├── .github └── workflows │ └── test.yml ├── LICENSE ├── README.md ├── cmd └── memexec-gen │ └── main.go ├── go.mod ├── go.sum ├── memexec.go ├── memexec_all.go ├── memexec_linux.go ├── memexec_linux_test.go ├── memexec_test.go └── testdata ├── .gitignore └── main.go /.github/workflows/test.yml: -------------------------------------------------------------------------------- 1 | name: Test and Lint 2 | on: 3 | push: 4 | branches: 5 | - main 6 | pull_request: 7 | branches: 8 | - main 9 | 10 | jobs: 11 | test: 12 | name: Test 13 | strategy: 14 | matrix: 15 | platform: 16 | - ubuntu-latest 17 | - macos-latest 18 | - windows-latest 19 | runs-on: ${{ matrix.platform }} 20 | steps: 21 | - uses: actions/checkout@v3 22 | - uses: actions/setup-go@v3 23 | with: 24 | go-version: 1.19 25 | - name: Run Tests 26 | run: go test -v ./... 27 | 28 | lint: 29 | name: Lint 30 | runs-on: ubuntu-latest 31 | steps: 32 | - uses: actions/checkout@v3 33 | - uses: actions/setup-go@v3 34 | with: 35 | go-version: 1.19 36 | - name: Run golangci-lint 37 | uses: golangci/golangci-lint-action@v3 38 | with: 39 | version: v1.52.0 40 | args: --enable=gofumpt,goimports,whitespace,gocritic,exportloopref,unconvert,prealloc 41 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # go-memexec 2 | 3 | Small library that executes binaries from the memory. 4 | 5 | ## Usage 6 | 7 | ## Static Binary 8 | 9 | Running static binaries is quite simple, it's only needed to embed it into the app and pass its content to `memexec.New`: 10 | 11 | ```go 12 | import ( 13 | _ "embed" 14 | 15 | "github.com/amenzhinsky/go-memexec" 16 | ) 17 | 18 | // go:embed path-to-binary 19 | var mybinary []byte 20 | 21 | exe, err := memexec.New(mybinary) 22 | if err != nil { 23 | return err 24 | } 25 | defer exe.Close() 26 | 27 | cmd := exe.Command(argv...) 28 | cmd.Output() // cmd is a `*exec.Cmd` from the standard library 29 | ``` 30 | 31 | ## Dynamic Binary (Linux only) 32 | 33 | With dynamic linked binaries things get more complicated, it's needed to embed all dependencies along with the executable. 34 | 35 | At the runtime deps are copied to a temp dir and executable receives the corresponding `LD_LIBRARY_PATH` that forces the dynamic linker to use the copied libraries. 36 | 37 | The dynamic linker must be the same on both building and running machines since it's not included in the resulting binary (there's no interoperability between musl and GNU systems). 38 | 39 | The following script helps generating packages, say `python3`: 40 | 41 | ```sh 42 | go install github.com/amenzhinsky/go-memexec/cmd/memexec-gen@latest 43 | PATH=$(go env GOPATH)/bin:$PATH memexec-gen /usr/bin/python3 44 | ``` 45 | 46 | It produces `python3` directory with binaries are to embed and `gen.go` file, that is a go package: 47 | 48 | ```go 49 | import "mypackagename/python3" 50 | 51 | exe, err := python3.New() 52 | if err != nil { 53 | return err 54 | } 55 | defer exe.Close() 56 | 57 | b, err := exe.Command("-c", "print('Hello World')").CombinedOutput() 58 | if err != nil { 59 | return err 60 | } 61 | ``` 62 | -------------------------------------------------------------------------------- /cmd/memexec-gen/main.go: -------------------------------------------------------------------------------- 1 | //go:build linux 2 | 3 | package main 4 | 5 | import ( 6 | "debug/elf" 7 | "flag" 8 | "fmt" 9 | "io" 10 | "os" 11 | "path/filepath" 12 | "runtime" 13 | "strings" 14 | ) 15 | 16 | var ( 17 | destFlag string 18 | packageFlag string 19 | ) 20 | 21 | func main() { 22 | flag.Usage = func() { 23 | fmt.Fprint(os.Stderr, `Usage: memexec-gen PATH 24 | 25 | Environment variables: 26 | LD_LIBRARY_PATH 27 | list of directories where to search libraries, see 'man 7 ld.so' 28 | 29 | Options: 30 | `) 31 | flag.PrintDefaults() 32 | } 33 | flag.StringVar(&destFlag, "dest", "", 34 | "`path` where binaries and go file are written to, defaults to PATH basename", 35 | ) 36 | flag.StringVar(&packageFlag, "package", "", 37 | "generated package `name`, defaults to PATH basename", 38 | ) 39 | flag.Parse() 40 | if flag.NArg() != 1 { 41 | flag.Usage() 42 | os.Exit(2) 43 | } 44 | if err := run(flag.Arg(0)); err != nil { 45 | fmt.Fprintf(os.Stderr, "error: %s\n", err) 46 | os.Exit(127) 47 | } 48 | } 49 | 50 | func run(bin string) error { 51 | base := filepath.Base(bin) 52 | if destFlag == "" { 53 | destFlag = base 54 | } 55 | if packageFlag == "" { 56 | packageFlag = base 57 | } 58 | 59 | err := os.MkdirAll(destFlag, 0o755) 60 | if err != nil && !os.IsExist(err) { 61 | return err 62 | } 63 | output, err = os.OpenFile( 64 | filepath.Join(destFlag, "memexec.go"), 65 | os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 66 | 0o644, 67 | ) 68 | if err != nil { 69 | return err 70 | } 71 | 72 | libs := map[string]string{} 73 | if err := ldd(libs, bin, func(name string) (string, error) { 74 | return name, nil 75 | }); err != nil { 76 | return err 77 | } 78 | for name, path := range libs { 79 | src, err := os.Open(path) 80 | if err != nil { 81 | return err 82 | } 83 | if name == bin { 84 | name = base 85 | } 86 | dst, err := os.OpenFile( 87 | filepath.Join(destFlag, name), 88 | os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 89 | 0o755, 90 | ) 91 | if err != nil { 92 | return err 93 | } 94 | if _, err := io.Copy(dst, src); err != nil { 95 | return err 96 | } 97 | if err := dst.Close(); err != nil { 98 | return err 99 | } 100 | if err := src.Close(); err != nil { 101 | return err 102 | } 103 | } 104 | 105 | out("// Code generated by memexec-gen. DO NOT EDIT.") 106 | out("package ", packageFlag) 107 | out() 108 | out("import (") 109 | out(` _ "embed"`) 110 | out(` "os"`) 111 | out(` "os/exec"`) 112 | out(` "path/filepath"`) 113 | out() 114 | out(` "github.com/amenzhinsky/go-memexec"`) 115 | out(")") 116 | out() 117 | 118 | for name := range libs { 119 | if name == bin { 120 | name = base 121 | } 122 | out("//go:embed ", name) 123 | out("var ", goName(name), " []byte") 124 | out() 125 | } 126 | 127 | out("func New(opts ...memexec.Option) (*memexec.Exec, error) {") 128 | out(` temp, err := os.MkdirTemp("", "")`) 129 | out(" if err != nil {") 130 | out(" return nil, err") 131 | out(" }") 132 | for name := range libs { 133 | if name == bin { 134 | continue 135 | } 136 | out(` if err := os.WriteFile(filepath.Join(temp, "`, name, `"), `, goName(name), ", 0o755); err != nil {") 137 | out(" return nil, err") 138 | out(" }") 139 | } 140 | out(" return memexec.New(", goName(base), ", append([]memexec.Option{") 141 | out(" memexec.WithPrepare(func(exe *exec.Cmd) {") 142 | out(` exe.Env = append(exe.Env, "LD_LIBRARY_PATH="+temp)`) 143 | out(" }),") 144 | out(" memexec.WithCleanup(func() error {") 145 | out(" return os.RemoveAll(temp)") 146 | out(" }),") 147 | out(" }, opts...)...)") 148 | out("}") 149 | 150 | return nil 151 | } 152 | 153 | var output io.Writer 154 | 155 | func out(strs ...string) { 156 | for _, str := range strs { 157 | if _, err := fmt.Fprint(output, str); err != nil { 158 | panic(err) 159 | } 160 | } 161 | if _, err := fmt.Fprintln(output); err != nil { 162 | panic(err) 163 | } 164 | } 165 | 166 | func goName(name string) string { 167 | name = strings.ReplaceAll(name, ".", "_") 168 | name = strings.ReplaceAll(name, "-", "_") 169 | return "memexec_" + name 170 | } 171 | 172 | func ldd( 173 | deps map[string]string, name string, look func(name string) (string, error), 174 | ) error { 175 | path, err := look(name) 176 | if err != nil { 177 | return err 178 | } 179 | deps[name] = path 180 | e, err := elf.Open(path) 181 | if err != nil { 182 | return err 183 | } 184 | l, err := e.ImportedLibraries() 185 | if err != nil { 186 | return err 187 | } 188 | rpaths, err := e.DynString(elf.DT_RPATH) 189 | if err != nil { 190 | return err 191 | } 192 | runpaths, err := e.DynString(elf.DT_RUNPATH) 193 | if err != nil { 194 | return err 195 | } 196 | if err := e.Close(); err != nil { 197 | return err 198 | } 199 | for _, lib := range l { 200 | if _, ok := deps[lib]; ok { 201 | continue 202 | } 203 | if err := ldd(deps, lib, func(name string) (string, error) { 204 | return lookLibrary(name, rpaths, runpaths) 205 | }); err != nil { 206 | return err 207 | } 208 | } 209 | return nil 210 | } 211 | 212 | var ldPaths = []string{"/lib", "/usr/local/lib", "/usr/lib"} 213 | 214 | func init() { 215 | // TODO: os.ReadFile(fmt.Sprintf("/etc/ld-musl-$(ARCH).path")) 216 | switch runtime.GOARCH { 217 | case "amd64": 218 | ldPaths = append(ldPaths, 219 | "/lib64", 220 | "/usr/lib64", 221 | "/usr/local/lib/x86_64-linux-gnu", 222 | "/lib/x86_64-linux-gnu", 223 | "/usr/lib/x86_64-linux-gnu", 224 | ) 225 | case "arm64": 226 | ldPaths = append(ldPaths, 227 | "/usr/local/lib/aarch64-linux-gnu", 228 | "/lib/aarch64-linux-gnu", 229 | "/usr/lib/aarch64-linux-gnu", 230 | ) 231 | } 232 | if s := os.Getenv("LD_LIBRARY_PATH"); s != "" { 233 | ldPaths = append(ldPaths, filepath.SplitList(s)...) 234 | } 235 | } 236 | 237 | func lookLibrary(name string, rpaths, runpaths []string) (string, error) { 238 | for _, dir := range append(rpaths, append(ldPaths, runpaths...)...) { 239 | path := filepath.Join(dir, name) 240 | stat, err := os.Stat(path) 241 | if err != nil { 242 | if os.IsNotExist(err) { 243 | continue 244 | } 245 | return "", err 246 | } 247 | if !stat.IsDir() { 248 | return path, nil 249 | } 250 | } 251 | return "", fmt.Errorf("dynamic library %s not found", name) 252 | } 253 | -------------------------------------------------------------------------------- /go.mod: -------------------------------------------------------------------------------- 1 | module github.com/amenzhinsky/go-memexec 2 | 3 | go 1.19 4 | 5 | require golang.org/x/sys v0.0.0-20210903071746-97244b99971b 6 | -------------------------------------------------------------------------------- /go.sum: -------------------------------------------------------------------------------- 1 | golang.org/x/sys v0.0.0-20210903071746-97244b99971b h1:3Dq0eVHn0uaQJmPO+/aYPI/fRMqdrVDbu7MQcku54gg= 2 | golang.org/x/sys v0.0.0-20210903071746-97244b99971b/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= 3 | -------------------------------------------------------------------------------- /memexec.go: -------------------------------------------------------------------------------- 1 | package memexec 2 | 3 | import ( 4 | "context" 5 | "os" 6 | "os/exec" 7 | ) 8 | 9 | type Option func(e *Exec) 10 | 11 | // Exec is an in-memory executable code unit. 12 | type Exec struct { 13 | f *os.File 14 | opts []func(cmd *exec.Cmd) 15 | clean func() error 16 | } 17 | 18 | // WithPrepare configures cmd with default values such as Env, Dir, etc. 19 | func WithPrepare(fn func(cmd *exec.Cmd)) Option { 20 | return func(e *Exec) { 21 | e.opts = append(e.opts, fn) 22 | } 23 | } 24 | 25 | // WithCleanup is executed right after Exec.Close. 26 | func WithCleanup(fn func() error) Option { 27 | return func(e *Exec) { 28 | e.clean = fn 29 | } 30 | } 31 | 32 | // New creates new memory execution object that can be 33 | // used for executing commands on a memory based binary. 34 | func New(b []byte, opts ...Option) (*Exec, error) { 35 | f, err := open(b) 36 | if err != nil { 37 | return nil, err 38 | } 39 | e := &Exec{f: f} 40 | for _, opt := range opts { 41 | opt(e) 42 | } 43 | return e, nil 44 | } 45 | 46 | // Command is an equivalent of `exec.Command`, 47 | // except that the path to the executable is being omitted. 48 | func (m *Exec) Command(args ...string) *exec.Cmd { 49 | return m.CommandContext(context.Background(), args...) 50 | } 51 | 52 | // CommandContext is an equivalent of `exec.CommandContext`, 53 | // except that the path to the executable is being omitted. 54 | func (m *Exec) CommandContext(ctx context.Context, args ...string) *exec.Cmd { 55 | exe := exec.CommandContext(ctx, m.f.Name(), args...) 56 | for _, opt := range m.opts { 57 | opt(exe) 58 | } 59 | return exe 60 | } 61 | 62 | // Close closes Exec object. 63 | // 64 | // Any further command will fail, it's client's responsibility 65 | // to control the flow by using synchronization algorithms. 66 | func (m *Exec) Close() error { 67 | if err := clean(m.f); err != nil { 68 | if m.clean != nil { 69 | _ = m.clean() 70 | } 71 | return err 72 | } 73 | if m.clean == nil { 74 | return nil 75 | } 76 | return m.clean() 77 | } 78 | -------------------------------------------------------------------------------- /memexec_all.go: -------------------------------------------------------------------------------- 1 | //go:build !linux 2 | // +build !linux 3 | 4 | package memexec 5 | 6 | import ( 7 | "os" 8 | "runtime" 9 | ) 10 | 11 | func open(b []byte) (*os.File, error) { 12 | pattern := "go-memexec-" 13 | if runtime.GOOS == "windows" { 14 | pattern = "go-memexec-*.exe" 15 | } 16 | f, err := os.CreateTemp("", pattern) 17 | if err != nil { 18 | return nil, err 19 | } 20 | defer func() { 21 | if err != nil { 22 | _ = clean(f) 23 | } 24 | }() 25 | if err = os.Chmod(f.Name(), 0o500); err != nil { 26 | return nil, err 27 | } 28 | if _, err = f.Write(b); err != nil { 29 | return nil, err 30 | } 31 | if err = f.Close(); err != nil { 32 | return nil, err 33 | } 34 | return f, nil 35 | } 36 | 37 | func clean(f *os.File) error { 38 | return os.Remove(f.Name()) 39 | } 40 | -------------------------------------------------------------------------------- /memexec_linux.go: -------------------------------------------------------------------------------- 1 | //go:build linux 2 | // +build linux 3 | 4 | package memexec 5 | 6 | import ( 7 | "fmt" 8 | "os" 9 | 10 | "golang.org/x/sys/unix" 11 | ) 12 | 13 | func open(b []byte) (*os.File, error) { 14 | fd, err := unix.MemfdCreate("", unix.MFD_CLOEXEC) 15 | if err != nil { 16 | return nil, err 17 | } 18 | f := os.NewFile(uintptr(fd), fmt.Sprintf("/proc/%d/fd/%d", os.Getpid(), fd)) 19 | if _, err := f.Write(b); err != nil { 20 | _ = f.Close() 21 | return nil, err 22 | } 23 | return f, nil 24 | } 25 | 26 | func clean(f *os.File) error { 27 | return f.Close() 28 | } 29 | -------------------------------------------------------------------------------- /memexec_linux_test.go: -------------------------------------------------------------------------------- 1 | //go:build linux 2 | 3 | package memexec 4 | 5 | import ( 6 | "os/exec" 7 | "testing" 8 | ) 9 | 10 | func TestGenLinux(t *testing.T) { 11 | e := exec.Command("go", "run", "../cmd/memexec-gen", "/usr/bin/python3") 12 | e.Dir = "testdata" 13 | _ = runCommand(t, e) 14 | 15 | e = exec.Command("go", "run", ".", "-c", "print(42)") 16 | e.Dir = "testdata" 17 | if have := runCommand(t, e); have != "42" { 18 | t.Fatalf("output mismatch:\n\thave: %s\n\twant: %s", have, "42") 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /memexec_test.go: -------------------------------------------------------------------------------- 1 | package memexec 2 | 3 | import ( 4 | "bytes" 5 | "context" 6 | "os" 7 | "os/exec" 8 | "runtime" 9 | "strings" 10 | "testing" 11 | "time" 12 | ) 13 | 14 | func TestCommand(t *testing.T) { 15 | exe := newEchoExec(t) 16 | defer func() { 17 | if err := exe.Close(); err != nil { 18 | t.Fatalf("close error: %s", err) 19 | } 20 | }() 21 | 22 | c := exe.Command("test") 23 | if have := runCommand(t, c); !strings.HasPrefix(have, "test") { 24 | t.Errorf("command output = %q doesn't contain %q", have, "test") 25 | } 26 | } 27 | 28 | func TestCommand_Shell(t *testing.T) { 29 | if runtime.GOOS == "windows" { 30 | return 31 | } 32 | 33 | exe, err := New([]byte("#!/bin/sh\necho hello")) 34 | if err != nil { 35 | panic(err) 36 | } 37 | defer exe.Close() 38 | 39 | b, err := exe.Command().CombinedOutput() 40 | if err != nil { 41 | t.Fatalf("err = %v, output = %q", err, b) 42 | } 43 | if !bytes.Equal(b, []byte("hello\n")) { 44 | t.Fatalf("output = %q, want %q", string(b), []byte("hello\n")) 45 | } 46 | } 47 | 48 | func TestCommandContext(t *testing.T) { 49 | // the test is failing on windows, probably due to missing sleep command, 50 | // unfortunately I have no windows machines around to fix this 51 | if runtime.GOOS == "windows" { 52 | return 53 | } 54 | 55 | exe := newSleepExec(t) 56 | defer func() { 57 | if err := exe.Close(); err != nil { 58 | t.Fatalf("close error: %s", err) 59 | } 60 | }() 61 | 62 | ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond*500) 63 | defer cancel() 64 | 65 | c := exe.CommandContext(ctx, "1") 66 | 67 | start := time.Now() 68 | if err := c.Start(); err != nil { 69 | t.Fatalf("start failed: %s", err) 70 | } 71 | if err := c.Wait(); err != nil && err.Error() != "signal: killed" { 72 | t.Fatalf("command execution failed: %s", err) 73 | } 74 | stop := time.Now() 75 | if delta := stop.Sub(start); delta > time.Millisecond*600 || delta < time.Millisecond*500 { 76 | t.Fatalf("unexpected command execution time: delta=%s", delta) 77 | } 78 | } 79 | 80 | func BenchmarkCommand(b *testing.B) { 81 | exe := newEchoExec(b) 82 | defer func() { 83 | if err := exe.Close(); err != nil { 84 | b.Fatalf("close error: %s", err) 85 | } 86 | }() 87 | 88 | for i := 0; i < b.N; i++ { 89 | cmd := exe.Command("test") 90 | if _, err := cmd.Output(); err != nil { 91 | b.Fatal(err) 92 | } 93 | } 94 | } 95 | 96 | func newExec(t testing.TB, name string) *Exec { 97 | path, err := exec.LookPath(name) 98 | if err != nil { 99 | t.Fatal(err) 100 | } 101 | b, err := os.ReadFile(path) 102 | if err != nil { 103 | t.Fatal(err) 104 | } 105 | 106 | exe, err := New(b) 107 | if err != nil { 108 | t.Fatal(err) 109 | } 110 | return exe 111 | } 112 | 113 | func newEchoExec(t testing.TB) *Exec { 114 | // lookup echo binary that is provided on all unix systems 115 | // and it's not a built-in opposed to `ls` and `type` 116 | return newExec(t, "echo") 117 | } 118 | 119 | func newSleepExec(t testing.TB) *Exec { 120 | return newExec(t, "sleep") 121 | } 122 | 123 | func runCommand(t *testing.T, cmd *exec.Cmd) string { 124 | t.Helper() 125 | b, err := cmd.CombinedOutput() 126 | if err != nil { 127 | if b != nil { 128 | t.Fatalf("failed to run: %q", string(b)) 129 | } 130 | t.Fatal(err) 131 | } 132 | return string(b) 133 | } 134 | -------------------------------------------------------------------------------- /testdata/.gitignore: -------------------------------------------------------------------------------- 1 | python3 2 | -------------------------------------------------------------------------------- /testdata/main.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "fmt" 5 | "os" 6 | "strings" 7 | 8 | "github.com/amenzhinsky/go-memexec/testdata/python3" 9 | ) 10 | 11 | func main() { 12 | exe, err := python3.New() 13 | if err != nil { 14 | panic(err) 15 | } 16 | c := exe.Command(os.Args[1:]...) 17 | c.Stdin = os.Stdin 18 | b, err := c.CombinedOutput() 19 | if err != nil { 20 | panic(err) 21 | } 22 | fmt.Print(strings.TrimSpace(string(b))) 23 | } 24 | --------------------------------------------------------------------------------