go/src/cmd/internal/buildid/buildid.go

var errBuildIDMalformed …

var bangArch …

var pkgdef …

var goobject …

var buildid …

// ReadFile reads the build ID from an archive or executable file.
func ReadFile(name string) (id string, err error) { … }

// readGccgoArchive tries to parse the archive as a standard Unix
// archive file, and fetch the build ID from the _buildid.o entry.
// The _buildid.o entry is written by (*Builder).gccgoBuildIDELFFile
// in cmd/go/internal/work/exec.go.
func readGccgoArchive(name string, f *os.File) (string, error) { … }

// readGccgoBigArchive tries to parse the archive as an AIX big
// archive file, and fetch the build ID from the _buildid.o entry.
// The _buildid.o entry is written by (*Builder).gccgoBuildIDXCOFFFile
// in cmd/go/internal/work/exec.go.
func readGccgoBigArchive(name string, f *os.File) (string, error) { … }

var goBuildPrefix …

var goBuildEnd …

var elfPrefix …

var machoPrefixes …

var readSize …

// readBinary reads the build ID from a binary.
//
// ELF binaries store the build ID in a proper PT_NOTE section.
//
// Other binary formats are not so flexible. For those, the linker
// stores the build ID as non-instruction bytes at the very beginning
// of the text segment, which should appear near the beginning
// of the file. This is clumsy but fairly portable. Custom locations
// can be added for other binary types as needed, like we did for ELF.
func readBinary(name string, f *os.File) (id string, err error) { … }

// readRaw finds the raw build ID stored in text segment data.
func readRaw(name string, data []byte) (id string, err error) { … }

// HashToString converts the hash h to a string to be recorded
// in package archives and binaries as part of the build ID.
// We use the first 120 bits of the hash (5 chunks of 24 bits each) and encode
// it in base64, resulting in a 20-byte string. Because this is only used for
// detecting the need to rebuild installed files (not for lookups
// in the object file cache), 120 bits are sufficient to drive the
// probability of a false "do not need to rebuild" decision to effectively zero.
// We embed two different hashes in archives and four in binaries,
// so cutting to 20 bytes is a significant savings when build IDs are displayed.
// (20*4+3 = 83 bytes compared to 64*4+3 = 259 bytes for the
// more straightforward option of printing the entire h in base64).
func HashToString(h [32]byte) string { … }