main: Align STUB_SIZE to 16K boundary

Blocks are 4K, but let's do 16K for good measure.

Signed-off-by: Hector Martin <[email protected]>

Author: marcan

src/main.py

@@ -6,7 +6,7 @@
 import system, osenum, stub, diskutil
 from util import *
 
-STUB_SIZE = 2500 * 1000 * 1000
+STUB_SIZE = align_up(2500 * 1000 * 1000)
 
 @dataclass
 class IPSW:
@@ -354,7 +354,7 @@ def main(self):
                 continue
             if p.free:
                 p.desc = f"(free space: {ssize(p.size)})"
-                if p.size > STUB_SIZE:
+                if p.size >= STUB_SIZE:
                     parts_free.append(p)
             elif p.type.startswith("Apple_APFS"):
                 p.desc = "APFS"

src/util.py

@@ -23,3 +23,11 @@ def split_ver(s):
         parts2[-3] -= 1
         parts2[-2] = 99
     return tuple(parts2)
+
+def align_up(v, a=16384):
+    return (v + a - 1) & ~(a - 1)
+
+align = align_up
+
+def align_down(v, a=16384):
+    return v & ~(a - 1)