os/exec: add Cmd.RunContext and Cmd.WaitContext

Updates #14660

Change-Id: Ifa5c97ba327ad7ceea0a9a252e3dbd9d079dae54
Reviewed-on: https://go-review.googlesource.com/22529
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/dist/deps.go b/src/cmd/dist/deps.go
index 0838914b9c51ba4b73c01419ca73bd655f2b49a4..e8dd6cf3d921dc0cadbfac0c647a579d2c9da440 100644 (file)
--- a/src/cmd/dist/deps.go
+++ b/src/cmd/dist/deps.go
@@ -8,6 +8,7 @@ var builddeps = map[string][]string{
        "compress/flate":                    {"bufio", "bytes", "errors", "fmt", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
        "compress/zlib":                     {"bufio", "bytes", "compress/flate", "errors", "fmt", "hash", "hash/adler32", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
        "container/heap":                    {"runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort"},
+       "context":                           {"errors", "fmt", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "syscall", "time", "unicode/utf16", "unicode/utf8"},
        "crypto":                            {"errors", "hash", "internal/race", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"},
        "crypto/sha1":                       {"crypto", "errors", "hash", "internal/race", "io", "math", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strconv", "sync", "sync/atomic", "unicode/utf8"},
        "debug/dwarf":                       {"encoding/binary", "errors", "fmt", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "path", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
@@ -39,7 +40,7 @@ var builddeps = map[string][]string{
        "math":                    {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
        "net/url":                 {"bytes", "errors", "fmt", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
        "os":                      {"errors", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sync", "sync/atomic", "syscall", "time", "unicode/utf16", "unicode/utf8"},
-       "os/exec":                 {"bytes", "errors", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "path/filepath", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
+       "os/exec":                 {"bytes", "context", "errors", "fmt", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "math", "os", "path/filepath", "reflect", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
        "os/signal":               {"errors", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "os", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sync", "sync/atomic", "syscall", "time", "unicode/utf16", "unicode/utf8"},
        "path":                    {"errors", "internal/race", "io", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "strings", "sync", "sync/atomic", "unicode", "unicode/utf8"},
        "path/filepath":           {"errors", "internal/race", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "os", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strings", "sync", "sync/atomic", "syscall", "time", "unicode", "unicode/utf16", "unicode/utf8"},
@@ -61,5 +62,5 @@ var builddeps = map[string][]string{
        "unicode":                 {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
        "unicode/utf16":           {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
        "unicode/utf8":            {"runtime", "runtime/internal/atomic", "runtime/internal/sys"},
-       "cmd/go":                  {"bufio", "bytes", "compress/flate", "compress/zlib", "container/heap", "crypto", "crypto/sha1", "debug/dwarf", "debug/elf", "debug/macho", "encoding", "encoding/base64", "encoding/binary", "encoding/json", "errors", "flag", "fmt", "go/ast", "go/build", "go/doc", "go/parser", "go/scanner", "go/token", "hash", "hash/adler32", "internal/race", "internal/singleflight", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "io/ioutil", "log", "math", "net/url", "os", "os/exec", "os/signal", "path", "path/filepath", "reflect", "regexp", "regexp/syntax", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "text/template", "text/template/parse", "time", "unicode", "unicode/utf16", "unicode/utf8"},
+       "cmd/go":                  {"bufio", "bytes", "compress/flate", "compress/zlib", "container/heap", "context", "crypto", "crypto/sha1", "debug/dwarf", "debug/elf", "debug/macho", "encoding", "encoding/base64", "encoding/binary", "encoding/json", "errors", "flag", "fmt", "go/ast", "go/build", "go/doc", "go/parser", "go/scanner", "go/token", "hash", "hash/adler32", "internal/race", "internal/singleflight", "internal/syscall/windows", "internal/syscall/windows/registry", "internal/syscall/windows/sysdll", "io", "io/ioutil", "log", "math", "net/url", "os", "os/exec", "os/signal", "path", "path/filepath", "reflect", "regexp", "regexp/syntax", "runtime", "runtime/internal/atomic", "runtime/internal/sys", "sort", "strconv", "strings", "sync", "sync/atomic", "syscall", "text/template", "text/template/parse", "time", "unicode", "unicode/utf16", "unicode/utf8"},
 }

diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 2db5ba67d1f769fe6d627d5bcb18c0b2e2098215..a87de577b5b1346cb977dd187c7a44bb8a973bce 100644 (file)
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -140,7 +140,7 @@ var pkgDeps = map[string][]string{
        "os":            {"L1", "os", "syscall", "time", "internal/syscall/windows"},
        "path/filepath": {"L2", "os", "syscall"},
        "io/ioutil":     {"L2", "os", "path/filepath", "time"},
-       "os/exec":       {"L2", "os", "path/filepath", "syscall"},
+       "os/exec":       {"L2", "os", "context", "path/filepath", "syscall"},
        "os/signal":     {"L2", "os", "syscall"},
 
        // OS enables basic operating system functionality,

diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index 340ebd498b7e7ab11441762d69b93b0a86c82cc7..76fcba90bf383eb134ef8950ee3388c5e626e0e5 100644 (file)
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -13,6 +13,7 @@ package exec
 
 import (
        "bytes"
+       "context"
        "errors"
        "io"
        "os"
@@ -262,6 +263,15 @@ func (c *Cmd) Run() error {
        return c.Wait()
 }
 
+// RunContext is like Run, but kills the process (by calling os.Process.Kill)
+// if ctx is done before the process ends on its own.
+func (c *Cmd) RunContext(ctx context.Context) error {
+       if err := c.Start(); err != nil {
+               return err
+       }
+       return c.WaitContext(ctx)
+}
+
 // lookExtensions finds windows executable by its dir and path.
 // It uses LookPath to try appropriate extensions.
 // lookExtensions does not search PATH, instead it converts `prog` into `.\prog`.
@@ -386,6 +396,12 @@ func (e *ExitError) Error() string {
 //
 // Wait releases any resources associated with the Cmd.
 func (c *Cmd) Wait() error {
+       return c.WaitContext(nil)
+}
+
+// WaitContext is like Wait, but kills the process (by calling os.Process.Kill)
+// if ctx is done before the process ends on its own.
+func (c *Cmd) WaitContext(ctx context.Context) error {
        if c.Process == nil {
                return errors.New("exec: not started")
        }
@@ -393,7 +409,22 @@ func (c *Cmd) Wait() error {
                return errors.New("exec: Wait was already called")
        }
        c.finished = true
+
+       var waitDone chan struct{}
+       if ctx != nil {
+               waitDone := make(chan struct{})
+               go func() {
+                       select {
+                       case <-ctx.Done():
+                               c.Process.Kill()
+                       case <-waitDone:
+                       }
+               }()
+       }
        state, err := c.Process.Wait()
+       if waitDone != nil {
+               close(waitDone)
+       }
        c.ProcessState = state
 
        var copyError error

diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index ed2721bb5e57089694f2167ad9ad57cadff2c7e4..1151ca7d0f0c26dd7d34ce698ff7e3cd614fb5b9 100644 (file)
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -10,6 +10,7 @@ package exec_test
 import (
        "bufio"
        "bytes"
+       "context"
        "fmt"
        "internal/testenv"
        "io"
@@ -835,3 +836,41 @@ func TestOutputStderrCapture(t *testing.T) {
                t.Errorf("ExitError.Stderr = %q; want %q", got, want)
        }
 }
+
+func TestContext(t *testing.T) {
+       c := helperCommand(t, "pipetest")
+       stdin, err := c.StdinPipe()
+       if err != nil {
+               t.Fatal(err)
+       }
+       stdout, err := c.StdoutPipe()
+       if err != nil {
+               t.Fatal(err)
+       }
+       ctx, cancel := context.WithCancel(context.Background())
+       if err := c.Start(); err != nil {
+               t.Fatal(err)
+       }
+
+       if _, err := stdin.Write([]byte("O:hi\n")); err != nil {
+               t.Fatal(err)
+       }
+       buf := make([]byte, 5)
+       n, err := io.ReadFull(stdout, buf)
+       if n != len(buf) || err != nil || string(buf) != "O:hi\n" {
+               t.Fatalf("ReadFull = %d, %v, %q", n, err, buf[:n])
+       }
+       waitErr := make(chan error, 1)
+       go func() {
+               waitErr <- c.WaitContext(ctx)
+       }()
+       cancel()
+       select {
+       case err := <-waitErr:
+               if err == nil {
+                       t.Fatal("expected Wait failure")
+               }
+       case <-time.After(3 * time.Second):
+               t.Fatal("timeout waiting for child process death")
+       }
+}