NAME

       af_find, af_cachefind, af_initattrs, af_getkey, af_dropkey, af_dropset, af_dropall  - AtFS
       retrieve interface

SYNOPSIS

       #include <atfs.h>

       int af_find (Af_attrs *attrbuf, Af_set *resultset)

       int af_cachefind (Af_attrs *attrbuf, Af_set *resultset)

       int af_initattrs (Af_attrs *attrbuf)

       int af_getkey (char *syspath, char *name, char *type, int gen, int rev, Af_key *aso)

       int af_dropkey (Af_key *key)

       int af_dropset (Af_set *set)

       int af_dropall (void)

DESCRIPTION

       af_find and af_cachefind retrieve ASOs by given attributes.  af_find  operates  on  source
       objects  and af_cachefind only on derived objects. The keys of all found ASOs are returned
       in  resultset.   The  keys  returned  in  resultset  are  randomly  ordered.  af_find  and
       af_cachefind  expect  resultset  to be a pointer to an empty set structure. Both functions
       return the number of found ASOs.

       The retrieve arguments are passed in an attribute  buffer  (attrbuf).  Attrbuf  should  be
       initialized  by  af_initattrs  before  calling  af_find (resp. af_cachefind). af_initattrs
       disables all fields in the attribute buffer. The application may then enable single fields
       by setting a desired attribute value. The initial settings of the single fields are listed
       below with the structure of the attribute buffer.

       Setting one of the Af_user fields in the attribute buffer to AF_NOUSER causes only ASOs to
       be  selected, where the corresponding user attribute is not set. This makes only sense for
       af_locker, when the selection of ASOs that are not locked is desired.

       On the af_mode field, a bitwise comparison is performed. In this case, all  ASOs  will  be
       selected  that  have  at least all required mode bits (given in af_mode) set in their mode
       field. An exact match is not required.

       The first two fields in the attribute buffer denote  the  search  space.   Generally,  the
       search  space for a retrieve operation is a directory.  The directory name is given in the
       af_syspath field in the attribute  buffer.  If  no  system  path  is  given,  the  current
       directory  is  searched.  The  fields  af_host  in  the attribute buffer is ignored in the
       current implementation.

       The structure of the attribute buffer is the following:
       typedef struct {                                  initial value
           char  af_host[MAXHOSTNAMELEN];                /* hostname (ignored) */""
           char  af_syspath[MAXPATHLEN+1];               /* system path */""
           char  af_name[MAXNAMLEN+1];                   /* filename */"*"
           char  af_type[MAXTYPLEN]; /* filename extension (type) */"*"
           int   af_gen;             /* generation number */-1
           int   af_rev;             /* revision number */-1
           int   af_state;           /* version state */ -1
           Af_user                   af_owner;           /* owner */{ "", "", "" }
           Af_user                   af_author;          /* author */{ "", "", "" }
           off_t af_size;            /* size of file */  -1
           u_short                   af_mode;            /* protection */0
           Af_user                   af_locker;          /* locker */{ "", "", "" }
           time_t                    af_mtime;           /* date of last modification */-1
           time_t                    af_atime;           /* date of last access */-1
           time_t                    af_ctime;           /* date of last status change*/-1
           time_t                    af_stime;           /* save date */-1
           time_t                    af_ltime;           /* date of last lock change */-1
           char  *af_udattrs[AF_MAXUDAS];                /* user defined attributes */
       } Af_attrs;

       It is possible to pass a list of user defined attributes as retrieve arguments.  The  list
       of  pointers  af_udattrs  in  the  attribute buffer can be filled with strings of the form
       name[=value].  The list must be terminated by a nil pointer.

       The user defined attributes are interpreted in the following way:

       empty list (first entry is a nil pointer)
                             matches every ASO.

       "" (first entry is an empty string)
                             matches every ASO that has no user defined attributes.

       name[=]               matches, if a user defined attribute with the given name is present.

       name=value            matches all ASOs that have a corresponding user  defined  attribute,
                             that has at least the given value.

       af_getkey  builds  up  an object key by a combination of attributes (pathname, name, type,
       generation number, revision number and variant name) uniquely identifying  a  source  ASO.
       Upon  successful  completion, the found object key is returned in the buffer key.  Instead
       of explicit version numbers, you can pass the pseudo-numbers AF_BUSYVERS, AF_FIRSTVERS  or
       AF_LASTVERS to af_getkey.  af_getkey works only on source objects. The call

              af_getkey ("", "otto", "c", AF_BUSYVERS, AF_BUSYVERS, key)

       leads to the key of the file (busy version) named otto.c in the current directory.

              af_getkey ("", "otto", "c", AF_LASTVERS, AF_LASTVERS, key)

       delivers the last saved version (if present) of the history of otto.c.

       After  having  retrieved  a  key  or  a set of keys, the data for the corresponding object
       version(s) remains cached in memory as long as the application does  not  explicitly  give
       the key back. The function af_dropkey gives a key back and releases the object version.  A
       retrieved set of keys has to be given back by  use  of  af_dropset.  af_dropall  sets  all
       reference  counters  for cached object versions to zero, that means, it gives all formerly
       retrieved keys and sets back.

DIAGNOSTICS

       af_find returns the number of found ASOs. Upon error, -1 is returned and af_errno  is  set
       to the corresponding error number.