add Apk::merge

androscalpel/src/apk.rs

@@ -3307,4 +3307,64 @@ impl Apk {
             }))
         }
     }
+
+    /// Merget two application into one.
+    pub fn merge(&mut self, Self { mut dex_files }: Self) -> Result<()> {
+        let mut i = 0;
+        let mut name: String = "classes.dex".into();
+        while self.dex_files.contains_key(&name) {
+            i += 1;
+            name = format!("classes{}.dex", i + 1);
+        }
+        let mut j = 0;
+        let mut other_name: String = "classes.dex".into();
+        while let Some(file) = dex_files.remove(&other_name) {
+            self.dex_files.insert(name.clone(), file);
+            j += 1;
+            other_name = format!("classes{}.dex", j + 1);
+            while self.dex_files.contains_key(&name) {
+                i += 1;
+                name = format!("classes{}.dex", i + 1);
+            }
+        }
+
+        // Maybe not a good idea reinserting invalid .dex as valid ones, so explicitly skip one
+        // index to keep the files invalids.
+        i += 1;
+        name = format!("classes{}.dex", i + 1);
+        while self.dex_files.contains_key(&name) {
+            i += 1;
+            name = format!("classes{}.dex", i + 1);
+        }
+
+        for (other_name, dex) in dex_files.into_iter() {
+            if get_dex_name_index(&other_name).is_some() {
+                self.dex_files.insert(name.clone(), dex);
+                while self.dex_files.contains_key(&name) {
+                    i += 1;
+                    name = format!("classes{}.dex", i + 1);
+                }
+            } else {
+                let mut new_name = other_name.clone();
+                let mut k = 1;
+                while self.dex_files.contains_key(&new_name) {
+                    k += 1;
+                    new_name = format!("{other_name}-{k}")
+                }
+                self.dex_files.insert(new_name, dex);
+            }
+        }
+        Ok(())
+    }
+}
+
+/// Parse a .dex file name, and if it is a valid android file, return the index of the file.
+fn get_dex_name_index(name: &str) -> Option<usize> {
+    if name == "classes.dex" {
+        return Some(0);
+    }
+    name.strip_prefix("classes")
+        .and_then(|name| name.strip_suffix(".dex"))
+        .and_then(|name| name.parse::<usize>().ok())
+        .and_then(|idx| if idx <= 1 { None } else { Some(idx - 1) })
 }