feat: nice errors when failing to load plugins

partially fixes #7305

plugin/loader/load_nocgo.go

@@ -0,0 +1,17 @@
+// +build linux,!cgo,!noplugin darwin,!cgo,!noplugin
+
+package loader
+
+import (
+	"errors"
+
+	iplugin "github.com/ipfs/go-ipfs/plugin"
+)
+
+func init() {
+	loadPluginFunc = nocgoLoadPlugin
+}
+
+func nocgoLoadPlugin(fi string) ([]iplugin.Plugin, error) {
+	return nil, errors.New("not built with cgo support")
+}

plugin/loader/load_noplugin.go

@@ -0,0 +1,17 @@
+// +build noplugin
+
+package loader
+
+import (
+	"errors"
+
+	iplugin "github.com/ipfs/go-ipfs/plugin"
+)
+
+func init() {
+	loadPluginFunc = nopluginLoadPlugin
+}
+
+func nopluginLoadPlugin(string) ([]iplugin.Plugin, error) {
+	return nil, errors.New("not built with plugin support")
+}

plugin/loader/load_unix.go

@@ -5,52 +5,16 @@ package loader
 
 import (
 	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
 	"plugin"
 
 	iplugin "github.com/ipfs/go-ipfs/plugin"
 )
 
 func init() {
-	loadPluginsFunc = linuxLoadFunc
+	loadPluginFunc = unixLoadPlugin
 }
 
-func linuxLoadFunc(pluginDir string) ([]iplugin.Plugin, error) {
-	var plugins []iplugin.Plugin
-
-	err := filepath.Walk(pluginDir, func(fi string, info os.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-		if info.IsDir() {
-			if fi != pluginDir {
-				log.Warnf("found directory inside plugins directory: %s", fi)
-			}
-			return nil
-		}
-
-		if info.Mode().Perm()&0111 == 0 {
-			// file is not executable let's not load it
-			// this is to prevent loading plugins from for example non-executable
-			// mounts, some /tmp mounts are marked as such for security
-			log.Errorf("non-executable file in plugins directory: %s", fi)
-			return nil
-		}
-
-		if newPlugins, err := loadPlugin(fi); err == nil {
-			plugins = append(plugins, newPlugins...)
-		} else {
-			return fmt.Errorf("loading plugin %s: %s", fi, err)
-		}
-		return nil
-	})
-
-	return plugins, err
-}
-
-func loadPlugin(fi string) ([]iplugin.Plugin, error) {
+func unixLoadPlugin(fi string) ([]iplugin.Plugin, error) {
 	pl, err := plugin.Open(fi)
 	if err != nil {
 		return nil, err

plugin/loader/loader.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	config "github.com/ipfs/go-ipfs-config"
@@ -30,8 +31,8 @@ func Preload(plugins ...plugin.Plugin) {
 
 var log = logging.Logger("plugin/loader")
 
-var loadPluginsFunc = func(string) ([]plugin.Plugin, error) {
-	return nil, nil
+var loadPluginFunc = func(string) ([]plugin.Plugin, error) {
+	return nil, fmt.Errorf("unsupported platform %s", runtime.GOOS)
 }
 
 type loaderState int
@@ -182,7 +183,36 @@ func loadDynamicPlugins(pluginDir string) ([]plugin.Plugin, error) {
 		return nil, err
 	}
 
-	return loadPluginsFunc(pluginDir)
+	var plugins []plugin.Plugin
+
+	err = filepath.Walk(pluginDir, func(fi string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			if fi != pluginDir {
+				log.Warnf("found directory inside plugins directory: %s", fi)
+			}
+			return nil
+		}
+
+		if info.Mode().Perm()&0111 == 0 {
+			// file is not executable let's not load it
+			// this is to prevent loading plugins from for example non-executable
+			// mounts, some /tmp mounts are marked as such for security
+			log.Errorf("non-executable file in plugins directory: %s", fi)
+			return nil
+		}
+
+		if newPlugins, err := loadPluginFunc(fi); err == nil {
+			plugins = append(plugins, newPlugins...)
+		} else {
+			return fmt.Errorf("loading plugin %s: %s", fi, err)
+		}
+		return nil
+	})
+
+	return plugins, err
 }
 
 // Initialize initializes all loaded plugins

test/sharness/t0280-plugin.sh

@@ -89,4 +89,14 @@ test_expect_success "configure the plugin" '
 
 test_plugin true "$IPFS_PATH" "foobar"
 
+test_expect_success "noplugin flag works" '
+  test_must_fail go run -tags=noplugin github.com/ipfs/go-ipfs/cmd/ipfs id > output 2>&1
+  test_should_contain "not built with plugin support" output
+'
+
+test_expect_success "noplugin flag works" '
+  CGO_ENABLED=0 test_must_fail go run github.com/ipfs/go-ipfs/cmd/ipfs id > output 2>&1
+  test_should_contain "not built with cgo support" output
+'
+
 test_done