SETBUF(3)                  POSIX Programmer's Manual                 SETBUF(3)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       setbuf -- assign buffering to a stream

SSYYNNOOPPSSIISS
       #include <stdio.h>

       void setbuf(FILE *restrict _s_t_r_e_a_m, char *restrict _b_u_f);

DDEESSCCRRIIPPTTIIOONN
       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.1-2017
       defers to the ISO C standard.

       Except that it returns no value, the function call:


           setbuf(stream, buf)

       shall be equivalent to:


           setvbuf(stream, buf, _IOFBF, BUFSIZ)

       if _b_u_f is not a null pointer, or to:


           setvbuf(stream, buf, _IONBF, BUFSIZ)

       if _b_u_f is a null pointer.

RREETTUURRNN VVAALLUUEE
       The _s_e_t_b_u_f() function shall not return a value.

EERRRROORRSS
       Although the _s_e_t_v_b_u_f() interface may set _e_r_r_n_o in defined ways, the
       value of _e_r_r_n_o after a call to _s_e_t_b_u_f() is unspecified.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       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 _s_e_t_b_u_f(), allocating a buffer of BUFSIZ bytes does not necessarily
       imply that all of BUFSIZ bytes are used for the buffer area.

       Since _e_r_r_n_o is not required to be unchanged on success, in order to
       correctly detect and possibly recover from errors, applications should
       use _s_e_t_v_b_u_f() instead of _s_e_t_b_u_f().

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._5, _S_t_a_n_d_a_r_d _I_/_O _S_t_r_e_a_m_s, _f_o_p_e_n(), _s_e_t_v_b_u_f()

       The Base Definitions volume of POSIX.1-2017, <<ssttddiioo..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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                  2017                            SETBUF(3)
