PoC: sync: add sudo support

cmd/mutagen/sync/create.go

@@ -589,6 +589,9 @@ var createConfiguration struct {
 	// permission propagation mode, taking priority over defaultGroup on beta if
 	// specified.
 	defaultGroupBeta string
+	// sudo specifies if the agent should be started with 'sudo'. This can
+	// be useful when root SSH is disabled.
+	sudo bool
 }
 
 func init() {

pkg/agent/dial.go

@@ -32,7 +32,7 @@ const (
 // remote environment is cmd.exe-based and returns hints as to whether or not
 // installation should be attempted and whether or not the remote environment is
 // cmd.exe-based.
-func connect(logger *logging.Logger, transport Transport, mode, prompter string, cmdExe bool) (io.ReadWriteCloser, bool, bool, error) {
+func connect(logger *logging.Logger, transport Transport, mode, prompter string, cmdExe bool, sudo bool) (io.ReadWriteCloser, bool, bool, error) {
 	// Compute the agent invocation command, relative to the user's home
 	// directory on the remote. Unless we have reason to assume that this is a
 	// cmd.exe environment, we construct a path using forward slashes. This will
@@ -66,6 +66,9 @@ func connect(logger *logging.Logger, transport Transport, mode, prompter string,
 
 	// Compute the command to invoke.
 	command := fmt.Sprintf("%s %s", agentInvocationPath, mode)
+	if sudo && !cmdExe {
+		command = "sudo " + command
+	}
 
 	// Create an agent process.
 	message := "Connecting to agent (POSIX)..."
@@ -168,7 +171,7 @@ func connect(logger *logging.Logger, transport Transport, mode, prompter string,
 
 // Dial connects to an agent-based endpoint using the specified transport,
 // connection mode, and prompter.
-func Dial(logger *logging.Logger, transport Transport, mode, prompter string) (io.ReadWriteCloser, error) {
+func Dial(logger *logging.Logger, transport Transport, mode string, sudo bool, prompter string) (io.ReadWriteCloser, error) {
 	// Validate that the mode is sane.
 	if !(mode == ModeSynchronizer || mode == ModeForwarder) {
 		panic("invalid agent dial mode")
@@ -177,11 +180,11 @@ func Dial(logger *logging.Logger, transport Transport, mode, prompter string) (i
 	// Attempt a connection. If this fails but we detect a Windows cmd.exe
 	// environment in the process, then re-attempt a connection under the
 	// cmd.exe assumption.
-	stream, tryInstall, cmdExe, err := connect(logger, transport, mode, prompter, false)
+	stream, tryInstall, cmdExe, err := connect(logger, transport, mode, prompter, false, sudo)
 	if err == nil {
 		return stream, nil
 	} else if cmdExe {
-		stream, tryInstall, cmdExe, err = connect(logger, transport, mode, prompter, true)
+		stream, tryInstall, cmdExe, err = connect(logger, transport, mode, prompter, true, sudo)
 		if err == nil {
 			return stream, nil
 		}
@@ -199,7 +202,7 @@ func Dial(logger *logging.Logger, transport Transport, mode, prompter string) (i
 	}
 
 	// Re-attempt connectivity.
-	stream, _, _, err = connect(logger, transport, mode, prompter, cmdExe)
+	stream, _, _, err = connect(logger, transport, mode, prompter, cmdExe, sudo)
 	if err != nil {
 		return nil, err
 	}

pkg/agent/transport/ssh/transport.go

@@ -184,7 +184,7 @@ func (t *sshTransport) ClassifyError(processState *os.ProcessState, errorOutput
 	// hypothesis (instead of the cmd.exe hypothesis).
 	if process.IsPOSIXShellInvalidCommand(processState) {
 		return true, false, nil
-	} else if process.IsPOSIXShellCommandNotFound(processState) {
+	} else if process.IsPOSIXShellCommandNotFound(processState, errorOutput) {
 		return true, false, nil
 	} else if process.OutputIsWindowsInvalidCommand(errorOutput) {
 		// A Windows invalid command error doesn't necessarily indicate that

pkg/configuration/synchronization/configuration.go

@@ -63,6 +63,9 @@ type Configuration struct {
 		// setting ownership of new files and directories in "portable"
 		// permission propagation mode.
 		DefaultGroup string `yaml:"defaultGroup"`
+		// Sudo specifies if the agent should be started with 'sudo'. This can
+		// be useful when root SSH is disabled.
+		Sudo bool `yaml:"sudo"`
 	} `yaml:"permissions"`
 }
 
@@ -86,5 +89,6 @@ func (c *Configuration) Configuration() *synchronization.Configuration {
 		DefaultDirectoryMode:   uint32(c.Permissions.DefaultDirectoryMode),
 		DefaultOwner:           c.Permissions.DefaultOwner,
 		DefaultGroup:           c.Permissions.DefaultGroup,
+		Sudo:                   c.Permissions.Sudo,
 	}
 }

pkg/forwarding/protocols/docker/protocol.go

@@ -65,7 +65,7 @@ func (p *protocolHandler) Connect(
 	// cancellation.
 	go func() {
 		// Perform the dialing operation.
-		stream, err := agent.Dial(logger, transport, agent.ModeForwarder, prompter)
+		stream, err := agent.Dial(logger, transport, agent.ModeForwarder, false, prompter)
 
 		// Transmit the result or, if cancelled, close the stream.
 		select {

pkg/forwarding/protocols/ssh/protocol.go

@@ -73,7 +73,7 @@ func (p *protocolHandler) Connect(
 	// cancellation.
 	go func() {
 		// Perform the dialing operation.
-		stream, err := agent.Dial(logger, transport, agent.ModeForwarder, prompter)
+		stream, err := agent.Dial(logger, transport, agent.ModeForwarder, false, prompter)
 
 		// Transmit the result or, if cancelled, close the stream.
 		select {

pkg/process/exit_code.go

@@ -2,6 +2,7 @@ package process
 
 import (
 	"os"
+	"strings"
 )
 
 const (
@@ -35,6 +36,13 @@ func IsPOSIXShellInvalidCommand(state *os.ProcessState) bool {
 
 // IsPOSIXShellCommandNotFound returns whether or not a process state represents
 // a "command not found" error from a POSIX shell.
-func IsPOSIXShellCommandNotFound(state *os.ProcessState) bool {
-	return state.ExitCode() == posixShellCommandNotFoundExitCode
+func IsPOSIXShellCommandNotFound(state *os.ProcessState, errorOutput string) bool {
+	if state.ExitCode() == posixShellCommandNotFoundExitCode {
+		return true
+	}
+	if state.ExitCode() == 1 &&
+		strings.HasSuffix(strings.TrimSpace(errorOutput), "command not found") {
+		return true
+	}
+	return false
 }

pkg/synchronization/configuration.go

@@ -161,7 +161,8 @@ func (c *Configuration) Equal(other *Configuration) bool {
 		c.DefaultFileMode == other.DefaultFileMode &&
 		c.DefaultDirectoryMode == other.DefaultDirectoryMode &&
 		c.DefaultOwner == other.DefaultOwner &&
-		c.DefaultGroup == other.DefaultGroup
+		c.DefaultGroup == other.DefaultGroup &&
+		c.Sudo == other.Sudo
 }
 
 // MergeConfigurations merges two configurations of differing priorities. Both
@@ -278,6 +279,11 @@ func MergeConfigurations(lower, higher *Configuration) *Configuration {
 		result.DefaultGroup = lower.DefaultGroup
 	}
 
+	// Merge sudo.
+	if higher.Sudo || lower.Sudo {
+		result.Sudo = true
+	}
+
 	// Done.
 	return result
 }

pkg/synchronization/configuration.proto

@@ -116,5 +116,9 @@ message Configuration {
     // propagation mode.
     string defaultGroup = 66;
 
-    // Fields 67-80 are reserved for future permission configuration parameters.
+    // Sudo specifies if the agent should be started with 'sudo'. This can
+    // be useful when root SSH is disabled.
+    bool sudo = 67;
+
+    // Fields 68-80 are reserved for future permission configuration parameters.
 }

pkg/synchronization/protocols/docker/protocol.go

@@ -58,7 +58,7 @@ func (h *protocolHandler) Connect(
 	// cancellation.
 	go func() {
 		// Perform the dialing operation.
-		stream, err := agent.Dial(logger, transport, agent.ModeSynchronizer, prompter)
+		stream, err := agent.Dial(logger, transport, agent.ModeSynchronizer, false, prompter)
 
 		// Transmit the result or, if cancelled, close the stream.
 		select {

pkg/synchronization/protocols/ssh/protocol.go

@@ -62,11 +62,13 @@ func (h *protocolHandler) Connect(
 	// Create a channel to deliver the dialing result.
 	results := make(chan dialResult)
 
+	logger.Debug("configuration.Sudo:", configuration.Sudo)
+
 	// Perform dialing in a background Goroutine so that we can monitor for
 	// cancellation.
 	go func() {
 		// Perform the dialing operation.
-		stream, err := agent.Dial(logger, transport, agent.ModeSynchronizer, prompter)
+		stream, err := agent.Dial(logger, transport, agent.ModeSynchronizer, configuration.Sudo, prompter)
 
 		// Transmit the result or, if cancelled, close the stream.
 		select {