| // 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/abi" |
| "internal/bytealg" |
| "internal/goarch" |
| "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, a0, a1 string) string { |
| return concatstrings(buf, []string{a0, a1}) |
| } |
| |
| func concatstring3(buf *tmpBuf, a0, a1, a2 string) string { |
| return concatstrings(buf, []string{a0, a1, a2}) |
| } |
| |
| func concatstring4(buf *tmpBuf, a0, a1, a2, a3 string) string { |
| return concatstrings(buf, []string{a0, a1, a2, a3}) |
| } |
| |
| func concatstring5(buf *tmpBuf, a0, a1, a2, a3, a4 string) string { |
| return concatstrings(buf, []string{a0, a1, a2, a3, a4}) |
| } |
| |
| // 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) 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(), |
| abi.FuncPCABIInternal(slicebytetostring)) |
| } |
| if msanenabled { |
| msanread(unsafe.Pointer(ptr), uintptr(n)) |
| } |
| if asanenabled { |
| asanread(unsafe.Pointer(ptr), uintptr(n)) |
| } |
| if n == 1 { |
| p := unsafe.Pointer(&staticuint64s[*ptr]) |
| if goarch.BigEndian { |
| p = add(p, 7) |
| } |
| return unsafe.String((*byte)(p), 1) |
| } |
| |
| var p unsafe.Pointer |
| if buf != nil && n <= len(buf) { |
| p = unsafe.Pointer(buf) |
| } else { |
| p = mallocgc(uintptr(n), nil, false) |
| } |
| memmove(p, unsafe.Pointer(ptr), uintptr(n)) |
| return unsafe.String((*byte)(p), n) |
| } |
| |
| // stringDataOnStack reports whether the string's data is |
| // stored on the current goroutine's stack. |
| func stringDataOnStack(s string) bool { |
| ptr := uintptr(unsafe.Pointer(unsafe.StringData(s))) |
| 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) string { |
| if raceenabled && n > 0 { |
| racereadrangepc(unsafe.Pointer(ptr), |
| uintptr(n), |
| getcallerpc(), |
| abi.FuncPCABIInternal(slicebytetostringtmp)) |
| } |
| if msanenabled && n > 0 { |
| msanread(unsafe.Pointer(ptr), uintptr(n)) |
| } |
| if asanenabled && n > 0 { |
| asanread(unsafe.Pointer(ptr), uintptr(n)) |
| } |
| return unsafe.String(ptr, n) |
| } |
| |
| 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(), |
| abi.FuncPCABIInternal(slicerunetostring)) |
| } |
| if msanenabled && len(a) > 0 { |
| msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0])) |
| } |
| if asanenabled && len(a) > 0 { |
| asanread(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) |
| return unsafe.String((*byte)(p), size), unsafe.Slice((*byte)(p), size) |
| } |
| |
| // 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 |
| } |
| |
| // internal_syscall_gostring is a version of gostring for internal/syscall/unix. |
| // |
| //go:linkname internal_syscall_gostring internal/syscall/unix.gostring |
| func internal_syscall_gostring(p *byte) string { |
| return gostring(p) |
| } |
| |
| 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 |
| } |
| |
| func hasSuffix(s, suffix string) bool { |
| return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix |
| } |
| |
| const ( |
| maxUint64 = ^uint64(0) |
| maxInt64 = int64(maxUint64 >> 1) |
| ) |
| |
| // 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] == '-' { |
| 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] |
| } |