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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdio/] [setvbuf.c] - Rev 232
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/* * Copyright (c) 1990 The Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the University of California, Berkeley. The name of the * University may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ /* FUNCTION <<setvbuf>>---specify file or stream buffering INDEX setvbuf ANSI_SYNOPSIS #include <stdio.h> int setvbuf(FILE *<[fp]>, char *<[buf]>, int <[mode]>, size_t <[size]>); TRAD_SYNOPSIS #include <stdio.h> int setvbuf(<[fp]>, <[buf]>, <[mode]>, <[size]>) FILE *<[fp]>; char *<[buf]>; int <[mode]>; size_t <[size]>; DESCRIPTION Use <<setvbuf>> to specify what kind of buffering you want for the file or stream identified by <[fp]>, by using one of the following values (from <<stdio.h>>) as the <[mode]> argument: o+ o _IONBF Do not use a buffer: send output directly to the host system for the file or stream identified by <[fp]>. o _IOFBF Use full output buffering: output will be passed on to the host system only when the buffer is full, or when an input operation intervenes. o _IOLBF Use line buffering: pass on output to the host system at every newline, as well as when the buffer is full, or when an input operation intervenes. o- Use the <[size]> argument to specify how large a buffer you wish. You can supply the buffer itself, if you wish, by passing a pointer to a suitable area of memory as <[buf]>. Otherwise, you may pass <<NULL>> as the <[buf]> argument, and <<setvbuf>> will allocate the buffer. WARNINGS You may only use <<setvbuf>> before performing any file operation other than opening the file. If you supply a non-null <[buf]>, you must ensure that the associated storage continues to be available until you close the stream identified by <[fp]>. RETURNS A <<0>> result indicates success, <<EOF>> failure (invalid <[mode]> or <[size]> can cause failure). PORTABILITY Both ANSI C and the System V Interface Definition (Issue 2) require <<setvbuf>>. However, they differ on the meaning of a <<NULL>> buffer pointer: the SVID issue 2 specification says that a <<NULL>> buffer pointer requests unbuffered output. For maximum portability, avoid <<NULL>> buffer pointers. Both specifications describe the result on failure only as a nonzero value. Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, <<lseek>>, <<read>>, <<sbrk>>, <<write>>. */ #include <_ansi.h> #include <stdio.h> #include <stdlib.h> #include "local.h" /* * Set one of the three kinds of buffering, optionally including a buffer. */ int _DEFUN(setvbuf, (fp, buf, mode, size), register FILE * fp _AND char *buf _AND register int mode _AND register size_t size) { int ret = 0; CHECK_INIT (_REENT, fp); _flockfile (fp); /* * Verify arguments. The `int' limit on `size' is due to this * particular implementation. */ if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) || (int)(_POINTER_INT) size < 0) { _funlockfile (fp); return (EOF); } /* * Write current buffer, if any; drop read count, if any. * Make sure putc() will not think fp is line buffered. * Free old buffer if it was from malloc(). Clear line and * non buffer flags, and clear malloc flag. */ _fflush_r (_REENT, fp); fp->_r = 0; fp->_lbfsize = 0; if (fp->_flags & __SMBF) _free_r (_REENT, (_PTR) fp->_bf._base); fp->_flags &= ~(__SLBF | __SNBF | __SMBF); if (mode == _IONBF) goto nbf; /* * Allocate buffer if needed. */ if (buf == NULL) { /* we need this here because malloc() may return a pointer even if size == 0 */ if (!size) size = BUFSIZ; if ((buf = malloc (size)) == NULL) { ret = EOF; /* Try another size... */ buf = malloc (BUFSIZ); size = BUFSIZ; } if (buf == NULL) { /* Can't allocate it, let's try another approach */ nbf: fp->_flags |= __SNBF; fp->_w = 0; fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; _funlockfile (fp); return (ret); } fp->_flags |= __SMBF; } /* * Now put back whichever flag is needed, and fix _lbfsize * if line buffered. Ensure output flush on exit if the * stream will be buffered at all. * If buf is NULL then make _lbfsize 0 to force the buffer * to be flushed and hence malloced on first use */ switch (mode) { case _IOLBF: fp->_flags |= __SLBF; fp->_lbfsize = buf ? -size : 0; /* FALLTHROUGH */ case _IOFBF: /* no flag */ _REENT->__cleanup = _cleanup_r; fp->_bf._base = fp->_p = (unsigned char *) buf; fp->_bf._size = size; break; } /* * Patch up write count if necessary. */ if (fp->_flags & __SWR) fp->_w = fp->_flags & (__SLBF | __SNBF) ? 0 : size; _funlockfile (fp); return 0; }
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