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Add IO extension
[perl5.git] / ext / IO / lib / IO / Handle.pm
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PP
1#
2
3package IO::Handle;
4
5=head1 NAME
6
7IO::Handle - supply object methods for filehandles
8
9=head1 SYNOPSIS
10
11 use IO::Handle;
12
13 $fh = new IO::Handle;
14 if ($fh->open "< file") {
15 print <$fh>;
16 $fh->close;
17 }
18
19 $fh = new IO::Handle "> FOO";
20 if (defined $fh) {
21 print $fh "bar\n";
22 $fh->close;
23 }
24
25 $fh = new IO::Handle "file", "r";
26 if (defined $fh) {
27 print <$fh>;
28 undef $fh; # automatically closes the file
29 }
30
31 $fh = new IO::Handle "file", O_WRONLY|O_APPEND;
32 if (defined $fh) {
33 print $fh "corge\n";
34 undef $fh; # automatically closes the file
35 }
36
37 $pos = $fh->getpos;
38 $fh->setpos $pos;
39
40 $fh->setvbuf($buffer_var, _IOLBF, 1024);
41
42 autoflush STDOUT 1;
43
44=head1 DESCRIPTION
45
46C<IO::Handle::new> creates a C<IO::Handle>, which is a reference to a
47newly created symbol (see the C<Symbol> package). If it receives any
48parameters, they are passed to C<IO::Handle::open>; if the open fails,
49the C<IO::Handle> object is destroyed. Otherwise, it is returned to
50the caller.
51
52C<IO::Handle::new_from_fd> creates a C<IO::Handle> like C<new> does.
53It requires two parameters, which are passed to C<IO::Handle::fdopen>;
54if the fdopen fails, the C<IO::Handle> object is destroyed.
55Otherwise, it is returned to the caller.
56
57C<IO::Handle::open> accepts one parameter or two. With one parameter,
58it is just a front end for the built-in C<open> function. With two
59parameters, the first parameter is a filename that may include
60whitespace or other special characters, and the second parameter is
61the open mode in either Perl form (">", "+<", etc.) or POSIX form
62("w", "r+", etc.).
63
64C<IO::Handle::fdopen> is like C<open> except that its first parameter
65is not a filename but rather a file handle name, a IO::Handle object,
66or a file descriptor number.
67
68C<IO::Handle::write> is like C<write> found in C, that is it is the
69opposite of read. The wrapper for the perl C<write> function is
70called C<format_write>.
71
72C<IO::Handle::opened> returns true if the object is currently a valid
73file descriptor.
74
75If the C functions fgetpos() and fsetpos() are available, then
76C<IO::Handle::getpos> returns an opaque value that represents the
77current position of the IO::Handle, and C<IO::Handle::setpos> uses
78that value to return to a previously visited position.
79
80If the C function setvbuf() is available, then C<IO::Handle::setvbuf>
81sets the buffering policy for the IO::Handle. The calling sequence
82for the Perl function is the same as its C counterpart, including the
83macros C<_IOFBF>, C<_IOLBF>, and C<_IONBF>, except that the buffer
84parameter specifies a scalar variable to use as a buffer. WARNING: A
85variable used as a buffer by C<IO::Handle::setvbuf> must not be
86modified in any way until the IO::Handle is closed or until
87C<IO::Handle::setvbuf> is called again, or memory corruption may
88result!
89
90See L<perlfunc> for complete descriptions of each of the following
91supported C<IO::Handle> methods, which are just front ends for the
92corresponding built-in functions:
93
94 close
95 fileno
96 getc
97 gets
98 eof
99 read
100 truncate
101 stat
102
103See L<perlvar> for complete descriptions of each of the following
104supported C<IO::Handle> methods:
105
106 autoflush
107 output_field_separator
108 output_record_separator
109 input_record_separator
110 input_line_number
111 format_page_number
112 format_lines_per_page
113 format_lines_left
114 format_name
115 format_top_name
116 format_line_break_characters
117 format_formfeed
118 format_write
119
120Furthermore, for doing normal I/O you might need these:
121
122=over
123
124=item $fh->print
125
126See L<perlfunc/print>.
127
128=item $fh->printf
129
130See L<perlfunc/printf>.
131
132=item $fh->getline
133
134This works like <$fh> described in L<perlop/"I/O Operators">
135except that it's more readable and can be safely called in an
136array context but still returns just one line.
137
138=item $fh->getlines
139
140This works like <$fh> when called in an array context to
141read all the remaining lines in a file, except that it's more readable.
142It will also croak() if accidentally called in a scalar context.
143
144=back
145
146=head1
147
148The reference returned from new is a GLOB reference. Some modules that
149inherit from C<IO::Handle> may want to keep object related variables
150in the hash table part of the GLOB. In an attempt to prevent modules
151trampling on each other I propose the that any such module should prefix
152its variables with its own name separated by _'s. For example the IO::Socket
153module keeps a C<timeout> variable in 'io_socket_timeout'.
154
155=head1 SEE ALSO
156
157L<perlfunc>,
158L<perlop/"I/O Operators">,
159L<POSIX/"FileHandle">
160
161=head1 BUGS
162
163Due to backwards compatibility, all filehandles resemble objects
164of class C<IO::Handle>, or actually classes derived from that class.
165They actually aren't. Which means you can't derive your own
166class from C<IO::Handle> and inherit those methods.
167
168=head1 HISTORY
169
170Derived from FileHandle.pm by Graham Barr <bodg@tiuk.ti.com>
171
172=cut
173
174require 5.000;
175use vars qw($VERSION @EXPORT_OK $AUTOLOAD);
176use Carp;
177use Symbol;
178use SelectSaver;
179
180require Exporter;
181@ISA = qw(Exporter);
182
183##
184## TEMPORARY workaround as perl expects handles to be <FileHandle> objects
185##
186@FileHandle::ISA = qw(IO::Handle);
187
188
189$VERSION = sprintf("%d.%02d", q$Revision: 1.8 $ =~ /(\d+)\.(\d+)/);
190
191@EXPORT_OK = qw(
192 autoflush
193 output_field_separator
194 output_record_separator
195 input_record_separator
196 input_line_number
197 format_page_number
198 format_lines_per_page
199 format_lines_left
200 format_name
201 format_top_name
202 format_line_break_characters
203 format_formfeed
204 format_write
205
206 print
207 printf
208 getline
209 getlines
210
211 SEEK_SET
212 SEEK_CUR
213 SEEK_END
214 _IOFBF
215 _IOLBF
216 _IONBF
217
218 _open_mode_string
219);
220
221
222################################################
223## Interaction with the XS.
224##
225
226require DynaLoader;
227@IO::ISA = qw(DynaLoader);
228bootstrap IO $VERSION;
229
230sub AUTOLOAD {
231 if ($AUTOLOAD =~ /::(_?[a-z])/) {
232 $AutoLoader::AUTOLOAD = $AUTOLOAD;
233 goto &AutoLoader::AUTOLOAD
234 }
235 my $constname = $AUTOLOAD;
236 $constname =~ s/.*:://;
237 my $val = constant($constname);
238 defined $val or croak "$constname is not a valid IO::Handle macro";
239 *$AUTOLOAD = sub { $val };
240 goto &$AUTOLOAD;
241}
242
243
244################################################
245## Constructors, destructors.
246##
247
248sub new {
249 @_ == 1 or croak 'usage: new IO::Handle';
250 my $class = ref($_[0]) || $_[0];
251 my $fh = gensym;
252 bless $fh, $class;
253}
254
255sub new_from_fd {
256 @_ == 3 or croak 'usage: new_from_fd IO::Handle FD, MODE';
257 my $class = shift;
258 my $fh = gensym;
259 IO::Handle::fdopen($fh, @_)
260 or return undef;
261 bless $fh, $class;
262 $fh->_ref_fd;
263 $fh;
264}
265
266# FileHandle::DESTROY use to call close(). This creates a problem
267# if 2 Handle objects have the same fd. sv_clear will call io close
268# when the refcount in the xpvio becomes zero.
269#
270# It is defined as empty to stop AUTOLOAD being called :-)
271
272sub DESTROY { }
273
274################################################
275## Open and close.
276##
277
278sub _open_mode_string {
279 my ($mode) = @_;
280 $mode =~ /^\+?(<|>>?)$/
281 or $mode =~ s/^r(\+?)$/$1</
282 or $mode =~ s/^w(\+?)$/$1>/
283 or $mode =~ s/^a(\+?)$/$1>>/
284 or croak "IO::Handle: bad open mode: $mode";
285 $mode;
286}
287
288sub fdopen {
289 @_ == 3 or croak 'usage: $fh->fdopen(FD, MODE)';
290 my ($fh, $fd, $mode) = @_;
291 local(*GLOB);
292
293 if (ref($fd) && "".$fd =~ /GLOB\(/o) {
294 # It's a glob reference; Alias it as we cannot get name of anon GLOBs
295 my $n = qualify(*GLOB);
296 *GLOB = *{*$fd};
297 $fd = $n;
298 } elsif ($fd =~ m#^\d+$#) {
299 # It's an FD number; prefix with "=".
300 $fd = "=$fd";
301 }
302
303 open($fh, _open_mode_string($mode) . '&' . $fd)
304 ? $fh : undef;
305}
306
307sub close {
308 @_ == 1 or croak 'usage: $fh->close()';
309 my($fh) = @_;
310 my $r = close($fh);
311
312 # This may seem as though it should be in IO::Pipe, but the
313 # object gets blessed out of IO::Pipe when reader/writer is called
314 waitpid(${*$fh}{'io_pipe_pid'},0)
315 if(defined ${*$fh}{'io_pipe_pid'});
316
317 $r;
318}
319
320################################################
321## Normal I/O functions.
322##
323
324# fcntl
325# flock
326# ioctl
327# select
328# sysread
329# syswrite
330
331sub opened {
332 @_ == 1 or croak 'usage: $fh->opened()';
333 defined fileno($_[0]);
334}
335
336sub fileno {
337 @_ == 1 or croak 'usage: $fh->fileno()';
338 fileno($_[0]);
339}
340
341sub getc {
342 @_ == 1 or croak 'usage: $fh->getc()';
343 getc($_[0]);
344}
345
346sub gets {
347 @_ == 1 or croak 'usage: $fh->gets()';
348 my ($handle) = @_;
349 scalar <$handle>;
350}
351
352sub eof {
353 @_ == 1 or croak 'usage: $fh->eof()';
354 eof($_[0]);
355}
356
357sub print {
358 @_ or croak 'usage: $fh->print([ARGS])';
359 my $this = shift;
360 print $this @_;
361}
362
363sub printf {
364 @_ >= 2 or croak 'usage: $fh->printf(FMT,[ARGS])';
365 my $this = shift;
366 printf $this @_;
367}
368
369sub getline {
370 @_ == 1 or croak 'usage: $fh->getline';
371 my $this = shift;
372 return scalar <$this>;
373}
374
375sub getlines {
376 @_ == 1 or croak 'usage: $fh->getline()';
377 my $this = shift;
378 wantarray or
379 croak "Can't call IO::Handle::getlines in a scalar context, use IO::Handle::getline";
380 return <$this>;
381}
382
383sub truncate {
384 @_ == 2 or croak 'usage: $fh->truncate(LEN)';
385 truncate($_[0], $_[1]);
386}
387
388sub read {
389 @_ == 3 || @_ == 4 or croak '$fh->read(BUF, LEN [, OFFSET])';
390 read($_[0], $_[1], $_[2], $_[3] || 0);
391}
392
393sub write {
394 @_ == 3 || @_ == 4 or croak '$fh->write(BUF, LEN [, OFFSET])';
395 local($\) = "";
396 print { $_[0] } substr($_[1], $_[3] || 0, $_[2]);
397}
398
399sub stat {
400 @_ == 1 or croak 'usage: $fh->stat()';
401 stat($_[0]);
402}
403
404################################################
405## State modification functions.
406##
407
408sub autoflush {
409 my $old = new SelectSaver qualify($_[0], caller);
410 my $prev = $|;
411 $| = @_ > 1 ? $_[1] : 1;
412 $prev;
413}
414
415sub output_field_separator {
416 my $old = new SelectSaver qualify($_[0], caller);
417 my $prev = $,;
418 $, = $_[1] if @_ > 1;
419 $prev;
420}
421
422sub output_record_separator {
423 my $old = new SelectSaver qualify($_[0], caller);
424 my $prev = $\;
425 $\ = $_[1] if @_ > 1;
426 $prev;
427}
428
429sub input_record_separator {
430 my $old = new SelectSaver qualify($_[0], caller);
431 my $prev = $/;
432 $/ = $_[1] if @_ > 1;
433 $prev;
434}
435
436sub input_line_number {
437 my $old = new SelectSaver qualify($_[0], caller);
438 my $prev = $.;
439 $. = $_[1] if @_ > 1;
440 $prev;
441}
442
443sub format_page_number {
444 my $old = new SelectSaver qualify($_[0], caller);
445 my $prev = $%;
446 $% = $_[1] if @_ > 1;
447 $prev;
448}
449
450sub format_lines_per_page {
451 my $old = new SelectSaver qualify($_[0], caller);
452 my $prev = $=;
453 $= = $_[1] if @_ > 1;
454 $prev;
455}
456
457sub format_lines_left {
458 my $old = new SelectSaver qualify($_[0], caller);
459 my $prev = $-;
460 $- = $_[1] if @_ > 1;
461 $prev;
462}
463
464sub format_name {
465 my $old = new SelectSaver qualify($_[0], caller);
466 my $prev = $~;
467 $~ = qualify($_[1], caller) if @_ > 1;
468 $prev;
469}
470
471sub format_top_name {
472 my $old = new SelectSaver qualify($_[0], caller);
473 my $prev = $^;
474 $^ = qualify($_[1], caller) if @_ > 1;
475 $prev;
476}
477
478sub format_line_break_characters {
479 my $old = new SelectSaver qualify($_[0], caller);
480 my $prev = $:;
481 $: = $_[1] if @_ > 1;
482 $prev;
483}
484
485sub format_formfeed {
486 my $old = new SelectSaver qualify($_[0], caller);
487 my $prev = $^L;
488 $^L = $_[1] if @_ > 1;
489 $prev;
490}
491
492sub formline {
493 my $fh = shift;
494 my $picture = shift;
495 local($^A) = $^A;
496 local($\) = "";
497 formline($picture, @_);
498 print $fh $^A;
499}
500
501sub format_write {
502 @_ < 3 || croak 'usage: $fh->write( [FORMAT_NAME] )';
503 if (@_ == 2) {
504 my ($fh, $fmt) = @_;
505 my $oldfmt = $fh->format_name($fmt);
506 write($fh);
507 $fh->format_name($oldfmt);
508 } else {
509 write($_[0]);
510 }
511}
512
513
5141;