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-rw-r--r--src/debug/gosym/pclntab.go561
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diff --git a/src/debug/gosym/pclntab.go b/src/debug/gosym/pclntab.go
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+// Copyright 2009 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.
+
+/*
+ * Line tables
+ */
+
+package gosym
+
+import (
+ "bytes"
+ "encoding/binary"
+ "sync"
+)
+
+// version of the pclntab
+type version int
+
+const (
+ verUnknown version = iota
+ ver11
+ ver12
+ ver116
+)
+
+// A LineTable is a data structure mapping program counters to line numbers.
+//
+// In Go 1.1 and earlier, each function (represented by a Func) had its own LineTable,
+// and the line number corresponded to a numbering of all source lines in the
+// program, across all files. That absolute line number would then have to be
+// converted separately to a file name and line number within the file.
+//
+// In Go 1.2, the format of the data changed so that there is a single LineTable
+// for the entire program, shared by all Funcs, and there are no absolute line
+// numbers, just line numbers within specific files.
+//
+// For the most part, LineTable's methods should be treated as an internal
+// detail of the package; callers should use the methods on Table instead.
+type LineTable struct {
+ Data []byte
+ PC uint64
+ Line int
+
+ // This mutex is used to keep parsing of pclntab synchronous.
+ mu sync.Mutex
+
+ // Contains the version of the pclntab section.
+ version version
+
+ // Go 1.2/1.16 state
+ binary binary.ByteOrder
+ quantum uint32
+ ptrsize uint32
+ funcnametab []byte
+ cutab []byte
+ funcdata []byte
+ functab []byte
+ nfunctab uint32
+ filetab []byte
+ pctab []byte // points to the pctables.
+ nfiletab uint32
+ funcNames map[uint32]string // cache the function names
+ strings map[uint32]string // interned substrings of Data, keyed by offset
+ // fileMap varies depending on the version of the object file.
+ // For ver12, it maps the name to the index in the file table.
+ // For ver116, it maps the name to the offset in filetab.
+ fileMap map[string]uint32
+}
+
+// NOTE(rsc): This is wrong for GOARCH=arm, which uses a quantum of 4,
+// but we have no idea whether we're using arm or not. This only
+// matters in the old (pre-Go 1.2) symbol table format, so it's not worth
+// fixing.
+const oldQuantum = 1
+
+func (t *LineTable) parse(targetPC uint64, targetLine int) (b []byte, pc uint64, line int) {
+ // The PC/line table can be thought of as a sequence of
+ // <pc update>* <line update>
+ // batches. Each update batch results in a (pc, line) pair,
+ // where line applies to every PC from pc up to but not
+ // including the pc of the next pair.
+ //
+ // Here we process each update individually, which simplifies
+ // the code, but makes the corner cases more confusing.
+ b, pc, line = t.Data, t.PC, t.Line
+ for pc <= targetPC && line != targetLine && len(b) > 0 {
+ code := b[0]
+ b = b[1:]
+ switch {
+ case code == 0:
+ if len(b) < 4 {
+ b = b[0:0]
+ break
+ }
+ val := binary.BigEndian.Uint32(b)
+ b = b[4:]
+ line += int(val)
+ case code <= 64:
+ line += int(code)
+ case code <= 128:
+ line -= int(code - 64)
+ default:
+ pc += oldQuantum * uint64(code-128)
+ continue
+ }
+ pc += oldQuantum
+ }
+ return b, pc, line
+}
+
+func (t *LineTable) slice(pc uint64) *LineTable {
+ data, pc, line := t.parse(pc, -1)
+ return &LineTable{Data: data, PC: pc, Line: line}
+}
+
+// PCToLine returns the line number for the given program counter.
+//
+// Deprecated: Use Table's PCToLine method instead.
+func (t *LineTable) PCToLine(pc uint64) int {
+ if t.isGo12() {
+ return t.go12PCToLine(pc)
+ }
+ _, _, line := t.parse(pc, -1)
+ return line
+}
+
+// LineToPC returns the program counter for the given line number,
+// considering only program counters before maxpc.
+//
+// Deprecated: Use Table's LineToPC method instead.
+func (t *LineTable) LineToPC(line int, maxpc uint64) uint64 {
+ if t.isGo12() {
+ return 0
+ }
+ _, pc, line1 := t.parse(maxpc, line)
+ if line1 != line {
+ return 0
+ }
+ // Subtract quantum from PC to account for post-line increment
+ return pc - oldQuantum
+}
+
+// NewLineTable returns a new PC/line table
+// corresponding to the encoded data.
+// Text must be the start address of the
+// corresponding text segment.
+func NewLineTable(data []byte, text uint64) *LineTable {
+ return &LineTable{Data: data, PC: text, Line: 0, funcNames: make(map[uint32]string), strings: make(map[uint32]string)}
+}
+
+// Go 1.2 symbol table format.
+// See golang.org/s/go12symtab.
+//
+// A general note about the methods here: rather than try to avoid
+// index out of bounds errors, we trust Go to detect them, and then
+// we recover from the panics and treat them as indicative of a malformed
+// or incomplete table.
+//
+// The methods called by symtab.go, which begin with "go12" prefixes,
+// are expected to have that recovery logic.
+
+// isGo12 reports whether this is a Go 1.2 (or later) symbol table.
+func (t *LineTable) isGo12() bool {
+ t.parsePclnTab()
+ return t.version >= ver12
+}
+
+const go12magic = 0xfffffffb
+const go116magic = 0xfffffffa
+
+// uintptr returns the pointer-sized value encoded at b.
+// The pointer size is dictated by the table being read.
+func (t *LineTable) uintptr(b []byte) uint64 {
+ if t.ptrsize == 4 {
+ return uint64(t.binary.Uint32(b))
+ }
+ return t.binary.Uint64(b)
+}
+
+// parsePclnTab parses the pclntab, setting the version.
+func (t *LineTable) parsePclnTab() {
+ t.mu.Lock()
+ defer t.mu.Unlock()
+ if t.version != verUnknown {
+ return
+ }
+
+ // Note that during this function, setting the version is the last thing we do.
+ // If we set the version too early, and parsing failed (likely as a panic on
+ // slice lookups), we'd have a mistaken version.
+ //
+ // Error paths through this code will default the version to 1.1.
+ t.version = ver11
+
+ defer func() {
+ // If we panic parsing, assume it's a Go 1.1 pclntab.
+ recover()
+ }()
+
+ // Check header: 4-byte magic, two zeros, pc quantum, pointer size.
+ if len(t.Data) < 16 || t.Data[4] != 0 || t.Data[5] != 0 ||
+ (t.Data[6] != 1 && t.Data[6] != 2 && t.Data[6] != 4) || // pc quantum
+ (t.Data[7] != 4 && t.Data[7] != 8) { // pointer size
+ return
+ }
+
+ var possibleVersion version
+ leMagic := binary.LittleEndian.Uint32(t.Data)
+ beMagic := binary.BigEndian.Uint32(t.Data)
+ switch {
+ case leMagic == go12magic:
+ t.binary, possibleVersion = binary.LittleEndian, ver12
+ case beMagic == go12magic:
+ t.binary, possibleVersion = binary.BigEndian, ver12
+ case leMagic == go116magic:
+ t.binary, possibleVersion = binary.LittleEndian, ver116
+ case beMagic == go116magic:
+ t.binary, possibleVersion = binary.BigEndian, ver116
+ default:
+ return
+ }
+
+ // quantum and ptrSize are the same between 1.2 and 1.16
+ t.quantum = uint32(t.Data[6])
+ t.ptrsize = uint32(t.Data[7])
+
+ switch possibleVersion {
+ case ver116:
+ t.nfunctab = uint32(t.uintptr(t.Data[8:]))
+ t.nfiletab = uint32(t.uintptr(t.Data[8+t.ptrsize:]))
+ offset := t.uintptr(t.Data[8+2*t.ptrsize:])
+ t.funcnametab = t.Data[offset:]
+ offset = t.uintptr(t.Data[8+3*t.ptrsize:])
+ t.cutab = t.Data[offset:]
+ offset = t.uintptr(t.Data[8+4*t.ptrsize:])
+ t.filetab = t.Data[offset:]
+ offset = t.uintptr(t.Data[8+5*t.ptrsize:])
+ t.pctab = t.Data[offset:]
+ offset = t.uintptr(t.Data[8+6*t.ptrsize:])
+ t.funcdata = t.Data[offset:]
+ t.functab = t.Data[offset:]
+ functabsize := t.nfunctab*2*t.ptrsize + t.ptrsize
+ t.functab = t.functab[:functabsize]
+ case ver12:
+ t.nfunctab = uint32(t.uintptr(t.Data[8:]))
+ t.funcdata = t.Data
+ t.funcnametab = t.Data
+ t.functab = t.Data[8+t.ptrsize:]
+ t.pctab = t.Data
+ functabsize := t.nfunctab*2*t.ptrsize + t.ptrsize
+ fileoff := t.binary.Uint32(t.functab[functabsize:])
+ t.functab = t.functab[:functabsize]
+ t.filetab = t.Data[fileoff:]
+ t.nfiletab = t.binary.Uint32(t.filetab)
+ t.filetab = t.filetab[:t.nfiletab*4]
+ default:
+ panic("unreachable")
+ }
+ t.version = possibleVersion
+}
+
+// go12Funcs returns a slice of Funcs derived from the Go 1.2 pcln table.
+func (t *LineTable) go12Funcs() []Func {
+ // Assume it is malformed and return nil on error.
+ defer func() {
+ recover()
+ }()
+
+ n := len(t.functab) / int(t.ptrsize) / 2
+ funcs := make([]Func, n)
+ for i := range funcs {
+ f := &funcs[i]
+ f.Entry = t.uintptr(t.functab[2*i*int(t.ptrsize):])
+ f.End = t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):])
+ info := t.funcdata[t.uintptr(t.functab[(2*i+1)*int(t.ptrsize):]):]
+ f.LineTable = t
+ f.FrameSize = int(t.binary.Uint32(info[t.ptrsize+2*4:]))
+ f.Sym = &Sym{
+ Value: f.Entry,
+ Type: 'T',
+ Name: t.funcName(t.binary.Uint32(info[t.ptrsize:])),
+ GoType: 0,
+ Func: f,
+ }
+ }
+ return funcs
+}
+
+// findFunc returns the func corresponding to the given program counter.
+func (t *LineTable) findFunc(pc uint64) []byte {
+ if pc < t.uintptr(t.functab) || pc >= t.uintptr(t.functab[len(t.functab)-int(t.ptrsize):]) {
+ return nil
+ }
+
+ // The function table is a list of 2*nfunctab+1 uintptrs,
+ // alternating program counters and offsets to func structures.
+ f := t.functab
+ nf := t.nfunctab
+ for nf > 0 {
+ m := nf / 2
+ fm := f[2*t.ptrsize*m:]
+ if t.uintptr(fm) <= pc && pc < t.uintptr(fm[2*t.ptrsize:]) {
+ return t.funcdata[t.uintptr(fm[t.ptrsize:]):]
+ } else if pc < t.uintptr(fm) {
+ nf = m
+ } else {
+ f = f[(m+1)*2*t.ptrsize:]
+ nf -= m + 1
+ }
+ }
+ return nil
+}
+
+// readvarint reads, removes, and returns a varint from *pp.
+func (t *LineTable) readvarint(pp *[]byte) uint32 {
+ var v, shift uint32
+ p := *pp
+ for shift = 0; ; shift += 7 {
+ b := p[0]
+ p = p[1:]
+ v |= (uint32(b) & 0x7F) << shift
+ if b&0x80 == 0 {
+ break
+ }
+ }
+ *pp = p
+ return v
+}
+
+// funcName returns the name of the function found at off.
+func (t *LineTable) funcName(off uint32) string {
+ if s, ok := t.funcNames[off]; ok {
+ return s
+ }
+ i := bytes.IndexByte(t.funcnametab[off:], 0)
+ s := string(t.funcnametab[off : off+uint32(i)])
+ t.funcNames[off] = s
+ return s
+}
+
+// stringFrom returns a Go string found at off from a position.
+func (t *LineTable) stringFrom(arr []byte, off uint32) string {
+ if s, ok := t.strings[off]; ok {
+ return s
+ }
+ i := bytes.IndexByte(arr[off:], 0)
+ s := string(arr[off : off+uint32(i)])
+ t.strings[off] = s
+ return s
+}
+
+// string returns a Go string found at off.
+func (t *LineTable) string(off uint32) string {
+ return t.stringFrom(t.funcdata, off)
+}
+
+// step advances to the next pc, value pair in the encoded table.
+func (t *LineTable) step(p *[]byte, pc *uint64, val *int32, first bool) bool {
+ uvdelta := t.readvarint(p)
+ if uvdelta == 0 && !first {
+ return false
+ }
+ if uvdelta&1 != 0 {
+ uvdelta = ^(uvdelta >> 1)
+ } else {
+ uvdelta >>= 1
+ }
+ vdelta := int32(uvdelta)
+ pcdelta := t.readvarint(p) * t.quantum
+ *pc += uint64(pcdelta)
+ *val += vdelta
+ return true
+}
+
+// pcvalue reports the value associated with the target pc.
+// off is the offset to the beginning of the pc-value table,
+// and entry is the start PC for the corresponding function.
+func (t *LineTable) pcvalue(off uint32, entry, targetpc uint64) int32 {
+ p := t.pctab[off:]
+
+ val := int32(-1)
+ pc := entry
+ for t.step(&p, &pc, &val, pc == entry) {
+ if targetpc < pc {
+ return val
+ }
+ }
+ return -1
+}
+
+// findFileLine scans one function in the binary looking for a
+// program counter in the given file on the given line.
+// It does so by running the pc-value tables mapping program counter
+// to file number. Since most functions come from a single file, these
+// are usually short and quick to scan. If a file match is found, then the
+// code goes to the expense of looking for a simultaneous line number match.
+func (t *LineTable) findFileLine(entry uint64, filetab, linetab uint32, filenum, line int32, cutab []byte) uint64 {
+ if filetab == 0 || linetab == 0 {
+ return 0
+ }
+
+ fp := t.pctab[filetab:]
+ fl := t.pctab[linetab:]
+ fileVal := int32(-1)
+ filePC := entry
+ lineVal := int32(-1)
+ linePC := entry
+ fileStartPC := filePC
+ for t.step(&fp, &filePC, &fileVal, filePC == entry) {
+ fileIndex := fileVal
+ if t.version == ver116 {
+ fileIndex = int32(t.binary.Uint32(cutab[fileVal*4:]))
+ }
+ if fileIndex == filenum && fileStartPC < filePC {
+ // fileIndex is in effect starting at fileStartPC up to
+ // but not including filePC, and it's the file we want.
+ // Run the PC table looking for a matching line number
+ // or until we reach filePC.
+ lineStartPC := linePC
+ for linePC < filePC && t.step(&fl, &linePC, &lineVal, linePC == entry) {
+ // lineVal is in effect until linePC, and lineStartPC < filePC.
+ if lineVal == line {
+ if fileStartPC <= lineStartPC {
+ return lineStartPC
+ }
+ if fileStartPC < linePC {
+ return fileStartPC
+ }
+ }
+ lineStartPC = linePC
+ }
+ }
+ fileStartPC = filePC
+ }
+ return 0
+}
+
+// go12PCToLine maps program counter to line number for the Go 1.2 pcln table.
+func (t *LineTable) go12PCToLine(pc uint64) (line int) {
+ defer func() {
+ if recover() != nil {
+ line = -1
+ }
+ }()
+
+ f := t.findFunc(pc)
+ if f == nil {
+ return -1
+ }
+ entry := t.uintptr(f)
+ linetab := t.binary.Uint32(f[t.ptrsize+5*4:])
+ return int(t.pcvalue(linetab, entry, pc))
+}
+
+// go12PCToFile maps program counter to file name for the Go 1.2 pcln table.
+func (t *LineTable) go12PCToFile(pc uint64) (file string) {
+ defer func() {
+ if recover() != nil {
+ file = ""
+ }
+ }()
+
+ f := t.findFunc(pc)
+ if f == nil {
+ return ""
+ }
+ entry := t.uintptr(f)
+ filetab := t.binary.Uint32(f[t.ptrsize+4*4:])
+ fno := t.pcvalue(filetab, entry, pc)
+ if t.version == ver12 {
+ if fno <= 0 {
+ return ""
+ }
+ return t.string(t.binary.Uint32(t.filetab[4*fno:]))
+ }
+ // Go ≥ 1.16
+ if fno < 0 { // 0 is valid for ≥ 1.16
+ return ""
+ }
+ cuoff := t.binary.Uint32(f[t.ptrsize+7*4:])
+ if fnoff := t.binary.Uint32(t.cutab[(cuoff+uint32(fno))*4:]); fnoff != ^uint32(0) {
+ return t.stringFrom(t.filetab, fnoff)
+ }
+ return ""
+}
+
+// go12LineToPC maps a (file, line) pair to a program counter for the Go 1.2/1.16 pcln table.
+func (t *LineTable) go12LineToPC(file string, line int) (pc uint64) {
+ defer func() {
+ if recover() != nil {
+ pc = 0
+ }
+ }()
+
+ t.initFileMap()
+ filenum, ok := t.fileMap[file]
+ if !ok {
+ return 0
+ }
+
+ // Scan all functions.
+ // If this turns out to be a bottleneck, we could build a map[int32][]int32
+ // mapping file number to a list of functions with code from that file.
+ var cutab []byte
+ for i := uint32(0); i < t.nfunctab; i++ {
+ f := t.funcdata[t.uintptr(t.functab[2*t.ptrsize*i+t.ptrsize:]):]
+ entry := t.uintptr(f)
+ filetab := t.binary.Uint32(f[t.ptrsize+4*4:])
+ linetab := t.binary.Uint32(f[t.ptrsize+5*4:])
+ if t.version == ver116 {
+ cuoff := t.binary.Uint32(f[t.ptrsize+7*4:]) * 4
+ cutab = t.cutab[cuoff:]
+ }
+ pc := t.findFileLine(entry, filetab, linetab, int32(filenum), int32(line), cutab)
+ if pc != 0 {
+ return pc
+ }
+ }
+ return 0
+}
+
+// initFileMap initializes the map from file name to file number.
+func (t *LineTable) initFileMap() {
+ t.mu.Lock()
+ defer t.mu.Unlock()
+
+ if t.fileMap != nil {
+ return
+ }
+ m := make(map[string]uint32)
+
+ if t.version == ver12 {
+ for i := uint32(1); i < t.nfiletab; i++ {
+ s := t.string(t.binary.Uint32(t.filetab[4*i:]))
+ m[s] = i
+ }
+ } else {
+ var pos uint32
+ for i := uint32(0); i < t.nfiletab; i++ {
+ s := t.stringFrom(t.filetab, pos)
+ m[s] = pos
+ pos += uint32(len(s) + 1)
+ }
+ }
+ t.fileMap = m
+}
+
+// go12MapFiles adds to m a key for every file in the Go 1.2 LineTable.
+// Every key maps to obj. That's not a very interesting map, but it provides
+// a way for callers to obtain the list of files in the program.
+func (t *LineTable) go12MapFiles(m map[string]*Obj, obj *Obj) {
+ defer func() {
+ recover()
+ }()
+
+ t.initFileMap()
+ for file := range t.fileMap {
+ m[file] = obj
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-02-25 19:21:29 +0000