Initial commit: Go 1.23 release state
This commit is contained in:
Vorapol Rinsatitnon
590
src/runtime/string.go
Normal file
590
src/runtime/string.go
Normal file
@@ -0,0 +1,590 @@
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"internal/abi"
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"internal/bytealg"
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"internal/goarch"
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"unsafe"
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)
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// The constant is known to the compiler.
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// There is no fundamental theory behind this number.
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const tmpStringBufSize = 32
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type tmpBuf [tmpStringBufSize]byte
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// concatstrings implements a Go string concatenation x+y+z+...
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// The operands are passed in the slice a.
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// If buf != nil, the compiler has determined that the result does not
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// escape the calling function, so the string data can be stored in buf
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// if small enough.
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func concatstrings(buf *tmpBuf, a []string) string {
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idx := 0
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l := 0
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count := 0
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for i, x := range a {
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n := len(x)
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if n == 0 {
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continue
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}
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if l+n < l {
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throw("string concatenation too long")
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}
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l += n
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count++
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idx = i
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}
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if count == 0 {
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return ""
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}
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// If there is just one string and either it is not on the stack
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// or our result does not escape the calling frame (buf != nil),
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// then we can return that string directly.
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if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
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return a[idx]
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}
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s, b := rawstringtmp(buf, l)
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for _, x := range a {
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copy(b, x)
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b = b[len(x):]
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}
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return s
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}
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func concatstring2(buf *tmpBuf, a0, a1 string) string {
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return concatstrings(buf, []string{a0, a1})
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}
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func concatstring3(buf *tmpBuf, a0, a1, a2 string) string {
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return concatstrings(buf, []string{a0, a1, a2})
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}
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func concatstring4(buf *tmpBuf, a0, a1, a2, a3 string) string {
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return concatstrings(buf, []string{a0, a1, a2, a3})
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}
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func concatstring5(buf *tmpBuf, a0, a1, a2, a3, a4 string) string {
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return concatstrings(buf, []string{a0, a1, a2, a3, a4})
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}
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// slicebytetostring converts a byte slice to a string.
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// It is inserted by the compiler into generated code.
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// ptr is a pointer to the first element of the slice;
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// n is the length of the slice.
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// Buf is a fixed-size buffer for the result,
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// it is not nil if the result does not escape.
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//
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// slicebytetostring should be an internal detail,
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// but widely used packages access it using linkname.
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// Notable members of the hall of shame include:
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// - github.com/cloudwego/frugal
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//
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// Do not remove or change the type signature.
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// See go.dev/issue/67401.
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//
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//go:linkname slicebytetostring
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func slicebytetostring(buf *tmpBuf, ptr *byte, n int) string {
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if n == 0 {
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// Turns out to be a relatively common case.
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// Consider that you want to parse out data between parens in "foo()bar",
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// you find the indices and convert the subslice to string.
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return ""
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}
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if raceenabled {
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racereadrangepc(unsafe.Pointer(ptr),
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uintptr(n),
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getcallerpc(),
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abi.FuncPCABIInternal(slicebytetostring))
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}
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if msanenabled {
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msanread(unsafe.Pointer(ptr), uintptr(n))
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}
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if asanenabled {
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asanread(unsafe.Pointer(ptr), uintptr(n))
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}
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if n == 1 {
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p := unsafe.Pointer(&staticuint64s[*ptr])
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if goarch.BigEndian {
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p = add(p, 7)
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}
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return unsafe.String((*byte)(p), 1)
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}
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var p unsafe.Pointer
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if buf != nil && n <= len(buf) {
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p = unsafe.Pointer(buf)
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} else {
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p = mallocgc(uintptr(n), nil, false)
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}
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memmove(p, unsafe.Pointer(ptr), uintptr(n))
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return unsafe.String((*byte)(p), n)
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}
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// stringDataOnStack reports whether the string's data is
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// stored on the current goroutine's stack.
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func stringDataOnStack(s string) bool {
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ptr := uintptr(unsafe.Pointer(unsafe.StringData(s)))
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stk := getg().stack
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return stk.lo <= ptr && ptr < stk.hi
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}
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func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
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if buf != nil && l <= len(buf) {
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b = buf[:l]
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s = slicebytetostringtmp(&b[0], len(b))
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} else {
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s, b = rawstring(l)
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}
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return
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}
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// slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
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//
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// Callers need to ensure that the returned string will not be used after
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// the calling goroutine modifies the original slice or synchronizes with
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// another goroutine.
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//
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// The function is only called when instrumenting
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// and otherwise intrinsified by the compiler.
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//
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// Some internal compiler optimizations use this function.
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// - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)]
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// where k is []byte, T1 to Tn is a nesting of struct and array literals.
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// - Used for "<"+string(b)+">" concatenation where b is []byte.
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// - Used for string(b)=="foo" comparison where b is []byte.
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func slicebytetostringtmp(ptr *byte, n int) string {
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if raceenabled && n > 0 {
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racereadrangepc(unsafe.Pointer(ptr),
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uintptr(n),
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getcallerpc(),
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abi.FuncPCABIInternal(slicebytetostringtmp))
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}
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if msanenabled && n > 0 {
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msanread(unsafe.Pointer(ptr), uintptr(n))
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}
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if asanenabled && n > 0 {
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asanread(unsafe.Pointer(ptr), uintptr(n))
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}
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return unsafe.String(ptr, n)
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}
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func stringtoslicebyte(buf *tmpBuf, s string) []byte {
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var b []byte
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if buf != nil && len(s) <= len(buf) {
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*buf = tmpBuf{}
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b = buf[:len(s)]
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} else {
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b = rawbyteslice(len(s))
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}
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copy(b, s)
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return b
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}
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func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
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// two passes.
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// unlike slicerunetostring, no race because strings are immutable.
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n := 0
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for range s {
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n++
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}
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var a []rune
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if buf != nil && n <= len(buf) {
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*buf = [tmpStringBufSize]rune{}
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a = buf[:n]
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} else {
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a = rawruneslice(n)
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}
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n = 0
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for _, r := range s {
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a[n] = r
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n++
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}
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return a
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}
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func slicerunetostring(buf *tmpBuf, a []rune) string {
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if raceenabled && len(a) > 0 {
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racereadrangepc(unsafe.Pointer(&a[0]),
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uintptr(len(a))*unsafe.Sizeof(a[0]),
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getcallerpc(),
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abi.FuncPCABIInternal(slicerunetostring))
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}
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if msanenabled && len(a) > 0 {
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msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
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}
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if asanenabled && len(a) > 0 {
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asanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
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}
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var dum [4]byte
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size1 := 0
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for _, r := range a {
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size1 += encoderune(dum[:], r)
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}
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s, b := rawstringtmp(buf, size1+3)
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size2 := 0
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for _, r := range a {
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// check for race
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if size2 >= size1 {
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break
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}
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size2 += encoderune(b[size2:], r)
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}
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return s[:size2]
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}
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type stringStruct struct {
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str unsafe.Pointer
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len int
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}
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// Variant with *byte pointer type for DWARF debugging.
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type stringStructDWARF struct {
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str *byte
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len int
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}
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func stringStructOf(sp *string) *stringStruct {
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return (*stringStruct)(unsafe.Pointer(sp))
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}
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func intstring(buf *[4]byte, v int64) (s string) {
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var b []byte
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if buf != nil {
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b = buf[:]
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s = slicebytetostringtmp(&b[0], len(b))
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} else {
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s, b = rawstring(4)
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}
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if int64(rune(v)) != v {
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v = runeError
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}
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n := encoderune(b, rune(v))
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return s[:n]
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}
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// rawstring allocates storage for a new string. The returned
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// string and byte slice both refer to the same storage.
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// The storage is not zeroed. Callers should use
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// b to set the string contents and then drop b.
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func rawstring(size int) (s string, b []byte) {
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p := mallocgc(uintptr(size), nil, false)
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return unsafe.String((*byte)(p), size), unsafe.Slice((*byte)(p), size)
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}
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// rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
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func rawbyteslice(size int) (b []byte) {
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cap := roundupsize(uintptr(size), true)
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p := mallocgc(cap, nil, false)
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if cap != uintptr(size) {
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memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
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}
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*(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
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return
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}
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// rawruneslice allocates a new rune slice. The rune slice is not zeroed.
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func rawruneslice(size int) (b []rune) {
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if uintptr(size) > maxAlloc/4 {
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throw("out of memory")
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}
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mem := roundupsize(uintptr(size)*4, true)
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p := mallocgc(mem, nil, false)
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if mem != uintptr(size)*4 {
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memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
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}
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*(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
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return
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}
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// used by cmd/cgo
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func gobytes(p *byte, n int) (b []byte) {
|
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if n == 0 {
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return make([]byte, 0)
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}
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if n < 0 || uintptr(n) > maxAlloc {
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panic(errorString("gobytes: length out of range"))
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}
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|
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bp := mallocgc(uintptr(n), nil, false)
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memmove(bp, unsafe.Pointer(p), uintptr(n))
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*(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n}
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return
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}
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// This is exported via linkname to assembly in syscall (for Plan9) and cgo.
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//
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//go:linkname gostring
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func gostring(p *byte) string {
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l := findnull(p)
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if l == 0 {
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return ""
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}
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s, b := rawstring(l)
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memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
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return s
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}
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// internal_syscall_gostring is a version of gostring for internal/syscall/unix.
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//
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//go:linkname internal_syscall_gostring internal/syscall/unix.gostring
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func internal_syscall_gostring(p *byte) string {
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return gostring(p)
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}
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|
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func gostringn(p *byte, l int) string {
|
||||
if l == 0 {
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return ""
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||||
}
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s, b := rawstring(l)
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memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
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return s
|
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}
|
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|
||||
const (
|
||||
maxUint64 = ^uint64(0)
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||||
maxInt64 = int64(maxUint64 >> 1)
|
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)
|
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|
||||
// atoi64 parses an int64 from a string s.
|
||||
// The bool result reports whether s is a number
|
||||
// representable by a value of type int64.
|
||||
func atoi64(s string) (int64, bool) {
|
||||
if s == "" {
|
||||
return 0, false
|
||||
}
|
||||
|
||||
neg := false
|
||||
if s[0] == '-' {
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neg = true
|
||||
s = s[1:]
|
||||
}
|
||||
|
||||
un := uint64(0)
|
||||
for i := 0; i < len(s); i++ {
|
||||
c := s[i]
|
||||
if c < '0' || c > '9' {
|
||||
return 0, false
|
||||
}
|
||||
if un > maxUint64/10 {
|
||||
// overflow
|
||||
return 0, false
|
||||
}
|
||||
un *= 10
|
||||
un1 := un + uint64(c) - '0'
|
||||
if un1 < un {
|
||||
// overflow
|
||||
return 0, false
|
||||
}
|
||||
un = un1
|
||||
}
|
||||
|
||||
if !neg && un > uint64(maxInt64) {
|
||||
return 0, false
|
||||
}
|
||||
if neg && un > uint64(maxInt64)+1 {
|
||||
return 0, false
|
||||
}
|
||||
|
||||
n := int64(un)
|
||||
if neg {
|
||||
n = -n
|
||||
}
|
||||
|
||||
return n, true
|
||||
}
|
||||
|
||||
// atoi is like atoi64 but for integers
|
||||
// that fit into an int.
|
||||
func atoi(s string) (int, bool) {
|
||||
if n, ok := atoi64(s); n == int64(int(n)) {
|
||||
return int(n), ok
|
||||
}
|
||||
return 0, false
|
||||
}
|
||||
|
||||
// atoi32 is like atoi but for integers
|
||||
// that fit into an int32.
|
||||
func atoi32(s string) (int32, bool) {
|
||||
if n, ok := atoi64(s); n == int64(int32(n)) {
|
||||
return int32(n), ok
|
||||
}
|
||||
return 0, false
|
||||
}
|
||||
|
||||
// parseByteCount parses a string that represents a count of bytes.
|
||||
//
|
||||
// s must match the following regular expression:
|
||||
//
|
||||
// ^[0-9]+(([KMGT]i)?B)?$
|
||||
//
|
||||
// In other words, an integer byte count with an optional unit
|
||||
// suffix. Acceptable suffixes include one of
|
||||
// - KiB, MiB, GiB, TiB which represent binary IEC/ISO 80000 units, or
|
||||
// - B, which just represents bytes.
|
||||
//
|
||||
// Returns an int64 because that's what its callers want and receive,
|
||||
// but the result is always non-negative.
|
||||
func parseByteCount(s string) (int64, bool) {
|
||||
// The empty string is not valid.
|
||||
if s == "" {
|
||||
return 0, false
|
||||
}
|
||||
// Handle the easy non-suffix case.
|
||||
last := s[len(s)-1]
|
||||
if last >= '0' && last <= '9' {
|
||||
n, ok := atoi64(s)
|
||||
if !ok || n < 0 {
|
||||
return 0, false
|
||||
}
|
||||
return n, ok
|
||||
}
|
||||
// Failing a trailing digit, this must always end in 'B'.
|
||||
// Also at this point there must be at least one digit before
|
||||
// that B.
|
||||
if last != 'B' || len(s) < 2 {
|
||||
return 0, false
|
||||
}
|
||||
// The one before that must always be a digit or 'i'.
|
||||
if c := s[len(s)-2]; c >= '0' && c <= '9' {
|
||||
// Trivial 'B' suffix.
|
||||
n, ok := atoi64(s[:len(s)-1])
|
||||
if !ok || n < 0 {
|
||||
return 0, false
|
||||
}
|
||||
return n, ok
|
||||
} else if c != 'i' {
|
||||
return 0, false
|
||||
}
|
||||
// Finally, we need at least 4 characters now, for the unit
|
||||
// prefix and at least one digit.
|
||||
if len(s) < 4 {
|
||||
return 0, false
|
||||
}
|
||||
power := 0
|
||||
switch s[len(s)-3] {
|
||||
case 'K':
|
||||
power = 1
|
||||
case 'M':
|
||||
power = 2
|
||||
case 'G':
|
||||
power = 3
|
||||
case 'T':
|
||||
power = 4
|
||||
default:
|
||||
// Invalid suffix.
|
||||
return 0, false
|
||||
}
|
||||
m := uint64(1)
|
||||
for i := 0; i < power; i++ {
|
||||
m *= 1024
|
||||
}
|
||||
n, ok := atoi64(s[:len(s)-3])
|
||||
if !ok || n < 0 {
|
||||
return 0, false
|
||||
}
|
||||
un := uint64(n)
|
||||
if un > maxUint64/m {
|
||||
// Overflow.
|
||||
return 0, false
|
||||
}
|
||||
un *= m
|
||||
if un > uint64(maxInt64) {
|
||||
// Overflow.
|
||||
return 0, false
|
||||
}
|
||||
return int64(un), true
|
||||
}
|
||||
|
||||
//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]
|
||||
}
|
||||
Reference in New Issue
Block a user