1// Copyright 2022 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
5package pprof
6
7import (
8	"errors"
9	"internal/syscall/windows"
10	"os"
11	"syscall"
12)
13
14// readMapping adds memory mapping information to the profile.
15func (b *profileBuilder) readMapping() {
16	snap, err := createModuleSnapshot()
17	if err != nil {
18		// pprof expects a map entry, so fake one, when we haven't added anything yet.
19		b.addMappingEntry(0, 0, 0, "", "", true)
20		return
21	}
22	defer func() { _ = syscall.CloseHandle(snap) }()
23
24	var module windows.ModuleEntry32
25	module.Size = uint32(windows.SizeofModuleEntry32)
26	err = windows.Module32First(snap, &module)
27	if err != nil {
28		// pprof expects a map entry, so fake one, when we haven't added anything yet.
29		b.addMappingEntry(0, 0, 0, "", "", true)
30		return
31	}
32	for err == nil {
33		exe := syscall.UTF16ToString(module.ExePath[:])
34		b.addMappingEntry(
35			uint64(module.ModBaseAddr),
36			uint64(module.ModBaseAddr)+uint64(module.ModBaseSize),
37			0,
38			exe,
39			peBuildID(exe),
40			false,
41		)
42		err = windows.Module32Next(snap, &module)
43	}
44}
45
46func readMainModuleMapping() (start, end uint64, exe, buildID string, err error) {
47	exe, err = os.Executable()
48	if err != nil {
49		return 0, 0, "", "", err
50	}
51	snap, err := createModuleSnapshot()
52	if err != nil {
53		return 0, 0, "", "", err
54	}
55	defer func() { _ = syscall.CloseHandle(snap) }()
56
57	var module windows.ModuleEntry32
58	module.Size = uint32(windows.SizeofModuleEntry32)
59	err = windows.Module32First(snap, &module)
60	if err != nil {
61		return 0, 0, "", "", err
62	}
63
64	return uint64(module.ModBaseAddr), uint64(module.ModBaseAddr) + uint64(module.ModBaseSize), exe, peBuildID(exe), nil
65}
66
67func createModuleSnapshot() (syscall.Handle, error) {
68	for {
69		snap, err := syscall.CreateToolhelp32Snapshot(windows.TH32CS_SNAPMODULE|windows.TH32CS_SNAPMODULE32, uint32(syscall.Getpid()))
70		var errno syscall.Errno
71		if err != nil && errors.As(err, &errno) && errno == windows.ERROR_BAD_LENGTH {
72			// When CreateToolhelp32Snapshot(SNAPMODULE|SNAPMODULE32, ...) fails
73			// with ERROR_BAD_LENGTH then it should be retried until it succeeds.
74			continue
75		}
76		return snap, err
77	}
78}
79