292 lines
7.2 KiB
C
292 lines
7.2 KiB
C
/*
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* CDE - Common Desktop Environment
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*
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* Copyright (c) 1993-2012, The Open Group. All rights reserved.
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*
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* These libraries and programs are free software; you can
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* redistribute them and/or modify them under the terms of the GNU
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* Lesser General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* These libraries and programs are distributed in the hope that
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* they will be useful, but WITHOUT ANY WARRANTY; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU Lesser General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with these libraries and programs; if not, write
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* to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
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* Floor, Boston, MA 02110-1301 USA
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*/
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/*
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* $XConsortium: rw_lock.cc /main/3 1996/06/11 17:38:50 cde-hal $
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*
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* Copyright (c) 1993 HAL Computer Systems International, Ltd.
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* All rights reserved. Unpublished -- rights reserved under
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* the Copyright Laws of the United States. USE OF A COPYRIGHT
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* NOTICE IS PRECAUTIONARY ONLY AND DOES NOT IMPLY PUBLICATION
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* OR DISCLOSURE.
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*
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* THIS SOFTWARE CONTAINS CONFIDENTIAL INFORMATION AND TRADE
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* SECRETS OF HAL COMPUTER SYSTEMS INTERNATIONAL, LTD. USE,
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* DISCLOSURE, OR REPRODUCTION IS PROHIBITED WITHOUT THE
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* PRIOR EXPRESS WRITTEN PERMISSION OF HAL COMPUTER SYSTEMS
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* INTERNATIONAL, LTD.
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*
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* RESTRICTED RIGHTS LEGEND
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* Use, duplication, or disclosure by the Government is subject
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* to the restrictions as set forth in subparagraph (c)(l)(ii)
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* of the Rights in Technical Data and Computer Software clause
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* at DFARS 252.227-7013.
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*
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* HAL COMPUTER SYSTEMS INTERNATIONAL, LTD.
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* 1315 Dell Avenue
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* Campbell, CA 95008
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*
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*/
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#include "atomic_lock.h"
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#include "rw_lock.h"
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Boolean read_lock(char* lock_file_path,
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char* writing_lock_file_path,
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char* ai_path,
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char* reader_info, int& offset,
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char*& ai_info
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)
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{
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atomic_lock l(lock_file_path);
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if ( l.lock() == false ) {
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MESSAGE(cerr, "read_lock(): can't do atomic locking");
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return false;
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}
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Boolean ok;
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if ( false == exist_file( writing_lock_file_path ) ) {
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fstream x(ai_path, ios::app);
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if ( !x ) {
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MESSAGE(cerr, "read_lock(): can't open lock file");
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throw(streamException(x.rdstate()));
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}
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#ifdef C_API
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offset = bytes(x.rdbuf() -> fd());
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#else
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offset = bytes(ai_info);
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#endif
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x << "A-" << reader_info << "\n";
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x.close();
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ok = true;
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} else {
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fstream x(ai_path, ios::in);
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if ( !x ) {
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MESSAGE(cerr, "read_lock(): can't open lock file");
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throw(streamException(x.rdstate()));
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}
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#ifdef C_API
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int sz = bytes(x.rdbuf() -> fd());
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#else
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int sz = bytes(ai_info);
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#endif
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ai_info = new char[sz+1];
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ai_info[0] = 0;
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x.getline(ai_info, sz);
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x.close();
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ok = false;
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}
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if ( l.unlock() == false ) {
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MESSAGE(cerr, "read_lock(): can't do atomic unlocking");
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return false;
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}
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return ok;
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}
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Boolean read_unlock(char* lock_file_path, char* ai_path, int offset)
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{
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atomic_lock l(lock_file_path);
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if ( l.lock() == false ) {
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MESSAGE(cerr, "read_lock(): can't do atomic locking");
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return false;
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}
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Boolean ok ;
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fstream x(ai_path, ios::in|ios::out);
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if ( !x ) {
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MESSAGE(cerr, "read_unlock(): can't open lock file");
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throw(streamException(x.rdstate()));
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}
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x.seekg( offset, ios::beg );
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x.put('I');
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///////////////////////////////////////////////
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// truncate the info_file if no active readers
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// and the file size is over 1k
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///////////////////////////////////////////////
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#ifdef C_API
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if ( bytes(x.rdbuf() -> fd()) > 1024 ) {
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#else
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if ( bytes(ai_path) > 1024 ) {
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#endif
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ok = false;
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char buf[BUFSIZ];
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/////////////////////////////////////////
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// scan the info file for active readers
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/////////////////////////////////////////
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while ( x.getline(buf, BUFSIZ) ) {
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if ( buf[0] == 'A' ) {
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ok = true;
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break;
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}
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}
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if ( ok == false )
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if ( truncate(ai_path, 0) != 0 ) {
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MESSAGE(cerr, "read_unlock(): can't truncate");
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throw(systemException(errno));
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}
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}
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x.close();
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if ( l.unlock() == false ) {
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MESSAGE(cerr, "read_lock(): can't do atomic locking");
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return false;
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}
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return true;
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}
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Boolean write_lock(char* lock_file_path,
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char* writing_lock_path,
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char* ai_path, char* writer_info,
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char*& ai_info
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)
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{
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unsigned int len, slen;
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atomic_lock l(lock_file_path);
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if ( l.lock() == false ) {
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MESSAGE(cerr, "write_lock(): can't do atomic locking");
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return false;
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}
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Boolean ok = true;
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fstream x(ai_path, ios::in|ios::out);
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if (!x) {
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MESSAGE(cerr, "write_lock(): can't open info file");
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throw(streamException(x.rdstate()));
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}
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char buf[BUFSIZ];
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#ifdef C_API
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int sz = bytes(x.rdbuf() -> fd());
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#else
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int sz = bytes(ai_path);
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#endif
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ai_info = new char[sz+1];
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ai_info[0] = 0;
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/////////////////////////////////////////
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// scan the info file for active readers
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/////////////////////////////////////////
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while ( x.getline(buf, BUFSIZ) ) {
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if ( buf[0] == 'A' ) {
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ok = false;
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slen = strlen(ai_info);
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len = MIN(strlen(buf+1), BUFSIZ - 1 - slen);
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*((char *) memcpy(ai_info + slen, buf+1, len) + len) = '\0';
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slen = strlen(ai_info);
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len = MIN(1, BUFSIZ - 1 - slen);
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*((char *) memcpy(ai_info + slen, "\n", len) + len) = '\0';
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}
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}
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x.close();
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if ( exist_file( writing_lock_path ) == false ) {
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if ( ok == true ) {
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delete [] ai_info;
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/////////////////////////////////////////
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// create the access info file
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/////////////////////////////////////////
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if(truncate(ai_path, 0) != 0 ) {
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throw(systemException(errno));
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}
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fstream x(ai_path, ios::out);
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x << "A-" << writer_info << "\n";
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/////////////////////////////////////////
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// create the writing lock file
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/////////////////////////////////////////
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if ( creat(writing_lock_path, 0755) == -1 )
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ok = false;
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}
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} else
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ok = false;
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if ( l.unlock() == false ) {
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MESSAGE(cerr, "write_lock(): can't do atomic unlocking");
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return false;
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}
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return ok;
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}
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Boolean write_unlock(char* lock_file_path, char* writing_lock_path,
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char* ai_path
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)
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{
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atomic_lock l(lock_file_path);
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if ( l.lock() == false ) {
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MESSAGE(cerr, "write_unlock(): can't do atomic locking");
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return false;
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}
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Boolean ok;
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if ( del_file(writing_lock_path) == 0 &&
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del_file(ai_path) == 0
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)
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ok = true;
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else
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ok = false;
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if ( l.unlock() == false ) {
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MESSAGE(cerr, "write_unlock(): can't do atomic unlocking");
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return false;
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}
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return ok;
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}
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