1// Copyright 2017 syzkaller project authors. All rights reserved.
2// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
3
4// +build freebsd,!appengine netbsd,!appengine linux,!appengine darwin,!appengine
5
6package osutil
7
8import (
9	"fmt"
10	"io"
11	"io/ioutil"
12	"os"
13	"os/signal"
14	"path/filepath"
15	"strconv"
16	"syscall"
17)
18
19// ProcessTempDir creates a new temp dir in where and returns its path and an unique index.
20// It also cleans up old, unused temp dirs after dead processes.
21func ProcessTempDir(where string) (string, error) {
22	lk := filepath.Join(where, "instance-lock")
23	lkf, err := syscall.Open(lk, syscall.O_RDWR|syscall.O_CREAT, DefaultFilePerm)
24	if err != nil {
25		return "", err
26	}
27	defer syscall.Close(lkf)
28	if err := syscall.Flock(lkf, syscall.LOCK_EX); err != nil {
29		return "", err
30	}
31	defer syscall.Flock(lkf, syscall.LOCK_UN)
32
33	for i := 0; i < 1e3; i++ {
34		path := filepath.Join(where, fmt.Sprintf("instance-%v", i))
35		pidfile := filepath.Join(path, ".pid")
36		err := os.Mkdir(path, DefaultDirPerm)
37		if os.IsExist(err) {
38			// Try to clean up.
39			data, err := ioutil.ReadFile(pidfile)
40			if err == nil && len(data) > 0 {
41				pid, err := strconv.Atoi(string(data))
42				if err == nil && pid > 1 {
43					if err := syscall.Kill(pid, 0); err == syscall.ESRCH {
44						if os.Remove(pidfile) == nil {
45							if os.RemoveAll(path) == nil {
46								i--
47								continue
48							}
49						}
50					}
51				}
52			}
53			// If err != nil, assume that the pid file is not created yet.
54			continue
55		}
56		if err != nil {
57			return "", err
58		}
59		if err := WriteFile(pidfile, []byte(strconv.Itoa(syscall.Getpid()))); err != nil {
60			return "", err
61		}
62		return path, nil
63	}
64	return "", fmt.Errorf("too many live instances")
65}
66
67// HandleInterrupts closes shutdown chan on first SIGINT
68// (expecting that the program will gracefully shutdown and exit)
69// and terminates the process on third SIGINT.
70func HandleInterrupts(shutdown chan struct{}) {
71	go func() {
72		c := make(chan os.Signal, 3)
73		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
74		<-c
75		close(shutdown)
76		fmt.Fprint(os.Stderr, "SIGINT: shutting down...\n")
77		<-c
78		fmt.Fprint(os.Stderr, "SIGINT: shutting down harder...\n")
79		<-c
80		fmt.Fprint(os.Stderr, "SIGINT: terminating\n")
81		os.Exit(int(syscall.SIGINT))
82	}()
83}
84
85func LongPipe() (io.ReadCloser, io.WriteCloser, error) {
86	r, w, err := os.Pipe()
87	if err != nil {
88		return nil, nil, fmt.Errorf("failed to create pipe: %v", err)
89	}
90	prolongPipe(r, w)
91	return r, w, err
92}
93
94// CreateMemMappedFile creates a temp file with the requested size and maps it into memory.
95func CreateMemMappedFile(size int) (f *os.File, mem []byte, err error) {
96	f, err = ioutil.TempFile("./", "syzkaller-shm")
97	if err != nil {
98		err = fmt.Errorf("failed to create temp file: %v", err)
99		return
100	}
101	if err = f.Truncate(int64(size)); err != nil {
102		err = fmt.Errorf("failed to truncate shm file: %v", err)
103		f.Close()
104		os.Remove(f.Name())
105		return
106	}
107	f.Close()
108	fname := f.Name()
109	f, err = os.OpenFile(f.Name(), os.O_RDWR, DefaultFilePerm)
110	if err != nil {
111		err = fmt.Errorf("failed to open shm file: %v", err)
112		os.Remove(fname)
113		return
114	}
115	mem, err = syscall.Mmap(int(f.Fd()), 0, size, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED)
116	if err != nil {
117		err = fmt.Errorf("failed to mmap shm file: %v", err)
118		f.Close()
119		os.Remove(f.Name())
120		return
121	}
122	return
123}
124
125// CloseMemMappedFile destroys memory mapping created by CreateMemMappedFile.
126func CloseMemMappedFile(f *os.File, mem []byte) error {
127	err1 := syscall.Munmap(mem)
128	err2 := f.Close()
129	err3 := os.Remove(f.Name())
130	switch {
131	case err1 != nil:
132		return err1
133	case err2 != nil:
134		return err2
135	case err3 != nil:
136		return err3
137	default:
138		return nil
139	}
140}
141
142// ProcessExitStatus returns process exit status.
143// This is here only because of fuchsia that does not implement WaitStatus.
144func ProcessExitStatus(ps *os.ProcessState) int {
145	return ps.Sys().(syscall.WaitStatus).ExitStatus()
146}
147