1 """ |
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2 Generic configuration file output |
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3 """ |
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4 |
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5 import os, os.path, tempfile, shutil |
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6 |
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7 class ConfObject (object) : |
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8 """ |
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9 An object that can be written to a ConfFile, as multiple lines of text. |
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10 """ |
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11 |
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12 def __init__ (self, comments=None) : |
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13 """ |
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14 Initialize with the given list of comments. Comments that are None should be ignore. |
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15 """ |
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16 |
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17 # init the comments list |
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18 self.comments = comments or [] |
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19 |
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20 def add_comment (self, comment) : |
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21 """ |
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22 Add a comment to be rendered in the output. |
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23 """ |
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24 |
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25 # add it |
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26 self.comments.append(comment) |
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27 |
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28 def fmt_lines (self) : |
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29 """ |
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30 Yield a series of lines to be output in the file |
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31 """ |
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32 |
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33 abstract |
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34 |
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35 class File (ConfObject) : |
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36 """ |
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37 A single configuration file on the filesystem. |
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38 |
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39 Configuration files are themselves ConfObject's, although this must be implemented in the inheriting class. |
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40 """ |
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41 |
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42 def __init__ (self, name, path, backup_suffix='.bak', mode=0644) : |
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43 """ |
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44 Initialize the config file, but don't open it yet |
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45 |
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46 @param name the human-readable friendly name for the config file |
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47 @param path the full filesystem path for the file |
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48 @param backup_suffix rename the old file by adding this suffix when replacing it |
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49 @param mode the permission bits for the new file |
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50 """ |
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51 |
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52 self.name = name |
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53 self.path = path |
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54 self.backup_suffix = backup_suffix |
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55 self.mode = mode |
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56 |
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57 def write_file (self, file) : |
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58 """ |
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59 Write out this config's stuff into the given file |
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60 """ |
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61 |
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62 writer = Writer(file) |
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63 writer.write_obj(self) |
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64 |
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65 def write (self) : |
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66 """ |
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67 Write out a new config file with this config's stuff using the following procedure: |
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68 |
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69 * lock the real file |
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70 * open a new temporary file, and write out the objects into that, closing it |
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71 * move the real file out of the way |
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72 * move the temporary file into the real file's place |
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73 * unlock the real file |
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74 """ |
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75 |
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76 # XXX: how to aquire the lock? |
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77 # XXX: this needs checking over |
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78 |
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79 # open the new temporary file |
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80 # XXX: ensure fd is closed |
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81 tmp_fd, tmp_path = tempfile.mkstemp(prefix=self.name) |
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82 |
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83 # ...as a file |
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84 tmp_file = os.fdopen(tmp_fd, "w") |
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85 |
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86 # fix the permissions |
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87 os.chmod(tmp_path, self.mode) |
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88 |
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89 # write it |
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90 self.write_file(tmp_file) |
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91 |
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92 # close it |
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93 tmp_file.close() |
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94 |
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95 # move the old file out of the way |
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96 if os.path.exists(self.path) : |
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97 os.rename(self.path, self.path + self.backup_suffix) |
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98 |
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99 # move the new file in |
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100 shutil.move(tmp_path, self.path) |
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101 |
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102 class Writer (object) : |
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103 """ |
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104 A conf.Writer is used to write out a new conf.File (as a temporary file) |
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105 """ |
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106 |
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107 def __init__ (self, file) : |
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108 """ |
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109 @param file the temporary file object |
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110 """ |
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111 |
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112 self.file = file |
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113 |
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114 def write_line (self, line) : |
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115 """ |
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116 Write a single line to the file |
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117 """ |
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118 |
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119 self.file.write("%s\n" % (line, )) |
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120 |
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121 def write_lines (self, lines) : |
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122 """ |
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123 Write a series of lines into the file |
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124 """ |
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125 |
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126 for line in lines : |
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127 self.write_line(line) |
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128 |
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129 def write_obj (self, obj) : |
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130 """ |
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131 Write a single object to the file |
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132 """ |
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133 |
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134 # just write out all the lines |
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135 self.write_lines(obj.fmt_lines()) |
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136 |
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