File size: 3,647 Bytes
f7a7bb1 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 | // Copyright 2021 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 decodemeta
// This package contains APIs and helpers for decoding a single package's
// meta data "blob" emitted by the compiler when coverage instrumentation
// is turned on.
import (
"encoding/binary"
"fmt"
"internal/coverage"
"internal/coverage/slicereader"
"internal/coverage/stringtab"
"io"
"os"
)
// See comments in the encodecovmeta package for details on the format.
type CoverageMetaDataDecoder struct {
r *slicereader.Reader
hdr coverage.MetaSymbolHeader
strtab *stringtab.Reader
tmp []byte
debug bool
}
func NewCoverageMetaDataDecoder(b []byte, readonly bool) (*CoverageMetaDataDecoder, error) {
slr := slicereader.NewReader(b, readonly)
x := &CoverageMetaDataDecoder{
r: slr,
tmp: make([]byte, 0, 256),
}
if err := x.readHeader(); err != nil {
return nil, err
}
if err := x.readStringTable(); err != nil {
return nil, err
}
return x, nil
}
func (d *CoverageMetaDataDecoder) readHeader() error {
if err := binary.Read(d.r, binary.LittleEndian, &d.hdr); err != nil {
return err
}
if d.debug {
fmt.Fprintf(os.Stderr, "=-= after readHeader: %+v\n", d.hdr)
}
return nil
}
func (d *CoverageMetaDataDecoder) readStringTable() error {
// Seek to the correct location to read the string table.
stringTableLocation := int64(coverage.CovMetaHeaderSize + 4*d.hdr.NumFuncs)
if _, err := d.r.Seek(stringTableLocation, io.SeekStart); err != nil {
return err
}
// Read the table itself.
d.strtab = stringtab.NewReader(d.r)
d.strtab.Read()
return nil
}
func (d *CoverageMetaDataDecoder) PackagePath() string {
return d.strtab.Get(d.hdr.PkgPath)
}
func (d *CoverageMetaDataDecoder) PackageName() string {
return d.strtab.Get(d.hdr.PkgName)
}
func (d *CoverageMetaDataDecoder) ModulePath() string {
return d.strtab.Get(d.hdr.ModulePath)
}
func (d *CoverageMetaDataDecoder) NumFuncs() uint32 {
return d.hdr.NumFuncs
}
// ReadFunc reads the coverage meta-data for the function with index
// 'findex', filling it into the FuncDesc pointed to by 'f'.
func (d *CoverageMetaDataDecoder) ReadFunc(fidx uint32, f *coverage.FuncDesc) error {
if fidx >= d.hdr.NumFuncs {
return fmt.Errorf("illegal function index")
}
// Seek to the correct location to read the function offset and read it.
funcOffsetLocation := int64(coverage.CovMetaHeaderSize + 4*fidx)
if _, err := d.r.Seek(funcOffsetLocation, io.SeekStart); err != nil {
return err
}
foff := d.r.ReadUint32()
// Check assumptions
if foff < uint32(funcOffsetLocation) || foff > d.hdr.Length {
return fmt.Errorf("malformed func offset %d", foff)
}
// Seek to the correct location to read the function.
floc := int64(foff)
if _, err := d.r.Seek(floc, io.SeekStart); err != nil {
return err
}
// Preamble containing number of units, file, and function.
numUnits := uint32(d.r.ReadULEB128())
fnameidx := uint32(d.r.ReadULEB128())
fileidx := uint32(d.r.ReadULEB128())
f.Srcfile = d.strtab.Get(fileidx)
f.Funcname = d.strtab.Get(fnameidx)
// Now the units
f.Units = f.Units[:0]
if cap(f.Units) < int(numUnits) {
f.Units = make([]coverage.CoverableUnit, 0, numUnits)
}
for k := uint32(0); k < numUnits; k++ {
f.Units = append(f.Units,
coverage.CoverableUnit{
StLine: uint32(d.r.ReadULEB128()),
StCol: uint32(d.r.ReadULEB128()),
EnLine: uint32(d.r.ReadULEB128()),
EnCol: uint32(d.r.ReadULEB128()),
NxStmts: uint32(d.r.ReadULEB128()),
})
}
lit := d.r.ReadULEB128()
f.Lit = lit != 0
return nil
}
|