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-rw-r--r--src/runtime/string.go485
1 files changed, 485 insertions, 0 deletions
diff --git a/src/runtime/string.go b/src/runtime/string.go
new file mode 100644
index 0000000..9a601f0
--- /dev/null
+++ b/src/runtime/string.go
@@ -0,0 +1,485 @@
+// Copyright 2014 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 runtime
+
+import (
+ "internal/bytealg"
+ "runtime/internal/sys"
+ "unsafe"
+)
+
+// The constant is known to the compiler.
+// There is no fundamental theory behind this number.
+const tmpStringBufSize = 32
+
+type tmpBuf [tmpStringBufSize]byte
+
+// concatstrings implements a Go string concatenation x+y+z+...
+// The operands are passed in the slice a.
+// If buf != nil, the compiler has determined that the result does not
+// escape the calling function, so the string data can be stored in buf
+// if small enough.
+func concatstrings(buf *tmpBuf, a []string) string {
+ idx := 0
+ l := 0
+ count := 0
+ for i, x := range a {
+ n := len(x)
+ if n == 0 {
+ continue
+ }
+ if l+n < l {
+ throw("string concatenation too long")
+ }
+ l += n
+ count++
+ idx = i
+ }
+ if count == 0 {
+ return ""
+ }
+
+ // If there is just one string and either it is not on the stack
+ // or our result does not escape the calling frame (buf != nil),
+ // then we can return that string directly.
+ if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
+ return a[idx]
+ }
+ s, b := rawstringtmp(buf, l)
+ for _, x := range a {
+ copy(b, x)
+ b = b[len(x):]
+ }
+ return s
+}
+
+func concatstring2(buf *tmpBuf, a [2]string) string {
+ return concatstrings(buf, a[:])
+}
+
+func concatstring3(buf *tmpBuf, a [3]string) string {
+ return concatstrings(buf, a[:])
+}
+
+func concatstring4(buf *tmpBuf, a [4]string) string {
+ return concatstrings(buf, a[:])
+}
+
+func concatstring5(buf *tmpBuf, a [5]string) string {
+ return concatstrings(buf, a[:])
+}
+
+// slicebytetostring converts a byte slice to a string.
+// It is inserted by the compiler into generated code.
+// ptr is a pointer to the first element of the slice;
+// n is the length of the slice.
+// Buf is a fixed-size buffer for the result,
+// it is not nil if the result does not escape.
+func slicebytetostring(buf *tmpBuf, ptr *byte, n int) (str string) {
+ if n == 0 {
+ // Turns out to be a relatively common case.
+ // Consider that you want to parse out data between parens in "foo()bar",
+ // you find the indices and convert the subslice to string.
+ return ""
+ }
+ if raceenabled {
+ racereadrangepc(unsafe.Pointer(ptr),
+ uintptr(n),
+ getcallerpc(),
+ funcPC(slicebytetostring))
+ }
+ if msanenabled {
+ msanread(unsafe.Pointer(ptr), uintptr(n))
+ }
+ if n == 1 {
+ p := unsafe.Pointer(&staticuint64s[*ptr])
+ if sys.BigEndian {
+ p = add(p, 7)
+ }
+ stringStructOf(&str).str = p
+ stringStructOf(&str).len = 1
+ return
+ }
+
+ var p unsafe.Pointer
+ if buf != nil && n <= len(buf) {
+ p = unsafe.Pointer(buf)
+ } else {
+ p = mallocgc(uintptr(n), nil, false)
+ }
+ stringStructOf(&str).str = p
+ stringStructOf(&str).len = n
+ memmove(p, unsafe.Pointer(ptr), uintptr(n))
+ return
+}
+
+// stringDataOnStack reports whether the string's data is
+// stored on the current goroutine's stack.
+func stringDataOnStack(s string) bool {
+ ptr := uintptr(stringStructOf(&s).str)
+ stk := getg().stack
+ return stk.lo <= ptr && ptr < stk.hi
+}
+
+func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
+ if buf != nil && l <= len(buf) {
+ b = buf[:l]
+ s = slicebytetostringtmp(&b[0], len(b))
+ } else {
+ s, b = rawstring(l)
+ }
+ return
+}
+
+// slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
+//
+// Callers need to ensure that the returned string will not be used after
+// the calling goroutine modifies the original slice or synchronizes with
+// another goroutine.
+//
+// The function is only called when instrumenting
+// and otherwise intrinsified by the compiler.
+//
+// Some internal compiler optimizations use this function.
+// - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)]
+// where k is []byte, T1 to Tn is a nesting of struct and array literals.
+// - Used for "<"+string(b)+">" concatenation where b is []byte.
+// - Used for string(b)=="foo" comparison where b is []byte.
+func slicebytetostringtmp(ptr *byte, n int) (str string) {
+ if raceenabled && n > 0 {
+ racereadrangepc(unsafe.Pointer(ptr),
+ uintptr(n),
+ getcallerpc(),
+ funcPC(slicebytetostringtmp))
+ }
+ if msanenabled && n > 0 {
+ msanread(unsafe.Pointer(ptr), uintptr(n))
+ }
+ stringStructOf(&str).str = unsafe.Pointer(ptr)
+ stringStructOf(&str).len = n
+ return
+}
+
+func stringtoslicebyte(buf *tmpBuf, s string) []byte {
+ var b []byte
+ if buf != nil && len(s) <= len(buf) {
+ *buf = tmpBuf{}
+ b = buf[:len(s)]
+ } else {
+ b = rawbyteslice(len(s))
+ }
+ copy(b, s)
+ return b
+}
+
+func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
+ // two passes.
+ // unlike slicerunetostring, no race because strings are immutable.
+ n := 0
+ for range s {
+ n++
+ }
+
+ var a []rune
+ if buf != nil && n <= len(buf) {
+ *buf = [tmpStringBufSize]rune{}
+ a = buf[:n]
+ } else {
+ a = rawruneslice(n)
+ }
+
+ n = 0
+ for _, r := range s {
+ a[n] = r
+ n++
+ }
+ return a
+}
+
+func slicerunetostring(buf *tmpBuf, a []rune) string {
+ if raceenabled && len(a) > 0 {
+ racereadrangepc(unsafe.Pointer(&a[0]),
+ uintptr(len(a))*unsafe.Sizeof(a[0]),
+ getcallerpc(),
+ funcPC(slicerunetostring))
+ }
+ if msanenabled && len(a) > 0 {
+ msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
+ }
+ var dum [4]byte
+ size1 := 0
+ for _, r := range a {
+ size1 += encoderune(dum[:], r)
+ }
+ s, b := rawstringtmp(buf, size1+3)
+ size2 := 0
+ for _, r := range a {
+ // check for race
+ if size2 >= size1 {
+ break
+ }
+ size2 += encoderune(b[size2:], r)
+ }
+ return s[:size2]
+}
+
+type stringStruct struct {
+ str unsafe.Pointer
+ len int
+}
+
+// Variant with *byte pointer type for DWARF debugging.
+type stringStructDWARF struct {
+ str *byte
+ len int
+}
+
+func stringStructOf(sp *string) *stringStruct {
+ return (*stringStruct)(unsafe.Pointer(sp))
+}
+
+func intstring(buf *[4]byte, v int64) (s string) {
+ var b []byte
+ if buf != nil {
+ b = buf[:]
+ s = slicebytetostringtmp(&b[0], len(b))
+ } else {
+ s, b = rawstring(4)
+ }
+ if int64(rune(v)) != v {
+ v = runeError
+ }
+ n := encoderune(b, rune(v))
+ return s[:n]
+}
+
+// rawstring allocates storage for a new string. The returned
+// string and byte slice both refer to the same storage.
+// The storage is not zeroed. Callers should use
+// b to set the string contents and then drop b.
+func rawstring(size int) (s string, b []byte) {
+ p := mallocgc(uintptr(size), nil, false)
+
+ stringStructOf(&s).str = p
+ stringStructOf(&s).len = size
+
+ *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
+
+ return
+}
+
+// rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
+func rawbyteslice(size int) (b []byte) {
+ cap := roundupsize(uintptr(size))
+ p := mallocgc(cap, nil, false)
+ if cap != uintptr(size) {
+ memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
+ }
+
+ *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
+ return
+}
+
+// rawruneslice allocates a new rune slice. The rune slice is not zeroed.
+func rawruneslice(size int) (b []rune) {
+ if uintptr(size) > maxAlloc/4 {
+ throw("out of memory")
+ }
+ mem := roundupsize(uintptr(size) * 4)
+ p := mallocgc(mem, nil, false)
+ if mem != uintptr(size)*4 {
+ memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
+ }
+
+ *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
+ return
+}
+
+// used by cmd/cgo
+func gobytes(p *byte, n int) (b []byte) {
+ if n == 0 {
+ return make([]byte, 0)
+ }
+
+ if n < 0 || uintptr(n) > maxAlloc {
+ panic(errorString("gobytes: length out of range"))
+ }
+
+ bp := mallocgc(uintptr(n), nil, false)
+ memmove(bp, unsafe.Pointer(p), uintptr(n))
+
+ *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n}
+ return
+}
+
+// This is exported via linkname to assembly in syscall (for Plan9).
+//go:linkname gostring
+func gostring(p *byte) string {
+ l := findnull(p)
+ if l == 0 {
+ return ""
+ }
+ s, b := rawstring(l)
+ memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
+ return s
+}
+
+func gostringn(p *byte, l int) string {
+ if l == 0 {
+ return ""
+ }
+ s, b := rawstring(l)
+ memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
+ return s
+}
+
+func hasPrefix(s, prefix string) bool {
+ return len(s) >= len(prefix) && s[:len(prefix)] == prefix
+}
+
+const (
+ maxUint = ^uint(0)
+ maxInt = int(maxUint >> 1)
+)
+
+// atoi parses an int from a string s.
+// The bool result reports whether s is a number
+// representable by a value of type int.
+func atoi(s string) (int, bool) {
+ if s == "" {
+ return 0, false
+ }
+
+ neg := false
+ if s[0] == '-' {
+ neg = true
+ s = s[1:]
+ }
+
+ un := uint(0)
+ for i := 0; i < len(s); i++ {
+ c := s[i]
+ if c < '0' || c > '9' {
+ return 0, false
+ }
+ if un > maxUint/10 {
+ // overflow
+ return 0, false
+ }
+ un *= 10
+ un1 := un + uint(c) - '0'
+ if un1 < un {
+ // overflow
+ return 0, false
+ }
+ un = un1
+ }
+
+ if !neg && un > uint(maxInt) {
+ return 0, false
+ }
+ if neg && un > uint(maxInt)+1 {
+ return 0, false
+ }
+
+ n := int(un)
+ if neg {
+ n = -n
+ }
+
+ return n, true
+}
+
+// atoi32 is like atoi but for integers
+// that fit into an int32.
+func atoi32(s string) (int32, bool) {
+ if n, ok := atoi(s); n == int(int32(n)) {
+ return int32(n), ok
+ }
+ return 0, false
+}
+
+//go:nosplit
+func findnull(s *byte) int {
+ if s == nil {
+ return 0
+ }
+
+ // Avoid IndexByteString on Plan 9 because it uses SSE instructions
+ // on x86 machines, and those are classified as floating point instructions,
+ // which are illegal in a note handler.
+ if GOOS == "plan9" {
+ p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s))
+ l := 0
+ for p[l] != 0 {
+ l++
+ }
+ return l
+ }
+
+ // pageSize is the unit we scan at a time looking for NULL.
+ // It must be the minimum page size for any architecture Go
+ // runs on. It's okay (just a minor performance loss) if the
+ // actual system page size is larger than this value.
+ const pageSize = 4096
+
+ offset := 0
+ ptr := unsafe.Pointer(s)
+ // IndexByteString uses wide reads, so we need to be careful
+ // with page boundaries. Call IndexByteString on
+ // [ptr, endOfPage) interval.
+ safeLen := int(pageSize - uintptr(ptr)%pageSize)
+
+ for {
+ t := *(*string)(unsafe.Pointer(&stringStruct{ptr, safeLen}))
+ // Check one page at a time.
+ if i := bytealg.IndexByteString(t, 0); i != -1 {
+ return offset + i
+ }
+ // Move to next page
+ ptr = unsafe.Pointer(uintptr(ptr) + uintptr(safeLen))
+ offset += safeLen
+ safeLen = pageSize
+ }
+}
+
+func findnullw(s *uint16) int {
+ if s == nil {
+ return 0
+ }
+ p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s))
+ l := 0
+ for p[l] != 0 {
+ l++
+ }
+ return l
+}
+
+//go:nosplit
+func gostringnocopy(str *byte) string {
+ ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
+ s := *(*string)(unsafe.Pointer(&ss))
+ return s
+}
+
+func gostringw(strw *uint16) string {
+ var buf [8]byte
+ str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw))
+ n1 := 0
+ for i := 0; str[i] != 0; i++ {
+ n1 += encoderune(buf[:], rune(str[i]))
+ }
+ s, b := rawstring(n1 + 4)
+ n2 := 0
+ for i := 0; str[i] != 0; i++ {
+ // check for race
+ if n2 >= n1 {
+ break
+ }
+ n2 += encoderune(b[n2:], rune(str[i]))
+ }
+ b[n2] = 0 // for luck
+ return s[:n2]
+}