without C<-DDEBUGGING>, or when the C<-Di> command-line switch |
591 | is not specified, or under taint, PerlIO_debug() is a no-op. | |
760ac839 | 592 | |
54310121 | 593 | =back |