librostlab  1.0.20
rostlab/cwd_resource.h
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00001 /*
00002     Copyright (C) 2011 Laszlo Kajan, Technical University of Munich, Germany
00003 
00004     This file is part of librostlab.
00005 
00006     librostlab is free software: you can redistribute it and/or modify
00007     it under the terms of the GNU Lesser General Public License as published by
00008     the Free Software Foundation, either version 3 of the License, or
00009     (at your option) any later version.
00010 
00011     This program is distributed in the hope that it will be useful,
00012     but WITHOUT ANY WARRANTY; without even the implied warranty of
00013     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014     GNU Lesser General Public License for more details.
00015 
00016     You should have received a copy of the GNU Lesser General Public License
00017     along with this program.  If not, see <http://www.gnu.org/licenses/>.
00018 */
00019 #ifndef ROSTLAB_CWD_RESOURCE
00020 #define ROSTLAB_CWD_RESOURCE
00021 
00022 #include <errno.h>
00023 #include <stdexcept>
00024 #include <unistd.h>
00025 #include <string.h>
00026 
00027 namespace rostlab {
00028 
00029 class cwd_resource
00030 {
00031   private:
00032     string        _olddir;
00033     // this is a resource - disable copy contructor and copy assignment
00034                   cwd_resource( const cwd_resource& ){};
00035     cwd_resource&
00036                   operator=(const cwd_resource&){return *this;};
00037   public:
00038                   cwd_resource() : _olddir("") {};
00039 
00040                   cwd_resource( const string& __dirname ) : _olddir("")
00041     {
00042       acquire( __dirname );
00043     }
00044 
00045     inline void   acquire( const string& __dirname ) throw (runtime_error)
00046     {
00047       release();
00048       //
00049       char *buf = NULL;
00050       if( ( buf = getcwd( NULL, 0 ) ) == NULL ) throw runtime_error( string("failed to get working directory: ") + strerror( errno ) );
00051       string cwd = buf; free( buf ); buf = NULL;
00052 
00053       if( chdir( __dirname.c_str() ) ) throw runtime_error( "failed to chdir to '" + __dirname + "': " + strerror( errno ) );
00054       _olddir = cwd;
00055     }
00056 
00057     inline void   release() throw (runtime_error)
00058     {
00059       if( _olddir != "" )
00060       {
00061         if( chdir( _olddir.c_str() ) ) throw runtime_error( "failed to chdir to '" + _olddir + "': " + strerror( errno ) );
00062         _olddir = "";
00063       }
00064     }
00065 
00066     virtual       ~cwd_resource()
00067     {
00068       release();
00069     }
00070 };
00071 
00072 };
00073 
00074 #endif // ROSTLAB_CWD_RESOURCE
00075 // vim:et:ts=2:ai:
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