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1185
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1 /* strftime - custom formatting of date and/or time |
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2 Copyright (C) 1989, 1991, 1992 Free Software Foundation, Inc. |
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3 |
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4 This program is free software; you can redistribute it and/or modify |
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5 it under the terms of the GNU General Public License as published by |
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6 the Free Software Foundation; either version 2, or (at your option) |
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7 any later version. |
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8 |
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9 This program is distributed in the hope that it will be useful, |
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10 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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12 GNU General Public License for more details. |
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13 |
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14 You should have received a copy of the GNU General Public License |
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15 along with this program; if not, write to the Free Software |
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16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
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17 |
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18 /* Note: this version of strftime lacks locale support, |
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19 but it is standalone. |
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20 |
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21 Performs `%' substitutions similar to those in printf. Except |
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22 where noted, substituted fields have a fixed size; numeric fields are |
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23 padded if necessary. Padding is with zeros by default; for fields |
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24 that display a single number, padding can be changed or inhibited by |
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25 following the `%' with one of the modifiers described below. Unknown |
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26 field specifiers are copied as normal characters. All other |
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27 characters are copied to the output without change. |
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28 |
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29 Supports a superset of the ANSI C field specifiers. |
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30 |
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31 Literal character fields: |
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32 % % |
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33 n newline |
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34 t tab |
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35 |
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36 Numeric modifiers (a nonstandard extension): |
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37 - do not pad the field |
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38 _ pad the field with spaces |
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39 |
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40 Time fields: |
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41 %H hour (00..23) |
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42 %I hour (01..12) |
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43 %k hour ( 0..23) |
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44 %l hour ( 1..12) |
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45 %M minute (00..59) |
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46 %p locale's AM or PM |
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47 %r time, 12-hour (hh:mm:ss [AP]M) |
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48 %R time, 24-hour (hh:mm) |
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49 %s time in seconds since 00:00:00, Jan 1, 1970 (a nonstandard extension) |
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50 %S second (00..61) |
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51 %T time, 24-hour (hh:mm:ss) |
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52 %X locale's time representation (%H:%M:%S) |
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53 %Z time zone (EDT), or nothing if no time zone is determinable |
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54 |
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55 Date fields: |
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56 %a locale's abbreviated weekday name (Sun..Sat) |
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57 %A locale's full weekday name, variable length (Sunday..Saturday) |
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58 %b locale's abbreviated month name (Jan..Dec) |
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59 %B locale's full month name, variable length (January..December) |
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60 %c locale's date and time (Sat Nov 04 12:02:33 EST 1989) |
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61 %C century (00..99) |
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62 %d day of month (01..31) |
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63 %e day of month ( 1..31) |
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64 %D date (mm/dd/yy) |
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65 %h same as %b |
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66 %j day of year (001..366) |
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67 %m month (01..12) |
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68 %U week number of year with Sunday as first day of week (00..53) |
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69 %w day of week (0..6) |
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70 %W week number of year with Monday as first day of week (00..53) |
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71 %x locale's date representation (mm/dd/yy) |
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72 %y last two digits of year (00..99) |
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73 %Y year (1970...) |
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74 |
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75 David MacKenzie <djm@gnu.ai.mit.edu> */ |
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76 |
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77 #ifdef HAVE_CONFIG_H |
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78 #include <config.h> |
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79 #endif |
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80 |
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81 #include <stdio.h> |
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82 #include <sys/types.h> |
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83 #if defined(TM_IN_SYS_TIME) || (!defined(HAVE_TM_ZONE) && !defined(HAVE_TZNAME)) |
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84 #include <sys/time.h> |
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85 #else |
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86 #include <time.h> |
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87 #endif |
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88 |
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89 #ifndef STDC_HEADERS |
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90 time_t mktime (); |
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91 #endif |
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92 |
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93 #if defined(HAVE_TZNAME) |
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94 extern char *tzname[2]; |
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95 #endif |
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96 |
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97 /* Types of padding for numbers in date and time. */ |
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98 enum padding |
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99 { |
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100 none, blank, zero |
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101 }; |
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102 |
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103 static char const* const days[] = |
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104 { |
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105 "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" |
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106 }; |
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107 |
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108 static char const * const months[] = |
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109 { |
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110 "January", "February", "March", "April", "May", "June", |
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111 "July", "August", "September", "October", "November", "December" |
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112 }; |
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113 |
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114 /* Add character C to STRING and increment LENGTH, |
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115 unless LENGTH would exceed MAX. */ |
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116 |
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117 #define add_char(c) \ |
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118 do \ |
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119 { \ |
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120 if (length + 1 <= max) \ |
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121 string[length++] = (c); \ |
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122 } \ |
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123 while (0) |
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124 |
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125 /* Add a 2 digit number to STRING, padding if specified. |
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126 Return the number of characters added, up to MAX. */ |
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127 |
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128 static int |
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129 add_num2 (string, num, max, pad) |
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130 char *string; |
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131 int num; |
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132 int max; |
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133 enum padding pad; |
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134 { |
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135 int top = num / 10; |
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136 int length = 0; |
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137 |
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138 if (top == 0 && pad == blank) |
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139 add_char (' '); |
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140 else if (top != 0 || pad == zero) |
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141 add_char (top + '0'); |
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142 add_char (num % 10 + '0'); |
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143 return length; |
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144 } |
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145 |
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146 /* Add a 3 digit number to STRING, padding if specified. |
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147 Return the number of characters added, up to MAX. */ |
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148 |
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149 static int |
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150 add_num3 (string, num, max, pad) |
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151 char *string; |
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152 int num; |
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153 int max; |
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154 enum padding pad; |
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155 { |
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156 int top = num / 100; |
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157 int mid = (num - top * 100) / 10; |
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158 int length = 0; |
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159 |
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160 if (top == 0 && pad == blank) |
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161 add_char (' '); |
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162 else if (top != 0 || pad == zero) |
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163 add_char (top + '0'); |
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164 if (mid == 0 && top == 0 && pad == blank) |
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165 add_char (' '); |
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166 else if (mid != 0 || top != 0 || pad == zero) |
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167 add_char (mid + '0'); |
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168 add_char (num % 10 + '0'); |
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169 return length; |
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170 } |
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171 |
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172 /* Like strncpy except return the number of characters copied. */ |
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173 |
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174 static int |
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175 add_str (to, from, max) |
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176 char *to; |
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177 const char *from; |
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178 int max; |
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179 { |
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180 int i; |
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181 |
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182 for (i = 0; from[i] && i <= max; ++i) |
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183 to[i] = from[i]; |
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184 return i; |
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185 } |
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186 |
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187 static int |
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188 add_num_time_t (string, max, num) |
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189 char *string; |
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190 int max; |
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191 time_t num; |
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192 { |
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193 /* This buffer is large enough to hold the character representation |
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194 (including the trailing NUL) of any unsigned decimal quantity |
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195 whose binary representation fits in 128 bits. */ |
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196 char buf[40]; |
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197 int length; |
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198 |
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199 if (sizeof (num) > 16) |
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200 abort (); |
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201 sprintf (buf, "%lu", (unsigned long) num); |
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202 length = add_str (string, buf, max); |
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203 return length; |
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204 } |
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205 |
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206 /* Return the week in the year of the time in TM, with the weeks |
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207 starting on Sundays. */ |
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208 |
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209 static int |
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210 sun_week (tm) |
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211 struct tm *tm; |
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212 { |
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213 int dl; |
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214 |
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215 /* Set `dl' to the day in the year of the last day of the week previous |
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216 to the one containing the day specified in TM. If the day specified |
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217 in TM is in the first week of the year, `dl' will be negative or 0. |
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218 Otherwise, calculate the number of complete weeks before our week |
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219 (dl / 7) and add any partial week at the start of the year (dl % 7). */ |
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220 dl = tm->tm_yday - tm->tm_wday; |
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221 return dl <= 0 ? 0 : dl / 7 + (dl % 7 != 0); |
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222 } |
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223 |
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224 /* Return the week in the year of the time in TM, with the weeks |
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225 starting on Mondays. */ |
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226 |
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227 static int |
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228 mon_week (tm) |
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229 struct tm *tm; |
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230 { |
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231 int dl, wday; |
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232 |
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233 if (tm->tm_wday == 0) |
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234 wday = 6; |
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235 else |
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236 wday = tm->tm_wday - 1; |
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237 dl = tm->tm_yday - wday; |
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238 return dl <= 0 ? 0 : dl / 7 + (dl % 7 != 0); |
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239 } |
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240 |
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241 #if !defined(HAVE_TM_ZONE) && !defined(HAVE_TZNAME) |
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242 char * |
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243 zone_name (tp) |
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244 struct tm *tp; |
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245 { |
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246 char *timezone (); |
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247 struct timeval tv; |
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248 struct timezone tz; |
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249 |
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250 gettimeofday (&tv, &tz); |
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251 return timezone (tz.tz_minuteswest, tp->tm_isdst); |
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252 } |
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253 #endif |
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254 |
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255 /* Format the time given in TM according to FORMAT, and put the |
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256 results in STRING. |
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257 Return the number of characters (not including terminating null) |
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258 that were put into STRING, or 0 if the length would have |
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259 exceeded MAX. */ |
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260 |
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261 size_t |
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262 strftime (string, max, format, tm) |
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263 char *string; |
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264 size_t max; |
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265 const char *format; |
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266 const struct tm *tm; |
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267 { |
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268 enum padding pad; /* Type of padding to apply. */ |
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269 size_t length = 0; /* Characters put in STRING so far. */ |
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270 |
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271 for (; *format && length < max; ++format) |
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272 { |
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273 if (*format != '%') |
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274 add_char (*format); |
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275 else |
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276 { |
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277 ++format; |
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278 /* Modifiers: */ |
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279 if (*format == '-') |
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280 { |
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281 pad = none; |
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282 ++format; |
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283 } |
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284 else if (*format == '_') |
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285 { |
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286 pad = blank; |
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287 ++format; |
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288 } |
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289 else |
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290 pad = zero; |
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291 |
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292 switch (*format) |
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293 { |
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294 /* Literal character fields: */ |
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295 case 0: |
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296 case '%': |
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297 add_char ('%'); |
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298 break; |
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299 case 'n': |
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300 add_char ('\n'); |
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301 break; |
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302 case 't': |
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303 add_char ('\t'); |
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304 break; |
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305 default: |
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306 add_char (*format); |
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307 break; |
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308 |
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309 /* Time fields: */ |
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310 case 'H': |
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311 case 'k': |
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312 length += |
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313 add_num2 (&string[length], tm->tm_hour, max - length, |
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314 *format == 'H' ? pad : blank); |
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315 break; |
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316 case 'I': |
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317 case 'l': |
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318 { |
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319 int hour12; |
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320 |
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321 if (tm->tm_hour == 0) |
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322 hour12 = 12; |
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323 else if (tm->tm_hour > 12) |
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324 hour12 = tm->tm_hour - 12; |
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325 else |
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326 hour12 = tm->tm_hour; |
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327 length += |
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328 add_num2 (&string[length], hour12, max - length, |
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329 *format == 'I' ? pad : blank); |
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330 } |
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331 break; |
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332 case 'M': |
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333 length += |
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334 add_num2 (&string[length], tm->tm_min, max - length, pad); |
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335 break; |
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336 case 'p': |
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337 if (tm->tm_hour < 12) |
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338 add_char ('A'); |
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339 else |
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340 add_char ('P'); |
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341 add_char ('M'); |
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342 break; |
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343 case 'r': |
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344 length += |
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345 strftime (&string[length], max - length, "%I:%M:%S %p", tm); |
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346 break; |
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347 case 'R': |
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348 length += |
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349 strftime (&string[length], max - length, "%H:%M", tm); |
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350 break; |
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351 |
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352 case 's': |
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353 { |
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354 struct tm writable_tm; |
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355 writable_tm = *tm; |
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356 length += add_num_time_t (&string[length], max - length, |
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357 mktime (&writable_tm)); |
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358 } |
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359 break; |
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360 |
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361 case 'S': |
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362 length += |
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363 add_num2 (&string[length], tm->tm_sec, max - length, pad); |
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364 break; |
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365 case 'T': |
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366 length += |
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367 strftime (&string[length], max - length, "%H:%M:%S", tm); |
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368 break; |
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369 case 'X': |
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370 length += |
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371 strftime (&string[length], max - length, "%H:%M:%S", tm); |
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372 break; |
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373 case 'Z': |
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374 #ifdef HAVE_TM_ZONE |
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375 length += add_str (&string[length], tm->tm_zone, max - length); |
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376 #else |
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377 #ifdef HAVE_TZNAME |
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378 if (tm->tm_isdst && tzname[1] && *tzname[1]) |
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379 length += add_str (&string[length], tzname[1], max - length); |
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380 else |
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381 length += add_str (&string[length], tzname[0], max - length); |
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382 #else |
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383 length += add_str (&string[length], zone_name (tm), max - length); |
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384 #endif |
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385 #endif |
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386 break; |
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387 |
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388 /* Date fields: */ |
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389 case 'a': |
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390 add_char (days[tm->tm_wday][0]); |
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391 add_char (days[tm->tm_wday][1]); |
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392 add_char (days[tm->tm_wday][2]); |
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393 break; |
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394 case 'A': |
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395 length += |
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396 add_str (&string[length], days[tm->tm_wday], max - length); |
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397 break; |
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398 case 'b': |
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399 case 'h': |
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400 add_char (months[tm->tm_mon][0]); |
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401 add_char (months[tm->tm_mon][1]); |
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402 add_char (months[tm->tm_mon][2]); |
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403 break; |
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404 case 'B': |
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405 length += |
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406 add_str (&string[length], months[tm->tm_mon], max - length); |
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407 break; |
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408 case 'c': |
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409 length += |
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410 strftime (&string[length], max - length, |
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411 "%a %b %d %H:%M:%S %Z %Y", tm); |
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412 break; |
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413 case 'C': |
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414 length += |
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415 add_num2 (&string[length], (tm->tm_year + 1900) / 100, |
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416 max - length, pad); |
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417 break; |
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418 case 'd': |
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419 length += |
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420 add_num2 (&string[length], tm->tm_mday, max - length, pad); |
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421 break; |
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422 case 'e': |
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423 length += |
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424 add_num2 (&string[length], tm->tm_mday, max - length, blank); |
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425 break; |
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426 case 'D': |
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427 length += |
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428 strftime (&string[length], max - length, "%m/%d/%y", tm); |
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429 break; |
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430 case 'j': |
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431 length += |
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432 add_num3 (&string[length], tm->tm_yday + 1, max - length, pad); |
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433 break; |
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434 case 'm': |
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435 length += |
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436 add_num2 (&string[length], tm->tm_mon + 1, max - length, pad); |
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437 break; |
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438 case 'U': |
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439 length += |
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440 add_num2 (&string[length], sun_week (tm), max - length, pad); |
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441 break; |
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442 case 'w': |
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443 add_char (tm->tm_wday + '0'); |
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444 break; |
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445 case 'W': |
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446 length += |
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447 add_num2 (&string[length], mon_week (tm), max - length, pad); |
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448 break; |
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449 case 'x': |
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450 length += |
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451 strftime (&string[length], max - length, "%m/%d/%y", tm); |
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452 break; |
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453 case 'y': |
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454 length += |
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455 add_num2 (&string[length], tm->tm_year % 100, |
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456 max - length, pad); |
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457 break; |
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458 case 'Y': |
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459 add_char ((tm->tm_year + 1900) / 1000 + '0'); |
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460 length += |
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461 add_num3 (&string[length], |
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462 (1900 + tm->tm_year) % 1000, max - length, zero); |
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463 break; |
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464 } |
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465 } |
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466 } |
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467 add_char (0); |
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468 return length - 1; |
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469 } |
