1 // Copyright 2019 The Prometheus Authors 2 // Licensed under the Apache License, Version 2.0 (the "License"); 3 // you may not use this file except in compliance with the License. 4 // You may obtain a copy of the License at 5 // 6 // http://www.apache.org/licenses/LICENSE-2.0 7 // 8 // Unless required by applicable law or agreed to in writing, software 9 // distributed under the License is distributed on an "AS IS" BASIS, 10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // See the License for the specific language governing permissions and 12 // limitations under the License. 13 14 package util 15 16 import ( 17 "io" 18 "os" 19 ) 20 21 // ReadFileNoStat uses io.ReadAll to read contents of entire file. 22 // This is similar to os.ReadFile but without the call to os.Stat, because 23 // many files in /proc and /sys report incorrect file sizes (either 0 or 4096). 24 // Reads a max file size of 1024kB. For files larger than this, a scanner 25 // should be used. 26 func ReadFileNoStat(filename string) ([]byte, error) { 27 const maxBufferSize = 1024 * 1024 28 29 f, err := os.Open(filename) 30 if err != nil { 31 return nil, err 32 } 33 defer f.Close() 34 35 reader := io.LimitReader(f, maxBufferSize) 36 return io.ReadAll(reader) 37 } 38