sys::ctl Namespace Reference

This namespace contains safer c++ wrappers for the sysctl() interface. More...

Classes
struct	error
	The domain error type. More...
class	Once
	A read once representation of a Sysctl. More...
class	Sync
	This is a wrapper around Sysctl that allows semantically transparent use of a sysctl. More...
class	Sysctl
	Represents a sysctl MIB address. More...
class	Sysctl< 0 >
	This is a specialisation of Sysctl for sysctls using symbolic names. More...

Typedefs
typedef int	mib_t
	Management Information Base identifier type (see sysctl(3)).
template<typename T , size_t MibDepth = 0>
using	SysctlSync = Sync< T, Sysctl< MibDepth > >
	A convenience alias around Sync. More...
template<typename T , size_t MibDepth = 0>
using	SysctlOnce = Once< T, Sysctl< MibDepth > >
	A convenience alias around Once. More...

Functions
void	sysctl_raw (mib_t const *name, u_int const namelen, void *const oldp, size_t *const oldlenp, void const *const newp, size_t const newlen)
	A wrapper around the sysctl() function. More...
template<size_t MibDepth>
void	sysctl_get (mib_t const (&mib)[MibDepth], void *const oldp, size_t &oldlen)
	Returns a sysctl() value to a buffer. More...
template<size_t MibDepth>
void	sysctl_set (mib_t const (&mib)[MibDepth], void const *const newp, size_t const newlen)
	Sets a sysctl() value. More...
template<typename ... ArgTs>
	Sysctl (mib_t const, ArgTs const ...) -> Sysctl<(1+sizeof...(ArgTs))>
	Create a Sysctl from a set of predefined MIBs. More...
	Sysctl (char const *const) -> Sysctl< 0 >
	Create a Sysctl<0> by name.
	Sysctl () -> Sysctl< 0 >
	Default construct a Sysctl<0>.

Detailed Description

This namespace contains safer c++ wrappers for the sysctl() interface.

The template class Sysctl represents a sysctl address and offers handles to retrieve or set the stored value.

The template class Sync represents a sysctl value that is read and written synchronously.

The template class Once represents a read once value.

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Class Documentation

sys::ctl::error

struct sys::ctl::error

The domain error type.

Typedef Documentation

SysctlOnce

template<typename T , size_t MibDepth = 0>

using sys::ctl::SysctlOnce = typedef Once<T, Sysctl<MibDepth> >

A convenience alias around Once.

// Once<coreid_t, Sysctl<2>> ncpu{0, {CTL_HW, HW_NCPU}};
SysctlOnce<coreid_t, 2> ncpu{1, {CTL_HW, HW_NCPU}};

Template Parameters

T	The type to represent the sysctl as
MibDepth	The maximum allowed MIB depth

SysctlSync

template<typename T , size_t MibDepth = 0>

using sys::ctl::SysctlSync = typedef Sync<T, Sysctl<MibDepth> >

A convenience alias around Sync.

// Sync<int, Sysctl<0>> sndUnit{{"hw.snd.default_unit"}};
SysctlSync<int> sndUnit{{"hw.snd.default_unit"}};
if (sndUnit != 3) {    // read from sysctl
    sndUnit = 3;      // assign to sysctl
}

Template Parameters

T	The type to represent the sysctl as
MibDepth	The MIB depth, provide only for compile time initialisation

Function Documentation

Sysctl()

template<typename ... ArgTs>

sys::ctl::Sysctl	(	mib_t const	,
		ArgTs	const ...
	)		-> Sysctl<(1+sizeof...(ArgTs))>

Create a Sysctl from a set of predefined MIBs.

Template Parameters

Args	List of argument types, should all be mib_t

sysctl_get()

template<size_t MibDepth>

void sys::ctl::sysctl_get	(	mib_t const (&)	mib[MibDepth],
		void *const	oldp,
		size_t &	oldlen
	)

Returns a sysctl() value to a buffer.

Template Parameters

MibDepth

The length of the MIB buffer

Parameters

mib	The MIB buffer
oldp,oldlen	A pointers to the return buffer and a reference to its length

Exceptions

sys::sc_error<error>

Throws if sysctl() fails for any reason

sysctl_raw()

void sys::ctl::sysctl_raw ( mib_t const *  name, u_int const  namelen, void *const  oldp, size_t *const  oldlenp, void const *const  newp, size_t const  newlen  )

inline

A wrapper around the sysctl() function.

All it does is throw an exception if sysctl() fails.

Parameters

name,namelen	The MIB buffer and its length
oldp,oldlenp	Pointers to the return buffer and its length
newp,newlen	A pointer to the buffer with the new value and the buffer length

Exceptions

sys::sc_error<error>

Throws if sysctl() fails for any reason

sysctl_set()

template<size_t MibDepth>

void sys::ctl::sysctl_set	(	mib_t const (&)	mib[MibDepth],
		void const *const	newp,
		size_t const	newlen
	)

Sets a sysctl() value.

Template Parameters

MibDepth

The length of the MIB buffer

Parameters

mib	The MIB buffer
newp,newlen	A pointer to the buffer with the new value and the buffer length

Exceptions

sys::sc_error<error>

Throws if sysctl() fails for any reason