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// Copyright 2015 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package csource
import (
"bytes"
"fmt"
"io/ioutil"
"os"
"os/exec"
"strings"
"unsafe"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/sys"
)
type Options struct {
Threaded bool
Collide bool
}
func Write(p *prog.Prog, opts Options) []byte {
exec := p.SerializeForExec()
w := new(bytes.Buffer)
fmt.Fprintf(w, `// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdint.h>
#include <pthread.h>
`)
handled := make(map[string]bool)
for _, c := range p.Calls {
name := c.Meta.CallName
if handled[name] {
continue
}
handled[name] = true
fmt.Fprintf(w, "#ifndef SYS_%v\n", name)
fmt.Fprintf(w, "#define SYS_%v %v\n", name, c.Meta.NR)
fmt.Fprintf(w, "#endif\n")
}
fmt.Fprintf(w, "\n")
calls, nvar := generateCalls(exec)
fmt.Fprintf(w, "long r[%v];\n\n", nvar)
if !opts.Threaded && !opts.Collide {
fmt.Fprintf(w, "int main()\n{\n")
fmt.Fprintf(w, "\tmemset(r, -1, sizeof(r));\n")
for _, c := range calls {
fmt.Fprintf(w, "%s", c)
}
fmt.Fprintf(w, "\treturn 0;\n}\n")
} else {
fmt.Fprintf(w, "void *thr(void *arg)\n{\n")
fmt.Fprintf(w, "\tswitch ((long)arg) {\n")
for i, c := range calls {
fmt.Fprintf(w, "\tcase %v:\n", i)
fmt.Fprintf(w, "%s", strings.Replace(c, "\t", "\t\t", -1))
fmt.Fprintf(w, "\t\tbreak;\n")
}
fmt.Fprintf(w, "\t}\n")
fmt.Fprintf(w, "\treturn 0;\n}\n\n")
fmt.Fprintf(w, "int main()\n{\n")
fmt.Fprintf(w, "\tlong i;\n")
fmt.Fprintf(w, "\tpthread_t th[%v];\n", len(calls))
fmt.Fprintf(w, "\n")
fmt.Fprintf(w, "\tmemset(r, -1, sizeof(r));\n")
fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
fmt.Fprintf(w, "\t\tusleep(10000);\n")
fmt.Fprintf(w, "\t}\n")
if opts.Collide {
fmt.Fprintf(w, "\tfor (i = 0; i < %v; i++) {\n", len(calls))
fmt.Fprintf(w, "\t\tpthread_create(&th[i], 0, thr, (void*)i);\n")
fmt.Fprintf(w, "\t\tif (i%%2==0)\n")
fmt.Fprintf(w, "\t\t\tusleep(10000);\n")
fmt.Fprintf(w, "\t}\n")
}
fmt.Fprintf(w, "\tusleep(100000);\n")
fmt.Fprintf(w, "\treturn 0;\n}\n")
}
return w.Bytes()
}
func generateCalls(exec []byte) ([]string, int) {
read := func() uintptr {
if len(exec) < 8 {
panic("exec program overflow")
}
v := *(*uint64)(unsafe.Pointer(&exec[0]))
exec = exec[8:]
return uintptr(v)
}
resultRef := func() string {
arg := read()
res := fmt.Sprintf("r[%v]", arg)
if opDiv := read(); opDiv != 0 {
res = fmt.Sprintf("%v/%v", res, opDiv)
}
if opAdd := read(); opAdd != 0 {
res = fmt.Sprintf("%v+%v", res, opAdd)
}
return res
}
lastCall := 0
seenCall := false
var calls []string
w := new(bytes.Buffer)
newCall := func() {
if seenCall {
seenCall = false
calls = append(calls, w.String())
w = new(bytes.Buffer)
}
}
n := 0
loop:
for ; ; n++ {
switch instr := read(); instr {
case prog.ExecInstrEOF:
break loop
case prog.ExecInstrCopyin:
newCall()
addr := read()
typ := read()
size := read()
switch typ {
case prog.ExecArgConst:
arg := read()
fmt.Fprintf(w, "\t*(uint%v_t*)0x%x = (uint%v_t)0x%x;\n", size*8, addr, size*8, arg)
case prog.ExecArgResult:
fmt.Fprintf(w, "\t*(uint%v_t*)0x%x = %v;\n", size*8, addr, resultRef())
case prog.ExecArgData:
data := exec[:size]
exec = exec[(size+7)/8*8:]
var esc []byte
for _, v := range data {
hex := func(v byte) byte {
if v < 10 {
return '0' + v
}
return 'a' + v - 10
}
esc = append(esc, '\\', 'x', hex(v>>4), hex(v<<4>>4))
}
fmt.Fprintf(w, "\tmemcpy((void*)0x%x, \"%s\", %v);\n", addr, esc, size)
default:
panic("bad argument type")
}
case prog.ExecInstrCopyout:
addr := read()
size := read()
fmt.Fprintf(w, "\tif (r[%v] != -1)\n", lastCall)
fmt.Fprintf(w, "\t\tr[%v] = *(uint%v_t*)0x%x;\n", n, size*8, addr)
default:
// Normal syscall.
newCall()
meta := sys.Calls[instr]
fmt.Fprintf(w, "\tr[%v] = syscall(SYS_%v", n, meta.CallName)
nargs := read()
for i := uintptr(0); i < nargs; i++ {
typ := read()
size := read()
_ = size
switch typ {
case prog.ExecArgConst:
fmt.Fprintf(w, ", 0x%xul", read())
case prog.ExecArgResult:
fmt.Fprintf(w, ", %v", resultRef())
default:
panic("unknown arg type")
}
}
for i := nargs; i < 6; i++ {
fmt.Fprintf(w, ", 0")
}
fmt.Fprintf(w, ");\n")
lastCall = n
seenCall = true
}
}
newCall()
return calls, n
}
// Build builds a C/C++ program from source file src
// and returns name of the resulting binary.
func Build(src string) (string, error) {
bin, err := ioutil.TempFile("", "syzkaller")
if err != nil {
return "", fmt.Errorf("failed to create temp file: %v", err)
}
bin.Close()
out, err := exec.Command("gcc", "-x", "c++", "-std=gnu++11", src, "-o", bin.Name(), "-lpthread", "-static", "-O1", "-g").CombinedOutput()
if err != nil {
os.Remove(bin.Name())
data, _ := ioutil.ReadFile(src)
return "", fmt.Errorf("failed to build program::\n%s\n%s", data, out)
}
return bin.Name(), nil
}
// Format reformats C source using clang-format.
func Format(src []byte) ([]byte, error) {
stdout, stderr := new(bytes.Buffer), new(bytes.Buffer)
cmd := exec.Command("clang-format", "-assume-filename=/src.c", "-style", style)
cmd.Stdin = bytes.NewReader(src)
cmd.Stdout = stdout
cmd.Stderr = stderr
if err := cmd.Run(); err != nil {
return nil, fmt.Errorf("failed to format source: %v\n%v", err, stderr.String())
}
return stdout.Bytes(), nil
}
// Something acceptable for kernel developers and email-friendly.
var style = `{
BasedOnStyle: LLVM,
IndentWidth: 2,
UseTab: Never,
BreakBeforeBraces: Linux,
IndentCaseLabels: false,
DerivePointerAlignment: false,
PointerAlignment: Left,
AlignTrailingComments: true,
AllowShortBlocksOnASingleLine: false,
AllowShortCaseLabelsOnASingleLine: false,
AllowShortFunctionsOnASingleLine: false,
AllowShortIfStatementsOnASingleLine: false,
AllowShortLoopsOnASingleLine: false,
ColumnLimit: 72,
}`
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