internal

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Published: May 10, 2022 License: MIT Imports: 19 Imported by: 1

README

btf-internals

Fork of internal parts of https://github.com/cilium/ebpf making them usable from outside the module.

Documentation

Index

Constants

View Source
const ClangEndian = "el"

ClangEndian is set to either "el" or "eb" depending on the host's endianness.

View Source
const (
	// Version constant used in ELF binaries indicating that the loader needs to
	// substitute the eBPF program's version with the value of the kernel's
	// KERNEL_VERSION compile-time macro. Used for compatibility with BCC, gobpf
	// and RedSift.
	MagicKernelVersion = 0xFFFFFFFE
)

Variables

View Source
var ErrNotSupported = errors.New("not supported")

ErrNotSupported indicates that a feature is not supported by the current kernel.

NativeEndian is set to either binary.BigEndian or binary.LittleEndian, depending on the host's endianness.

Functions

func Align

func Align(n, alignment int) int

Align returns 'n' updated to 'alignment' boundary.

func ErrorWithLog

func ErrorWithLog(err error, log []byte, logErr error) error

ErrorWithLog returns an error that includes logs from the kernel verifier.

logErr should be the error returned by the syscall that generated the log. It is used to check for truncation of the output.

func FeatureTest

func FeatureTest(name, version string, fn FeatureTestFn) func() error

FeatureTest wraps a function so that it is run at most once.

name should identify the tested feature, while version must be in the form Major.Minor[.Patch].

Returns an error wrapping ErrNotSupported if the feature is not supported.

func Identifier

func Identifier(str string) string

Identifier turns a C style type or field name into an exportable Go equivalent.

func KernelRelease

func KernelRelease() (string, error)

KernelRelease returns the release string of the running kernel. Its format depends on the Linux distribution and corresponds to directory names in /lib/modules by convention. Some examples are 5.15.17-1-lts and 4.19.0-16-amd64.

func NewBufferedSectionReader

func NewBufferedSectionReader(ra io.ReaderAt, off, n int64) *bufio.Reader

NewBufferedSectionReader wraps an io.ReaderAt in an appropriately-sized buffered reader. It is a convenience function for reading subsections of ELF sections while minimizing the amount of read() syscalls made.

Syscall overhead is non-negligible in continuous integration context where ELFs might be accessed over virtual filesystems with poor random access performance. Buffering reads makes sense because (sub)sections end up being read completely anyway.

Use instead of the r.Seek() + io.LimitReader() pattern.

func Pin

func Pin(currentPath, newPath string, fd *sys.FD) error

func PossibleCPUs

func PossibleCPUs() (int, error)

PossibleCPUs returns the max number of CPUs a system may possibly have Logical CPU numbers must be of the form 0-n

func ReadAllCompressed

func ReadAllCompressed(file string) ([]byte, error)

ReadAllCompressed decompresses a gzipped file into memory.

func Unpin

func Unpin(pinnedPath string) error

func WriteFormatted

func WriteFormatted(src []byte, out io.Writer) error

WriteFormatted outputs a formatted src into out.

If formatting fails it returns an informative error message.

Types

type DiscardZeroes

type DiscardZeroes struct{}

DiscardZeroes makes sure that all written bytes are zero before discarding them.

func (DiscardZeroes) Write

func (DiscardZeroes) Write(p []byte) (int, error)

type FeatureTestFn

type FeatureTestFn func() error

FeatureTestFn is used to determine whether the kernel supports a certain feature.

The return values have the following semantics:

err == ErrNotSupported: the feature is not available
err == nil: the feature is available
err != nil: the test couldn't be executed

type SafeELFFile

type SafeELFFile struct {
	*elf.File
}

func NewSafeELFFile

func NewSafeELFFile(r io.ReaderAt) (safe *SafeELFFile, err error)

NewSafeELFFile reads an ELF safely.

Any panic during parsing is turned into an error. This is necessary since there are a bunch of unfixed bugs in debug/elf.

https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+debug%2Felf+in%3Atitle

func OpenSafeELFFile

func OpenSafeELFFile(path string) (safe *SafeELFFile, err error)

OpenSafeELFFile reads an ELF from a file.

It works like NewSafeELFFile, with the exception that safe.Close will close the underlying file.

func (*SafeELFFile) DynamicSymbols

func (se *SafeELFFile) DynamicSymbols() (syms []elf.Symbol, err error)

DynamicSymbols is the safe version of elf.File.DynamicSymbols.

func (*SafeELFFile) SectionsByType

func (se *SafeELFFile) SectionsByType(typ elf.SectionType) []*elf.Section

SectionsByType returns all sections in the file with the specified section type.

func (*SafeELFFile) Symbols

func (se *SafeELFFile) Symbols() (syms []elf.Symbol, err error)

Symbols is the safe version of elf.File.Symbols.

type UnsupportedFeatureError

type UnsupportedFeatureError struct {
	// The minimum Linux mainline version required for this feature.
	// Used for the error string, and for sanity checking during testing.
	MinimumVersion Version

	// The name of the feature that isn't supported.
	Name string
}

UnsupportedFeatureError is returned by FeatureTest() functions.

func (*UnsupportedFeatureError) Error

func (ufe *UnsupportedFeatureError) Error() string

func (*UnsupportedFeatureError) Is

func (ufe *UnsupportedFeatureError) Is(target error) bool

Is indicates that UnsupportedFeatureError is ErrNotSupported.

type VerifierError

type VerifierError struct {
	// contains filtered or unexported fields
}

VerifierError includes information from the eBPF verifier.

func (*VerifierError) Error

func (le *VerifierError) Error() string

func (*VerifierError) Unwrap

func (le *VerifierError) Unwrap() error

type Version

type Version [3]uint16

A Version in the form Major.Minor.Patch.

func KernelVersion

func KernelVersion() (Version, error)

KernelVersion returns the version of the currently running kernel.

func NewVersion

func NewVersion(ver string) (Version, error)

NewVersion creates a version from a string like "Major.Minor.Patch".

Patch is optional.

func NewVersionFromCode

func NewVersionFromCode(code uint32) Version

NewVersionFromCode creates a version from a LINUX_VERSION_CODE.

func (Version) Kernel

func (v Version) Kernel() uint32

Kernel implements the kernel's KERNEL_VERSION macro from linux/version.h. It represents the kernel version and patch level as a single value.

func (Version) Less

func (v Version) Less(other Version) bool

Less returns true if the version is less than another version.

func (Version) String

func (v Version) String() string

func (Version) Unspecified

func (v Version) Unspecified() bool

Unspecified returns true if the version is all zero.

Directories

Path Synopsis
Package btf handles data encoded according to the BPF Type Format.
Package btf handles data encoded according to the BPF Type Format.
Package sys contains bindings for the BPF syscall.
Package sys contains bindings for the BPF syscall.

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