=item B<PerlIO_read(f,buf,count)>, B<PerlIO_write(f,buf,count)>
-These correspond to fread() and fwrite(). Note that arguments are
-different, there is only one "count" and order has "file"
-first. Returns a byte count if successful (which may be zero or positive), returns
-negative value and sets C<errno> on error. Depending on
-implementation C<errno> may be C<EINTR> if operation was interrupted
-by a signal.
+These correspond functionally to fread() and fwrite() but the
+arguments and return values are different. The PerlIO_read() and
+PerlIO_write() signatures have been modeled on the more sane low level
+read() and write() functions instead: The "file" argument is passed
+first, there is only one "count", and the return value can distinguish
+between error and C<EOF>.
+
+Returns a byte count if successful (which may be zero or
+positive), returns negative value and sets C<errno> on error.
+Depending on implementation C<errno> may be C<EINTR> if operation was
+interrupted by a signal.
=item B<PerlIO_close(f)>
This corresponds to fflush(). Sends any buffered write data to the
underlying file. If called with C<NULL> this may flush all open
-streams (or core dump with some USE_STDIO implementattions).
-Calling on a handle open for read only, or on which last operation was a read of some kind
-may lead to undefined behaviour on some USE_STDIO implementations.
-The USE_PERLIO (layers) implementation tries to behave better: it flushes all open streams
-when passed C<NULL>, and attempts to retain data on read streams either in the buffer
-or by seeking the handle to the current logical position.
+streams (or core dump with some USE_STDIO implementations). Calling
+on a handle open for read only, or on which last operation was a read
+of some kind may lead to undefined behaviour on some USE_STDIO
+implementations. The USE_PERLIO (layers) implementation tries to
+behave better: it flushes all open streams when passed C<NULL>, and
+attempts to retain data on read streams either in the buffer or by
+seeking the handle to the current logical position.
=item B<PerlIO_seek(f,offset,whence)>
This corresponds to fseek(). Sends buffered write data to the
underlying file, or discards any buffered read data, then positions
-the file desciptor as specified by B<offset> and B<whence> (sic).
+the file descriptor as specified by B<offset> and B<whence> (sic).
This is the correct thing to do when switching between read and write
on the same handle (see issues with PerlIO_flush() above). Offset is
of type C<Off_t> which is a perl Configure value which may not be same
Used to get a PerlIO * from a FILE *.
-The mode argument should be a string as would be passed to fopen/PerlIO_open.
-If it is NULL then - for legacy support - the code will (depending upon
-the platform and the implementation) either attempt to empirically determine the mode in
-which I<f> is open, or use "r+" to indicate a read/write stream.
+The mode argument should be a string as would be passed to
+fopen/PerlIO_open. If it is NULL then - for legacy support - the code
+will (depending upon the platform and the implementation) either
+attempt to empirically determine the mode in which I<f> is open, or
+use "r+" to indicate a read/write stream.
Once called the FILE * should I<ONLY> be closed by calling
C<PerlIO_close()> on the returned PerlIO *.
=item B<PerlIO_exportFILE(f,mode)>
Given a PerlIO * create a 'native' FILE * suitable for passing to code
-expecting to be compiled and linked with ANSI C I<stdio.h>.
-The mode argument should be a string as would be passed to fopen/PerlIO_open.
-If it is NULL then - for legacy support - the FILE * is opened
-in same mode as the PerlIO *.
-
-The fact that such a FILE * has been 'exported' is recorded, (normally by
-pushing a new :stdio "layer" onto the PerlIO *), which may affect future
-PerlIO operations on the original PerlIO *.
-You should not call C<fclose()> on the file unless you call
-C<PerlIO_releaseFILE()> to disassociate it from the PerlIO *.
-(Do not use PerlIO_importFILE() for doing the disassociation.)
+expecting to be compiled and linked with ANSI C I<stdio.h>. The mode
+argument should be a string as would be passed to fopen/PerlIO_open.
+If it is NULL then - for legacy support - the FILE * is opened in same
+mode as the PerlIO *.
+
+The fact that such a FILE * has been 'exported' is recorded, (normally
+by pushing a new :stdio "layer" onto the PerlIO *), which may affect
+future PerlIO operations on the original PerlIO *. You should not
+call C<fclose()> on the file unless you call C<PerlIO_releaseFILE()>
+to disassociate it from the PerlIO *. (Do not use PerlIO_importFILE()
+for doing the disassociation.)
Calling this function repeatedly will create a FILE * on each call
(and will push an :stdio layer each time as well).
=item B<PerlIO_fast_gets(f)>
Returns true if implementation has all the interfaces required to
-allow perl's C<sv_gets> to "bypass" normal IO mechanism.
-This can vary from handle to handle.
+allow perl's C<sv_gets> to "bypass" normal IO mechanism. This can
+vary from handle to handle.
PerlIO_fast_gets(f) = PerlIO_has_cntptr(f) && \
PerlIO_canset_cnt(f) && \
The new interface to the USE_PERLIO implementation. The layers ":crlf"
and ":raw" are only ones allowed for other implementations and those
-are silently ignored. (As of perl5.8 ":raw" is deprecated.)
-Use PerlIO_binmode() below for the portable case.
+are silently ignored. (As of perl5.8 ":raw" is deprecated.) Use
+PerlIO_binmode() below for the portable case.
=item PerlIO_binmode(f,ptype,imode,layers)
B<imode> is C<O_BINARY> or C<O_TEXT>.
-B<layers> is a string of layers to apply, only ":crlf" makes sense in the non USE_PERLIO
-case. (As of perl5.8 ":raw" is deprecated in favour of passing NULL.)
+B<layers> is a string of layers to apply, only ":crlf" makes sense in
+the non USE_PERLIO case. (As of perl5.8 ":raw" is deprecated in favour
+of passing NULL.)
Portable cases are:
- PerlIO_binmode(f,ptype,O_BINARY,Nullch);
+ PerlIO_binmode(f,ptype,O_BINARY,NULL);
and
PerlIO_binmode(f,ptype,O_TEXT,":crlf");
https://perl5.git.perl.org / perl5.git / blobdiff