Ubuntu Manpage: af_find, af_cachefind, af_initattrs, af_getkey, af_dropkey, af_dropset, af_dropall

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.