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2 | pj | 1 | /*- |
2 | * Copyright (c) 1990, 1993 |
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3 | * The Regents of the University of California. All rights reserved. |
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4 | * |
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5 | * This code is derived from software contributed to Berkeley by |
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6 | * Chris Torek. |
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7 | * |
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8 | * Redistribution and use in source and binary forms, with or without |
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9 | * modification, are permitted provided that the following conditions |
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10 | * are met: |
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11 | * 1. Redistributions of source code must retain the above copyright |
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12 | * notice, this list of conditions and the following disclaimer. |
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13 | * 2. Redistributions in binary form must reproduce the above copyright |
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14 | * notice, this list of conditions and the following disclaimer in the |
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15 | * documentation and/or other materials provided with the distribution. |
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16 | * 3. All advertising materials mentioning features or use of this software |
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17 | * must display the following acknowledgement: |
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18 | * This product includes software developed by the University of |
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19 | * California, Berkeley and its contributors. |
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20 | * 4. Neither the name of the University nor the names of its contributors |
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21 | * may be used to endorse or promote products derived from this software |
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22 | * without specific prior written permission. |
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23 | * |
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24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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34 | * SUCH DAMAGE. |
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35 | */ |
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36 | |||
37 | #if defined(LIBC_SCCS) && !defined(lint) |
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38 | static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; |
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39 | #endif /* LIBC_SCCS and not lint */ |
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40 | |||
41 | #include <sys/types.h> |
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42 | #include <sys/stat.h> |
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43 | #include <unistd.h> |
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44 | #include <stdio.h> |
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45 | #include <stdlib.h> |
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46 | #include "local.h" |
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47 | |||
48 | /* |
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49 | * Allocate a file buffer, or switch to unbuffered I/O. |
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50 | * Per the ANSI C standard, ALL tty devices default to line buffered. |
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51 | * |
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52 | * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek |
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53 | * optimisation) right after the fstat() that finds the buffer size. |
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54 | */ |
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55 | void |
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56 | __smakebuf(fp) |
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57 | register FILE *fp; |
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58 | { |
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59 | register void *p; |
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60 | register int flags; |
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61 | size_t size; |
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62 | int couldbetty; |
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63 | |||
64 | if (fp->_flags & __SNBF) { |
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65 | fp->_bf._base = fp->_p = fp->_nbuf; |
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66 | fp->_bf._size = 1; |
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67 | return; |
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68 | } |
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69 | flags = __swhatbuf(fp, &size, &couldbetty); |
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70 | if ((p = malloc(size)) == NULL) { |
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71 | fp->_flags |= __SNBF; |
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72 | fp->_bf._base = fp->_p = fp->_nbuf; |
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73 | fp->_bf._size = 1; |
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74 | return; |
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75 | } |
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76 | __cleanup = _cleanup; |
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77 | flags |= __SMBF; |
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78 | fp->_bf._base = fp->_p = p; |
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79 | fp->_bf._size = size; |
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80 | if (couldbetty && isatty(fp->_file)) |
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81 | flags |= __SLBF; |
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82 | fp->_flags |= flags; |
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83 | } |
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84 | |||
85 | /* |
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86 | * Internal routine to determine `proper' buffering for a file. |
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87 | */ |
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88 | int |
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89 | __swhatbuf(fp, bufsize, couldbetty) |
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90 | register FILE *fp; |
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91 | size_t *bufsize; |
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92 | int *couldbetty; |
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93 | { |
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94 | struct stat st; |
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95 | |||
96 | if (fp->_file < 0 || fstat(fp->_file, &st) < 0) { |
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97 | *couldbetty = 0; |
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98 | *bufsize = BUFSIZ; |
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99 | return (__SNPT); |
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100 | } |
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101 | |||
102 | /* could be a tty iff it is a character device */ |
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103 | *couldbetty = (st.st_mode & S_IFMT) == S_IFCHR; |
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104 | if (st.st_blksize <= 0) { |
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105 | *bufsize = BUFSIZ; |
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106 | return (__SNPT); |
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107 | } |
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108 | |||
109 | /* |
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110 | * Optimise fseek() only if it is a regular file. (The test for |
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111 | * __sseek is mainly paranoia.) It is safe to set _blksize |
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112 | * unconditionally; it will only be used if __SOPT is also set. |
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113 | */ |
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114 | *bufsize = st.st_blksize; |
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115 | fp->_blksize = st.st_blksize; |
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116 | return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? |
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117 | __SOPT : __SNPT); |
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118 | } |