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.Dd February 19, 2015
.Dt LIBHAMMER 3
.Os
.Sh NAME
.Nm hammer
.Nd HAMMER file system interface
.Sh LIBRARY
.Lb libhammer
.Sh SYNOPSIS
.In libhammer.h
.Sh DESCRIPTION
The
.Nm
library provides a set of functions which serve as an interface to applications
that need to obtain information or perform maintenance operations in
.Xr HAMMER 5
file systems.
.Sh INTRODUCTION
This library is an attempt to factor out most of the code in the initial
.Xr hammer 8
program greatly reducing its complexity and taking advantage of all the
functionality it contained helping other programs to reuse it.
.Pp
There are several parts of the
.Xr HAMMER 5
file system for which this library provides an API:
.Bl -bullet
.It
.Em Information facilities:
The following information is gathered and exposed by this library:
.Bl -dash -offset indent
.It
File system specific information such as size, big block details, version,
PFSes, snapshots, mount points.
.It
Statistical data like number of B-Tree operations, number of device operations,
number of undo operations.
.El
.It
.Em Pseudo-file systems:
These are independent sub file systems within a HAMMER file system.
After
.Nm
library initialisation the list of pseudo-file systems will be available in the
.Vt libhammer_fsinfo
structure within a
.Dv TAILQ .
.Pp
Creating and deleting pseudo-file systems is not yet supported by this library.
.It
.Em Snapshots:
Per PFS point in time snapshots are kept in the file system meta-data since
HAMMER version 3.
A list of snapshots is collected and placed within a
.Dv TAILQ
for each PFS.
.Pp
Creating and deleting snapshots is not yet supported by this library.
.El
.Sh INITIALISATION
Before any API call the library must be initalised with the
.Fn libhammer_get_fsinfo
function.
This will perform all the operations needed to initialise the data structures in
which the API function rely for the specified HAMMER file system.
.Pp
Once you are done, the special function
.Fn libhammer_free_fsinfo
will release all the resources used by the library during its initialisation and
usage.
.Sh SEE ALSO
.Xr libhammer_fsinfo 3 ,
.Xr libhammer_snapshot 3 ,
.Xr libhammer_stats 3 ,
.Xr HAMMER 5 ,
.Xr hammer 8
.Sh AUTHORS
This man page was written by
.An Antonio Huete Jimenez Aq Mt tuxillo@quantumachine.net .
.Sh BUGS
Please note that, at the moment of writing this man page, the
.Nm
library is incomplete.