PERLAPIO(1) Perl Programmers Reference Guide PERLAPIO(1)NAMEperlapio - perl's IO abstraction interface.
SYNOPSIS
PerlIO *PerlIO_stdin(void);
PerlIO *PerlIO_stdout(void);
PerlIO *PerlIO_stderr(void);
PerlIO *PerlIO_open(const char *,const char *);
int PerlIO_close(PerlIO *);
int PerlIO_stdoutf(const char *,...)
int PerlIO_puts(PerlIO *,const char *);
int PerlIO_putc(PerlIO *,int);
int PerlIO_write(PerlIO *,const void *,size_t);
int PerlIO_printf(PerlIO *, const char *,...);
int PerlIO_vprintf(PerlIO *, const char *, va_list);
int PerlIO_flush(PerlIO *);
int PerlIO_eof(PerlIO *);
int PerlIO_error(PerlIO *);
void PerlIO_clearerr(PerlIO *);
int PerlIO_getc(PerlIO *);
int PerlIO_ungetc(PerlIO *,int);
int PerlIO_read(PerlIO *,void *,size_t);
int PerlIO_fileno(PerlIO *);
PerlIO *PerlIO_fdopen(int, const char *);
PerlIO *PerlIO_importFILE(FILE *, int flags);
FILE *PerlIO_exportFILE(PerlIO *, int flags);
FILE *PerlIO_findFILE(PerlIO *);
void PerlIO_releaseFILE(PerlIO *,FILE *);
void PerlIO_setlinebuf(PerlIO *);
long PerlIO_tell(PerlIO *);
int PerlIO_seek(PerlIO *,off_t,int);
int PerlIO_getpos(PerlIO *,Fpos_t *)
int PerlIO_setpos(PerlIO *,Fpos_t *)
void PerlIO_rewind(PerlIO *);
int PerlIO_has_base(PerlIO *);
int PerlIO_has_cntptr(PerlIO *);
int PerlIO_fast_gets(PerlIO *);
int PerlIO_canset_cnt(PerlIO *);
char *PerlIO_get_ptr(PerlIO *);
int PerlIO_get_cnt(PerlIO *);
void PerlIO_set_cnt(PerlIO *,int);
void PerlIO_set_ptrcnt(PerlIO *,char *,int);
char *PerlIO_get_base(PerlIO *);
int PerlIO_get_bufsiz(PerlIO *);
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PERLAPIO(1) Perl Programmers Reference Guide PERLAPIO(1)DESCRIPTION
Perl's source code should use the above functions instead
of those defined in ANSI C's stdio.h. The perl headers
will #define them to the I/O mechanism selected at
Configure time.
The functions are modeled on those in stdio.h, but
parameter order has been "tidied up a little".
PerlIO *
This takes the place of FILE *. Like FILE * it should
be treated as opaque (it is probably safe to assume it
is a pointer to something).
PerlIO_stdin(), PerlIO_stdout(), PerlIO_stderr()
Use these rather than stdin, stdout, stderr. They are
written to look like "function calls" rather than
variables because this makes it easier to make them
function calls if platform cannot export data to
loaded modules, or if (say) different "threads" might
have different values.
PerlIO_open(path, mode), PerlIO_fdopen(fd,mode)
These correspond to fopen()/fdopen() arguments are the
same.
PerlIO_printf(f,fmt,...), PerlIO_vprintf(f,fmt,a)
These are fprintf()/vfprintf() equivalents.
PerlIO_stdoutf(fmt,...)
This is printf() equivalent. printf is #defined to
this function, so it is (currently) legal to use
printf(fmt,...) in perl sources.
PerlIO_read(f,buf,count), 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.
PerlIO_close(f)
PerlIO_puts(f,s), PerlIO_putc(f,c)
These correspond to fputs() and fputc(). Note that
arguments have been revised to have "file" first.
PerlIO_ungetc(f,c)
This corresponds to ungetc(). Note that arguments
have been revised to have "file" first.
PerlIO_getc(f)
This corresponds to getc().
PerlIO_eof(f)
This corresponds to feof().
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PERLAPIO(1) Perl Programmers Reference Guide PERLAPIO(1)PerlIO_error(f)
This corresponds to ferror().
PerlIO_fileno(f)
This corresponds to fileno(), note that on some
platforms, the meaning of "fileno" may not match Unix.
PerlIO_clearerr(f)
This corresponds to clearerr(), i.e., clears 'eof' and
'error' flags for the "stream".
PerlIO_flush(f)
This corresponds to fflush().
PerlIO_tell(f)
This corresponds to ftell().
PerlIO_seek(f,o,w)
This corresponds to fseek().
PerlIO_getpos(f,p), PerlIO_setpos(f,p)
These correspond to fgetpos() and fsetpos(). If
platform does not have the stdio calls then they are
implemented in terms of PerlIO_tell() and
PerlIO_seek().
PerlIO_rewind(f)
This corresponds to rewind(). Note may be redefined in
terms of PerlIO_seek() at some point.
PerlIO_tmpfile()
This corresponds to tmpfile(), i.e., returns an
anonymous PerlIO which will automatically be deleted
when closed.
Co-existence with stdio
There is outline support for co-existence of PerlIO with
stdio. Obviously if PerlIO is implemented in terms of
stdio there is no problem. However if perlio is
implemented on top of (say) sfio then mechanisms must
exist to create a FILE * which can be passed to library
code which is going to use stdio calls.
PerlIO_importFILE(f,flags)
Used to get a PerlIO * from a FILE *. May need
additional arguments, interface under review.
PerlIO_exportFILE(f,flags)
Given an PerlIO * return a 'native' FILE * suitable
for passing to code expecting to be compiled and
linked with ANSI C stdio.h.
The fact that such a FILE * has been 'exported' is
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recorded, and may affect future PerlIO operations on
the original PerlIO *.
PerlIO_findFILE(f)
Returns previously 'exported' FILE * (if any). Place
holder until interface is fully defined.
PerlIO_releaseFILE(p,f)
Calling PerlIO_releaseFILE informs PerlIO that all use
of FILE * is complete. It is removed from list of
'exported' FILE *s, and associated PerlIO * should
revert to original behaviour.
PerlIO_setlinebuf(f)
This corresponds to setlinebuf(). Use is deprecated
pending further discussion. (Perl core uses it only
when "dumping"; it has nothing to do with $| auto-
flush.)
In addition to user API above there is an "implementation"
interface which allows perl to get at internals of PerlIO.
The following calls correspond to the various FILE_xxx
macros determined by Configure. This section is really of
interest to only those concerned with detailed perl-core
behaviour or implementing a PerlIO mapping.
PerlIO_has_cntptr(f)
Implementation can return pointer to current position
in the "buffer" and a count of bytes available in the
buffer.
PerlIO_get_ptr(f)
Return pointer to next readable byte in buffer.
PerlIO_get_cnt(f)
Return count of readable bytes in the buffer.
PerlIO_canset_cnt(f)
Implementation can adjust its idea of number of bytes
in the buffer.
PerlIO_fast_gets(f)
Implementation has all the interfaces required to
allow perl's fast code to handle <FILE> mechanism.
PerlIO_fast_gets(f) = PerlIO_has_cntptr(f) && \
PerlIO_canset_cnt(f) && \
`Can set pointer into buffer'
PerlIO_set_ptrcnt(f,p,c)
Set pointer into buffer, and a count of bytes still in
the buffer. Should be used only to set pointer to
within range implied by previous calls to
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PerlIO_get_ptr and PerlIO_get_cnt.
PerlIO_set_cnt(f,c)
Obscure - set count of bytes in the buffer.
Deprecated. Currently used in only doio.c to force
count < -1 to -1. Perhaps should be PerlIO_set_empty
or similar. This call may actually do nothing if
"count" is deduced from pointer and a "limit".
PerlIO_has_base(f)
Implementation has a buffer, and can return pointer to
whole buffer and its size. Used by perl for -T / -B
tests. Other uses would be very obscure...
PerlIO_get_base(f)
Return start of buffer.
PerlIO_get_bufsiz(f)
Return total size of buffer.
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