| // 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. |
| |
| // Runtime type representation. |
| |
| package runtime |
| |
| import ( |
| "internal/abi" |
| "unsafe" |
| ) |
| |
| // tflag is documented in reflect/type.go. |
| // |
| // tflag values must be kept in sync with copies in: |
| // |
| // cmd/compile/internal/reflectdata/reflect.go |
| // cmd/link/internal/ld/decodesym.go |
| // reflect/type.go |
| // internal/reflectlite/type.go |
| type tflag uint8 |
| |
| const ( |
| tflagUncommon tflag = 1 << 0 |
| tflagExtraStar tflag = 1 << 1 |
| tflagNamed tflag = 1 << 2 |
| tflagRegularMemory tflag = 1 << 3 // equal and hash can treat values of this type as a single region of t.size bytes |
| ) |
| |
| // Needs to be in sync with ../cmd/link/internal/ld/decodesym.go:/^func.commonsize, |
| // ../cmd/compile/internal/reflectdata/reflect.go:/^func.dcommontype and |
| // ../reflect/type.go:/^type.rtype. |
| // ../internal/reflectlite/type.go:/^type.rtype. |
| type _type struct { |
| size uintptr |
| ptrdata uintptr // size of memory prefix holding all pointers |
| hash uint32 |
| tflag tflag |
| align uint8 |
| fieldAlign uint8 |
| kind uint8 |
| // function for comparing objects of this type |
| // (ptr to object A, ptr to object B) -> ==? |
| equal func(unsafe.Pointer, unsafe.Pointer) bool |
| // gcdata stores the GC type data for the garbage collector. |
| // If the KindGCProg bit is set in kind, gcdata is a GC program. |
| // Otherwise it is a ptrmask bitmap. See mbitmap.go for details. |
| gcdata *byte |
| str nameOff |
| ptrToThis typeOff |
| } |
| |
| func (t *_type) string() string { |
| s := t.nameOff(t.str).name() |
| if t.tflag&tflagExtraStar != 0 { |
| return s[1:] |
| } |
| return s |
| } |
| |
| func (t *_type) uncommon() *uncommontype { |
| if t.tflag&tflagUncommon == 0 { |
| return nil |
| } |
| switch t.kind & kindMask { |
| case kindStruct: |
| type u struct { |
| structtype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindPtr: |
| type u struct { |
| ptrtype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindFunc: |
| type u struct { |
| functype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindSlice: |
| type u struct { |
| slicetype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindArray: |
| type u struct { |
| arraytype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindChan: |
| type u struct { |
| chantype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindMap: |
| type u struct { |
| maptype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| case kindInterface: |
| type u struct { |
| interfacetype |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| default: |
| type u struct { |
| _type |
| u uncommontype |
| } |
| return &(*u)(unsafe.Pointer(t)).u |
| } |
| } |
| |
| func (t *_type) name() string { |
| if t.tflag&tflagNamed == 0 { |
| return "" |
| } |
| s := t.string() |
| i := len(s) - 1 |
| sqBrackets := 0 |
| for i >= 0 && (s[i] != '.' || sqBrackets != 0) { |
| switch s[i] { |
| case ']': |
| sqBrackets++ |
| case '[': |
| sqBrackets-- |
| } |
| i-- |
| } |
| return s[i+1:] |
| } |
| |
| // pkgpath returns the path of the package where t was defined, if |
| // available. This is not the same as the reflect package's PkgPath |
| // method, in that it returns the package path for struct and interface |
| // types, not just named types. |
| func (t *_type) pkgpath() string { |
| if u := t.uncommon(); u != nil { |
| return t.nameOff(u.pkgpath).name() |
| } |
| switch t.kind & kindMask { |
| case kindStruct: |
| st := (*structtype)(unsafe.Pointer(t)) |
| return st.pkgPath.name() |
| case kindInterface: |
| it := (*interfacetype)(unsafe.Pointer(t)) |
| return it.pkgpath.name() |
| } |
| return "" |
| } |
| |
| // reflectOffs holds type offsets defined at run time by the reflect package. |
| // |
| // When a type is defined at run time, its *rtype data lives on the heap. |
| // There are a wide range of possible addresses the heap may use, that |
| // may not be representable as a 32-bit offset. Moreover the GC may |
| // one day start moving heap memory, in which case there is no stable |
| // offset that can be defined. |
| // |
| // To provide stable offsets, we add pin *rtype objects in a global map |
| // and treat the offset as an identifier. We use negative offsets that |
| // do not overlap with any compile-time module offsets. |
| // |
| // Entries are created by reflect.addReflectOff. |
| var reflectOffs struct { |
| lock mutex |
| next int32 |
| m map[int32]unsafe.Pointer |
| minv map[unsafe.Pointer]int32 |
| } |
| |
| func reflectOffsLock() { |
| lock(&reflectOffs.lock) |
| if raceenabled { |
| raceacquire(unsafe.Pointer(&reflectOffs.lock)) |
| } |
| } |
| |
| func reflectOffsUnlock() { |
| if raceenabled { |
| racerelease(unsafe.Pointer(&reflectOffs.lock)) |
| } |
| unlock(&reflectOffs.lock) |
| } |
| |
| func resolveNameOff(ptrInModule unsafe.Pointer, off nameOff) name { |
| if off == 0 { |
| return name{} |
| } |
| base := uintptr(ptrInModule) |
| for md := &firstmoduledata; md != nil; md = md.next { |
| if base >= md.types && base < md.etypes { |
| res := md.types + uintptr(off) |
| if res > md.etypes { |
| println("runtime: nameOff", hex(off), "out of range", hex(md.types), "-", hex(md.etypes)) |
| throw("runtime: name offset out of range") |
| } |
| return name{(*byte)(unsafe.Pointer(res))} |
| } |
| } |
| |
| // No module found. see if it is a run time name. |
| reflectOffsLock() |
| res, found := reflectOffs.m[int32(off)] |
| reflectOffsUnlock() |
| if !found { |
| println("runtime: nameOff", hex(off), "base", hex(base), "not in ranges:") |
| for next := &firstmoduledata; next != nil; next = next.next { |
| println("\ttypes", hex(next.types), "etypes", hex(next.etypes)) |
| } |
| throw("runtime: name offset base pointer out of range") |
| } |
| return name{(*byte)(res)} |
| } |
| |
| func (t *_type) nameOff(off nameOff) name { |
| return resolveNameOff(unsafe.Pointer(t), off) |
| } |
| |
| func resolveTypeOff(ptrInModule unsafe.Pointer, off typeOff) *_type { |
| if off == 0 || off == -1 { |
| // -1 is the sentinel value for unreachable code. |
| // See cmd/link/internal/ld/data.go:relocsym. |
| return nil |
| } |
| base := uintptr(ptrInModule) |
| var md *moduledata |
| for next := &firstmoduledata; next != nil; next = next.next { |
| if base >= next.types && base < next.etypes { |
| md = next |
| break |
| } |
| } |
| if md == nil { |
| reflectOffsLock() |
| res := reflectOffs.m[int32(off)] |
| reflectOffsUnlock() |
| if res == nil { |
| println("runtime: typeOff", hex(off), "base", hex(base), "not in ranges:") |
| for next := &firstmoduledata; next != nil; next = next.next { |
| println("\ttypes", hex(next.types), "etypes", hex(next.etypes)) |
| } |
| throw("runtime: type offset base pointer out of range") |
| } |
| return (*_type)(res) |
| } |
| if t := md.typemap[off]; t != nil { |
| return t |
| } |
| res := md.types + uintptr(off) |
| if res > md.etypes { |
| println("runtime: typeOff", hex(off), "out of range", hex(md.types), "-", hex(md.etypes)) |
| throw("runtime: type offset out of range") |
| } |
| return (*_type)(unsafe.Pointer(res)) |
| } |
| |
| func (t *_type) typeOff(off typeOff) *_type { |
| return resolveTypeOff(unsafe.Pointer(t), off) |
| } |
| |
| func (t *_type) textOff(off textOff) unsafe.Pointer { |
| if off == -1 { |
| // -1 is the sentinel value for unreachable code. |
| // See cmd/link/internal/ld/data.go:relocsym. |
| return unsafe.Pointer(abi.FuncPCABIInternal(unreachableMethod)) |
| } |
| base := uintptr(unsafe.Pointer(t)) |
| var md *moduledata |
| for next := &firstmoduledata; next != nil; next = next.next { |
| if base >= next.types && base < next.etypes { |
| md = next |
| break |
| } |
| } |
| if md == nil { |
| reflectOffsLock() |
| res := reflectOffs.m[int32(off)] |
| reflectOffsUnlock() |
| if res == nil { |
| println("runtime: textOff", hex(off), "base", hex(base), "not in ranges:") |
| for next := &firstmoduledata; next != nil; next = next.next { |
| println("\ttypes", hex(next.types), "etypes", hex(next.etypes)) |
| } |
| throw("runtime: text offset base pointer out of range") |
| } |
| return res |
| } |
| res := md.textAddr(uint32(off)) |
| return unsafe.Pointer(res) |
| } |
| |
| func (t *functype) in() []*_type { |
| // See funcType in reflect/type.go for details on data layout. |
| uadd := uintptr(unsafe.Sizeof(functype{})) |
| if t.typ.tflag&tflagUncommon != 0 { |
| uadd += unsafe.Sizeof(uncommontype{}) |
| } |
| return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[:t.inCount] |
| } |
| |
| func (t *functype) out() []*_type { |
| // See funcType in reflect/type.go for details on data layout. |
| uadd := uintptr(unsafe.Sizeof(functype{})) |
| if t.typ.tflag&tflagUncommon != 0 { |
| uadd += unsafe.Sizeof(uncommontype{}) |
| } |
| outCount := t.outCount & (1<<15 - 1) |
| return (*[1 << 20]*_type)(add(unsafe.Pointer(t), uadd))[t.inCount : t.inCount+outCount] |
| } |
| |
| func (t *functype) dotdotdot() bool { |
| return t.outCount&(1<<15) != 0 |
| } |
| |
| type nameOff int32 |
| type typeOff int32 |
| type textOff int32 |
| |
| type method struct { |
| name nameOff |
| mtyp typeOff |
| ifn textOff |
| tfn textOff |
| } |
| |
| type uncommontype struct { |
| pkgpath nameOff |
| mcount uint16 // number of methods |
| xcount uint16 // number of exported methods |
| moff uint32 // offset from this uncommontype to [mcount]method |
| _ uint32 // unused |
| } |
| |
| type imethod struct { |
| name nameOff |
| ityp typeOff |
| } |
| |
| type interfacetype struct { |
| typ _type |
| pkgpath name |
| mhdr []imethod |
| } |
| |
| type maptype struct { |
| typ _type |
| key *_type |
| elem *_type |
| bucket *_type // internal type representing a hash bucket |
| // function for hashing keys (ptr to key, seed) -> hash |
| hasher func(unsafe.Pointer, uintptr) uintptr |
| keysize uint8 // size of key slot |
| elemsize uint8 // size of elem slot |
| bucketsize uint16 // size of bucket |
| flags uint32 |
| } |
| |
| // Note: flag values must match those used in the TMAP case |
| // in ../cmd/compile/internal/reflectdata/reflect.go:writeType. |
| func (mt *maptype) indirectkey() bool { // store ptr to key instead of key itself |
| return mt.flags&1 != 0 |
| } |
| func (mt *maptype) indirectelem() bool { // store ptr to elem instead of elem itself |
| return mt.flags&2 != 0 |
| } |
| func (mt *maptype) reflexivekey() bool { // true if k==k for all keys |
| return mt.flags&4 != 0 |
| } |
| func (mt *maptype) needkeyupdate() bool { // true if we need to update key on an overwrite |
| return mt.flags&8 != 0 |
| } |
| func (mt *maptype) hashMightPanic() bool { // true if hash function might panic |
| return mt.flags&16 != 0 |
| } |
| |
| type arraytype struct { |
| typ _type |
| elem *_type |
| slice *_type |
| len uintptr |
| } |
| |
| type chantype struct { |
| typ _type |
| elem *_type |
| dir uintptr |
| } |
| |
| type slicetype struct { |
| typ _type |
| elem *_type |
| } |
| |
| type functype struct { |
| typ _type |
| inCount uint16 |
| outCount uint16 |
| } |
| |
| type ptrtype struct { |
| typ _type |
| elem *_type |
| } |
| |
| type structfield struct { |
| name name |
| typ *_type |
| offsetAnon uintptr |
| } |
| |
| func (f *structfield) offset() uintptr { |
| return f.offsetAnon >> 1 |
| } |
| |
| type structtype struct { |
| typ _type |
| pkgPath name |
| fields []structfield |
| } |
| |
| // name is an encoded type name with optional extra data. |
| // See reflect/type.go for details. |
| type name struct { |
| bytes *byte |
| } |
| |
| func (n name) data(off int) *byte { |
| return (*byte)(add(unsafe.Pointer(n.bytes), uintptr(off))) |
| } |
| |
| func (n name) isExported() bool { |
| return (*n.bytes)&(1<<0) != 0 |
| } |
| |
| func (n name) readvarint(off int) (int, int) { |
| v := 0 |
| for i := 0; ; i++ { |
| x := *n.data(off + i) |
| v += int(x&0x7f) << (7 * i) |
| if x&0x80 == 0 { |
| return i + 1, v |
| } |
| } |
| } |
| |
| func (n name) name() (s string) { |
| if n.bytes == nil { |
| return "" |
| } |
| i, l := n.readvarint(1) |
| if l == 0 { |
| return "" |
| } |
| hdr := (*stringStruct)(unsafe.Pointer(&s)) |
| hdr.str = unsafe.Pointer(n.data(1 + i)) |
| hdr.len = l |
| return |
| } |
| |
| func (n name) tag() (s string) { |
| if *n.data(0)&(1<<1) == 0 { |
| return "" |
| } |
| i, l := n.readvarint(1) |
| i2, l2 := n.readvarint(1 + i + l) |
| hdr := (*stringStruct)(unsafe.Pointer(&s)) |
| hdr.str = unsafe.Pointer(n.data(1 + i + l + i2)) |
| hdr.len = l2 |
| return |
| } |
| |
| func (n name) pkgPath() string { |
| if n.bytes == nil || *n.data(0)&(1<<2) == 0 { |
| return "" |
| } |
| i, l := n.readvarint(1) |
| off := 1 + i + l |
| if *n.data(0)&(1<<1) != 0 { |
| i2, l2 := n.readvarint(off) |
| off += i2 + l2 |
| } |
| var nameOff nameOff |
| copy((*[4]byte)(unsafe.Pointer(&nameOff))[:], (*[4]byte)(unsafe.Pointer(n.data(off)))[:]) |
| pkgPathName := resolveNameOff(unsafe.Pointer(n.bytes), nameOff) |
| return pkgPathName.name() |
| } |
| |
| func (n name) isBlank() bool { |
| if n.bytes == nil { |
| return false |
| } |
| _, l := n.readvarint(1) |
| return l == 1 && *n.data(2) == '_' |
| } |
| |
| // typelinksinit scans the types from extra modules and builds the |
| // moduledata typemap used to de-duplicate type pointers. |
| func typelinksinit() { |
| if firstmoduledata.next == nil { |
| return |
| } |
| typehash := make(map[uint32][]*_type, len(firstmoduledata.typelinks)) |
| |
| modules := activeModules() |
| prev := modules[0] |
| for _, md := range modules[1:] { |
| // Collect types from the previous module into typehash. |
| collect: |
| for _, tl := range prev.typelinks { |
| var t *_type |
| if prev.typemap == nil { |
| t = (*_type)(unsafe.Pointer(prev.types + uintptr(tl))) |
| } else { |
| t = prev.typemap[typeOff(tl)] |
| } |
| // Add to typehash if not seen before. |
| tlist := typehash[t.hash] |
| for _, tcur := range tlist { |
| if tcur == t { |
| continue collect |
| } |
| } |
| typehash[t.hash] = append(tlist, t) |
| } |
| |
| if md.typemap == nil { |
| // If any of this module's typelinks match a type from a |
| // prior module, prefer that prior type by adding the offset |
| // to this module's typemap. |
| tm := make(map[typeOff]*_type, len(md.typelinks)) |
| pinnedTypemaps = append(pinnedTypemaps, tm) |
| md.typemap = tm |
| for _, tl := range md.typelinks { |
| t := (*_type)(unsafe.Pointer(md.types + uintptr(tl))) |
| for _, candidate := range typehash[t.hash] { |
| seen := map[_typePair]struct{}{} |
| if typesEqual(t, candidate, seen) { |
| t = candidate |
| break |
| } |
| } |
| md.typemap[typeOff(tl)] = t |
| } |
| } |
| |
| prev = md |
| } |
| } |
| |
| type _typePair struct { |
| t1 *_type |
| t2 *_type |
| } |
| |
| // typesEqual reports whether two types are equal. |
| // |
| // Everywhere in the runtime and reflect packages, it is assumed that |
| // there is exactly one *_type per Go type, so that pointer equality |
| // can be used to test if types are equal. There is one place that |
| // breaks this assumption: buildmode=shared. In this case a type can |
| // appear as two different pieces of memory. This is hidden from the |
| // runtime and reflect package by the per-module typemap built in |
| // typelinksinit. It uses typesEqual to map types from later modules |
| // back into earlier ones. |
| // |
| // Only typelinksinit needs this function. |
| func typesEqual(t, v *_type, seen map[_typePair]struct{}) bool { |
| tp := _typePair{t, v} |
| if _, ok := seen[tp]; ok { |
| return true |
| } |
| |
| // mark these types as seen, and thus equivalent which prevents an infinite loop if |
| // the two types are identical, but recursively defined and loaded from |
| // different modules |
| seen[tp] = struct{}{} |
| |
| if t == v { |
| return true |
| } |
| kind := t.kind & kindMask |
| if kind != v.kind&kindMask { |
| return false |
| } |
| if t.string() != v.string() { |
| return false |
| } |
| ut := t.uncommon() |
| uv := v.uncommon() |
| if ut != nil || uv != nil { |
| if ut == nil || uv == nil { |
| return false |
| } |
| pkgpatht := t.nameOff(ut.pkgpath).name() |
| pkgpathv := v.nameOff(uv.pkgpath).name() |
| if pkgpatht != pkgpathv { |
| return false |
| } |
| } |
| if kindBool <= kind && kind <= kindComplex128 { |
| return true |
| } |
| switch kind { |
| case kindString, kindUnsafePointer: |
| return true |
| case kindArray: |
| at := (*arraytype)(unsafe.Pointer(t)) |
| av := (*arraytype)(unsafe.Pointer(v)) |
| return typesEqual(at.elem, av.elem, seen) && at.len == av.len |
| case kindChan: |
| ct := (*chantype)(unsafe.Pointer(t)) |
| cv := (*chantype)(unsafe.Pointer(v)) |
| return ct.dir == cv.dir && typesEqual(ct.elem, cv.elem, seen) |
| case kindFunc: |
| ft := (*functype)(unsafe.Pointer(t)) |
| fv := (*functype)(unsafe.Pointer(v)) |
| if ft.outCount != fv.outCount || ft.inCount != fv.inCount { |
| return false |
| } |
| tin, vin := ft.in(), fv.in() |
| for i := 0; i < len(tin); i++ { |
| if !typesEqual(tin[i], vin[i], seen) { |
| return false |
| } |
| } |
| tout, vout := ft.out(), fv.out() |
| for i := 0; i < len(tout); i++ { |
| if !typesEqual(tout[i], vout[i], seen) { |
| return false |
| } |
| } |
| return true |
| case kindInterface: |
| it := (*interfacetype)(unsafe.Pointer(t)) |
| iv := (*interfacetype)(unsafe.Pointer(v)) |
| if it.pkgpath.name() != iv.pkgpath.name() { |
| return false |
| } |
| if len(it.mhdr) != len(iv.mhdr) { |
| return false |
| } |
| for i := range it.mhdr { |
| tm := &it.mhdr[i] |
| vm := &iv.mhdr[i] |
| // Note the mhdr array can be relocated from |
| // another module. See #17724. |
| tname := resolveNameOff(unsafe.Pointer(tm), tm.name) |
| vname := resolveNameOff(unsafe.Pointer(vm), vm.name) |
| if tname.name() != vname.name() { |
| return false |
| } |
| if tname.pkgPath() != vname.pkgPath() { |
| return false |
| } |
| tityp := resolveTypeOff(unsafe.Pointer(tm), tm.ityp) |
| vityp := resolveTypeOff(unsafe.Pointer(vm), vm.ityp) |
| if !typesEqual(tityp, vityp, seen) { |
| return false |
| } |
| } |
| return true |
| case kindMap: |
| mt := (*maptype)(unsafe.Pointer(t)) |
| mv := (*maptype)(unsafe.Pointer(v)) |
| return typesEqual(mt.key, mv.key, seen) && typesEqual(mt.elem, mv.elem, seen) |
| case kindPtr: |
| pt := (*ptrtype)(unsafe.Pointer(t)) |
| pv := (*ptrtype)(unsafe.Pointer(v)) |
| return typesEqual(pt.elem, pv.elem, seen) |
| case kindSlice: |
| st := (*slicetype)(unsafe.Pointer(t)) |
| sv := (*slicetype)(unsafe.Pointer(v)) |
| return typesEqual(st.elem, sv.elem, seen) |
| case kindStruct: |
| st := (*structtype)(unsafe.Pointer(t)) |
| sv := (*structtype)(unsafe.Pointer(v)) |
| if len(st.fields) != len(sv.fields) { |
| return false |
| } |
| if st.pkgPath.name() != sv.pkgPath.name() { |
| return false |
| } |
| for i := range st.fields { |
| tf := &st.fields[i] |
| vf := &sv.fields[i] |
| if tf.name.name() != vf.name.name() { |
| return false |
| } |
| if !typesEqual(tf.typ, vf.typ, seen) { |
| return false |
| } |
| if tf.name.tag() != vf.name.tag() { |
| return false |
| } |
| if tf.offsetAnon != vf.offsetAnon { |
| return false |
| } |
| } |
| return true |
| default: |
| println("runtime: impossible type kind", kind) |
| throw("runtime: impossible type kind") |
| return false |
| } |
| } |
