1 | /* |
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2 | * Copyright (c) 1990 The Regents of the University of California. |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms are permitted |
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6 | * provided that the above copyright notice and this paragraph are |
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7 | * duplicated in all such forms and that any documentation, |
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8 | * advertising materials, and other materials related to such |
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9 | * distribution and use acknowledge that the software was developed |
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10 | * by the University of California, Berkeley. The name of the |
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11 | * University may not be used to endorse or promote products derived |
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12 | * from this software without specific prior written permission. |
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13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
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14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
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15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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16 | */ |
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17 | |
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18 | /* |
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19 | FUNCTION |
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20 | <<fgets>>, <<fgets_unlocked>>---get character string from a file or stream |
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21 | |
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22 | INDEX |
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23 | fgets |
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24 | INDEX |
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25 | fgets_unlocked |
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26 | INDEX |
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27 | _fgets_r |
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28 | INDEX |
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29 | _fgets_unlocked_r |
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30 | |
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31 | SYNOPSIS |
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32 | #include <stdio.h> |
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33 | char *fgets(char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>); |
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34 | |
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35 | #define _GNU_SOURCE |
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36 | #include <stdio.h> |
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37 | char *fgets_unlocked(char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>); |
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38 | |
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39 | #include <stdio.h> |
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40 | char *_fgets_r(struct _reent *<[ptr]>, char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>); |
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41 | |
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42 | #include <stdio.h> |
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43 | char *_fgets_unlocked_r(struct _reent *<[ptr]>, char *restrict <[buf]>, int <[n]>, FILE *restrict <[fp]>); |
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44 | |
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45 | DESCRIPTION |
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46 | Reads at most <[n-1]> characters from <[fp]> until a newline |
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47 | is found. The characters including to the newline are stored |
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48 | in <[buf]>. The buffer is terminated with a 0. |
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49 | |
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50 | <<fgets_unlocked>> is a non-thread-safe version of <<fgets>>. |
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51 | <<fgets_unlocked>> may only safely be used within a scope |
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52 | protected by flockfile() (or ftrylockfile()) and funlockfile(). This |
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53 | function may safely be used in a multi-threaded program if and only |
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54 | if they are called while the invoking thread owns the (FILE *) |
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55 | object, as is the case after a successful call to the flockfile() or |
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56 | ftrylockfile() functions. If threads are disabled, then |
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57 | <<fgets_unlocked>> is equivalent to <<fgets>>. |
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58 | |
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59 | The functions <<_fgets_r>> and <<_fgets_unlocked_r>> are simply |
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60 | reentrant versions that are passed the additional reentrant structure |
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61 | pointer argument: <[ptr]>. |
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62 | |
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63 | RETURNS |
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64 | <<fgets>> returns the buffer passed to it, with the data |
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65 | filled in. If end of file occurs with some data already |
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66 | accumulated, the data is returned with no other indication. If |
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67 | no data are read, NULL is returned instead. |
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68 | |
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69 | PORTABILITY |
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70 | <<fgets>> should replace all uses of <<gets>>. Note however |
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71 | that <<fgets>> returns all of the data, while <<gets>> removes |
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72 | the trailing newline (with no indication that it has done so.) |
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73 | |
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74 | <<fgets_unlocked>> is a GNU extension. |
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75 | |
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76 | Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>, |
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77 | <<lseek>>, <<read>>, <<sbrk>>, <<write>>. |
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78 | */ |
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79 | |
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80 | #include <_ansi.h> |
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81 | #include <stdio.h> |
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82 | #include <string.h> |
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83 | #include "local.h" |
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84 | |
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85 | #ifdef __IMPL_UNLOCKED__ |
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86 | #define _fgets_r _fgets_unlocked_r |
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87 | #define fgets fgets_unlocked |
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88 | #endif |
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89 | |
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90 | /* |
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91 | * Read at most n-1 characters from the given file. |
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92 | * Stop when a newline has been read, or the count runs out. |
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93 | * Return first argument, or NULL if no characters were read. |
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94 | */ |
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95 | |
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96 | char * |
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97 | _fgets_r (struct _reent * ptr, |
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98 | char *__restrict buf, |
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99 | int n, |
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100 | FILE *__restrict fp) |
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101 | { |
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102 | size_t len; |
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103 | char *s; |
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104 | unsigned char *p, *t; |
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105 | |
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106 | if (n < 2) /* sanity check */ |
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107 | return 0; |
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108 | |
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109 | s = buf; |
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110 | |
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111 | CHECK_INIT(ptr, fp); |
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112 | |
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113 | _newlib_flockfile_start (fp); |
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114 | #ifdef __SCLE |
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115 | if (fp->_flags & __SCLE) |
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116 | { |
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117 | int c = 0; |
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118 | /* Sorry, have to do it the slow way */ |
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119 | while (--n > 0 && (c = __sgetc_r (ptr, fp)) != EOF) |
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120 | { |
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121 | *s++ = c; |
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122 | if (c == '\n') |
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123 | break; |
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124 | } |
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125 | if (c == EOF && s == buf) |
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126 | { |
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127 | _newlib_flockfile_exit (fp); |
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128 | return NULL; |
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129 | } |
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130 | *s = 0; |
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131 | _newlib_flockfile_exit (fp); |
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132 | return buf; |
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133 | } |
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134 | #endif |
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135 | |
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136 | n--; /* leave space for NUL */ |
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137 | do |
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138 | { |
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139 | /* |
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140 | * If the buffer is empty, refill it. |
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141 | */ |
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142 | if ((len = fp->_r) <= 0) |
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143 | { |
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144 | if (__srefill_r (ptr, fp)) |
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145 | { |
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146 | /* EOF: stop with partial or no line */ |
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147 | if (s == buf) |
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148 | { |
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149 | _newlib_flockfile_exit (fp); |
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150 | return 0; |
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151 | } |
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152 | break; |
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153 | } |
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154 | len = fp->_r; |
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155 | } |
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156 | p = fp->_p; |
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157 | |
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158 | /* |
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159 | * Scan through at most n bytes of the current buffer, |
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160 | * looking for '\n'. If found, copy up to and including |
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161 | * newline, and stop. Otherwise, copy entire chunk |
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162 | * and loop. |
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163 | */ |
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164 | if (len > n) |
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165 | len = n; |
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166 | t = (unsigned char *) memchr ((void *) p, '\n', len); |
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167 | if (t != 0) |
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168 | { |
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169 | len = ++t - p; |
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170 | fp->_r -= len; |
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171 | fp->_p = t; |
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172 | (void) memcpy ((void *) s, (void *) p, len); |
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173 | s[len] = 0; |
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174 | _newlib_flockfile_exit (fp); |
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175 | return (buf); |
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176 | } |
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177 | fp->_r -= len; |
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178 | fp->_p += len; |
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179 | (void) memcpy ((void *) s, (void *) p, len); |
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180 | s += len; |
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181 | } |
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182 | while ((n -= len) != 0); |
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183 | *s = 0; |
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184 | _newlib_flockfile_end (fp); |
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185 | return buf; |
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186 | } |
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187 | |
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188 | #ifndef _REENT_ONLY |
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189 | |
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190 | char * |
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191 | fgets (char *__restrict buf, |
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192 | int n, |
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193 | FILE *__restrict fp) |
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194 | { |
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195 | return _fgets_r (_REENT, buf, n, fp); |
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196 | } |
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197 | |
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198 | #endif /* !_REENT_ONLY */ |
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