github.com/bytedance/gopkg@v0.0.0-20240514070511-01b2cbcf35e1/lang/dirtmake/bytes.go (about) 1 // Copyright 2024 ByteDance Inc. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package dirtmake 16 17 import ( 18 "unsafe" 19 ) 20 21 type slice struct { 22 data unsafe.Pointer 23 len int 24 cap int 25 } 26 27 //go:linkname mallocgc runtime.mallocgc 28 func mallocgc(size uintptr, typ unsafe.Pointer, needzero bool) unsafe.Pointer 29 30 // Bytes allocates a byte slice but does not clean up the memory it references. 31 // Throw a fatal error instead of panic if cap is greater than runtime.maxAlloc. 32 // NOTE: MUST set any byte element before it's read. 33 func Bytes(len, cap int) (b []byte) { 34 if len < 0 || len > cap { 35 panic("dirtmake.Bytes: len out of range") 36 } 37 p := mallocgc(uintptr(cap), nil, false) 38 sh := (*slice)(unsafe.Pointer(&b)) 39 sh.data = p 40 sh.len = len 41 sh.cap = cap 42 return 43 }