| // 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. |
| |
| // DWARF type information structures. |
| // The format is heavily biased toward C, but for simplicity |
| // the String methods use a pseudo-Go syntax. |
| |
| package dwarf |
| |
| import "strconv" |
| |
| // A Type conventionally represents a pointer to any of the |
| // specific Type structures (CharType, StructType, etc.). |
| type Type interface { |
| Common() *CommonType |
| String() string |
| Size() int64 |
| } |
| |
| // A CommonType holds fields common to multiple types. |
| // If a field is not known or not applicable for a given type, |
| // the zero value is used. |
| type CommonType struct { |
| ByteSize int64 // size of value of this type, in bytes |
| Name string // name that can be used to refer to type |
| } |
| |
| func (c *CommonType) Common() *CommonType { return c } |
| |
| func (c *CommonType) Size() int64 { return c.ByteSize } |
| |
| // Basic types |
| |
| // A BasicType holds fields common to all basic types. |
| type BasicType struct { |
| CommonType |
| BitSize int64 |
| BitOffset int64 |
| } |
| |
| func (b *BasicType) Basic() *BasicType { return b } |
| |
| func (t *BasicType) String() string { |
| if t.Name != "" { |
| return t.Name |
| } |
| return "?" |
| } |
| |
| // A CharType represents a signed character type. |
| type CharType struct { |
| BasicType |
| } |
| |
| // A UcharType represents an unsigned character type. |
| type UcharType struct { |
| BasicType |
| } |
| |
| // An IntType represents a signed integer type. |
| type IntType struct { |
| BasicType |
| } |
| |
| // A UintType represents an unsigned integer type. |
| type UintType struct { |
| BasicType |
| } |
| |
| // A FloatType represents a floating point type. |
| type FloatType struct { |
| BasicType |
| } |
| |
| // A ComplexType represents a complex floating point type. |
| type ComplexType struct { |
| BasicType |
| } |
| |
| // A BoolType represents a boolean type. |
| type BoolType struct { |
| BasicType |
| } |
| |
| // An AddrType represents a machine address type. |
| type AddrType struct { |
| BasicType |
| } |
| |
| // An UnspecifiedType represents an implicit, unknown, ambiguous or nonexistent type. |
| type UnspecifiedType struct { |
| BasicType |
| } |
| |
| // qualifiers |
| |
| // A QualType represents a type that has the C/C++ "const", "restrict", or "volatile" qualifier. |
| type QualType struct { |
| CommonType |
| Qual string |
| Type Type |
| } |
| |
| func (t *QualType) String() string { return t.Qual + " " + t.Type.String() } |
| |
| func (t *QualType) Size() int64 { return t.Type.Size() } |
| |
| // An ArrayType represents a fixed size array type. |
| type ArrayType struct { |
| CommonType |
| Type Type |
| StrideBitSize int64 // if > 0, number of bits to hold each element |
| Count int64 // if == -1, an incomplete array, like char x[]. |
| } |
| |
| func (t *ArrayType) String() string { |
| return "[" + strconv.FormatInt(t.Count, 10) + "]" + t.Type.String() |
| } |
| |
| func (t *ArrayType) Size() int64 { |
| if t.Count == -1 { |
| return 0 |
| } |
| return t.Count * t.Type.Size() |
| } |
| |
| // A VoidType represents the C void type. |
| type VoidType struct { |
| CommonType |
| } |
| |
| func (t *VoidType) String() string { return "void" } |
| |
| // A PtrType represents a pointer type. |
| type PtrType struct { |
| CommonType |
| Type Type |
| } |
| |
| func (t *PtrType) String() string { return "*" + t.Type.String() } |
| |
| // A StructType represents a struct, union, or C++ class type. |
| type StructType struct { |
| CommonType |
| StructName string |
| Kind string // "struct", "union", or "class". |
| Field []*StructField |
| Incomplete bool // if true, struct, union, class is declared but not defined |
| } |
| |
| // A StructField represents a field in a struct, union, or C++ class type. |
| type StructField struct { |
| Name string |
| Type Type |
| ByteOffset int64 |
| ByteSize int64 |
| BitOffset int64 // within the ByteSize bytes at ByteOffset |
| BitSize int64 // zero if not a bit field |
| } |
| |
| func (t *StructType) String() string { |
| if t.StructName != "" { |
| return t.Kind + " " + t.StructName |
| } |
| return t.Defn() |
| } |
| |
| func (t *StructType) Defn() string { |
| s := t.Kind |
| if t.StructName != "" { |
| s += " " + t.StructName |
| } |
| if t.Incomplete { |
| s += " /*incomplete*/" |
| return s |
| } |
| s += " {" |
| for i, f := range t.Field { |
| if i > 0 { |
| s += "; " |
| } |
| s += f.Name + " " + f.Type.String() |
| s += "@" + strconv.FormatInt(f.ByteOffset, 10) |
| if f.BitSize > 0 { |
| s += " : " + strconv.FormatInt(f.BitSize, 10) |
| s += "@" + strconv.FormatInt(f.BitOffset, 10) |
| } |
| } |
| s += "}" |
| return s |
| } |
| |
| // An EnumType represents an enumerated type. |
| // The only indication of its native integer type is its ByteSize |
| // (inside CommonType). |
| type EnumType struct { |
| CommonType |
| EnumName string |
| Val []*EnumValue |
| } |
| |
| // An EnumValue represents a single enumeration value. |
| type EnumValue struct { |
| Name string |
| Val int64 |
| } |
| |
| func (t *EnumType) String() string { |
| s := "enum" |
| if t.EnumName != "" { |
| s += " " + t.EnumName |
| } |
| s += " {" |
| for i, v := range t.Val { |
| if i > 0 { |
| s += "; " |
| } |
| s += v.Name + "=" + strconv.FormatInt(v.Val, 10) |
| } |
| s += "}" |
| return s |
| } |
| |
| // A FuncType represents a function type. |
| type FuncType struct { |
| CommonType |
| ReturnType Type |
| ParamType []Type |
| } |
| |
| func (t *FuncType) String() string { |
| s := "func(" |
| for i, t := range t.ParamType { |
| if i > 0 { |
| s += ", " |
| } |
| s += t.String() |
| } |
| s += ")" |
| if t.ReturnType != nil { |
| s += " " + t.ReturnType.String() |
| } |
| return s |
| } |
| |
| // A DotDotDotType represents the variadic ... function parameter. |
| type DotDotDotType struct { |
| CommonType |
| } |
| |
| func (t *DotDotDotType) String() string { return "..." } |
| |
| // A TypedefType represents a named type. |
| type TypedefType struct { |
| CommonType |
| Type Type |
| } |
| |
| func (t *TypedefType) String() string { return t.Name } |
| |
| func (t *TypedefType) Size() int64 { return t.Type.Size() } |
| |
| // typeReader is used to read from either the info section or the |
| // types section. |
| type typeReader interface { |
| Seek(Offset) |
| Next() (*Entry, error) |
| clone() typeReader |
| offset() Offset |
| } |
| |
| // Type reads the type at off in the DWARF ``info'' section. |
| func (d *Data) Type(off Offset) (Type, error) { |
| return d.readType("info", d.Reader(), off, d.typeCache) |
| } |
| |
| // readType reads a type from r at off of name using and updating a |
| // type cache. |
| func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Offset]Type) (Type, error) { |
| if t, ok := typeCache[off]; ok { |
| return t, nil |
| } |
| r.Seek(off) |
| e, err := r.Next() |
| if err != nil { |
| return nil, err |
| } |
| if e == nil || e.Offset != off { |
| return nil, DecodeError{name, off, "no type at offset"} |
| } |
| |
| // Parse type from Entry. |
| // Must always set typeCache[off] before calling |
| // d.Type recursively, to handle circular types correctly. |
| var typ Type |
| |
| nextDepth := 0 |
| |
| // Get next child; set err if error happens. |
| next := func() *Entry { |
| if !e.Children { |
| return nil |
| } |
| // Only return direct children. |
| // Skip over composite entries that happen to be nested |
| // inside this one. Most DWARF generators wouldn't generate |
| // such a thing, but clang does. |
| // See golang.org/issue/6472. |
| for { |
| kid, err1 := r.Next() |
| if err1 != nil { |
| err = err1 |
| return nil |
| } |
| if kid == nil { |
| err = DecodeError{name, r.offset(), "unexpected end of DWARF entries"} |
| return nil |
| } |
| if kid.Tag == 0 { |
| if nextDepth > 0 { |
| nextDepth-- |
| continue |
| } |
| return nil |
| } |
| if kid.Children { |
| nextDepth++ |
| } |
| if nextDepth > 0 { |
| continue |
| } |
| return kid |
| } |
| } |
| |
| // Get Type referred to by Entry's AttrType field. |
| // Set err if error happens. Not having a type is an error. |
| typeOf := func(e *Entry) Type { |
| tval := e.Val(AttrType) |
| var t Type |
| switch toff := tval.(type) { |
| case Offset: |
| if t, err = d.readType(name, r.clone(), toff, typeCache); err != nil { |
| return nil |
| } |
| case uint64: |
| if t, err = d.sigToType(toff); err != nil { |
| return nil |
| } |
| default: |
| // It appears that no Type means "void". |
| return new(VoidType) |
| } |
| return t |
| } |
| |
| switch e.Tag { |
| case TagArrayType: |
| // Multi-dimensional array. (DWARF v2 §5.4) |
| // Attributes: |
| // AttrType:subtype [required] |
| // AttrStrideSize: size in bits of each element of the array |
| // AttrByteSize: size of entire array |
| // Children: |
| // TagSubrangeType or TagEnumerationType giving one dimension. |
| // dimensions are in left to right order. |
| t := new(ArrayType) |
| typ = t |
| typeCache[off] = t |
| if t.Type = typeOf(e); err != nil { |
| goto Error |
| } |
| t.StrideBitSize, _ = e.Val(AttrStrideSize).(int64) |
| |
| // Accumulate dimensions, |
| var dims []int64 |
| for kid := next(); kid != nil; kid = next() { |
| // TODO(rsc): Can also be TagEnumerationType |
| // but haven't seen that in the wild yet. |
| switch kid.Tag { |
| case TagSubrangeType: |
| count, ok := kid.Val(AttrCount).(int64) |
| if !ok { |
| // Old binaries may have an upper bound instead. |
| count, ok = kid.Val(AttrUpperBound).(int64) |
| if ok { |
| count++ // Length is one more than upper bound. |
| } else if len(dims) == 0 { |
| count = -1 // As in x[]. |
| } |
| } |
| dims = append(dims, count) |
| case TagEnumerationType: |
| err = DecodeError{name, kid.Offset, "cannot handle enumeration type as array bound"} |
| goto Error |
| } |
| } |
| if len(dims) == 0 { |
| // LLVM generates this for x[]. |
| dims = []int64{-1} |
| } |
| |
| t.Count = dims[0] |
| for i := len(dims) - 1; i >= 1; i-- { |
| t.Type = &ArrayType{Type: t.Type, Count: dims[i]} |
| } |
| |
| case TagBaseType: |
| // Basic type. (DWARF v2 §5.1) |
| // Attributes: |
| // AttrName: name of base type in programming language of the compilation unit [required] |
| // AttrEncoding: encoding value for type (encFloat etc) [required] |
| // AttrByteSize: size of type in bytes [required] |
| // AttrBitOffset: for sub-byte types, size in bits |
| // AttrBitSize: for sub-byte types, bit offset of high order bit in the AttrByteSize bytes |
| name, _ := e.Val(AttrName).(string) |
| enc, ok := e.Val(AttrEncoding).(int64) |
| if !ok { |
| err = DecodeError{name, e.Offset, "missing encoding attribute for " + name} |
| goto Error |
| } |
| switch enc { |
| default: |
| err = DecodeError{name, e.Offset, "unrecognized encoding attribute value"} |
| goto Error |
| |
| case encAddress: |
| typ = new(AddrType) |
| case encBoolean: |
| typ = new(BoolType) |
| case encComplexFloat: |
| typ = new(ComplexType) |
| if name == "complex" { |
| // clang writes out 'complex' instead of 'complex float' or 'complex double'. |
| // clang also writes out a byte size that we can use to distinguish. |
| // See issue 8694. |
| switch byteSize, _ := e.Val(AttrByteSize).(int64); byteSize { |
| case 8: |
| name = "complex float" |
| case 16: |
| name = "complex double" |
| } |
| } |
| case encFloat: |
| typ = new(FloatType) |
| case encSigned: |
| typ = new(IntType) |
| case encUnsigned: |
| typ = new(UintType) |
| case encSignedChar: |
| typ = new(CharType) |
| case encUnsignedChar: |
| typ = new(UcharType) |
| } |
| typeCache[off] = typ |
| t := typ.(interface { |
| Basic() *BasicType |
| }).Basic() |
| t.Name = name |
| t.BitSize, _ = e.Val(AttrBitSize).(int64) |
| t.BitOffset, _ = e.Val(AttrBitOffset).(int64) |
| |
| case TagClassType, TagStructType, TagUnionType: |
| // Structure, union, or class type. (DWARF v2 §5.5) |
| // Attributes: |
| // AttrName: name of struct, union, or class |
| // AttrByteSize: byte size [required] |
| // AttrDeclaration: if true, struct/union/class is incomplete |
| // Children: |
| // TagMember to describe one member. |
| // AttrName: name of member [required] |
| // AttrType: type of member [required] |
| // AttrByteSize: size in bytes |
| // AttrBitOffset: bit offset within bytes for bit fields |
| // AttrBitSize: bit size for bit fields |
| // AttrDataMemberLoc: location within struct [required for struct, class] |
| // There is much more to handle C++, all ignored for now. |
| t := new(StructType) |
| typ = t |
| typeCache[off] = t |
| switch e.Tag { |
| case TagClassType: |
| t.Kind = "class" |
| case TagStructType: |
| t.Kind = "struct" |
| case TagUnionType: |
| t.Kind = "union" |
| } |
| t.StructName, _ = e.Val(AttrName).(string) |
| t.Incomplete = e.Val(AttrDeclaration) != nil |
| t.Field = make([]*StructField, 0, 8) |
| var lastFieldType *Type |
| var lastFieldBitOffset int64 |
| for kid := next(); kid != nil; kid = next() { |
| if kid.Tag == TagMember { |
| f := new(StructField) |
| if f.Type = typeOf(kid); err != nil { |
| goto Error |
| } |
| switch loc := kid.Val(AttrDataMemberLoc).(type) { |
| case []byte: |
| // TODO: Should have original compilation |
| // unit here, not unknownFormat. |
| b := makeBuf(d, unknownFormat{}, "location", 0, loc) |
| if b.uint8() != opPlusUconst { |
| err = DecodeError{name, kid.Offset, "unexpected opcode"} |
| goto Error |
| } |
| f.ByteOffset = int64(b.uint()) |
| if b.err != nil { |
| err = b.err |
| goto Error |
| } |
| case int64: |
| f.ByteOffset = loc |
| } |
| |
| haveBitOffset := false |
| f.Name, _ = kid.Val(AttrName).(string) |
| f.ByteSize, _ = kid.Val(AttrByteSize).(int64) |
| f.BitOffset, haveBitOffset = kid.Val(AttrBitOffset).(int64) |
| f.BitSize, _ = kid.Val(AttrBitSize).(int64) |
| t.Field = append(t.Field, f) |
| |
| bito := f.BitOffset |
| if !haveBitOffset { |
| bito = f.ByteOffset * 8 |
| } |
| if bito == lastFieldBitOffset && t.Kind != "union" { |
| // Last field was zero width. Fix array length. |
| // (DWARF writes out 0-length arrays as if they were 1-length arrays.) |
| zeroArray(lastFieldType) |
| } |
| lastFieldType = &f.Type |
| lastFieldBitOffset = bito |
| } |
| } |
| if t.Kind != "union" { |
| b, ok := e.Val(AttrByteSize).(int64) |
| if ok && b*8 == lastFieldBitOffset { |
| // Final field must be zero width. Fix array length. |
| zeroArray(lastFieldType) |
| } |
| } |
| |
| case TagConstType, TagVolatileType, TagRestrictType: |
| // Type modifier (DWARF v2 §5.2) |
| // Attributes: |
| // AttrType: subtype |
| t := new(QualType) |
| typ = t |
| typeCache[off] = t |
| if t.Type = typeOf(e); err != nil { |
| goto Error |
| } |
| switch e.Tag { |
| case TagConstType: |
| t.Qual = "const" |
| case TagRestrictType: |
| t.Qual = "restrict" |
| case TagVolatileType: |
| t.Qual = "volatile" |
| } |
| |
| case TagEnumerationType: |
| // Enumeration type (DWARF v2 §5.6) |
| // Attributes: |
| // AttrName: enum name if any |
| // AttrByteSize: bytes required to represent largest value |
| // Children: |
| // TagEnumerator: |
| // AttrName: name of constant |
| // AttrConstValue: value of constant |
| t := new(EnumType) |
| typ = t |
| typeCache[off] = t |
| t.EnumName, _ = e.Val(AttrName).(string) |
| t.Val = make([]*EnumValue, 0, 8) |
| for kid := next(); kid != nil; kid = next() { |
| if kid.Tag == TagEnumerator { |
| f := new(EnumValue) |
| f.Name, _ = kid.Val(AttrName).(string) |
| f.Val, _ = kid.Val(AttrConstValue).(int64) |
| n := len(t.Val) |
| if n >= cap(t.Val) { |
| val := make([]*EnumValue, n, n*2) |
| copy(val, t.Val) |
| t.Val = val |
| } |
| t.Val = t.Val[0 : n+1] |
| t.Val[n] = f |
| } |
| } |
| |
| case TagPointerType: |
| // Type modifier (DWARF v2 §5.2) |
| // Attributes: |
| // AttrType: subtype [not required! void* has no AttrType] |
| // AttrAddrClass: address class [ignored] |
| t := new(PtrType) |
| typ = t |
| typeCache[off] = t |
| if e.Val(AttrType) == nil { |
| t.Type = &VoidType{} |
| break |
| } |
| t.Type = typeOf(e) |
| |
| case TagSubroutineType: |
| // Subroutine type. (DWARF v2 §5.7) |
| // Attributes: |
| // AttrType: type of return value if any |
| // AttrName: possible name of type [ignored] |
| // AttrPrototyped: whether used ANSI C prototype [ignored] |
| // Children: |
| // TagFormalParameter: typed parameter |
| // AttrType: type of parameter |
| // TagUnspecifiedParameter: final ... |
| t := new(FuncType) |
| typ = t |
| typeCache[off] = t |
| if t.ReturnType = typeOf(e); err != nil { |
| goto Error |
| } |
| t.ParamType = make([]Type, 0, 8) |
| for kid := next(); kid != nil; kid = next() { |
| var tkid Type |
| switch kid.Tag { |
| default: |
| continue |
| case TagFormalParameter: |
| if tkid = typeOf(kid); err != nil { |
| goto Error |
| } |
| case TagUnspecifiedParameters: |
| tkid = &DotDotDotType{} |
| } |
| t.ParamType = append(t.ParamType, tkid) |
| } |
| |
| case TagTypedef: |
| // Typedef (DWARF v2 §5.3) |
| // Attributes: |
| // AttrName: name [required] |
| // AttrType: type definition [required] |
| t := new(TypedefType) |
| typ = t |
| typeCache[off] = t |
| t.Name, _ = e.Val(AttrName).(string) |
| t.Type = typeOf(e) |
| |
| case TagUnspecifiedType: |
| // Unspecified type (DWARF v3 §5.2) |
| // Attributes: |
| // AttrName: name |
| t := new(UnspecifiedType) |
| typ = t |
| typeCache[off] = t |
| t.Name, _ = e.Val(AttrName).(string) |
| } |
| |
| if err != nil { |
| goto Error |
| } |
| |
| { |
| b, ok := e.Val(AttrByteSize).(int64) |
| if !ok { |
| b = -1 |
| } |
| typ.Common().ByteSize = b |
| } |
| return typ, nil |
| |
| Error: |
| // If the parse fails, take the type out of the cache |
| // so that the next call with this offset doesn't hit |
| // the cache and return success. |
| delete(typeCache, off) |
| return nil, err |
| } |
| |
| func zeroArray(t *Type) { |
| if t == nil { |
| return |
| } |
| at, ok := (*t).(*ArrayType) |
| if !ok || at.Type.Size() == 0 { |
| return |
| } |
| // Make a copy to avoid invalidating typeCache. |
| tt := *at |
| tt.Count = 0 |
| *t = &tt |
| } |