MM-6839: search relative to executable (#8853)

* MM-6839: searching for paths relative to executable

In addition to searching relative to the current working directory, also
search relative to the location of the binary. This helps locate config
and i18n files when invoking an absolute path to the mattermost binary.

* MM-6839: find mattermost/ binary using utils.FindFile

cmd/platform/main.go

@@ -6,19 +6,10 @@ package main
 import (
 	"fmt"
 	"os"
-	"path/filepath"
 	"syscall"
-)
 
-func findMattermostBinary() string {
+	"github.com/mattermost/mattermost-server/utils"
-	for _, file := range []string{"./mattermost", "../mattermost", "./bin/mattermost"} {
+)
-		path, _ := filepath.Abs(file)
-		if stat, err := os.Stat(path); err == nil && !stat.IsDir() {
-			return path
-		}
-	}
-	return "./mattermost"
-}
 
 func main() {
 	// Print angry message to use mattermost command directly
@@ -33,7 +24,14 @@ The platform binary will be removed in a future version.
 	args := os.Args
 	args[0] = "mattermost"
 	args = append(args, "--platform")
-	if err := syscall.Exec(findMattermostBinary(), args, nil); err != nil {
+
+	realMattermost := utils.FindFile("mattermost")
+	if realMattermost == "" {
+		// This will still fail, of course.
+		realMattermost = "./mattermost"
+	}
+
+	if err := syscall.Exec(utils.FindFile("mattermost"), args, nil); err != nil {
 		fmt.Println("Could not start Mattermost, use the mattermost command directly.")
 	}
 }

utils/config.go

@@ -32,36 +32,94 @@ const (
 	LOG_FILENAME    = "mattermost.log"
 )
 
+var (
+	commonBaseSearchPaths = []string{
+		".",
+		"..",
+		"../..",
+		"../../..",
+	}
+)
+
+func FindPath(path string, baseSearchPaths []string, filter func(os.FileInfo) bool) string {
+	if filepath.IsAbs(path) {
+		if _, err := os.Stat(path); err == nil {
+			return path
+		}
+
+		return ""
+	}
+
+	searchPaths := []string{}
+	for _, baseSearchPath := range baseSearchPaths {
+		searchPaths = append(searchPaths, baseSearchPath)
+	}
+
+	// Additionally attempt to search relative to the location of the running binary.
+	var binaryDir string
+	if exe, err := os.Executable(); err == nil {
+		if exe, err = filepath.EvalSymlinks(exe); err == nil {
+			if exe, err = filepath.Abs(exe); err == nil {
+				binaryDir = filepath.Dir(exe)
+			}
+		}
+	}
+	if binaryDir != "" {
+		for _, baseSearchPath := range baseSearchPaths {
+			searchPaths = append(
+				searchPaths,
+				filepath.Join(binaryDir, baseSearchPath),
+			)
+		}
+	}
+
+	for _, parent := range searchPaths {
+		found, err := filepath.Abs(filepath.Join(parent, path))
+		if err != nil {
+			continue
+		} else if fileInfo, err := os.Stat(found); err == nil {
+			if filter != nil && filter(fileInfo) {
+				return found
+			} else {
+				return found
+			}
+		}
+	}
+
+	return ""
+}
+
 // FindConfigFile attempts to find an existing configuration file. fileName can be an absolute or
 // relative path or name such as "/opt/mattermost/config.json" or simply "config.json". An empty
 // string is returned if no configuration is found.
 func FindConfigFile(fileName string) (path string) {
-	if filepath.IsAbs(fileName) {
+	found := FindFile(filepath.Join("config", fileName))
-		if _, err := os.Stat(fileName); err == nil {
+	if found == "" {
-			return fileName
+		found = FindPath(fileName, []string{"."}, nil)
-		}
-	} else {
-		for _, dir := range []string{"./config", "../config", "../../config", "../../../config", "."} {
-			path, _ := filepath.Abs(filepath.Join(dir, fileName))
-			if _, err := os.Stat(path); err == nil {
-				return path
-			}
-		}
 	}
-	return ""
+
+	return found
 }
 
-// FindDir looks for the given directory in nearby ancestors, falling back to `./` if not found.
+// FindFile looks for the given file in nearby ancestors relative to the current working
+// directory as well as the directory of the executable.
+func FindFile(path string) string {
+	return FindPath(path, commonBaseSearchPaths, func(fileInfo os.FileInfo) bool {
+		return !fileInfo.IsDir()
+	})
+}
+
+// FindDir looks for the given directory in nearby ancestors relative to the current working
+// directory as well as the directory of the executable, falling back to `./` if not found.
 func FindDir(dir string) (string, bool) {
-	for _, parent := range []string{".", "..", "../..", "../../.."} {
+	found := FindPath(dir, commonBaseSearchPaths, func(fileInfo os.FileInfo) bool {
-		foundDir, err := filepath.Abs(filepath.Join(parent, dir))
+		return fileInfo.IsDir()
-		if err != nil {
+	})
-			continue
+	if found == "" {
-		} else if _, err := os.Stat(foundDir); err == nil {
+		return "./", false
-			return foundDir, true
-		}
 	}
-	return "./", false
+
+	return found, true
 }
 
 func MloggerConfigFromLoggerConfig(s *model.LogSettings) *mlog.LoggerConfiguration {

utils/config_test.go

@@ -46,20 +46,172 @@ func TestTimezoneConfig(t *testing.T) {
 }
 
 func TestFindConfigFile(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	t.Run("config.json in current working directory, not inside config/", func(t *testing.T) {
-	require.NoError(t, err)
+		// Force a unique working directory
-	defer os.RemoveAll(dir)
+		cwd, err := ioutil.TempDir("", "")
+		require.NoError(t, err)
+		defer os.RemoveAll(cwd)
 
-	path := filepath.Join(dir, "config.json")
+		prevDir, err := os.Getwd()
-	require.NoError(t, ioutil.WriteFile(path, []byte("{}"), 0600))
+		require.NoError(t, err)
+		defer os.Chdir(prevDir)
+		os.Chdir(cwd)
 
-	assert.Equal(t, path, FindConfigFile(path))
+		configJson, err := filepath.Abs("config.json")
+		require.NoError(t, err)
+		require.NoError(t, ioutil.WriteFile(configJson, []byte("{}"), 0600))
 
-	prevDir, err := os.Getwd()
+		// Relative paths end up getting symlinks fully resolved.
-	require.NoError(t, err)
+		configJsonResolved, err := filepath.EvalSymlinks(configJson)
-	defer os.Chdir(prevDir)
+		require.NoError(t, err)
-	os.Chdir(dir)
+
-	assert.Equal(t, path, FindConfigFile(path))
+		assert.Equal(t, configJsonResolved, FindConfigFile("config.json"))
+	})
+
+	t.Run("config/config.json from various paths", func(t *testing.T) {
+		// Create the following directory structure:
+		// tmpDir1/
+		//   config/
+		//     config.json
+		//   tmpDir2/
+		//     tmpDir3/
+		//       tmpDir4/
+		//         tmpDir5/
+		tmpDir1, err := ioutil.TempDir("", "")
+		require.NoError(t, err)
+		defer os.RemoveAll(tmpDir1)
+
+		err = os.Mkdir(filepath.Join(tmpDir1, "config"), 0700)
+		require.NoError(t, err)
+
+		tmpDir2, err := ioutil.TempDir(tmpDir1, "")
+		require.NoError(t, err)
+
+		tmpDir3, err := ioutil.TempDir(tmpDir2, "")
+		require.NoError(t, err)
+
+		tmpDir4, err := ioutil.TempDir(tmpDir3, "")
+		require.NoError(t, err)
+
+		tmpDir5, err := ioutil.TempDir(tmpDir4, "")
+		require.NoError(t, err)
+
+		configJson := filepath.Join(tmpDir1, "config", "config.json")
+		require.NoError(t, ioutil.WriteFile(configJson, []byte("{}"), 0600))
+
+		// Relative paths end up getting symlinks fully resolved, so use this below as necessary.
+		configJsonResolved, err := filepath.EvalSymlinks(configJson)
+		require.NoError(t, err)
+
+		testCases := []struct {
+			Description string
+			Cwd         *string
+			FileName    string
+			Expected    string
+		}{
+			{
+				"absolute path to config.json",
+				nil,
+				configJson,
+				configJson,
+			},
+			{
+				"absolute path to config.json from directory containing config.json",
+				&tmpDir1,
+				configJson,
+				configJson,
+			},
+			{
+				"relative path to config.json from directory containing config.json",
+				&tmpDir1,
+				"config.json",
+				configJsonResolved,
+			},
+			{
+				"subdirectory of directory containing config.json",
+				&tmpDir2,
+				"config.json",
+				configJsonResolved,
+			},
+			{
+				"twice-nested subdirectory of directory containing config.json",
+				&tmpDir3,
+				"config.json",
+				configJsonResolved,
+			},
+			{
+				"thrice-nested subdirectory of directory containing config.json",
+				&tmpDir4,
+				"config.json",
+				configJsonResolved,
+			},
+			{
+				"can't find from four nesting levels deep",
+				&tmpDir5,
+				"config.json",
+				"",
+			},
+		}
+
+		for _, testCase := range testCases {
+			t.Run(testCase.Description, func(t *testing.T) {
+				if testCase.Cwd != nil {
+					prevDir, err := os.Getwd()
+					require.NoError(t, err)
+					defer os.Chdir(prevDir)
+					os.Chdir(*testCase.Cwd)
+				}
+
+				assert.Equal(t, testCase.Expected, FindConfigFile(testCase.FileName))
+			})
+		}
+	})
+
+	t.Run("config/config.json relative to executable", func(t *testing.T) {
+		osExecutable, err := os.Executable()
+		require.NoError(t, err)
+		osExecutableDir := filepath.Dir(osExecutable)
+
+		// Force a working directory different than the executable.
+		cwd, err := ioutil.TempDir("", "")
+		require.NoError(t, err)
+		defer os.RemoveAll(cwd)
+
+		prevDir, err := os.Getwd()
+		require.NoError(t, err)
+		defer os.Chdir(prevDir)
+		os.Chdir(cwd)
+
+		testCases := []struct {
+			Description  string
+			RelativePath string
+		}{
+			{
+				"config/config.json",
+				".",
+			},
+			{
+				"../config/config.json",
+				"../",
+			},
+		}
+
+		for _, testCase := range testCases {
+			t.Run(testCase.Description, func(t *testing.T) {
+				// Install the config in config/config.json relative to the executable
+				configJson := filepath.Join(osExecutableDir, testCase.RelativePath, "config", "config.json")
+				require.NoError(t, os.Mkdir(filepath.Dir(configJson), 0700))
+				require.NoError(t, ioutil.WriteFile(configJson, []byte("{}"), 0600))
+				defer os.RemoveAll(filepath.Dir(configJson))
+
+				// Relative paths end up getting symlinks fully resolved.
+				configJsonResolved, err := filepath.EvalSymlinks(configJson)
+				require.NoError(t, err)
+
+				assert.Equal(t, configJsonResolved, FindConfigFile("config.json"))
+			})
+		}
+	})
 }
 
 func TestConfigFromEnviroVars(t *testing.T) {