1 // Copyright 2012 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package dwarf 6 7 import ( 8 "fmt" 9 "strconv" 10 ) 11 12 // Parse the type units stored in a DWARF4 .debug_types section. Each 13 // type unit defines a single primary type and an 8-byte signature. 14 // Other sections may then use formRefSig8 to refer to the type. 15 16 // The typeUnit format is a single type with a signature. It holds 17 // the same data as a compilation unit. 18 type typeUnit struct { 19 unit 20 toff Offset // Offset to signature type within data. 21 name string // Name of .debug_type section. 22 cache Type // Cache the type, nil to start. 23 } 24 25 // Parse a .debug_types section. 26 func (d *Data) parseTypes(name string, types []byte) error { 27 b := makeBuf(d, unknownFormat{}, name, 0, types) 28 for len(b.data) > 0 { 29 base := b.off 30 n, dwarf64 := b.unitLength() 31 if n != Offset(uint32(n)) { 32 b.error("type unit length overflow") 33 return b.err 34 } 35 hdroff := b.off 36 vers := int(b.uint16()) 37 if vers != 4 { 38 b.error("unsupported DWARF version " + strconv.Itoa(vers)) 39 return b.err 40 } 41 var ao uint64 42 if !dwarf64 { 43 ao = uint64(b.uint32()) 44 } else { 45 ao = b.uint64() 46 } 47 atable, err := d.parseAbbrev(ao, vers) 48 if err != nil { 49 return err 50 } 51 asize := b.uint8() 52 sig := b.uint64() 53 54 var toff uint32 55 if !dwarf64 { 56 toff = b.uint32() 57 } else { 58 to64 := b.uint64() 59 if to64 != uint64(uint32(to64)) { 60 b.error("type unit type offset overflow") 61 return b.err 62 } 63 toff = uint32(to64) 64 } 65 66 boff := b.off 67 d.typeSigs[sig] = &typeUnit{ 68 unit: unit{ 69 base: base, 70 off: boff, 71 data: b.bytes(int(n - (b.off - hdroff))), 72 atable: atable, 73 asize: int(asize), 74 vers: vers, 75 is64: dwarf64, 76 }, 77 toff: Offset(toff), 78 name: name, 79 } 80 if b.err != nil { 81 return b.err 82 } 83 } 84 return nil 85 } 86 87 // Return the type for a type signature. 88 func (d *Data) sigToType(sig uint64) (Type, error) { 89 tu := d.typeSigs[sig] 90 if tu == nil { 91 return nil, fmt.Errorf("no type unit with signature %v", sig) 92 } 93 if tu.cache != nil { 94 return tu.cache, nil 95 } 96 97 b := makeBuf(d, tu, tu.name, tu.off, tu.data) 98 r := &typeUnitReader{d: d, tu: tu, b: b} 99 t, err := d.readType(tu.name, r, tu.toff, make(map[Offset]Type), nil) 100 if err != nil { 101 return nil, err 102 } 103 104 tu.cache = t 105 return t, nil 106 } 107 108 // typeUnitReader is a typeReader for a tagTypeUnit. 109 type typeUnitReader struct { 110 d *Data 111 tu *typeUnit 112 b buf 113 err error 114 } 115 116 // Seek to a new position in the type unit. 117 func (tur *typeUnitReader) Seek(off Offset) { 118 tur.err = nil 119 doff := off - tur.tu.off 120 if doff < 0 || doff >= Offset(len(tur.tu.data)) { 121 tur.err = fmt.Errorf("%s: offset %d out of range; max %d", tur.tu.name, doff, len(tur.tu.data)) 122 return 123 } 124 tur.b = makeBuf(tur.d, tur.tu, tur.tu.name, off, tur.tu.data[doff:]) 125 } 126 127 // AddressSize returns the size in bytes of addresses in the current type unit. 128 func (tur *typeUnitReader) AddressSize() int { 129 return tur.tu.unit.asize 130 } 131 132 // Next reads the next Entry from the type unit. 133 func (tur *typeUnitReader) Next() (*Entry, error) { 134 if tur.err != nil { 135 return nil, tur.err 136 } 137 if len(tur.tu.data) == 0 { 138 return nil, nil 139 } 140 e := tur.b.entry(tur.tu.atable, tur.tu.base) 141 if tur.b.err != nil { 142 tur.err = tur.b.err 143 return nil, tur.err 144 } 145 return e, nil 146 } 147 148 // clone returns a new reader for the type unit. 149 func (tur *typeUnitReader) clone() typeReader { 150 return &typeUnitReader{ 151 d: tur.d, 152 tu: tur.tu, 153 b: makeBuf(tur.d, tur.tu, tur.tu.name, tur.tu.off, tur.tu.data), 154 } 155 } 156 157 // offset returns the current offset. 158 func (tur *typeUnitReader) offset() Offset { 159 return tur.b.off 160 } 161
