NAME

       rtapi_open_as_root - Open a file with "root" privilege

SYNTAX

       #include <rtapi.h>

       int rtapi_open_as_root(const char *filename, int flags)

ARGUMENTS

       filename
              The  filename to open, as in open(2).  Note that rtapi has no well-defined "current
              directory", so this should be an absolute path, but this is not enforced.

       flags  The open flags, as in open(2).  Should never include bits that open or create files
              (e.g.,  O_CREAT, O_APPEND, etc) as this API is not intended for creating or writing
              files, but this is not enforced.

DESCRIPTION

       In "uspace" realtime, root privileges are dropped whenever possible.  This API temporarily
       switches  on root privileges to open a file, and switches them off before returning.  This
       can be useful for example when accessing device nodes or memory-mapped I/O.

       In the case of PCI  devices  on  x86  and  x86-64  systems,  prefer  the  linux-style  PCI
       interfaces provided in <rtapi_pci.h>.

RETURN VALUE

       In  case of success, the nonnegative file descriptor opened.  If the caller does not close
       it, it remains open until rtapi_app exits.

       In case of failure, a negative errno value.

REALTIME CONSIDERATIONS

       Call only from realtime initcode in "uspace" realtime.

SEE ALSO

       open(2), rtapi_pci(3)