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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- G N A T . L O C K _ F I L E S --
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6 -- --
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7 -- B o d y --
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8 -- --
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9 -- Copyright (C) 1998-2017, Free Software Foundation, Inc. --
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 with System;
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33
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34 package body GNAT.Lock_Files is
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35
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36 Dir_Separator : Character;
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37 pragma Import (C, Dir_Separator, "__gnat_dir_separator");
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38
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39 ---------------
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40 -- Lock_File --
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41 ---------------
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42
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43 procedure Lock_File
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44 (Directory : Path_Name;
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45 Lock_File_Name : Path_Name;
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46 Wait : Duration := 1.0;
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47 Retries : Natural := Natural'Last)
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48 is
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49 Dir : aliased String := Directory & ASCII.NUL;
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50 File : aliased String := Lock_File_Name & ASCII.NUL;
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51
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52 function Try_Lock (Dir, File : System.Address) return Integer;
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53 pragma Import (C, Try_Lock, "__gnat_try_lock");
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54
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55 begin
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56 -- If a directory separator was provided, just remove the one we have
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57 -- added above.
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58
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59 if Directory (Directory'Last) = Dir_Separator
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60 or else Directory (Directory'Last) = '/'
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61 then
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62 Dir (Dir'Last - 1) := ASCII.NUL;
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63 end if;
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64
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65 -- Try to lock the file Retries times
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66
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67 for I in 0 .. Retries loop
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68 if Try_Lock (Dir'Address, File'Address) = 1 then
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69 return;
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70 end if;
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71
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72 exit when I = Retries;
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73 delay Wait;
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74 end loop;
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75
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76 raise Lock_Error;
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77 end Lock_File;
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78
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79 ---------------
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80 -- Lock_File --
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81 ---------------
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82
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83 procedure Lock_File
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84 (Lock_File_Name : Path_Name;
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85 Wait : Duration := 1.0;
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86 Retries : Natural := Natural'Last)
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87 is
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88 begin
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89 for J in reverse Lock_File_Name'Range loop
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90 if Lock_File_Name (J) = Dir_Separator
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91 or else Lock_File_Name (J) = '/'
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92 then
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93 Lock_File
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94 (Lock_File_Name (Lock_File_Name'First .. J - 1),
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95 Lock_File_Name (J + 1 .. Lock_File_Name'Last),
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96 Wait,
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97 Retries);
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98 return;
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99 end if;
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100 end loop;
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101
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102 Lock_File (".", Lock_File_Name, Wait, Retries);
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103 end Lock_File;
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104
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105 -----------------
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106 -- Unlock_File --
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107 -----------------
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108
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109 procedure Unlock_File (Lock_File_Name : Path_Name) is
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110 S : aliased String := Lock_File_Name & ASCII.NUL;
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111
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112 procedure unlink (A : System.Address);
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113 pragma Import (C, unlink, "unlink");
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114
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115 begin
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116 unlink (S'Address);
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117 end Unlock_File;
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118
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119 -----------------
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120 -- Unlock_File --
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121 -----------------
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122
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123 procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name) is
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124 begin
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125 if Directory (Directory'Last) = Dir_Separator
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126 or else Directory (Directory'Last) = '/'
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127 then
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128 Unlock_File (Directory & Lock_File_Name);
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129 else
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130 Unlock_File (Directory & Dir_Separator & Lock_File_Name);
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131 end if;
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132 end Unlock_File;
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133
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134 end GNAT.Lock_Files;
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