backends: make sure backends expand ~ and environment vars in file names they use

See: https://forum.rclone.org/t/relative-path-in-rclone-config-service-account-json/16693

backend/box/box.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/rclone/rclone/lib/encoder"
+	"github.com/rclone/rclone/lib/env"
 	"github.com/rclone/rclone/lib/jwtutil"
 
 	"github.com/youmark/pkcs8"
@@ -112,7 +113,7 @@ func init() {
 			Advanced: true,
 		}, {
 			Name: "box_config_file",
-			Help: "Box App config.json location\nLeave blank normally.",
+			Help: "Box App config.json location\nLeave blank normally." + env.ShellExpandHelp,
 		}, {
 			Name:    "box_sub_type",
 			Default: "user",
@@ -153,6 +154,7 @@ func init() {
 }
 
 func refreshJWTToken(jsonFile string, boxSubType string, name string, m configmap.Mapper) error {
+	jsonFile = env.ShellExpand(jsonFile)
 	boxConfig, err := getBoxConfig(jsonFile)
 	if err != nil {
 		log.Fatalf("Failed to configure token: %v", err)

backend/drive/drive.go

@@ -18,7 +18,6 @@ import (
 	"mime"
 	"net/http"
 	"net/url"
-	"os"
 	"path"
 	"sort"
 	"strconv"
@@ -41,6 +40,7 @@ import (
 	"github.com/rclone/rclone/fs/walk"
 	"github.com/rclone/rclone/lib/dircache"
 	"github.com/rclone/rclone/lib/encoder"
+	"github.com/rclone/rclone/lib/env"
 	"github.com/rclone/rclone/lib/oauthutil"
 	"github.com/rclone/rclone/lib/pacer"
 	"github.com/rclone/rclone/lib/readers"
@@ -229,7 +229,7 @@ in with the ID of the root folder.
 `,
 		}, {
 			Name: "service_account_file",
-			Help: "Service Account Credentials JSON file path \nLeave blank normally.\nNeeded only if you want use SA instead of interactive login.",
+			Help: "Service Account Credentials JSON file path \nLeave blank normally.\nNeeded only if you want use SA instead of interactive login." + env.ShellExpandHelp,
 		}, {
 			Name:     "service_account_credentials",
 			Help:     "Service Account Credentials JSON blob\nLeave blank normally.\nNeeded only if you want use SA instead of interactive login.",
@@ -1005,7 +1005,7 @@ func createOAuthClient(opt *Options, name string, m configmap.Mapper) (*http.Cli
 
 	// try loading service account credentials from env variable, then from a file
 	if len(opt.ServiceAccountCredentials) == 0 && opt.ServiceAccountFile != "" {
-		loadedCreds, err := ioutil.ReadFile(os.ExpandEnv(opt.ServiceAccountFile))
+		loadedCreds, err := ioutil.ReadFile(env.ShellExpand(opt.ServiceAccountFile))
 		if err != nil {
 			return nil, errors.Wrap(err, "error opening service account credentials file")
 		}

backend/googlecloudstorage/googlecloudstorage.go

@@ -21,7 +21,6 @@ import (
 	"io/ioutil"
 	"log"
 	"net/http"
-	"os"
 	"path"
 	"strings"
 	"time"
@@ -38,6 +37,7 @@ import (
 	"github.com/rclone/rclone/fs/walk"
 	"github.com/rclone/rclone/lib/bucket"
 	"github.com/rclone/rclone/lib/encoder"
+	"github.com/rclone/rclone/lib/env"
 	"github.com/rclone/rclone/lib/oauthutil"
 	"github.com/rclone/rclone/lib/pacer"
 	"golang.org/x/oauth2"
@@ -98,7 +98,7 @@ func init() {
 			Help: "Project number.\nOptional - needed only for list/create/delete buckets - see your developer console.",
 		}, {
 			Name: "service_account_file",
-			Help: "Service Account Credentials JSON file path\nLeave blank normally.\nNeeded only if you want use SA instead of interactive login.",
+			Help: "Service Account Credentials JSON file path\nLeave blank normally.\nNeeded only if you want use SA instead of interactive login." + env.ShellExpandHelp,
 		}, {
 			Name: "service_account_credentials",
 			Help: "Service Account Credentials JSON blob\nLeave blank normally.\nNeeded only if you want use SA instead of interactive login.",
@@ -405,7 +405,7 @@ func NewFs(name, root string, m configmap.Mapper) (fs.Fs, error) {
 
 	// try loading service account credentials from env variable, then from a file
 	if opt.ServiceAccountCredentials == "" && opt.ServiceAccountFile != "" {
-		loadedCreds, err := ioutil.ReadFile(os.ExpandEnv(opt.ServiceAccountFile))
+		loadedCreds, err := ioutil.ReadFile(env.ShellExpand(opt.ServiceAccountFile))
 		if err != nil {
 			return nil, errors.Wrap(err, "error opening service account credentials file")
 		}

backend/sftp/sftp.go

@@ -74,7 +74,7 @@ func init() {
 			Help: "Raw PEM-encoded private key, If specified, will override key_file parameter.",
 		}, {
 			Name: "key_file",
-			Help: "Path to PEM-encoded private key file, leave blank or set key-use-agent to use ssh-agent.",
+			Help: "Path to PEM-encoded private key file, leave blank or set key-use-agent to use ssh-agent." + env.ShellExpandHelp,
 		}, {
 			Name: "key_file_pass",
 			Help: `The passphrase to decrypt the PEM-encoded private key file.

lib/env/env.go

@@ -7,6 +7,9 @@ import (
 	homedir "github.com/mitchellh/go-homedir"
 )
 
+// ShellExpandHelp describes what ShellExpand does for inclusion into help
+const ShellExpandHelp = "\n\nLeading `~` will be expanded in the file name as will environment variables such as `${RCLONE_CONFIG_DIR}`.\n"
+
 // ShellExpand replaces a leading "~" with the home directory" and
 // expands all environment variables afterwards.
 func ShellExpand(s string) string {