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af_attrs(3) Attribute Filesystem (AtFS) af_attrs(3)

NAME

af_retattr, af_retnumattr, af_retuserattr, af_rettimeattr, af_setattr, af_allattrs, af_isstdval, af_freeattr, af_freeattrbuf - AtFS attribute handling

SYNOPSIS

#include <atfs.h>

char *af_retattr (Af_key *aso, char *attrName)

int af_retnumattr (Af_key *aso, char *attrName)

Af_user af_retuserattr (Af_key *aso, char *attrName)

time_t af_rettimeattr (Af_key *aso, char *attrName)

int af_setattr (Af_key *aso, int mode, char *attrName)

int af_allattrs (Af_key *aso, Af_attrs *attrBuf)

void af_freeattr (char *attrValue);

void af_freeattrbuf (Af_attrs *attrBuf);

int af_isstdval (char *attrValue);

DESCRIPTION

af_retattr returns the value of any ASO attribute in string representation. The attrName argument denotes either a standard attribute (according to the list below) or a user defined attribute. Standard attributes are converted to a meaningful string representation if necessary. If the attribute name given to af_retattr contains an equal sign (this may be the case with user defined attributes), only the part before the equal sign will be interpreted as name. If the named attribute is a user defined attribute carrying multiple values, these will be returned in one string, with the values separated by newline ('\n') characters. If the named attribute does not exist, af_retattr returns a null pointer. If the value is empty, an empty string is returned. Note: The result string of af_retattr may reside in static memory which is overwritten on subsequent calls of af_retattr.

af_retnumattr, af_retuserattr, and af_rettimeattr return the value of the named attribute as integer, user structure or time value. These functions only apply to standard attributes with a matching type.

Af_setattr sets, modifies, or deletes user defined attributes of the ASO identified by aso. The attr parameter is a string of the form: name=value. The name may consist of any characters (even non-printable) but it may not contain Ctrl-A (\001) characters. The first equal sign that appears in the string is interpreted as the delimiter between name and value. If the string does not contain an equal sign, it is interpreted as just an attribute name without value. The mode parameter is one of the following:

Attach the given attribute to the identified ASO. If an attribute with the given name already exists, add just the value to the existing attribute. Subsequent calls of af_setattr with the same attribute name construct attributes with multiple (any number) values.
Remove the named attribute. This mode requires only the attribute name to be given as attr parameter. Removal of single values is not supported.
Replace an existing user defined attribute. The replacement fails, if no attribute with the given name exists.

af_allattrs returns the complete attribute buffer (attrBuf) of the ASO identified by aso including standard and user defined attributes. The af_retrieve(3) manual page shows the structure of the attribute buffer.

af_freeattr and af_freeattrbuf release memory eventually allocated during a af_retattr or af_allattrs call. As the result of af_retattr may reside either in static or dynamic (malloc(3)) memory, you should not use free(3) for releasing attribute value memory.

af_isstdval returns TRUE if the given attrValue string is the return value of an af_retattr call where the result was written to static rather than allocated memory. Otherwise it returns FALSE.

AtFS STANDARD ATTRIBUTES

The following is an alphabetically ordered list of all known standard attributes. AF_ATT... are string constants that may be used as attrName argument for any of the function calls described on this manual page. In parenthesis behind each symbolic constant, the type of the attribute is shown.

The versions author.
The date of last access (read or write) to the version contents.
The version name in bound version notation (e.g. foo.c[1.2]).
Absolute pathname of the version in bound version notation (e.g. /usr/andy/foo.c[1.2]).
The date of last status change. Updated, when an attributes value is changed.
The size of the delta if there is any. If the version is not stored as delta, -1 is returned.
The generation number.
The host from where the version was accessed (this attribute is quite useless, as this is always the current host).
The user who has set a lock on the version (if any).
The date of last lock change. This is empty, when there was never a lock set.
The version file type and protection. Same as st_mode in struct stat (see stat(2)).
The date of the last contents modification.
The AtFS name of the version. This has the filename extension, if there is any, stripped off.
The versions owner.
The revision number.
The file size. This may be independent of the real storage size, as most saved versions are stored as deltas (see also AF_ATTDSIZE).
The UNIX pathname leading to the version. This may be different when accessing the version from different hosts.
The version state. States are numbered 0 trough 5 from busy to frozen.
The save date. This date is not set for busy versions.
The filename extension (the string behind the rightmost period in the versions full name). See af_misc(3) for details.
The full UNIX name (without path).
The full UNIX path.
The complete version number generation.revision .

SEE ALSO

stat(2), free(3), af_misc(3), af_retrieve(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.

LIMITS

Although AtFS promises the storage of an arbitrary number of user defined attributes, the current implementation limits their number to 255. af_setattr sets the corresponding error condition if the limit is reached.

Fri Jun 25 14:33:00 1993 AtFS-1.71