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// Copyright 2017 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"
"os"
"path/filepath"
"runtime"
"strings"
"testing"
"github.com/google/syzkaller/pkg/osutil"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/sys/targets"
)
// Build builds a C program from source src and returns name of the resulting binary.
func Build(target *prog.Target, src []byte) (string, error) {
return build(target, src, "", "")
}
// BuildNoWarn is the same as Build, but ignores all compilation warnings.
// Should not be used in tests, but may be used e.g. when we are bisecting and potentially
// using an old repro with newer compiler, or a compiler that we never seen before.
// In these cases it's more important to build successfully.
func BuildNoWarn(target *prog.Target, src []byte) (string, error) {
return build(target, src, "", "", "-fpermissive", "-w")
}
// BuildExecutor builds the executor binary for tests.
// rootDir must point to syzkaller root directory in slash notation.
func BuildExecutor(t *testing.T, target *prog.Target, rootDir string, cflags ...string) string {
// Build w/o optimizations for tests. Tests can build lots of versions of executor in parallel,
// and on overloaded machines it can be slow. On my machine this reduces executor build time
// from ~7.5 to ~3.5 secs.
cflags = append(cflags, "-O0")
bin, err := build(target, nil, filepath.FromSlash(rootDir),
filepath.FromSlash("executor/executor.cc"), cflags...)
if err != nil {
t.Fatalf("failed to build executor: %v", err)
}
t.Cleanup(func() {
os.Remove(bin)
})
return bin
}
func build(target *prog.Target, src []byte, dir, file string, cflags ...string) (string, error) {
// We call the binary syz-executor because it sometimes shows in bug titles,
// and we don't want 2 different bugs for when a crash is triggered during fuzzing and during repro.
bin, err := osutil.TempFile("syz-executor")
if err != nil {
return "", err
}
flags := []string{
"-o", bin,
"-DGOOS_" + target.OS + "=1",
"-DGOARCH_" + target.Arch + "=1",
"-DHOSTGOOS_" + runtime.GOOS + "=1",
}
if file == "" {
flags = append(flags, "-x", "c", "-")
} else {
flags = append(flags, file)
}
sysTarget := targets.Get(target.OS, target.Arch)
compiler, targetCFlags := sysTarget.CCompiler, sysTarget.CFlags
if file != "" && !strings.HasSuffix(file, ".c") {
compiler, targetCFlags = sysTarget.CxxCompiler, sysTarget.CxxFlags
}
flags = append(flags, targetCFlags...)
flags = append(flags, cflags...)
if sysTarget.PtrSize == 4 {
// We do generate uint64's for syscall arguments that overflow longs on 32-bit archs.
flags = append(flags, "-Wno-overflow")
}
cmd := osutil.Command(compiler, flags...)
cmd.Dir = dir
if file == "" {
cmd.Stdin = bytes.NewReader(src)
}
out, err := cmd.CombinedOutput()
if err != nil {
os.Remove(bin)
if file != "" {
src, _ = os.ReadFile(file)
}
return "", fmt.Errorf("failed to build program:\n%s\n%s\ncompiler invocation: %v %v",
src, out, compiler, flags)
}
return bin, nil
}
// Format reformats C source using clang-format.
func Format(src []byte) ([]byte, error) {
stdout, stderr := new(bytes.Buffer), new(bytes.Buffer)
cmd := osutil.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 src, fmt.Errorf("failed to format source: %w\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: 80,
}`
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