Provided by: atfs-dev_1.4pl6-16.1build1_amd64 
NAME
atRetAttr, atSetAttr, atAttrName, atAttrValue, atAllAttrs, atFreeAttrs - attribute
handling
SYNOPSIS
#include <atfs.h>
#include <atfstk.h>
char*atRetAttr (Af_key *aso, char *attributeName);
void atFreeAttr (char *attributeValue);
int atSetAttr (Af_key *aso, char *attribute, int mode);
int atSetAttrFile (Af_key *aso, char *filename);
char*atAttrName (char *attribute);
char*atAttrValue (char *attribute);
int atMatchAttr (Af_key *aso, char *attribute);
DESCRIPTION
The AtFS Toolkit Library extends the AtFS attribute handling. It introduces additional
standard attribute names and a list of attribute value types.
atRetAttr returns a string representation of the value(s) of the aso attribute named
attributeName. If the attribute value is preceded by a value special character (see list
below), it will be evaluated accordingly. When the evaluation fails, the original
attribute value, including value special character, is returned. When the attribute value
is empty, an empty string is returned. When the attribute does not exist or on any other
error condition, a null pointer is returned.
Attribute citations (like 7.0) in attribute values will always be expanded by atRetAttr.
There is no way to disable attribute expansion. If you need the raw, unexpanded attribute
value, use af_retattr (manual page af_attrs(3)).
The attribute value returned by atRetAttr either resides in static memory (in case of AtFS
standard attributes) or in allocated memory. Use atFreeAttr on each attribute value
returned by atRetAttr when this not needed any longer. This will recycle allocated memory
if possible.
atSetAttr sets the attribute attribute for aso. It calls af_setattr (manual page
af_attrs(3)) and hence understands the modes AF_ADD, AF_REMOVE, and AF_REPLACE.
Alternatively, the mode argument is ignored, when the equal sign between attribute name
and value is preceded by either a plus (+) or a minus (-) sign for adding and deleting
attribute values. The value special character at (@) will also be evaluated. atSetAttr
opens the file and reads its contents. If either the opening or reading fails, the
attribute setting is aborted and returns FALSE. On successful execution, atSetAttr returns
TRUE, otherwise FALSE.
atSetAttrFile evaluates a file containing attributes. If opens the named file (filename)
and interprets each line in the file as attribute argument to atSetAttr.
atAttrName fills a static memory buffer with the name of the given attribute and returns a
pointer to this buffer. Subsequent calls of atAttrName overwrite previous results.
atAttrValue returns a pointer to the value part of attribute.
atMatchAttr checks if aso has the given attribute. Result values are TRUE or FALSE. If
just an attribute name is given, atMatchAttr returns a positive result if the attribute
exists in the asos attribute list or, in the case that it is a standard attribute, if it's
value is non null. A full attribute (name and value) must match an attribute in the asos
attribute list. The value of the given attribute argument may be a (sh(1)) pattern.
ATTRIBUTE FORMAT
Attributes have the general format name=value. Additionally, a plus or minus sign may
precede and a value special character may follow the equal sign
(<name>[+-]=[^@!*]<value>).
plus (+)
A plus sign preceding the equal sign indicates, that the value shall be added to
existing values (no matter if there are any).
minus (-)
With the minus sign, the value shall be removed from the list of values, if it
exists.
The following is the complete list of value special characters recognized by AtFStk.
circumflex (^)
The value is regarded as a reference to a file or ASO carrying the real attribute
value as contents.
at (@) An attribute value starting with an at (@) is considered to be a file name from
where the real attribute value is to be taken. In contrary to the circumflex
notation above, this causes the file read only once, when setting the attribute
value.
exclam (!)
This introduces execution attributes. The attribute value is regarded as command
to be passed to a shell process. On access, the command will be executed and its
output will be catched as real attribute value.
asterisk (*)
This denotes a pointer attribute modeling relationships between attributed
software objects. When atSetAttr finds an attribute value with an asterisk as
first character it interprets the remaining value string as version identifier
and tries to bind it using atBindVersion (manual page atbind(3)). On success, the
network path (see atNetworkPath(3)) of the identifies ASO will be stored as
attribute value together with the leading asterisk. atRetAttr maps pointer
attributes to local pathnames using atLocalPath (manual page atnetwork(3)).
STANDARD ATTRIBUTES
There are a number of standard attributes defined by the AtFS toolkit library and by AtFS
(Attribute Filesystem) for each ASO. For a list of the AtFS standard attributes see the
af_attrs(3) manual page. This is a list of all standard attribute names defined in
AtFStk.
Header A compound attribute consisting of a $Header: Label followed by the bound file
name (AF_ATTBOUND), the version date (vtime - see below), the versions author and
state and a trailing dollar sign ($). Example:
$Header: attrs.c[1.1] Tue Dec 1 17:01:10 1992 andy@cs.tu-berlin.de proposed $
Log The versions modification history from the very beginning. This might be long.
note The modification note of the version as set by the author.
pred, succ
The physical predecessor/successor version as stored in AtFS. If there is none,
the string n/a (not available) is returned.
vtime The version date. For busy versions, this is the date of last modification, for
saved versions, it is the saving date.
xpon, xpoff
Pseudo attribute turning attribute expansion on and off (see above).
Some other names are mapped to the appropriate AtFS standard name:
AtFStk name AtFS name (constant definition)AtFStk nameAtFS name (constant definition)
atime AF_ATTATIME revision AF_ATTREV
author AF_ATTAUTHOR self AF_ATTBOUND
ctime AF_ATTCTIME selfpath AF_ATTBOUNDPATH
dsize AF_ATTDSIZE size AF_ATTSIZE
generation AF_ATTGEN stateAF_ATTSTATE
host AF_ATTHOST stime AF_ATTSTIME
lock AF_ATTLOCKER syspath AF_ATTSPATH
ltime AF_ATTLTIME type AF_ATTTYPE
mtime AF_ATTMTIME unixname AF_ATTUNIXNAME
name AF_ATTNAME version AF_ATTVERSION
owner AF_ATTOWNER
atSetAttr may also be used to set standard attributes where possible. Attributes that may
be altered are
Attribute Mapped to AtFS function
author af_chauthor (af_protect(3))
generation, revision, versionaf_svnum (af_version(3))
mode af_chmod (af_protect(3))
owner af_chowner (af_protect(3))
state af_sstate (af_version(3))
note af_snote (af_note(3))
RETURN VALUES
On error, the atError variable is set to a nun null value, and atErrMsg holds a diagnostic
message. atRetAttr returns a null pointer on error, or if the desired attribute does not
exist. atSetAttr and atSetAttrFile return FALSE on any error condition. atMatchAttr
returns FALSE if an error occurred or if the attribute does not match.
SEE ALSO
af_attrs(3), atbind(3), atnetwork(3)