root / prex-0.9.0 / usr / lib / libc / stdio / freopen.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*-
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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. Neither the name of the University nor the names of its contributors
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17 | * may be used to endorse or promote products derived from this software
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18 | * without specific prior written permission.
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19 | *
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20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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30 | * SUCH DAMAGE.
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31 | */
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32 | |||
33 | #include <sys/types.h> |
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34 | #include <sys/stat.h> |
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35 | #include <fcntl.h> |
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36 | #include <errno.h> |
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37 | #include <unistd.h> |
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38 | #include <stdio.h> |
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39 | #include <stdlib.h> |
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40 | #include "local.h" |
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41 | |||
42 | /*
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43 | * Re-direct an existing, open (probably) file to some other file.
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44 | * ANSI is written such that the original file gets closed if at
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45 | * all possible, no matter what.
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46 | */
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47 | FILE * |
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48 | freopen(file, mode, fp) |
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49 | const char *file, *mode; |
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50 | FILE *fp; |
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51 | { |
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52 | int f;
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53 | int flags, isopen, oflags, sverrno, wantfd;
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54 | |||
55 | if ((flags = __sflags(mode, &oflags)) == 0) { |
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56 | (void) fclose(fp);
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57 | return (NULL); |
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58 | } |
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59 | |||
60 | if (!__sdidinit)
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61 | __sinit(); |
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62 | |||
63 | /*
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64 | * There are actually programs that depend on being able to "freopen"
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65 | * descriptors that weren't originally open. Keep this from breaking.
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66 | * Remember whether the stream was open to begin with, and which file
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67 | * descriptor (if any) was associated with it. If it was attached to
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68 | * a descriptor, defer closing it; freopen("/dev/stdin", "r", stdin)
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69 | * should work. This is unnecessary if it was not a Unix file.
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70 | */
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71 | if (fp->_flags == 0) { |
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72 | fp->_flags = __SEOF; /* hold on to it */
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73 | isopen = 0;
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74 | wantfd = -1;
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75 | } else {
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76 | /* flush the stream; ANSI doesn't require this. */
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77 | if (fp->_flags & __SWR)
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78 | (void) __sflush(fp);
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79 | /* if close is NULL, closing is a no-op, hence pointless */
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80 | isopen = 1;
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81 | if ((wantfd = fp->_file) < 0 && isopen) { |
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82 | (void) __sclose(fp);
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83 | isopen = 0;
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84 | } |
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85 | } |
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86 | |||
87 | /* Get a new descriptor to refer to the new file. */
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88 | f = open(file, oflags, DEFFILEMODE); |
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89 | if (f < 0 && isopen) { |
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90 | /* If out of fd's close the old one and try again. */
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91 | if (errno == ENFILE || errno == EMFILE) {
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92 | (void) __sclose(fp);
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93 | isopen = 0;
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94 | f = open(file, oflags, DEFFILEMODE); |
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95 | } |
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96 | } |
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97 | sverrno = errno; |
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98 | |||
99 | /*
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100 | * Finish closing fp. Even if the open succeeded above, we cannot
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101 | * keep fp->_base: it may be the wrong size. This loses the effect
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102 | * of any setbuffer calls, but stdio has always done this before.
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103 | */
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104 | if (isopen)
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105 | (void) __sclose(fp);
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106 | if (fp->_flags & __SMBF)
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107 | free((char *)fp->_bf._base);
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108 | fp->_w = 0;
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109 | fp->_r = 0;
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110 | fp->_p = NULL;
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111 | fp->_bf._base = NULL;
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112 | fp->_bf._size = 0;
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113 | if (HASUB(fp))
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114 | FREEUB(fp); |
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115 | fp->_ub._size = 0;
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116 | |||
117 | if (f < 0) { /* did not get it after all */ |
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118 | fp->_flags = 0; /* set it free */ |
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119 | errno = sverrno; /* restore in case _close clobbered */
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120 | return (NULL); |
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121 | } |
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122 | |||
123 | /*
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124 | * If reopening something that was open before on a real file, try
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125 | * to maintain the descriptor. Various C library routines (perror)
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126 | * assume stderr is always fd STDERR_FILENO, even if being freopen'd.
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127 | */
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128 | if (wantfd >= 0 && f != wantfd) { |
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129 | if (dup2(f, wantfd) >= 0) { |
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130 | (void) close(f);
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131 | f = wantfd; |
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132 | } |
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133 | } |
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134 | |||
135 | fp->_flags = flags; |
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136 | fp->_file = f; |
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137 | return (fp);
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138 | } |