From 43a123c1ae6613b3efeed291fa552ecd909d3acf Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Tue, 16 Apr 2024 21:23:18 +0200 Subject: Adding upstream version 1.20.14. Signed-off-by: Daniel Baumann --- src/cmd/internal/buildid/note.go | 211 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 211 insertions(+) create mode 100644 src/cmd/internal/buildid/note.go (limited to 'src/cmd/internal/buildid/note.go') diff --git a/src/cmd/internal/buildid/note.go b/src/cmd/internal/buildid/note.go new file mode 100644 index 0000000..ab98701 --- /dev/null +++ b/src/cmd/internal/buildid/note.go @@ -0,0 +1,211 @@ +// Copyright 2015 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package buildid + +import ( + "bytes" + "debug/elf" + "debug/macho" + "encoding/binary" + "fmt" + "io" + "io/fs" + "os" +) + +func readAligned4(r io.Reader, sz int32) ([]byte, error) { + full := (sz + 3) &^ 3 + data := make([]byte, full) + _, err := io.ReadFull(r, data) + if err != nil { + return nil, err + } + data = data[:sz] + return data, nil +} + +func ReadELFNote(filename, name string, typ int32) ([]byte, error) { + f, err := elf.Open(filename) + if err != nil { + return nil, err + } + defer f.Close() + for _, sect := range f.Sections { + if sect.Type != elf.SHT_NOTE { + continue + } + r := sect.Open() + for { + var namesize, descsize, noteType int32 + err = binary.Read(r, f.ByteOrder, &namesize) + if err != nil { + if err == io.EOF { + break + } + return nil, fmt.Errorf("read namesize failed: %v", err) + } + err = binary.Read(r, f.ByteOrder, &descsize) + if err != nil { + return nil, fmt.Errorf("read descsize failed: %v", err) + } + err = binary.Read(r, f.ByteOrder, ¬eType) + if err != nil { + return nil, fmt.Errorf("read type failed: %v", err) + } + noteName, err := readAligned4(r, namesize) + if err != nil { + return nil, fmt.Errorf("read name failed: %v", err) + } + desc, err := readAligned4(r, descsize) + if err != nil { + return nil, fmt.Errorf("read desc failed: %v", err) + } + if name == string(noteName) && typ == noteType { + return desc, nil + } + } + } + return nil, nil +} + +var elfGoNote = []byte("Go\x00\x00") +var elfGNUNote = []byte("GNU\x00") + +// The Go build ID is stored in a note described by an ELF PT_NOTE prog +// header. The caller has already opened filename, to get f, and read +// at least 4 kB out, in data. +func readELF(name string, f *os.File, data []byte) (buildid string, err error) { + // Assume the note content is in the data, already read. + // Rewrite the ELF header to set shoff and shnum to 0, so that we can pass + // the data to elf.NewFile and it will decode the Prog list but not + // try to read the section headers and the string table from disk. + // That's a waste of I/O when all we care about is the Prog list + // and the one ELF note. + switch elf.Class(data[elf.EI_CLASS]) { + case elf.ELFCLASS32: + data[32], data[33], data[34], data[35] = 0, 0, 0, 0 + data[48] = 0 + data[49] = 0 + case elf.ELFCLASS64: + data[40], data[41], data[42], data[43] = 0, 0, 0, 0 + data[44], data[45], data[46], data[47] = 0, 0, 0, 0 + data[60] = 0 + data[61] = 0 + } + + const elfGoBuildIDTag = 4 + const gnuBuildIDTag = 3 + + ef, err := elf.NewFile(bytes.NewReader(data)) + if err != nil { + return "", &fs.PathError{Path: name, Op: "parse", Err: err} + } + var gnu string + for _, p := range ef.Progs { + if p.Type != elf.PT_NOTE || p.Filesz < 16 { + continue + } + + var note []byte + if p.Off+p.Filesz < uint64(len(data)) { + note = data[p.Off : p.Off+p.Filesz] + } else { + // For some linkers, such as the Solaris linker, + // the buildid may not be found in data (which + // likely contains the first 16kB of the file) + // or even the first few megabytes of the file + // due to differences in note segment placement; + // in that case, extract the note data manually. + _, err = f.Seek(int64(p.Off), io.SeekStart) + if err != nil { + return "", err + } + + note = make([]byte, p.Filesz) + _, err = io.ReadFull(f, note) + if err != nil { + return "", err + } + } + + filesz := p.Filesz + off := p.Off + for filesz >= 16 { + nameSize := ef.ByteOrder.Uint32(note) + valSize := ef.ByteOrder.Uint32(note[4:]) + tag := ef.ByteOrder.Uint32(note[8:]) + nname := note[12:16] + if nameSize == 4 && 16+valSize <= uint32(len(note)) && tag == elfGoBuildIDTag && bytes.Equal(nname, elfGoNote) { + return string(note[16 : 16+valSize]), nil + } + + if nameSize == 4 && 16+valSize <= uint32(len(note)) && tag == gnuBuildIDTag && bytes.Equal(nname, elfGNUNote) { + gnu = string(note[16 : 16+valSize]) + } + + nameSize = (nameSize + 3) &^ 3 + valSize = (valSize + 3) &^ 3 + notesz := uint64(12 + nameSize + valSize) + if filesz <= notesz { + break + } + off += notesz + align := p.Align + alignedOff := (off + align - 1) &^ (align - 1) + notesz += alignedOff - off + off = alignedOff + filesz -= notesz + note = note[notesz:] + } + } + + // If we didn't find a Go note, use a GNU note if available. + // This is what gccgo uses. + if gnu != "" { + return gnu, nil + } + + // No note. Treat as successful but build ID empty. + return "", nil +} + +// The Go build ID is stored at the beginning of the Mach-O __text segment. +// The caller has already opened filename, to get f, and read a few kB out, in data. +// Sadly, that's not guaranteed to hold the note, because there is an arbitrary amount +// of other junk placed in the file ahead of the main text. +func readMacho(name string, f *os.File, data []byte) (buildid string, err error) { + // If the data we want has already been read, don't worry about Mach-O parsing. + // This is both an optimization and a hedge against the Mach-O parsing failing + // in the future due to, for example, the name of the __text section changing. + if b, err := readRaw(name, data); b != "" && err == nil { + return b, err + } + + mf, err := macho.NewFile(f) + if err != nil { + return "", &fs.PathError{Path: name, Op: "parse", Err: err} + } + + sect := mf.Section("__text") + if sect == nil { + // Every binary has a __text section. Something is wrong. + return "", &fs.PathError{Path: name, Op: "parse", Err: fmt.Errorf("cannot find __text section")} + } + + // It should be in the first few bytes, but read a lot just in case, + // especially given our past problems on OS X with the build ID moving. + // There shouldn't be much difference between reading 4kB and 32kB: + // the hard part is getting to the data, not transferring it. + n := sect.Size + if n > uint64(readSize) { + n = uint64(readSize) + } + buf := make([]byte, n) + if _, err := f.ReadAt(buf, int64(sect.Offset)); err != nil { + return "", err + } + + return readRaw(name, buf) +} -- cgit v1.2.3