From feff1f6edd44da252212caa10442b274d4b203c9 Mon Sep 17 00:00:00 2001
From: Tai Groot <tai@taigrr.com>
Date: Fri, 14 May 2021 16:55:17 -0700
Subject: [PATCH] check stderr before reporting back error 1

---
 README.md         | 10 +++++-----
 errors.go         |  2 ++
 systemctl.go      | 27 ++++++++++++++++++++-------
 systemctl_test.go | 28 ++++++++++++++++++++++++++++
 util.go           | 13 +++++++++++++
 5 files changed, 68 insertions(+), 12 deletions(-)
 create mode 100644 systemctl_test.go

diff --git a/README.md b/README.md
index 76f7bd7..bc0e166 100644
--- a/README.md
+++ b/README.md
@@ -40,17 +40,17 @@ import (
     "log"
     "time"
 
-    "github.com/taigrr/systemctl/v1"
+    "github.com/taigrr/systemctl"
 )
 
 func main() {
     ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
     defer cancel()
-
-    // Equivalent to `systemctl enable dhcpd` with a 10 second timeout
-    err := systemctl.Enable(ctx, "dhcpd")
+    userMode := false
+    // Equivalent to `systemctl enable nginx` with a 10 second timeout
+    err := systemctl.Enable(ctx, "nginx", userMode)
     if err != nil {
-        log.Fatalf("unable to enable unit %s: %v", "dhcpd", err)
+        log.Fatalf("unable to enable unit %s: %v", "nginx", err)
     }
 }
 ```
diff --git a/errors.go b/errors.go
index 12a9278..b7f1157 100644
--- a/errors.go
+++ b/errors.go
@@ -17,4 +17,6 @@ var (
 
 	// ErrDoesNotExist means the unit specified doesn't exist or can't be found
 	ErrDoesNotExist = errors.New("Unit does not exist")
+	// ErrUnspecified means something in the stderr output contains the word `Failed`, but not a known case
+	ErrUnspecified = errors.New("Unknown error")
 )
diff --git a/systemctl.go b/systemctl.go
index 5d4060d..050d42a 100644
--- a/systemctl.go
+++ b/systemctl.go
@@ -2,8 +2,7 @@ package systemctl
 
 import (
 	"context"
-	"errors"
-	"strconv"
+	"fmt"
 )
 
 // TODO
@@ -44,22 +43,36 @@ func Enable(ctx context.Context, unit string, usermode bool) error {
 		args[1] = "--user"
 	}
 	_, stderr, code, err := execute(ctx, args)
-
-	if err != nil {
-		return err
+	customErr := filterErr(stderr)
+	if customErr != nil {
+		return customErr
 	}
-	err = filterErr(stderr)
 	if err != nil {
 		return err
 	}
 	if code != 0 {
-		return errors.New("received error code " + strconv.Itoa(code))
+		return fmt.Errorf("received error code %d for stderr `%s`: %w", code, stderr, ErrUnspecified)
 	}
 	return nil
 }
 
 // TODO
 func Disable(ctx context.Context, unit string, usermode bool) error {
+	var args = []string{"disable", "--system", unit}
+	if usermode {
+		args[1] = "--user"
+	}
+	_, stderr, code, err := execute(ctx, args)
+	customErr := filterErr(stderr)
+	if customErr != nil {
+		return customErr
+	}
+	if err != nil {
+		return err
+	}
+	if code != 0 {
+		return fmt.Errorf("received error code %d for stderr `%s`: %w", code, stderr, ErrUnspecified)
+	}
 	return nil
 }
 
diff --git a/systemctl_test.go b/systemctl_test.go
new file mode 100644
index 0000000..e20dee4
--- /dev/null
+++ b/systemctl_test.go
@@ -0,0 +1,28 @@
+package systemctl
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestEnableNonexistant(t *testing.T) {
+	unit := "nonexistant"
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	err := Enable(ctx, unit, true)
+	if err != ErrDoesNotExist {
+		t.Errorf("error is %v, but should have been %v", err, ErrDoesNotExist)
+	}
+
+}
+func TestEnableNoPermissions(t *testing.T) {
+	unit := "nginx"
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	err := Enable(ctx, unit, false)
+	if err != ErrInsufficientPermissions {
+		t.Errorf("error is %v, but should have been %v", err, ErrInsufficientPermissions)
+	}
+
+}
diff --git a/util.go b/util.go
index c87b7cc..499490b 100644
--- a/util.go
+++ b/util.go
@@ -45,6 +45,19 @@ func filterErr(stderr string) error {
 	if matched {
 		return ErrDoesNotExist
 	}
+	matched, _ = regexp.MatchString(`Interactive authentication required`, stderr)
+	if matched {
+		return ErrInsufficientPermissions
+	}
+	matched, _ = regexp.MatchString(`Access denied`, stderr)
+	if matched {
+		return ErrInsufficientPermissions
+	}
+
+	matched, _ = regexp.MatchString(`Failed`, stderr)
+	if matched {
+		return ErrUnspecified
+	}
 
 	return nil
 }