ksud: only backup stock boot if flashing (#1626)

userspace/ksud/src/boot_patch.rs

@@ -282,8 +282,10 @@ fn do_patch(
 ) -> Result<()> {
     println!(include_str!("banner"));
 
-    if image.is_none() {
+    let patch_file = image.is_some();
+
     #[cfg(target_os = "android")]
+    if !patch_file {
         ensure_gki_kernel()?;
     }
 
@@ -372,6 +374,9 @@ fn do_patch(
         if status.is_ok() {
             do_cpio_cmd(&magiskboot, workding_dir.path(), "mv init init.real")?;
         }
+
+        #[cfg(target_os = "android")]
+        if flash {
             println!("- Backup stock boot image");
             // magiskboot cpio ramdisk.cpio 'add 0755 orig.ksu'
             let output = Command::new(&magiskboot)
@@ -383,9 +388,6 @@ fn do_patch(
                 output.status.success(),
                 "Cannot calculate sha1 of original boot!"
             );
-
-        #[cfg(target_os = "android")]
-        {
             let output = String::from_utf8(output.stdout)?;
             let output = output.trim();
             let output = format!("{KSU_BACKUP_FILE_PREFIX}{output}");
@@ -423,7 +425,7 @@ fn do_patch(
     ensure!(status.success(), "magiskboot repack failed");
     let new_boot = workding_dir.path().join("new-boot.img");
 
-    if image.is_some() {
+    if patch_file {
         // if image is specified, write to output file
         let output_dir = out.unwrap_or(std::env::current_dir()?);
         let now = chrono::Utc::now();