sys::ctl::Sysctl< MibDepth > Class Template Reference

Represents a sysctl MIB address. More...

#include <sysctl.hpp>

Public Member Functions
template<typename... Tail>
constexpr	Sysctl (mib_t const head, Tail const ... tail) noexcept
	Initialise the MIB address directly. More...
size_t	size () const
	The size of the sysctl. More...
void	get (void *const buf, size_t const bufsize) const
	Update the given buffer with a value retrieved from the sysctl. More...
template<typename T >
void	get (T &value) const
	Update the given value with a value retreived from the sysctl. More...
template<typename T >
std::unique_ptr< T[]>	get () const
	Retrieve an array from the sysctl address. More...
void	set (void const *const buf, size_t const bufsize)
	Update the the sysctl value with the given buffer. More...
template<typename T >
void	set (T const &value)
	Update the the sysctl value with the given value. More...

Private Attributes
mib_t	mib [MibDepth]
	Stores the MIB address.

Detailed Description

template<size_t MibDepth>
class sys::ctl::Sysctl< MibDepth >

Represents a sysctl MIB address.

It offers set() and get() methods to access these sysctls.

There are two ways of initialising a Sysctl instance, by symbolic name or by directly using the MIB address. The latter one only makes sense for sysctls with a fixed address, known at compile time, e.g. Sysctl<2>{CTL_HW, HW_NCPU} for "hw.ncpu". Check /usr/include/sys/sysctl.h for predefined MIBs.

For all other sysctls, symbolic names must be used. E.g. Sysctl<0>{"dev.cpu.0.freq"}. Creating a Sysctl from a symbolic name may throw.

Suitable deduction guides usually allow omitting the template arguments, i.e. Sysctl{CTL_HW, HW_NCPU} and Sysctl{"dev.cpu.0.freq"} implicitly use the correct template argument.

Template Parameters

MibDepth

The MIB level, e.g. "hw.ncpu" is two levels deep

Constructor & Destructor Documentation

Sysctl()

template<size_t MibDepth>

template<typename... Tail>

constexpr sys::ctl::Sysctl< MibDepth >::Sysctl ( mib_t const  head, Tail const ...  tail  )

inlineconstexprnoexcept

Initialise the MIB address directly.

Some important sysctl values have a fixed address that can be initialised at compile time with a noexcept guarantee.

Spliting the MIB address into head and tail makes sure that Sysctl(char *) does not match the template and is instead implicitly cast to invoke Sysctl(char const *).

Template Parameters

Tail	The types of the trailing MIB address values (must be mib_t)

Parameters

head,tail

The mib

Member Function Documentation

get() [1/3]

template<size_t MibDepth>

template<typename T >

std::unique_ptr<T[]> sys::ctl::Sysctl< MibDepth >::get ( ) const

inline

Retrieve an array from the sysctl address.

This is useful to retrieve variable length sysctls, like characer strings.

Template Parameters

T	The type stored in the array

Returns

And array of T with the right length to store the whole sysctl value

Exceptions

sys::sc_error<error>

May throw if the size of the sysctl increases after the length was queried

get() [2/3]

template<size_t MibDepth>

template<typename T >

void sys::ctl::Sysctl< MibDepth >::get ( T &  value ) const

inline

Update the given value with a value retreived from the sysctl.

Template Parameters

T	The type store the sysctl value in

Parameters

value

A reference to the target value

Exceptions

sys::sc_error<error>

Throws if value retrieval fails or is incomplete, e.g. because the value does not fit into the target type

get() [3/3]

template<size_t MibDepth>

void sys::ctl::Sysctl< MibDepth >::get ( void *const  buf, size_t const  bufsize  ) const

inline

Update the given buffer with a value retrieved from the sysctl.

Parameters

buf,bufsize

The target buffer and its size

Exceptions

sys::sc_error<error>

Throws if value retrieval fails or is incomplete, e.g. because the value does not fit into the target buffer

set() [1/2]

template<size_t MibDepth>

template<typename T >

void sys::ctl::Sysctl< MibDepth >::set ( T const &  value )

inline

Update the the sysctl value with the given value.

Template Parameters

T	The value type

Parameters

value

The value to set the sysctl to

set() [2/2]

template<size_t MibDepth>

void sys::ctl::Sysctl< MibDepth >::set ( void const *const  buf, size_t const  bufsize  )

inline

Update the the sysctl value with the given buffer.

Parameters

buf,bufsize

The source buffer

Exceptions

sys::sc_error<error>

If the source buffer cannot be stored in the sysctl

size()

template<size_t MibDepth>

size_t sys::ctl::Sysctl< MibDepth >::size ( ) const

inline

The size of the sysctl.

Returns

The size in characters

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The documentation for this class was generated from the following file:

• src/sys/sysctl.hpp