Improve PVD detection

Locate PVD properly if it's not the first entry in the volume descriptor table.
An exception is thrown if PVD cannot be found.

This should not happen for PSP ISOs though (that I know of...).

Author: Altomare

redump_psp.py

@@ -8,17 +8,16 @@
 from sfo_info import get_sfo_info
 
 
-def hexdump(data, print_offset):
+def hexdump(data, offset, size):
     dump = ""
-    line_nb = len(data) // 0x10
+    line_nb = size // 0x10
     for i in range(line_nb):
-        line = f"{print_offset + i * 16:04x} : "
+        line = f"{offset + i * 16:04x} : "
         for j in range(0x10):
-            line += f"{data[i * 16 + j]:02X}"
+            line += f"{data[offset + i * 16 + j]:02X}"
             line += "  " if j == 0x7 else " "
-
         line += "  "
-        r_line = data[i * 0x10: i * 0x10 + 0x10]
+        r_line = data[offset + i * 0x10: offset + i * 0x10 + 0x10]
         line += "".join([chr(b) if 0x20 <= b <= 0x7F else "." for b in r_line])
         dump += line
         if i < line_nb - 1:
@@ -34,6 +33,7 @@ def read_in_chunks(file_object, chunk_size=1024):
                 break
             yield data
 
+    filestream.seek(0)
     prev_crc32 = 0
     sha1 = hashlib.sha1()
     md5 = hashlib.md5()
@@ -47,15 +47,24 @@ def read_in_chunks(file_object, chunk_size=1024):
             md5.hexdigest().zfill(32))
 
 
+def get_pvd_dump(filestream):
+    filestream.seek(0x8000)
+    raw_sector = filestream.read(0x800)
+    while raw_sector[0] != 0xFF:
+        if raw_sector[6] == 0x1:
+            return hexdump(raw_sector, 0x320, 0x60)
+        raw_sector = filestream.read(0x800)
+    raise Exception("Could not find PVD")
+
+
 def gen_psp_redump(iso, out):
     if not os.path.exists(iso):
         print(f"Unable to access {iso}")
         return
 
     with open(iso, 'rb') as f:
         hashes = gen_hashes(f)
-        f.seek(0x800 * 16 + 0x320)  # Go to sector 16 + offset of PVD
-        pvd_dump = hexdump(f.read(0x60), 0x320)
+        pvd_dump = get_pvd_dump(f)
     size_b = os.stat(iso).st_size
     size_mb = round(size_b / (1024 * 1024))
     sfo_info = get_sfo_info(iso)