newlib/libc/stdio/wbuf.c

   1 /*
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * and/or other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17 /* No user fns here.  Pesch 15apr92. */
  18
  19 #if defined(LIBC_SCCS) && !defined(lint)
  20 static char sccsid[] = "%W% (Berkeley) %G%";
  21 #endif /* LIBC_SCCS and not lint */
  22
  23 #include <_ansi.h>
  24 #include <stdio.h>
  25 #include <errno.h>
  26 #include "local.h"
  27 #include "fvwrite.h"
  28
  29 /*
  30  * Write the given character into the (probably full) buffer for
  31  * the given file.  Flush the buffer out if it is or becomes full,
  32  * or if c=='\n' and the file is line buffered.
  33  */
  34
  35 int
  36 __swbuf_r (struct _reent *ptr,
  37        register int c,
  38        register FILE *fp)
  39 {
  40   register int n;
  41
  42   /* Ensure stdio has been initialized.  */
  43
  44   CHECK_INIT (ptr, fp);
  45
  46   /*
  47    * In case we cannot write, or longjmp takes us out early,
  48    * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
  49    * (if line buffered) so that we will get called again.
  50    * If we did not do this, a sufficient number of putc()
  51    * calls might wrap _w from negative to positive.
  52    */
  53
  54   fp->_w = fp->_lbfsize;
  55   if (cantwrite (ptr, fp))
  56     return EOF;
  57   c = (unsigned char) c;
  58
  59   if (ORIENT (fp, -1) != -1)
  60     return EOF;
  61
  62   /*
  63    * If it is completely full, flush it out.  Then, in any case,
  64    * stuff c into the buffer.  If this causes the buffer to fill
  65    * completely, or if c is '\n' and the file is line buffered,
  66    * flush it (perhaps a second time).  The second flush will always
  67    * happen on unbuffered streams, where _bf._size==1; fflush()
  68    * guarantees that putc() will always call wbuf() by setting _w
  69    * to 0, so we need not do anything else.
  70    */
  71
  72   n = fp->_p - fp->_bf._base;
  73   if (n >= fp->_bf._size)
  74     {
  75       if (_fflush_r (ptr, fp))
  76         return EOF;
  77       n = 0;
  78     }
  79   fp->_w--;
  80   *fp->_p++ = c;
  81   if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
  82     if (_fflush_r (ptr, fp))
  83       return EOF;
  84   return c;
  85 }
  86
  87 /* This function isn't any longer declared in stdio.h, but it's
  88    required for backward compatibility with applications built against
  89    earlier dynamically built newlib libraries. */
  90 int
  91 __swbuf (register int c,
  92        register FILE *fp)
  93 {
  94   return __swbuf_r (_REENT, c, fp);
  95 }