package internal

import "github.com/cilium/ebpf/internal"

Index ¶

• Constants
• Variables
• func Align(n, alignment int) int
• func FeatureTest(name, version string, fn FeatureTestFn) func() error
• func Identifier(str string) string
• func KernelRelease() (string, error)
• func NewBufferedSectionReader(ra io.ReaderAt, off, n int64) *bufio.Reader
• func Pin(currentPath, newPath string, fd *sys.FD) error
• func PossibleCPUs() (int, error)
• func ReadAllCompressed(file string) ([]byte, error)
• func Unpin(pinnedPath string) error
• func WriteFormatted(src []byte, out io.Writer) error
• type Deque
• func (dq *Deque[T]) Empty() bool
• func (dq *Deque[T]) Pop() T
• func (dq *Deque[T]) Push(e T)
• func (dq *Deque[T]) Shift() T
• type DiscardZeroes
• func (DiscardZeroes) Write(p []byte) (int, error)
• type FeatureTestFn
• type SafeELFFile
• func NewSafeELFFile(r io.ReaderAt) (safe *SafeELFFile, err error)
• func OpenSafeELFFile(path string) (safe *SafeELFFile, err error)
• func (se *SafeELFFile) DynamicSymbols() (syms []elf.Symbol, err error)
• func (se *SafeELFFile) SectionsByType(typ elf.SectionType) []*elf.Section
• func (se *SafeELFFile) Symbols() (syms []elf.Symbol, err error)
• type UnsupportedFeatureError
• func (ufe *UnsupportedFeatureError) Error() string
• func (ufe *UnsupportedFeatureError) Is(target error) bool
• type VerifierError
• func ErrorWithLog(err error, log []byte, truncated bool) *VerifierError
• func (le *VerifierError) Error() string
• func (le *VerifierError) Format(f fmt.State, verb rune)
• func (le *VerifierError) Unwrap() error
• type Version
• func KernelVersion() (Version, error)
• func NewVersion(ver string) (Version, error)
• func NewVersionFromCode(code uint32) Version
• func (v Version) Kernel() uint32
• func (v Version) Less(other Version) bool
• func (v Version) String() string
• func (v Version) Unspecified() bool

Examples ¶

• VerifierError

Constants ¶

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 ¶

var EmptyBPFContext = make([]byte, 15)

EmptyBPFContext is the smallest-possible BPF input context to be used for invoking `Program.{Run,Benchmark,Test}`.

Programs require a context input buffer of at least 15 bytes. Looking in net/bpf/test_run.c, bpf_test_init() requires that the input is at least ETH_HLEN (14) bytes. As of Linux commit fd18942 ("bpf: Don't redirect packets with invalid pkt_len"), it also requires the skb to be non-empty after removing the Layer 2 header.

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

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

Functions ¶

func Align ¶

func Align(n, alignment int) int

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

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 Deque ¶

type Deque[T any] struct {
	// contains filtered or unexported fields
}

Deque implements a double ended queue.

func (*Deque[T]) Empty ¶

func (dq *Deque[T]) Empty() bool

func (*Deque[T]) Pop ¶

func (dq *Deque[T]) Pop() T

Pop returns the last element or the zero value.

func (*Deque[T]) Push ¶

func (dq *Deque[T]) Push(e T)

Push adds an element to the end.

func (*Deque[T]) Shift ¶

func (dq *Deque[T]) Shift() T

Shift returns the first element or the zero value.

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 {
	// The error which caused this error.
	Cause error
	// The verifier output split into lines.
	Log []string
	// Whether the log output is truncated, based on several heuristics.
	Truncated bool
}

VerifierError includes information from the eBPF verifier.

It summarises the log output, see Format if you want to output the full contents.

{
	err := &VerifierError{
		syscall.ENOSPC,
		[]string{"first", "second", "third"},
		false,
	}

	fmt.Printf("With %%s: %s\n", err)
	err.Truncated = true
	fmt.Printf("With %%v and a truncated log: %v\n", err)
	fmt.Printf("All log lines: %+v\n", err)
	fmt.Printf("First line: %+1v\n", err)
	fmt.Printf("Last two lines: %-2v\n", err)

	// Output: With %s: no space left on device: third (2 line(s) omitted)
	// With %v and a truncated log: no space left on device: second: third (truncated, 1 line(s) omitted)
	// All log lines: no space left on device:
	// 	first
	// 	second
	// 	third
	// 	(truncated)
	// First line: no space left on device:
	// 	first
	// 	(2 line(s) omitted)
	// 	(truncated)
	// Last two lines: no space left on device:
	// 	(1 line(s) omitted)
	// 	second
	// 	third
	// 	(truncated)
}

With %s: no space left on device: third (2 line(s) omitted)
With %v and a truncated log: no space left on device: second: third (truncated, 1 line(s) omitted)
All log lines: no space left on device:
	first
	second
	third
	(truncated)
First line: no space left on device:
	first
	(2 line(s) omitted)
	(truncated)
Last two lines: no space left on device:
	(1 line(s) omitted)
	second
	third
	(truncated)

func ErrorWithLog ¶

func ErrorWithLog(err error, log []byte, truncated bool) *VerifierError

ErrorWithLog wraps err in a VerifierError that includes the parsed verifier log buffer.

The default error output is a summary of the full log. The latter can be accessed via VerifierError.Log or by formatting the error, see Format.

func (*VerifierError) Error ¶

func (le *VerifierError) Error() string

func (*VerifierError) Format ¶

func (le *VerifierError) Format(f fmt.State, verb rune)

Format the error.

Understood verbs are %s and %v, which are equivalent to calling Error(). %v allows outputting additional information using the following flags:

%+<width>v: Output the first <width> lines, or all lines if no width is given.
%-<width>v: Output the last <width> lines, or all lines if no width is given.

Use width to specify how many lines to output. Use the '-' flag to output lines from the end of the log instead of the beginning.

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.

Source Files ¶

align.go cpu.go deque.go elf.go errors.go feature.go io.go output.go pinning.go prog.go vdso.go version.go

Directories ¶