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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SETVBUF(3P) POSIX Programmer's Manual SETVBUF(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
setvbuf — assign buffering to a stream
#include <stdio.h>
int setvbuf(FILE *restrict stream, char *restrict buf, int type,
size_t size);
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The setvbuf() function may be used after the stream pointed to by
stream is associated with an open file but before any other operation
(other than an unsuccessful call to setvbuf()) is performed on the
stream. The argument type determines how stream shall be buffered, as
follows:
* {_IOFBF} shall cause input/output to be fully buffered.
* {_IOLBF} shall cause input/output to be line buffered.
* {_IONBF} shall cause input/output to be unbuffered.
If buf is not a null pointer, the array it points to may be used
instead of a buffer allocated by setvbuf() and the argument size
specifies the size of the array; otherwise, size may determine the
size of a buffer allocated by the setvbuf() function. The contents of
the array at any time are unspecified.
For information about streams, see Section 2.5, Standard I/O Streams.
Upon successful completion, setvbuf() shall return 0. Otherwise, it
shall return a non-zero value if an invalid value is given for type
or if the request cannot be honored, and may set errno to indicate
the error.
The setvbuf() function may fail if:
EBADF The file descriptor underlying stream is not valid.
The following sections are informative.
None.
A common source of error is allocating buffer space as an
``automatic'' variable in a code block, and then failing to close the
stream in the same block.
With setvbuf(), allocating a buffer of size bytes does not
necessarily imply that all of size bytes are used for the buffer
area.
Applications should note that many implementations only provide line
buffering on input from terminal devices.
None.
None.
Section 2.5, Standard I/O Streams, fopen(3p), setbuf(3p)
The Base Definitions volume of POSIX.1‐2008, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 SETVBUF(3P)
Pages that refer to this page: stdio.h(0p), cat(1p), setbuf(3p), stdin(3p)
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