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.