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Rev | Author | Line No. | Line |
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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 | #if 0 |
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39 | static char sccsid[] = "@(#)ungetc.c 8.2 (Berkeley) 11/3/93"; |
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40 | #endif |
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41 | static const char rcsid[] = |
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42 | "$\Id: ungetc.c,v 1.3 1996/06/22 10:33:59 jraynard Exp $"; |
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43 | #endif /* LIBC_SCCS and not lint */ |
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44 | |||
45 | #include <stdio.h> |
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46 | #include <stdlib.h> |
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47 | #include <string.h> |
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48 | #include "local.h" |
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49 | #ifdef _THREAD_SAFE |
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50 | #include <pthread.h> |
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51 | #include "pthread_private.h" |
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52 | #endif |
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53 | |||
54 | static int __submore __P((FILE *)); |
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55 | |||
56 | /* |
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57 | * Expand the ungetc buffer `in place'. That is, adjust fp->_p when |
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58 | * the buffer moves, so that it points the same distance from the end, |
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59 | * and move the bytes in the buffer around as necessary so that they |
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60 | * are all at the end (stack-style). |
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61 | */ |
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62 | static int |
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63 | __submore(fp) |
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64 | register FILE *fp; |
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65 | { |
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66 | register int i; |
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67 | register unsigned char *p; |
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68 | |||
69 | if (fp->_ub._base == fp->_ubuf) { |
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70 | /* |
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71 | * Get a new buffer (rather than expanding the old one). |
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72 | */ |
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73 | if ((p = malloc((size_t)BUFSIZ)) == NULL) |
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74 | return (EOF); |
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75 | fp->_ub._base = p; |
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76 | fp->_ub._size = BUFSIZ; |
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77 | p += BUFSIZ - sizeof(fp->_ubuf); |
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78 | for (i = sizeof(fp->_ubuf); --i >= 0;) |
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79 | p[i] = fp->_ubuf[i]; |
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80 | fp->_p = p; |
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81 | return (0); |
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82 | } |
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83 | i = fp->_ub._size; |
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84 | p = realloc(fp->_ub._base, (size_t)(i << 1)); |
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85 | if (p == NULL) |
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86 | return (EOF); |
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87 | /* no overlap (hence can use memcpy) because we doubled the size */ |
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88 | (void)memcpy((void *)(p + i), (void *)p, (size_t)i); |
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89 | fp->_p = p + i; |
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90 | fp->_ub._base = p; |
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91 | fp->_ub._size = i << 1; |
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92 | return (0); |
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93 | } |
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94 | |||
95 | int |
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96 | ungetc(c, fp) |
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97 | int c; |
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98 | register FILE *fp; |
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99 | { |
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100 | if (c == EOF) |
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101 | return (EOF); |
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102 | if (!__sdidinit) |
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103 | __sinit(); |
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104 | #ifdef _THREAD_SAFE |
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105 | _thread_flockfile(fp,__FILE__,__LINE__); |
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106 | #endif |
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107 | if ((fp->_flags & __SRD) == 0) { |
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108 | /* |
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109 | * Not already reading: no good unless reading-and-writing. |
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110 | * Otherwise, flush any current write stuff. |
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111 | */ |
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112 | if ((fp->_flags & __SRW) == 0) { |
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113 | #ifdef _THREAD_SAFE |
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114 | _thread_funlockfile(fp); |
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115 | #endif |
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116 | return (EOF); |
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117 | } |
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118 | if (fp->_flags & __SWR) { |
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119 | if (__sflush(fp)) { |
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120 | #ifdef _THREAD_SAFE |
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121 | _thread_funlockfile(fp); |
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122 | #endif |
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123 | return (EOF); |
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124 | } |
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125 | fp->_flags &= ~__SWR; |
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126 | fp->_w = 0; |
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127 | fp->_lbfsize = 0; |
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128 | } |
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129 | fp->_flags |= __SRD; |
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130 | } |
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131 | c = (unsigned char)c; |
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132 | |||
133 | /* |
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134 | * If we are in the middle of ungetc'ing, just continue. |
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135 | * This may require expanding the current ungetc buffer. |
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136 | */ |
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137 | if (HASUB(fp)) { |
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138 | if (fp->_r >= fp->_ub._size && __submore(fp)) { |
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139 | #ifdef _THREAD_SAFE |
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140 | _thread_funlockfile(fp); |
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141 | #endif |
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142 | return (EOF); |
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143 | } |
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144 | *--fp->_p = c; |
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145 | fp->_r++; |
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146 | #ifdef _THREAD_SAFE |
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147 | _thread_funlockfile(fp); |
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148 | #endif |
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149 | return (c); |
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150 | } |
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151 | fp->_flags &= ~__SEOF; |
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152 | |||
153 | /* |
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154 | * If we can handle this by simply backing up, do so, |
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155 | * but never replace the original character. |
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156 | * (This makes sscanf() work when scanning `const' data.) |
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157 | */ |
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158 | if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && |
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159 | fp->_p[-1] == c) { |
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160 | fp->_p--; |
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161 | fp->_r++; |
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162 | #ifdef _THREAD_SAFE |
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163 | _thread_funlockfile(fp); |
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164 | #endif |
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165 | return (c); |
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166 | } |
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167 | |||
168 | /* |
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169 | * Create an ungetc buffer. |
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170 | * Initially, we will use the `reserve' buffer. |
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171 | */ |
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172 | fp->_ur = fp->_r; |
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173 | fp->_up = fp->_p; |
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174 | fp->_ub._base = fp->_ubuf; |
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175 | fp->_ub._size = sizeof(fp->_ubuf); |
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176 | fp->_ubuf[sizeof(fp->_ubuf) - 1] = c; |
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177 | fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1]; |
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178 | fp->_r = 1; |
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179 | #ifdef _THREAD_SAFE |
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180 | _thread_funlockfile(fp); |
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181 | #endif |
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182 | return (c); |
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183 | } |