parse.go (1813B)
1 // Copyright 2023 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package counter 6 7 import ( 8 "bytes" 9 "fmt" 10 "strings" 11 "unsafe" 12 13 "golang.org/x/telemetry/internal/mmap" 14 ) 15 16 type File struct { 17 Meta map[string]string 18 Count map[string]uint64 19 } 20 21 func Parse(filename string, data []byte) (*File, error) { 22 if !bytes.HasPrefix(data, []byte(hdrPrefix)) || len(data) < pageSize { 23 if len(data) < pageSize { 24 return nil, fmt.Errorf("%s: file too short (%d<%d)", filename, len(data), pageSize) 25 } 26 return nil, fmt.Errorf("%s: wrong hdr (not %q)", filename, hdrPrefix) 27 } 28 corrupt := func() (*File, error) { 29 // TODO(rfindley): return a useful error message. 30 return nil, fmt.Errorf("%s: corrupt counter file", filename) 31 } 32 33 f := &File{ 34 Meta: make(map[string]string), 35 Count: make(map[string]uint64), 36 } 37 np := round(len(hdrPrefix), 4) 38 hdrLen := *(*uint32)(unsafe.Pointer(&data[np])) 39 if hdrLen > pageSize { 40 return corrupt() 41 } 42 meta := data[np+4 : hdrLen] 43 if i := bytes.IndexByte(meta, 0); i >= 0 { 44 meta = meta[:i] 45 } 46 m := &mappedFile{ 47 meta: string(meta), 48 hdrLen: hdrLen, 49 mapping: &mmap.Data{Data: data}, 50 } 51 52 lines := strings.Split(m.meta, "\n") 53 for _, line := range lines { 54 if line == "" { 55 continue 56 } 57 k, v, ok := strings.Cut(line, ": ") 58 if !ok { 59 return corrupt() 60 } 61 f.Meta[k] = v 62 } 63 64 for i := uint32(0); i < numHash; i++ { 65 headOff := hdrLen + hashOff + i*4 66 head := m.load32(headOff) 67 off := head 68 for off != 0 { 69 ename, next, v, ok := m.entryAt(off) 70 if !ok { 71 return corrupt() 72 } 73 if _, ok := f.Count[string(ename)]; ok { 74 return corrupt() 75 } 76 ctrName := DecodeStack(string(ename)) 77 f.Count[ctrName] = v.Load() 78 off = next 79 } 80 } 81 return f, nil 82 }