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SymLink.h
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1//# SymLink.h: Get information about, and manipulate symbolic links
2//# Copyright (C) 1996
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//# $Id$
27
28
29#ifndef CASA_SYMLINK_H
30#define CASA_SYMLINK_H
31
32//# Includes
33#include <casacore/casa/aips.h>
34#include <casacore/casa/OS/Path.h>
35#include <casacore/casa/OS/File.h>
36
37
38namespace casacore { //# NAMESPACE CASACORE - BEGIN
39
40// <summary>
41// Get information about, and manipulate symbolic links
42// </summary>
43// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="" demos="">
44// </reviewed>
45
46// <use visibility=export>
47
48// <prerequisite>
49// <li> Basic knowledge of the UNIX file system
50// <li> <linkto class=File>File</linkto>
51// </prerequisite>
52
53// <etymology>
54// The class SymLink handles SYMbolic LINKs in the file system.
55// </etymology>
56
57// <synopsis>
58// SymLink provides functions to manipulate and to get information about
59// symbolic links. The functions for getting information (like ownership,
60// dates) about symbolic links are inherited from the
61// <linkto class=File>File</linkto> class.
62// <br>
63// The class SymLink itself provides functions to create, remove, copy, and
64// move symbolic links. There is a function readSymLink which reads a link and
65// then returns a path and there is a function followSymLink which reads a
66// link recursively. If the link eventually refers to itself (a loop),
67// an exception will be thrown.
68// </synopsis>
69
70// <example>
71// <srcblock>
72// SymLink symLink1("isLink");
73// SymLink symLink2("isLink2");
74// SymLink symLinkA("A");
75// SymLink symLinkB("B");
76//
77// symLink1.create("~", True); // Create a symbolic link to the home
78// // directory. When it exists it will be
79// // overwritten.
80// symLink2.create("isLink", False); // Create a symbolic link to
81// // isLink. When it exists it will not
82// // be overwritten.
83// symLinkA.create(Path("B")); // Create a recursive link
84// symLinkB.create(Path("A")); // Create a recursive link
85//
86// cout << symLink1.readSymLink() << endl; // The homedirectory is printed
87// cout << symLink2.readSymLink() << endl; // isLink is printed
88// cout << symLink2.followSymLink() << endl;// The homedirectory is printed
89// cout << symLinkA.readSymLink() << endl; // B is printed
90// cout << symLinkA.followSymLink() << endl;// An exception is thrown (loop)
91// </srcblock>
92// </example>
93
94// <motivation>
95// Provide functions for manipulating and getting information
96// about symbolic links.
97// </motivation>
98
99
100class SymLink: public File
101{
102public:
103
104 // The default constructor creates a SymLink with path ".".
106
107 // Create a SymLink with the given path.
108 // An exception is thrown if the path exist and is no symbolic link
109 // or if it does not exist, but cannot be created.
110 // <group>
111 SymLink (const Path& name);
112 SymLink (const String& name);
113 SymLink (const File& name);
114 // </group>
115
116 // Copy constructor (copy semantics).
117 SymLink (const SymLink& that);
118
120
121 // Assignment (copy semantics).
123
124 // Make a symbolic link to a file given by target.
125 // An exception will be thrown if:
126 // <br>-target already exists and is no symlink
127 // <br>-or target already exists and overwrite==False
128 // <group>
129 void create (const Path& target, Bool overwrite = True);
130 void create (const String& target, Bool overwrite = True);
131 // </group>
132
133 // Copy the symlink to the target path using the system command cp.
134 // The target path can be a directory or a file (as in cp).
135 // An exception is thrown if:
136 // <br>- the target directory is not writable
137 // <br>- or the target file already exists and overwrite==False
138 // <br>- or the target file already exists and is not writable
139 // <group>
140 void copy (const Path& target, Bool overwrite = True) const;
141 void copy (const String& target, Bool overwrite = True) const;
142 // </group>
143
144 // Move the symlink to the target path using the system command mv.
145 // The target path can be a directory or a file (as in mv).
146 // An exception is thrown if:
147 // <br>- the target directory is not writable
148 // <br>- or the target file already exists and overwrite==False
149 // <br>- or the target file already exists and is not writable
150 // <group>
151 void move (const Path& target, Bool overwrite = True);
152 void move (const String& target, Bool overwrite = True);
153 // </group>
154
155 // Remove a symbolic link.
156 void remove();
157
158 // Read value of a symbolic link and return it as a Path. If
159 // the symlink does not exist, an exception will be thrown.
160 // When the symlink points to a file with a relative name,
161 // the resulting file name gets prepended by the dirname of the symlink,
162 // which is similar to the way a shell handles symlinks.
163 // E.g.
164 // <srcblock>
165 // ls > subdir/a
166 // ln -s a subdir/b
167 // more subdir/b
168 // </srcblock>
169 // The more command shows the results of subdir/a.
171
172 // As readSymLink, but the entire symlink chain is followed
173 // when the symlinks points to other symlinks.
174 // An exception is thrown if this results in a loop (that is, if more
175 // than 25 links are encountered).
177
178private:
179 // Check if the path of the file is valid.
180 // Also resolve possible symlinks.
181 void checkPath() const;
182
183 // Get the value of the symlink.
185};
186
187
188inline void SymLink::create (const String& target, Bool overwrite)
189{
190 create (Path(target), overwrite);
191}
192inline void SymLink::copy (const String& target, Bool overwrite) const
193{
194 copy (Path(target), overwrite);
195}
196inline void SymLink::move (const String& target, Bool overwrite)
197{
198 move (Path(target), overwrite);
199}
200
201
202
203} //# NAMESPACE CASACORE - END
204
205#endif
String: the storage and methods of handling collections of characters.
Definition String.h:225
this file contains all the compiler specific defines
Definition mainpage.dox:28
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:42
const Bool True
Definition aipstype.h:43