diff options
Diffstat (limited to 'src/os/exec/exec.go')
| -rw-r--r-- | src/os/exec/exec.go | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go index 8e6f709a2f..e891ddca5a 100644 --- a/src/os/exec/exec.go +++ b/src/os/exec/exec.go @@ -94,6 +94,7 @@ import ( "bytes" "context" "errors" + "internal/godebug" "internal/syscall/execenv" "io" "os" @@ -243,6 +244,10 @@ type Cmd struct { ctxErr <-chan error // if non nil, receives the error from watchCtx exactly once + // The stack saved when the Command was created, if GODEBUG contains + // execwait=2. Used for debugging leaks. + createdByStack []byte + // For a security release long ago, we created x/sys/execabs, // which manipulated the unexported lookPathErr error field // in this struct. For Go 1.19 we exported the field as Err error, @@ -290,6 +295,43 @@ func Command(name string, arg ...string) *Cmd { Path: name, Args: append([]string{name}, arg...), } + + if execwait := godebug.Get("execwait"); execwait != "" { + if execwait == "2" { + // Obtain the caller stack. (This is equivalent to runtime/debug.Stack, + // copied to avoid importing the whole package.) + stack := make([]byte, 1024) + for { + n := runtime.Stack(stack, false) + if n < len(stack) { + stack = stack[:n] + break + } + stack = make([]byte, 2*len(stack)) + } + + if i := bytes.Index(stack, []byte("\nos/exec.Command(")); i >= 0 { + stack = stack[i+1:] + } + cmd.createdByStack = stack + } + + runtime.SetFinalizer(cmd, func(c *Cmd) { + if c.Process != nil && c.ProcessState == nil { + debugHint := "" + if c.createdByStack == nil { + debugHint = " (set GODEBUG=execwait=2 to capture stacks for debugging)" + } else { + os.Stderr.WriteString("GODEBUG=execwait=2 detected a leaked exec.Cmd created by:\n") + os.Stderr.Write(c.createdByStack) + os.Stderr.WriteString("\n") + debugHint = "" + } + panic("exec: Cmd started a Process but leaked without a call to Wait" + debugHint) + } + }) + } + if filepath.Base(name) == name { lp, err := LookPath(name) if lp != "" { |