1 /* No user fns here.  Pesch 15apr92. */
2 
3 /*
4  * Copyright (c) 1990 The Regents of the University of California.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms are permitted
8  * provided that the above copyright notice and this paragraph are
9  * duplicated in all such forms and that any documentation,
10  * advertising materials, and other materials related to such
11  * distribution and use acknowledge that the software was developed
12  * by the University of California, Berkeley.  The name of the
13  * University may not be used to endorse or promote products derived
14  * from this software without specific prior written permission.
15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
18  */
19 
20 #if defined(LIBC_SCCS) && !defined(lint)
21 static char sccsid[] = "%W% (Berkeley) %G%";
22 #endif /* LIBC_SCCS and not lint */
23 
24 #include <stdio.h>
25 #include "local.h"
26 #include "fvwrite.h"
27 
28 /*
29  * Write the given character into the (probably full) buffer for
30  * the given file.  Flush the buffer out if it is or becomes full,
31  * or if c=='\n' and the file is line buffered.
32  */
33 
34 int
35 __swbuf (c, fp)
36      register int c;
37      register FILE *fp;
38 {
39   register int n;
40 
41   /* Ensure stdio has been initialized.  */
42 
43   CHECK_INIT (fp);
44 
45   /*
46    * In case we cannot write, or longjmp takes us out early,
47    * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
48    * (if line buffered) so that we will get called again.
49    * If we did not do this, a sufficient number of putc()
50    * calls might wrap _w from negative to positive.
51    */
52 
53   fp->_w = fp->_lbfsize;
54   if (cantwrite (fp))
55     return EOF;
56   c = (unsigned char) c;
57 
58   /*
59    * If it is completely full, flush it out.  Then, in any case,
60    * stuff c into the buffer.  If this causes the buffer to fill
61    * completely, or if c is '\n' and the file is line buffered,
62    * flush it (perhaps a second time).  The second flush will always
63    * happen on unbuffered streams, where _bf._size==1; fflush()
64    * guarantees that putc() will always call wbuf() by setting _w
65    * to 0, so we need not do anything else.
66    */
67 
68   n = fp->_p - fp->_bf._base;
69   if (n >= fp->_bf._size)
70     {
71       if (fflush (fp))
72 	return EOF;
73       n = 0;
74     }
75   fp->_w--;
76   *fp->_p++ = c;
77   if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
78     if (fflush (fp))
79       return EOF;
80   return c;
81 }
82