selfupdate: consider arm version

cmd/selfupdate/selfupdate.go

@@ -336,11 +336,31 @@ func makeRandomExeName(baseName, extension string) (string, error) {
 
 func downloadUpdate(ctx context.Context, beta bool, version, siteURL, newFile, packageFormat string) error {
 	osName := runtime.GOOS
-	arch := runtime.GOARCH
 	if osName == "darwin" {
 		osName = "osx"
 	}
-
+	arch := runtime.GOARCH
+	if arch == "arm" {
+		// Check the ARM compatibility level of the current CPU.
+		// We don't know if this matches the rclone binary currently running, it
+		// could for example be a ARMv6 variant running on a ARMv7 compatible CPU,
+		// so we will simply pick the best possible variant.
+		switch buildinfo.GetSupportedGOARM() {
+		case 7:
+			// This system can run any binaries built with GOARCH=arm, including GOARM=7.
+			// Pick the ARMv7 variant of rclone, published with suffix "arm-v7".
+			arch = "arm-v7"
+		case 6:
+			// This system can run binaries built with GOARCH=arm and GOARM=6 or lower.
+			// Pick the ARMv6 variant of rclone, published with suffix "arm-v6".
+			arch = "arm-v6"
+		case 5:
+			// This system can only run binaries built with GOARCH=arm and GOARM=5.
+			// Pick the ARMv5 variant of rclone, which also works without hardfloat,
+			// published with suffix "arm".
+			arch = "arm"
+		}
+	}
 	archiveFilename := fmt.Sprintf("rclone-%s-%s-%s.%s", version, osName, arch, packageFormat)
 	archiveURL := fmt.Sprintf("%s/%s/%s", siteURL, version, archiveFilename)
 	archiveBuf, err := downloadFile(ctx, archiveURL)