Filedescriptors create files at construction, each later access becomes
a reopen on the now existing file.
file_handle_acquire() reopens the file to gain a handle when required
and checks that the file is really the one we expected (ino and dev num)
* add 'backend' for backend global initialization/destruction
and common functions.
* WIP: 'file' acts as interface to named files, provides posix
filehandles with and acquire/release function pair.
* 'filehandle' manages posix filehandles internally, refcounted.
* WIP: 'filehandlecache' keeps unused filehandles in a MRU cache
* WIP: test for filehandle management
* improved filedescriptor test
* make registry initialization singleton, no parameters.
* remove registry init from all functions, has to be called explicitly.
* some nobug improvements
It is now possible to acquire/release filedescriptors for existing files
and files to be created.
Filedescriptors are managed in a registry by refcounts, they get
automatically destructed when the last user releases them.
We have 'File' which associates a name with a file and will be used to
offer an interface for the application.
Posix 'Filehandles' which are managed in a 'Filehandlecache' to utilize
a limited number of fd's at optimum.
Internally we use 'Filedescriptor's which manage files, mapping and all
kinds of metadata. Filedescriptors weak referenced by a registry and freed
when the last user vanishes.
LUMIERA_MUTEX_SECTION takes now a nobug flag as first argument and
a nobug resource-handle as second argument.
This change works forward for the NoBug resource tracker and
deadlock detector.
* GNU_SOURCE by default now
* improved use of ACX_PTHREAD, replaces $CC and others
* all checks for mandatory things instantly exit for now
in future this might produce an report at the end
* ported checks from scons over here
