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36 * @(#)setvbuf.c 8.2 (Berkeley) 11/16/93
37 * $FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.7 1999/08/28 00:01:16 peter Exp $
38 * $DragonFly: src/lib/libc/stdio/setvbuf.c,v 1.7 2005/11/20 11:07:30 swildner Exp $
41 #include "namespace.h"
44 #include "un-namespace.h"
47 #include "libc_private.h"
48 #include "priv_stdio.h"
51 * Set one of the three kinds of buffering, optionally including
55 setvbuf(FILE *fp, char *buf, int mode, size_t size)
62 * Verify arguments. The `int' limit on `size' is due to this
63 * particular implementation. Note, buf and size are ignored
64 * when setting _IONBF.
67 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
72 * Write current buffer, if any. Discard unread input (including
73 * ungetc data), cancel line buffering, and free old buffer if
74 * malloc()ed. We also clear any eof condition, as if this were
81 fp->pub._r = fp->pub._lbfsize = 0;
82 flags = fp->pub._flags;
84 free((void *)fp->_bf._base);
85 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
87 /* If setting unbuffered mode, skip all the hard work. */
92 * Find optimal I/O size for seek optimization. This also returns
93 * a `tty flag' to suggest that we check isatty(fd), but we do not
94 * care since our caller told us how to buffer.
96 flags |= __swhatbuf(fp, &iosize, &ttyflag);
98 buf = NULL; /* force local allocation */
102 /* Allocate buffer if needed. */
104 if ((buf = malloc(size)) == NULL) {
106 * Unable to honor user's request. We will return
107 * failure, but try again with file system size.
110 if (size != iosize) {
116 /* No luck; switch to unbuffered I/O. */
118 fp->pub._flags = flags | __SNBF;
120 fp->_bf._base = fp->pub._p = fp->_nbuf;
129 * Kill any seek optimization if the buffer is not the
132 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
138 * Fix up the FILE fields, and set __cleanup for output flush on
139 * exit (since we are buffered in some way).
143 fp->pub._flags = flags;
144 fp->_bf._base = fp->pub._p = (unsigned char *)buf;
145 fp->_bf._size = size;
146 /* fp->_lbfsize is still 0 */
149 * Begin or continue writing: see __swsetup(). Note
150 * that __SNBF is impossible (it was handled earlier).
152 if (flags & __SLBF) {
154 fp->pub._lbfsize = -fp->_bf._size;
158 /* begin/continue reading, or stay in intermediate state */
161 __cleanup = _cleanup;