Added check to not use files under 128KiB

README.md

@@ -1,6 +1,7 @@
 ## Drastic to MelonDS
 
 This script will convert the dsv save from drastic emulator to a melonDS save file
+This also works for desmume to MelonDS save files since desmume also seems to add padding to the end of the file.
 
 ### Usage
 
@@ -17,6 +18,16 @@ optional arguments:
   -f, --force           Overwrite the output file if it exists
 ```
 
+### Install
+
+Add it to a folder in your $PATH
+
+```bash
+install -Dm755 dr2mds.py ~/.local/bin/dr2mds
+```
+
+_For windows users just run the script from the folder_
+
 ### How to use
 
 You need python 3 installed.  
@@ -33,7 +44,7 @@ You can also specify the output like
 ./dr2mds.py "Pokemon Black.dsv" -o "PKMN.sav"
 ```
 
-### How does this works ?
+### How does this work ?
 
 MelonDS determines the type of save using exact byte count in the save file
 

dr2mds.py

@@ -9,6 +9,16 @@ import os
 sys.tracebacklimit = 0
 
 
+class SaveFileTooSmallError(Exception):
+    def __init__(self, size, message="Save file is smaller than 128KiB"):
+        self.size = size
+        self.message = message
+        super().__init__(self.message)
+
+    def __str__(self):
+        return f"{self.size} is smaller than 131072 or 128KiB"
+
+
 def closest2pow(n):
     # int always returns the floor of the float
     # log(n)/log(2) gives log base 2 of n
@@ -18,6 +28,11 @@ def closest2pow(n):
 def drastic2melonds(infile, outfile):
     with open(infile, "rb") as inf, open(outfile, "wb") as ouf:
         in_bytes = os.stat(infile).st_size
+        if in_bytes < 131072:
+            print(f"The file {infile} seems to be smaller than 128KiB"
+                  " and not a valid save file", file=sys.stderr)
+            raise SaveFileTooSmallError(in_bytes)
+
         out_bytes = closest2pow(in_bytes)
         print(f"Reading {in_bytes} bytes from {infile}", file=sys.stderr)
         print(f"Writing {out_bytes} bytes to {outfile}", file=sys.stderr)