1 | /* backupfile.c -- make Emacs style backup file names |
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2 | Copyright (C) 1990,1991,1992,1993,1995,1997 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; see the file COPYING. |
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16 | If not, write to the Free Software Foundation, |
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17 | 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
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18 | |
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19 | /* Written by David MacKenzie <djm@gnu.ai.mit.edu>. |
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20 | Some algorithms adapted from GNU Emacs. */ |
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21 | |
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22 | #if HAVE_CONFIG_H |
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23 | # include <config.h> |
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24 | #endif |
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25 | |
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26 | #include <argmatch.h> |
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27 | #include <backupfile.h> |
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28 | |
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29 | #include <stdio.h> |
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30 | #include <sys/types.h> |
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31 | #if HAVE_STRING_H |
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32 | # include <string.h> |
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33 | #else |
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34 | # include <strings.h> |
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35 | #endif |
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36 | |
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37 | #if HAVE_DIRENT_H |
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38 | # include <dirent.h> |
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39 | # define NLENGTH(direct) strlen ((direct)->d_name) |
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40 | #else |
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41 | # define dirent direct |
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42 | # define NLENGTH(direct) ((size_t) (direct)->d_namlen) |
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43 | # if HAVE_SYS_NDIR_H |
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44 | # include <sys/ndir.h> |
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45 | # endif |
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46 | # if HAVE_SYS_DIR_H |
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47 | # include <sys/dir.h> |
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48 | # endif |
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49 | # if HAVE_NDIR_H |
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50 | # include <ndir.h> |
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51 | # endif |
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52 | #endif |
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53 | |
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54 | #if CLOSEDIR_VOID |
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55 | /* Fake a return value. */ |
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56 | # define CLOSEDIR(d) (closedir (d), 0) |
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57 | #else |
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58 | # define CLOSEDIR(d) closedir (d) |
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59 | #endif |
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60 | |
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61 | #if STDC_HEADERS |
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62 | # include <stdlib.h> |
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63 | #else |
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64 | char *malloc (); |
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65 | #endif |
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66 | |
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67 | #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H |
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68 | # define HAVE_DIR 1 |
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69 | #else |
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70 | # define HAVE_DIR 0 |
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71 | #endif |
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72 | |
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73 | #if HAVE_LIMITS_H |
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74 | # include <limits.h> |
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75 | #endif |
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76 | #ifndef CHAR_BIT |
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77 | #define CHAR_BIT 8 |
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78 | #endif |
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79 | /* Upper bound on the string length of an integer converted to string. |
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80 | 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit; |
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81 | add 1 for integer division truncation; add 1 more for a minus sign. */ |
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82 | #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2) |
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83 | |
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84 | /* ISDIGIT differs from isdigit, as follows: |
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85 | - Its arg may be any int or unsigned int; it need not be an unsigned char. |
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86 | - It's guaranteed to evaluate its argument exactly once. |
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87 | - It's typically faster. |
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88 | Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that |
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89 | only '0' through '9' are digits. Prefer ISDIGIT to isdigit unless |
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90 | it's important to use the locale's definition of `digit' even when the |
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91 | host does not conform to Posix. */ |
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92 | #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9) |
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93 | |
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94 | #if D_INO_IN_DIRENT |
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95 | # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0) |
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96 | #else |
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97 | # define REAL_DIR_ENTRY(dp) 1 |
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98 | #endif |
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99 | |
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100 | /* Which type of backup file names are generated. */ |
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101 | enum backup_type backup_type = none; |
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102 | |
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103 | /* The extension added to file names to produce a simple (as opposed |
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104 | to numbered) backup file name. */ |
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105 | const char *simple_backup_suffix = ".orig"; |
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106 | |
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107 | static int max_backup_version __BACKUPFILE_P ((const char *, const char *)); |
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108 | static int version_number __BACKUPFILE_P ((const char *, const char *, size_t)); |
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109 | |
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110 | /* Return the name of the new backup file for file FILE, |
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111 | allocated with malloc. Return 0 if out of memory. |
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112 | FILE must not end with a '/' unless it is the root directory. |
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113 | Do not call this function if backup_type == none. */ |
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114 | |
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115 | char * |
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116 | find_backup_file_name (file) |
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117 | const char *file; |
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118 | { |
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119 | size_t backup_suffix_size_max; |
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120 | size_t file_len = strlen (file); |
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121 | size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4; |
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122 | char *s; |
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123 | const char *suffix = simple_backup_suffix; |
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124 | |
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125 | /* Allow room for simple or `.~N~' backups. */ |
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126 | backup_suffix_size_max = strlen (simple_backup_suffix) + 1; |
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127 | if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max) |
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128 | backup_suffix_size_max = numbered_suffix_size_max; |
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129 | |
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130 | s = malloc (file_len + backup_suffix_size_max + numbered_suffix_size_max); |
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131 | if (s) |
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132 | { |
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133 | strcpy (s, file); |
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134 | |
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135 | #if HAVE_DIR |
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136 | if (backup_type != simple) |
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137 | { |
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138 | int highest_backup; |
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139 | size_t dir_len = base_name (s) - s; |
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140 | |
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141 | strcpy (s + dir_len, "."); |
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142 | highest_backup = max_backup_version (file + dir_len, s); |
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143 | if (! (backup_type == numbered_existing && highest_backup == 0)) |
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144 | { |
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145 | char *numbered_suffix = s + (file_len + backup_suffix_size_max); |
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146 | sprintf (numbered_suffix, ".~%d~", highest_backup + 1); |
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147 | suffix = numbered_suffix; |
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148 | } |
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149 | strcpy (s, file); |
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150 | } |
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151 | #endif /* HAVE_DIR */ |
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152 | |
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153 | addext (s, suffix, '~'); |
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154 | } |
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155 | return s; |
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156 | } |
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157 | |
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158 | #if HAVE_DIR |
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159 | |
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160 | /* Return the number of the highest-numbered backup file for file |
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161 | FILE in directory DIR. If there are no numbered backups |
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162 | of FILE in DIR, or an error occurs reading DIR, return 0. |
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163 | */ |
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164 | |
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165 | static int |
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166 | max_backup_version (file, dir) |
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167 | const char *file; |
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168 | const char *dir; |
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169 | { |
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170 | DIR *dirp; |
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171 | struct dirent *dp; |
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172 | int highest_version; |
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173 | int this_version; |
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174 | size_t file_name_length; |
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175 | |
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176 | dirp = opendir (dir); |
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177 | if (!dirp) |
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178 | return 0; |
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179 | |
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180 | highest_version = 0; |
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181 | file_name_length = strlen (file); |
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182 | |
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183 | while ((dp = readdir (dirp)) != 0) |
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184 | { |
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185 | if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4) |
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186 | continue; |
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187 | |
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188 | this_version = version_number (file, dp->d_name, file_name_length); |
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189 | if (this_version > highest_version) |
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190 | highest_version = this_version; |
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191 | } |
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192 | if (CLOSEDIR (dirp)) |
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193 | return 0; |
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194 | return highest_version; |
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195 | } |
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196 | |
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197 | /* If BACKUP is a numbered backup of BASE, return its version number; |
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198 | otherwise return 0. BASE_LENGTH is the length of BASE. |
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199 | */ |
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200 | |
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201 | static int |
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202 | version_number (base, backup, base_length) |
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203 | const char *base; |
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204 | const char *backup; |
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205 | size_t base_length; |
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206 | { |
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207 | int version; |
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208 | const char *p; |
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209 | |
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210 | version = 0; |
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211 | if (strncmp (base, backup, base_length) == 0 |
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212 | && backup[base_length] == '.' |
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213 | && backup[base_length + 1] == '~') |
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214 | { |
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215 | for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p) |
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216 | version = version * 10 + *p - '0'; |
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217 | if (p[0] != '~' || p[1]) |
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218 | version = 0; |
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219 | } |
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220 | return version; |
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221 | } |
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222 | #endif /* HAVE_DIR */ |
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223 | |
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224 | static const char * const backup_args[] = |
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225 | { |
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226 | "never", "simple", "nil", "existing", "t", "numbered", 0 |
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227 | }; |
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228 | |
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229 | static const enum backup_type backup_types[] = |
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230 | { |
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231 | simple, simple, numbered_existing, numbered_existing, numbered, numbered |
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232 | }; |
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233 | |
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234 | /* Return the type of backup indicated by VERSION. |
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235 | Unique abbreviations are accepted. */ |
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236 | |
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237 | enum backup_type |
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238 | get_version (version) |
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239 | const char *version; |
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240 | { |
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241 | int i; |
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242 | |
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243 | if (version == 0 || *version == 0) |
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244 | return numbered_existing; |
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245 | i = argmatch (version, backup_args); |
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246 | if (i < 0) |
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247 | { |
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248 | invalid_arg ("version control type", version, i); |
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249 | exit (2); |
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250 | } |
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251 | return backup_types[i]; |
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252 | } |
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