NAME

       af_crkey, af_open, af_close, af_rm, af_establish, af_restore - AtFS file system operations

SYNOPSIS

       #include <stdio.h>
       #include <atfs.h>

       int af_crkey (char *syspath, char *name, char *type, Af_key *aso)

       FILE *af_open (Af_key *aso, char *mode)

       int af_close (FILE *stream)

       int af_rm (Af_key *aso)

       int af_establish (Af_key *aso, char *filename)

       int af_restore (Af_key *aso, Af_key *restoredAso)

DESCRIPTION

       af_crkey creates an object key for a regular UNIX file identified by name, type and system
       path.  syspath is an either absolute or relative directory name. An empty  syspath  refers
       to  the  current  directory.  By convention, AtFS interprets the filename suffix of a UNIX
       file as type and the filename without suffix as name attribute.  To give an  example,  the
       path name

              /usr/andy/foo.c is split up in /usr/andy (syspath) foo (name) c (type)

       A  period  as  first  character  in the filename is always considered as part of the name.
       Hence .cshrc has a name but no type. "." and ".." are recognized as  names  too.   If  the
       named  UNIX  file does not exist, af_crkey creates an empty file.  The created key remains
       accessible until it is explicitly given up by af_dropkey (manual page af_retrieve(3)).

       af_open opens the contents of the ASO pointed to by aso and associates a stream with it. A
       pointer  to the FILE structure associated with the stream is returned. Mode is a character
       string that is either "r[+]", "w[+]" or "a[+]". See fopen(3)  for  further  details.  Upon
       error, af_open returns a NULL pointer.  Non-busy ASOs can only be opened with mode "r". If
       a non-busy ASO is opened, it's contents will be placed in a temporary  UNIX  file  due  to
       storage of versions as deltas.

       af_close  closes  a  stream  previously opened by af_open (see fclose(3)). Temporary files
       created by af_open, holding the contents of a saved  versions  are  unlinked  right  after
       being opened so that they will automatically disappear on closing.

       af_rm  removes  the specified ASO. The application has to have a lock (see af_lock(3)) set
       on the ASO that shall be deleted by af_rm. ASOs with the state attribute set  to  accessed
       or  frozen  cannot  be  removed.   If  you  keep  multiple  keys of one object (perhaps in
       different sets) af_rm invalidates all keys of  the  removed  object.   As  AtFS  does  not
       support  multiple  links  to  saved  ASOs, af_rm on a saved version always does a physical
       removal.

       af_establish establishes the contents of the saved version, pointed to by aso  in  a  file
       named filename. The resulting file gets the version's modification and access date.

       af_restore is used to restore formerly saved derived ASOs into their old file location. It
       also restores the file modification and access date. This function cannot  be  applied  to
       source  objects.  af_restore  returns  the  key  of  the  restored  version  in the buffer
       restoredAso.

SEE ALSO

       fopen(3), fclose(3), af_retrieve(3), af_lock(3)

DIAGNOSTICS

       Upon error, -1 or a nil pointer (depending on the return type) is returned and af_errno is
       set to the corresponding error number.