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Diffstat (limited to 'include/sane/sanei_access.h')
| -rw-r--r-- | include/sane/sanei_access.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/include/sane/sanei_access.h b/include/sane/sanei_access.h new file mode 100644 index 0000000..d668b98 --- /dev/null +++ b/include/sane/sanei_access.h @@ -0,0 +1,97 @@ +/* sane - Scanner Access Now Easy. + + Copyright (C) 2005 Gerhard Jaeger <gerhard@gjaeger.de> + + This file is part of the SANE package. + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, + MA 02111-1307, USA. + + As a special exception, the authors of SANE give permission for + additional uses of the libraries contained in this release of SANE. + + The exception is that, if you link a SANE library with other files + to produce an executable, this does not by itself cause the + resulting executable to be covered by the GNU General Public + License. Your use of that executable is in no way restricted on + account of linking the SANE library code into it. + + This exception does not, however, invalidate any other reasons why + the executable file might be covered by the GNU General Public + License. + + If you submit changes to SANE to the maintainers to be included in + a subsequent release, you agree by submitting the changes that + those changes may be distributed with this exception intact. + + If you write modifications of your own for SANE, it is your choice + whether to permit this exception to apply to your modifications. + If you do not wish that, delete this exception notice. + +*/ + +/** @file sanei_access.h + * Interface file for the sanei_access functions. + * + * The idea is to provide some simple locking/unlocking mecanism, which + * can be used to protect device access from more than one frontend + * simultaneously. + */ + +#ifndef sanei_access_h +#define sanei_access_h + +#include "../include/sane/config.h" +#include "../include/sane/sane.h" + +/** Initialize sanei_access. + * + * This function must be called before any other sanei_access function. + * + * @param backend - backend name, who uses this lib + */ +extern void sanei_access_init( const char * backend ); + +/** Set a lock. + * + * The function tries to open/create exclusively a lock file in + * $PATH_SANE_LOCK_DIR. + * If the file could be created successfully, the function fills in the + * process ID. + * The complete filename of the lockfile is created as follows: + * $PATH_SANE_LOCK_DIR/LCK..<devicename> + * If the lock could not be set, the function tries it until the timeout + * period has been elapsed. + * + * @param devicename - unique part of the lockfile name + * @param timeout - time in seconds to try to set a lock + * @return + * - SANE_STATUS_GOOD - if the lock has been successfully set + * - SANE_STATUS_ACCESS_DENIED - the lock could not set + */ +extern SANE_Status sanei_access_lock( const char * devicename, SANE_Word timeout ); + +/** Unlock a previously set lock. + * + * The function tries to unlock a previously created lock. The lockfile will be + * closed and removed. + * + * @param devicename - part of the lockfile name, use for sanei_acess_lock() + * @return + * - SANE_STATUS_GOOD - currently the one and only return value + */ +extern SANE_Status sanei_access_unlock( const char * devicename ); + +#endif /* sanei_access_h */ |