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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% | |
9 | */ | |
10 | ||
11 | #if defined(LIBC_SCCS) && !defined(lint) | |
cb631443 | 12 | static char sccsid[] = "@(#)makebuf.c 5.2 (Berkeley) %G%"; |
c9be6cfe KB |
13 | #endif /* LIBC_SCCS and not lint */ |
14 | ||
15 | #include <sys/types.h> | |
16 | #include <sys/stat.h> | |
cb631443 | 17 | #include <unistd.h> |
c9be6cfe KB |
18 | #include <stdio.h> |
19 | #include <stdlib.h> | |
20 | #include "local.h" | |
21 | ||
22 | /* | |
23 | * Allocate a file buffer, or switch to unbuffered I/O. | |
24 | * Per the ANSI C standard, ALL tty devices default to line buffered. | |
25 | * | |
26 | * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek | |
27 | * optimisation) right after the fstat() that finds the buffer size. | |
28 | */ | |
29 | void | |
30 | __smakebuf(fp) | |
31 | register FILE *fp; | |
32 | { | |
33 | register size_t size, couldbetty; | |
34 | register void *p; | |
35 | struct stat st; | |
36 | ||
37 | if (fp->_flags & __SNBF) { | |
38 | fp->_bf._base = fp->_p = fp->_nbuf; | |
39 | fp->_bf._size = 1; | |
40 | return; | |
41 | } | |
42 | if (fp->_file < 0 || fstat(fp->_file, &st) < 0) { | |
43 | couldbetty = 0; | |
44 | size = BUFSIZ; | |
45 | /* do not try to optimise fseek() */ | |
46 | fp->_flags |= __SNPT; | |
47 | } else { | |
48 | couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; | |
49 | size = st.st_blksize <= 0 ? BUFSIZ : st.st_blksize; | |
50 | /* | |
51 | * Optimise fseek() only if it is a regular file. | |
52 | * (The test for __sseek is mainly paranoia.) | |
53 | */ | |
54 | if ((st.st_mode & S_IFMT) == S_IFREG && | |
55 | fp->_seek == __sseek) { | |
56 | fp->_flags |= __SOPT; | |
57 | fp->_blksize = st.st_blksize; | |
58 | } else | |
59 | fp->_flags |= __SNPT; | |
60 | } | |
61 | if ((p = malloc(size)) == NULL) { | |
62 | fp->_flags |= __SNBF; | |
63 | fp->_bf._base = fp->_p = fp->_nbuf; | |
64 | fp->_bf._size = 1; | |
65 | } else { | |
66 | __cleanup = _cleanup; | |
67 | fp->_flags |= __SMBF; | |
68 | fp->_bf._base = fp->_p = p; | |
69 | fp->_bf._size = size; | |
70 | if (couldbetty && isatty(fp->_file)) | |
71 | fp->_flags |= __SLBF; | |
72 | } | |
73 | } |