pxattr Namespace Reference

Provide a uniform C++ API for extended file attributes on Linux/FreeBSD and MacOSX. More...

Enumerations
enum	nspace { PXATTR_USER }
	nspace might be used in the future if we support multiple namespaces. More...
enum	flags { PXATTR_NONE = 0, PXATTR_NOFOLLOW = 1, PXATTR_CREATE = 2, PXATTR_REPLACE = 4 }
	Flags can modify the behaviour of some methods. More...

Functions
bool	get (const string &path, const string &name, string *value, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Retrieve the named attribute from path.
bool	get (int fd, const string &name, string *value, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Retrieve the named attribute from open file.
bool	set (const string &path, const string &name, const string &value, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Set the named attribute on path.
bool	set (int fd, const string &name, const string &value, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Set the named attribute on open file.
bool	del (const string &path, const string &name, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Delete the named attribute from path.
bool	del (int fd, const string &name, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	Delete the named attribute from open file.
bool	list (const string &path, vector< string > *names, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	List attribute names from path.
bool	list (int fd, vector< string > *names, flags flags=PXATTR_NONE, nspace dom=PXATTR_USER)
	List attribute names from open file.
bool	sysname (nspace dom, const string &pname, string *sname)
	Compute actual/system attribute name from external name (ie: myattr->user.myattr)
bool	pxname (nspace dom, const string &sname, string *pname)
	Compute external name from actual/system name (ie: user.myattr->myattr)

Detailed Description

Provide a uniform C++ API for extended file attributes on Linux/FreeBSD and MacOSX.

We only deal with user attributes. Other namespaces are very system-specific and would be difficult to use in a portable way.

Linux and FreeBSD treat differently the attributes name space segmentation: Linux uses the first name segment ("user.", "system.", ...), FreeBSD uses an enumeration.

We handle this by using only domain-internal names in the interface: that is, the caller specifies the names as, ie, 'org.myapp.somename' not 'user.org.myapp.somename'. pxattr will deal with adding/removing the 'user.' part as needed.

MacOsX does not segment the attribute name space.

In order to avoid conflicts, it is recommended that attributes names be chosen in a "reverse dns" fashion, ie: org.recoll.indexing.status

The interface provided should work the same way on all 3 systems, it papers over such differences as the "list" output format, the existence of CREATE/UPDATE distinctions, etc.

Diagnostics: all functions return false on error, and preserve the errno value or set it as appropriate.

For path-based interfaces, the PXATTR_NOFOLLOW flag can be set to decide if symbolic links will be acted on or followed.

Enumeration Type Documentation

enum pxattr::flags

Flags can modify the behaviour of some methods.

Enumerator:

PXATTR_NOFOLLOW	Act on link instead of following it.
PXATTR_CREATE	Fail if existing.
PXATTR_REPLACE	Fail if new.

enum pxattr::nspace

nspace might be used in the future if we support multiple namespaces.

Enumerator:

PXATTR_USER

User name space.