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1 | /*- |
2 | * Copyright (c) 1990 The Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * This code is derived from software contributed to Berkeley by | |
6 | * Chris Torek. | |
7 | * | |
8 | * %sccs.include.redist.c% | |
586c39b1 DF |
9 | */ |
10 | ||
2ce81398 | 11 | #if defined(LIBC_SCCS) && !defined(lint) |
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12 | static char sccsid[] = "@(#)wbuf.c 5.6 (Berkeley) %G%"; |
13 | #endif /* LIBC_SCCS and not lint */ | |
49648f55 | 14 | |
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15 | #include <stdio.h> |
16 | #include "local.h" | |
62e7287b | 17 | |
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18 | /* |
19 | * Write the given character into the (probably full) buffer for | |
20 | * the given file. Flush the buffer out if it is or becomes full, | |
21 | * or if c=='\n' and the file is line buffered. | |
22 | */ | |
23 | __swbuf(c, fp) | |
24 | register int c; | |
25 | register FILE *fp; | |
62e7287b | 26 | { |
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27 | register int n; |
28 | ||
29 | /* | |
30 | * In case we cannot write, or longjmp takes us out early, | |
31 | * make sure _w is 0 (if fully- or un-buffered) or -_bf._size | |
32 | * (if line buffered) so that we will get called again. | |
33 | * If we did not do this, a sufficient number of putc() | |
34 | * calls might wrap _w from negative to positive. | |
35 | */ | |
36 | fp->_w = fp->_lbfsize; | |
37 | if (cantwrite(fp)) | |
38 | return (EOF); | |
39 | c = (unsigned char)c; | |
40 | ||
41 | /* | |
42 | * If it is completely full, flush it out. Then, in any case, | |
43 | * stuff c into the buffer. If this causes the buffer to fill | |
44 | * completely, or if c is '\n' and the file is line buffered, | |
45 | * flush it (perhaps a second time). The second flush will always | |
46 | * happen on unbuffered streams, where _bf._size==1; fflush() | |
47 | * guarantees that putc() will always call wbuf() by setting _w | |
48 | * to 0, so we need not do anything else. | |
49 | */ | |
50 | n = fp->_p - fp->_bf._base; | |
51 | if (n >= fp->_bf._size) { | |
52 | if (fflush(fp)) | |
53 | return (EOF); | |
54 | n = 0; | |
62e7287b | 55 | } |
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56 | fp->_w--; |
57 | *fp->_p++ = c; | |
58 | if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n')) | |
59 | if (fflush(fp)) | |
60 | return (EOF); | |
61 | return (c); | |
40754574 | 62 | } |