File : g-locfil.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- G N A T . L O C K _ F I L E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1998-2009, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
17 -- --
18 -- --
19 -- --
20 -- --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
31
32 with System;
33
34 package body GNAT.Lock_Files is
35
36 Dir_Separator : Character;
37 pragma Import (C, Dir_Separator, "__gnat_dir_separator");
38
39 ---------------
40 -- Lock_File --
41 ---------------
42
43 procedure Lock_File
44 (Directory : Path_Name;
45 Lock_File_Name : Path_Name;
46 Wait : Duration := 1.0;
47 Retries : Natural := Natural'Last)
48 is
49 Dir : aliased String := Directory & ASCII.NUL;
50 File : aliased String := Lock_File_Name & ASCII.NUL;
51
52 function Try_Lock (Dir, File : System.Address) return Integer;
53 pragma Import (C, Try_Lock, "__gnat_try_lock");
54
55 begin
56 -- If a directory separator was provided, just remove the one we have
57 -- added above.
58
59 if Directory (Directory'Last) = Dir_Separator
60 or else Directory (Directory'Last) = '/'
61 then
62 Dir (Dir'Last - 1) := ASCII.NUL;
63 end if;
64
65 -- Try to lock the file Retries times
66
67 for I in 0 .. Retries loop
68 if Try_Lock (Dir'Address, File'Address) = 1 then
69 return;
70 end if;
71
72 exit when I = Retries;
73 delay Wait;
74 end loop;
75
76 raise Lock_Error;
77 end Lock_File;
78
79 ---------------
80 -- Lock_File --
81 ---------------
82
83 procedure Lock_File
84 (Lock_File_Name : Path_Name;
85 Wait : Duration := 1.0;
86 Retries : Natural := Natural'Last)
87 is
88 begin
89 for J in reverse Lock_File_Name'Range loop
90 if Lock_File_Name (J) = Dir_Separator
91 or else Lock_File_Name (J) = '/'
92 then
93 Lock_File
94 (Lock_File_Name (Lock_File_Name'First .. J - 1),
95 Lock_File_Name (J + 1 .. Lock_File_Name'Last),
96 Wait,
97 Retries);
98 return;
99 end if;
100 end loop;
101
102 Lock_File (".", Lock_File_Name, Wait, Retries);
103 end Lock_File;
104
105 -----------------
106 -- Unlock_File --
107 -----------------
108
109 procedure Unlock_File (Lock_File_Name : Path_Name) is
110 S : aliased String := Lock_File_Name & ASCII.NUL;
111
112 procedure unlink (A : System.Address);
113 pragma Import (C, unlink, "unlink");
114
115 begin
116 unlink (S'Address);
117 end Unlock_File;
118
119 -----------------
120 -- Unlock_File --
121 -----------------
122
123 procedure Unlock_File (Directory : Path_Name; Lock_File_Name : Path_Name) is
124 begin
125 if Directory (Directory'Last) = Dir_Separator
126 or else Directory (Directory'Last) = '/'
127 then
128 Unlock_File (Directory & Lock_File_Name);
129 else
130 Unlock_File (Directory & Dir_Separator & Lock_File_Name);
131 end if;
132 end Unlock_File;
133
134 end GNAT.Lock_Files;