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researchv10 Dan Cross

.TH FIO 3
.CT 2 file_io
.SH NAME
Finit, Frdline, Fgetc, Fread, Fseek, Fundo,
Fputc, Fprint, Fwrite, Fflush, Ftie, Fclose, Fexit \(mi fast buffered input/output
.SH SYNOPSIS
.nf
.2C
.B #include <fio.h>
.PP
.B void Finit(fd, buf)
.B char *buf;
.PP
.B void Fclose(fd);
.PP
.B int Fprint(fildes, format [, arg ...])
.B int fildes;
.B char \(**format;
.PP
.B char *Frdline(fd)
.PP
.B int FIOLINELEN(fd)
.PP
.B long FIOSEEK(fd)
.PP
.B int Fgetc(fd)
.PP
.B void Fundo(fd)
.PP
.B long Fseek(fd, offset, ptr)
.B long offset;
.PP
.B int Fputc(fd, c)
.PP
.B long Fread(fd, addr, nbytes)
.B char *addr;
.B long nbytes;
.PP
.B int Fwrite(fd, addr, nbytes)
.B char *addr;
.B long nbytes;
.PP
.B int Fflush(fd)
.PP
.B void Ftie(ifd, ofd)
.PP
.B Fexit(type)
.1C
.fi
.SH DESCRIPTION
These routines provide buffered I/O, faster than, and incompatible
with
.IR stdio (3).
The routines can be called in any order.
I/O on different file descriptors is independent.
.PP
.I Finit
initializes a buffer (whose type is
.IR Fbuffer )
associated with the file descriptor
.IR fd .
Any buffered input associated with
.I fd
will be lost.
The buffer can be supplied by the user
(it should be at least
.B sizeof(Fbuffer)
bytes)
or if
.I buf
is
.BR "(char *)0" ,
.I Finit
will use
.IR malloc (3).
.IR Finit
must be called after a stretch of
.IR non- fio
activity, such as
.IR close
or
.IR lseek (2),
between
.I fio
calls on the same file descriptor number;
it is unnecessary, but harmless, before the first
.I fio
activity on a given file descriptor number.
.PP
.I Fclose
flushes the buffer for
.IR fd ,
.IR free s
the buffer if it was allocated by
.IR Finit ,
and then closes
.IR fd .
.PP
.I Frdline
reads a line from the file associated with the file descriptor
.IR fd .
The newline at the end of the line is replaced by a 0
byte.
Lines longer than 4096 characters will have characters deleted.
.I Frdline
returns a pointer to the start of the line or
.L (char *)0
on end of file or read error.
The macro
.I FIOLINELEN
returns the length (not including the 0
byte) of the most recent line returned by
.IR Frdline .
The value is undefined after a call to any other
.I fio
routine.
.PP
.I Fgetc
returns the next character from the file descriptor
.IR fd ,
or a negative value
at end of file.
.PP
.I Fread
reads
.I nbytes
of data from the file descriptor
.I fd
into memory starting at
.IR addr .
The number of bytes read is returned on success
and a negative value is returned if a read error occurred.
.PP
.I Fseek
applies
.IR lseek (2)
to
.I fd
taking buffering into account.
It returns the new file offset.
The macro
.I FIOSEEK
returns the file offset of the next character to be processed.
.PP
.I Fundo
makes the characters returned by the last call to
.I Frdline
or
.I Fgetc
available for reading again.
There is only one level of undo.
.PP
.I Fputc
outputs the low order 8 bits of
.I c
on the file associated with file descriptor
.IR fd .
If this causes a
.IR write
(see
.IR read (2))
to occur and there is an error,
a negative value is returned.
Otherwise, zero is returned.
.PP
.I Fprint
is a buffered interface to
.IR print (3).
If this causes a
.IR write
to occur and there is an error,
a negative value is returned.
Otherwise, the number of chars output is returned.
.PP
.I Fwrite
outputs
.I nbytes
bytes of data starting at
.I addr
to the file associated with file descriptor
.IR fd .
If this causes a
.IR write
to occur and there is an error,
a negative value is returned.
Otherwise, the number of bytes written is returned.
.PP
.I Fflush
causes any buffered output associated with
.I fd
to be written;
it must precede a call of
.I close
on
.IR fd.
The return is as for
.IR Fputc .
.PP
.I Ftie
links together two file descriptors such that any
.IR fio -initiated
.IR read (2)
on
.I ifd
causes a
.I Fflush
of
.I ofd
(if it has been initialized).
It is appropriate for most programs used as filters to do
.BR Ftie(0,1) .
The tie may be broken by
.BR "Ftie(ifd, -1)" .
.PP
.I Fexit
is used to clean up all
.I fio
buffers.
If
.I type
is zero, the buffers are
.IR Fflush ed,
otherwise they are
.IR Fclose d.
.B "Fexit(0)"
is automatically called at
.IR exit (3).
.SH SEE ALSO
.IR open (2),
.IR print (3),
.IR stdio (3)
.SH DIAGNOSTICS
.I Fio
routines that return integers yield
.B -1
if 
.I fd
is not the descriptor of an open file or if the operation
is inapplicable to
.I fd.
.SH BUGS
The data returned by
.I Frdline
may be overwritten by calls to any other
.I fio
routine.
.br
.I Fgetc
is much slower than
access through a pointer returned by
.I Frdline.
.br
There is no 
.IR scanf (3)
analogue.

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