vrb_read_min(3) [debian man page]

vrb_read_min(3) 					      VRB Programmer's Manual						   vrb_read_min(3)

NAME

       vrb_read_min - read a minimum of data into a VRB

LIBRARY

       -lvrb

SYNOPSIS

       #include <vrb.h>

       size_t vrb_read_min(vrb_p vrb, int fd, size_t maxsize, size_t minsize);

DESCRIPTION

       vrb_read_min  reads  a  minimum	amount	of data from a specified open file descriptor using read(2) into the specified virtual ring buffer
       until the specified maximum length has been read, the buffer is full, or end-of-file, or an error is returned (including EAGAIN or  EWOULD-
       BLOCK  for  a  non-blocking descriptor).  If there is insufficient space in the buffer to read the minimum amount, then read(2) will not be
       called.

ARGUMENTS

       vrb_p vrb
       specifies which virtual ring buffer.

       int fd
       specifies the open file descriptor to read from

       size_t maxsize
       specifies the maximum length to read, or ~0 for unlimited.

       size_t minsize
       specifies the minimum length to read.

RETURN VALUE

       size_t
       If successful, the actual length of data read into the buffer is returned.  If the minimum amount of space was not available to read  into,
       0  is returned.	If end-of-file occurs, the return value is ~0 and errno is 0.  If an error occurs from read(2), the return value is ~0 and
       errno is set by read(2).

ERRORS

       If an error is returned, then errno will have one of the following values:

       0      An end-of-file has occurred.  Note that this is a different way of returning an end-of-file condition than read(2) uses.

       EINVAL An invalid virtual ring buffer pointer was specified.

SEE ALSO

       vrb(3),	vrb_capacity(3),  vrb_data_len(3),  vrb_data_ptr(3),  vrb_destroy(3),  vrb_get(3),   vrb_get_min(3),   vrb_give(3),   vrb_init(3),
       vrb_init_opt(3),   vrb_is_empty(3),  vrb_is_full(3),  vrb_is_not_empty(3),  vrb_is_not_full(3),	vrb_move(3),  vrb_new(3),  vrb_new_opt(3),
       vrb_put(3), vrb_put_all(3), vrb_read(3),  vrb_resize(3),  vrb_space_len(3),  vrb_space_ptr(3),  vrb_take(3),  vrb_uninit(3),  vrb_write(3),
       vrb_write_min(3), read(2)

vrb								    2002-09-30							   vrb_read_min(3)

VBUF(1) 						      General Commands Manual							   VBUF(1)

NAME

       vbuf - Virtual Ring Buffer shell interface

SYNOPSIS

       vbuf [options]

DESCRIPTION

       This manual page documents briefly the vbuf command.

       vbuf  is  a  program  to glue two programs (a producer and a consumer) together, one of which not being able to fulfil the other's constant
       data rate requirements.

OPTIONS

       -h
	      Show short help message.

       --help
	      Show long help message.

       -p, --progress
	      Show progress status line.

       -q, --quiet
	      Suppress progress status line.  The default is to show the progress display.

       -s size, --size=size
	      Set buffer size in bytes.  Suffixes k, m, and g may be used.  The actual size used will be rounded up for  system  mapping  require-
	      ments.  The default is 1m, or 1048576 bytes.

       -t time, --time=seconds
	      Set time in seconds between progress display refreshes.  Fractions of a second may be used.  Default is 1.500000 seconds.

       -b, --bits
	      Set progress rate display units to bits per second.

       -B, --bytes
	      Set progress rate display units to bytes per second.  The default is bytes.

       -d, --decimal
	      Set progress rate display base to decimal.  The default is decimal.

       -x, --hexadecimal
	      Set progress rate display base to hexadecimal.

       --octal
	      Set progress rate display base to octal.

       -i file, --input=file
	      Specify an input file to be opened and used instead of using stdin.

       -o file, --output=file
	      Specify an output file to be opened and used instead of using stdout.

       -M file, --mapfile=file
	      Specify  a  file	which  will be used for backing store for the virtual ring buffer.  The allows using filesystem space in case swap
	      space is full.

       -r bytes, --read-min=bytes
	      Specify the minimum number of bytes to be requested by read.  Reading will not happen unless at least  this  much  buffer  space	is
	      available.  The default is 1.

       -R bytes, --read-max=bytes
	      Specify  the maximum number of bytes to be requested by read.  Reading will not request more even if more buffer space is available.
	      The default is the full buffer size.

       -w bytes, --write-min=bytes
	      Specify the minumum number of bytes to be written.  Writing will not be done unless at least this much data is available.  Once  end
	      of file is reached on input, a smaller amount may be written.  The default is 1.

       -W bytes, --write-max=bytes
	      Specify the maximum number of bytes to be written.  Writing will not write more each time even if more data is available in the buf-
	      fer.  The default is the full buffer size.

AUTHOR

       VRB and vbuf were written by Phil Howard <vrb@ipal.org>.

       This manual page was written by Szekelyi Szabolcs <cc@mail.3d.hu>, for the Debian project (but may be used by others).

								    2006 Sep 5								   VBUF(1)