From 12d6bc8c3065163e76179a46a5716c3c8a014231 Mon Sep 17 00:00:00 2001
From: Martin Atkins <mart@degeneration.co.uk>
Date: Fri, 1 Sep 2017 16:00:15 -0700
Subject: [PATCH] plugin/discovery: ignore non-files when discovering

If we encounter something that isn't a file -- for example, a dangling
symlink whose referent has been deleted -- we'll ignore it so that we
can either later produce a "no such plugin" error or auto-install a plugin
that will actually work.
---
 plugin/discovery/find.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/plugin/discovery/find.go b/plugin/discovery/find.go
index 10f8fce94..5c643f96f 100644
--- a/plugin/discovery/find.go
+++ b/plugin/discovery/find.go
@@ -3,6 +3,7 @@ package discovery
 import (
 	"io/ioutil"
 	"log"
+	"os"
 	"path/filepath"
 	"strings"
 )
@@ -70,6 +71,12 @@ func findPluginPaths(kind string, dirs []string) []string {
 					continue
 				}
 
+				// Check that the file we found is usable
+				if !pathIsFile(absPath) {
+					log.Printf("[ERROR] ignoring non-file %s", absPath)
+					continue
+				}
+
 				log.Printf("[DEBUG] found %s %q", kind, fullName)
 				ret = append(ret, filepath.Clean(absPath))
 				continue
@@ -82,6 +89,12 @@ func findPluginPaths(kind string, dirs []string) []string {
 				continue
 			}
 
+			// Check that the file we found is usable
+			if !pathIsFile(absPath) {
+				log.Printf("[ERROR] ignoring non-file %s", absPath)
+				continue
+			}
+
 			log.Printf("[WARNING] found legacy %s %q", kind, fullName)
 
 			ret = append(ret, filepath.Clean(absPath))
@@ -91,6 +104,17 @@ func findPluginPaths(kind string, dirs []string) []string {
 	return ret
 }
 
+// Returns true if and only if the given path refers to a file or a symlink
+// to a file.
+func pathIsFile(path string) bool {
+	info, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+
+	return !info.IsDir()
+}
+
 // ResolvePluginPaths takes a list of paths to plugin executables (as returned
 // by e.g. FindPluginPaths) and produces a PluginMetaSet describing the
 // referenced plugins.