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BIO(3)			   Library Functions Manual			BIO(3)

NAME
       Bopen, Bfdopen, Binit, Binits, Brdline, Brdstr, Bgetc, Bgetrune,	Bgetd,
       Bungetc,	Bungetrune, Bread, Bseek, Boffset, Bfildes,  Blinelen,	Bputc,
       Bputrune,  Bprint, Bvprint, Bwrite, Bflush, Bterm, Bbuffered - buffered
       input/output

SYNOPSIS
       #include	<u.h>
       #include	<libc.h>
       #include	<bio.h>

       Biobuf* Bopen(char *file, int mode)

       Biobuf* Bfdopen(int fd, int mode)

       int     Binit(Biobuf *bp, int fd, int mode)

       int     Binits(Biobufhdr	*bp, int fd, int mode, uchar *buf, int size)

       int     Bterm(Biobufhdr *bp)

       int     Bprint(Biobufhdr	*bp, char *format, ...)

       int     Bvprint(Biobufhdr *bp, char *format, va_list arglist);

       void*   Brdline(Biobufhdr *bp, int delim)

       char*   Brdstr(Biobufhdr	*bp, int delim,	int nulldelim)

       int     Blinelen(Biobufhdr *bp)

       vlong   Boffset(Biobufhdr *bp)

       int     Bfildes(Biobufhdr *bp)

       int     Bgetc(Biobufhdr *bp)

       long    Bgetrune(Biobufhdr *bp)

       int     Bgetd(Biobufhdr *bp, double *d)

       int     Bungetc(Biobufhdr *bp)

       int     Bungetrune(Biobufhdr *bp)

       vlong   Bseek(Biobufhdr *bp, vlong n, int type)

       int     Bputc(Biobufhdr *bp, int	c)

       int     Bputrune(Biobufhdr *bp, long c)

       long    Bread(Biobufhdr *bp, void *addr,	long nbytes)

       long    Bwrite(Biobufhdr	*bp, void *addr, long nbytes)

       int     Bflush(Biobufhdr	*bp)

       int     Bbuffered(Biobufhdr *bp)

DESCRIPTION
       These routines implement	fast buffered I/O.  I/O	on different file  de-
       scriptors is independent.

       Bopen  opens  file for mode OREAD or creates for	mode OWRITE.  It calls
       to allocate a buffer.

       Bfdopen allocates a buffer for the already-open file descriptor fd  for
       mode OREAD or OWRITE.  It calls to allocate a buffer.

       Binit  initializes  a  standard size buffer, type Biobuf, with the open
       file descriptor passed in by the	user.  Binits initializes a  non-stan-
       dard size buffer, type Biobufhdr, with the open file descriptor,	buffer
       area, and buffer	size passed in by the user.  Biobuf and	Biobufhdr  are
       related by the declaration:

	      typedef struct Biobuf Biobuf;
	      struct Biobuf
	      {
		      Biobufhdr;
		      uchar b[Bungetsize+Bsize];
	      };

       Arguments  of  types  pointer to	Biobuf and pointer to Biobufhdr	can be
       used interchangeably in the following routines.

       Bopen, Binit, or	Binits should be called	before any of the  other  rou-
       tines  on  that buffer.	Bfildes	returns	the integer file descriptor of
       the associated open file.

       Bterm flushes the buffer	for bp.	 If the	buffer was allocated by	Bopen,
       the buffer is freed and the file	is closed.

       Brdline	reads  a string	from the file associated with bp up to and in-
       cluding the first delim character.  The delimiter character at the  end
       of  the line is not altered.  Brdline returns a pointer to the start of
       the line	or on end-of-file or read error.  Blinelen returns the	length
       (including  the	delimiter)  of the most	recent string returned by Brd-
       line.

       Brdstr returns a	buffer containing the next line	of input delimited  by
       delim,  terminated  by  a  NUL (0) byte.	 Unlike	Brdline, which returns
       when its	buffer is full even if no delimiter  has  been	found,	Brdstr
       will return an arbitrarily long line in a single	call.  If nulldelim is
       set, the	terminal delimiter will	be overwritten with a  NUL.   After  a
       successful  call	 to  Brdstr,  the return value of Blinelen will	be the
       length of the returned buffer, excluding	the NUL.

       Bgetc returns the next character	from bp, or a negative value at	end of
       file.   Bungetc may be called immediately after Bgetc to	allow the same
       character to be reread.

       Bgetrune	calls Bgetc to read the	bytes of the next UTF sequence in  the
       input  stream  and returns the value of the rune	represented by the se-
       quence.	It returns a negative value at end of file.  Bungetrune	may be
       called  immediately after Bgetrune to allow the same UTF	sequence to be
       reread as either	bytes or a rune.  Bungetc and Bungetrune may back up a
       maximum of five bytes.

       Bgetd uses charstod (see	and Bgetc to read the formatted	floating-point
       number in the input stream, skipping  initial  blanks  and  tabs.   The
       value is	stored in *d.

       Bread  reads  nbytes of data from bp into memory	starting at addr.  The
       number of bytes read is returned	on success and a negative value	is re-
       turned if a read	error occurred.

       Bseek  applies to bp.  It returns the new file offset.  Boffset returns
       the file	offset of the next character to	be processed.

       Bputc outputs the low order 8 bits of c on bp.  If this causes a	 write
       to  occur  and there is an error, a negative value is returned.	Other-
       wise, a zero is returned.

       Bputrune	calls Bputc to output the low order 16 bits of c as a rune  in
       UTF format on the output	stream.

       Bprint  is  a buffered interface	to If this causes a write to occur and
       there is	an error, a negative value  (Beof)  is	returned.   Otherwise,
       Bprint  returns the number of bytes written.  Bvprint does the same ex-
       cept it takes as	argument a va_list parameter,  so  it  can  be	called
       within a	variadic function.

       Bwrite outputs nbytes of	data starting at addr to bp.  If this causes a
       write to	occur and there	is an error, a	negative  value	 is  returned.
       Otherwise, the number of	bytes written is returned.

       Bflush  causes  any  buffered  output associated	with bp	to be written.
       The return is as	for Bputc.  Bflush is called on	exit for every	buffer
       still open for writing.

       Bbuffered  returns  the	number	of bytes in the	buffer.	 When reading,
       this is the number of bytes still available from	the last read  on  the
       file; when writing, it is the number of bytes ready to be written.

SOURCE
       /src/libbio

SEE ALSO
DIAGNOSTICS
       Bio  routines that return integers yield	Beof if	bp is not the descrip-
       tor of an open file.  Bopen returns zero	if the file cannot  be	opened
       in the given mode.  All routines	set errstr on error.

BUGS
       Brdline	returns	 an error on strings longer than the buffer associated
       with the	file and also if the end-of-file is encountered	before	a  de-
       limiter.	 Blinelen will tell how	many characters	are available in these
       cases.  In the case of a	true end-of-file, Blinelen will	 return	 zero.
       At the cost of allocating a buffer, Brdstr sidesteps these issues.

       The  data  returned by Brdline may be overwritten by calls to any other
       bio routine on the same bp.

									BIO(3)

NAME | SYNOPSIS | DESCRIPTION | SOURCE | SEE ALSO | DIAGNOSTICS | BUGS

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