Re-implemented support for adjust signature keyword

src/binwalk/core/magic.py

@@ -34,6 +34,7 @@ class SignatureResult(object):
         self.size = 0
         self.name = None
         self.offset = 0
+        self.adjust = 0
         self.strlen = 0
         self.string = False
         self.invalid = False

src/binwalk/magic/firmware

@@ -320,7 +320,7 @@
 >(7.b+40)       string  x                       boot partition: "%s"
 
 # TP-Link firmware header structure; thanks to Jonathan McGowan for reversing and documenting this format
-0          string          TP-LINK\x20Technologies TP-Link firmware header,{offset-adjust:-4}
+4          string          TP-LINK\x20Technologies TP-Link firmware header,
 #>-4    lelong          x                       header version: %d,
 >0x94      beshort         x                       firmware version: %d.
 >0x96      beshort         x                       \b%d.
@@ -404,15 +404,14 @@
 >4      byte        0           {invalid},
 >4      string      x           version: "%s"
 
-0   string      \x00\x00\x00\x00PART    Ubiquiti partition header,{offset-adjust:4}
+4   string      \x00\x00\x00\x00PART    Ubiquiti partition header,
 >0  byte        x                       header size: 56 bytes,
 >8  byte        0                       {invalid}
 >8  string      x                       name: "%s",
 >44 belong      x                       base address: 0x%.8X,
->52 belong      x                       data size: %d bytes
->52 belong      x                       {file-size:%d}
+>52 belong      x                       data size: %d bytes{size:%d}
 
-0   string      \x00\x00\x00\x00END\x2e Ubiquiti end header, header size: 12 bytes,{offset-adjust:4}
+4   string      \x00\x00\x00\x00END\x2e Ubiquiti end header, header size: 12 bytes,
 >12 belong      !0                      {invalid},
 >8  belong      x                       cumulative ~CRC32: 0x%.8X
 
@@ -483,7 +482,7 @@
 >19     string  AES-256\n               \b, encrypted AES-256
 
 # http://forum.xda-developers.com/showthread.php?p=47818657
-0    string    imgARMcC         Roku aimage SB{offset-adjust:-8}
+8    string    imgARMcC         Roku aimage SB
 
 # Boot ROM images for Sun/Cobalt Linux server appliances
 0       string    Cobalt\ Networks\ Inc.\nFirmware\ v    Paged Sun/COBALT boot rom,

src/binwalk/modules/signature.py

@@ -152,10 +152,11 @@ class Signature(Module):
                     continue
 
                 # Keep a record of the relative offset of this signature inside the current data block
-                relative_offset = r.offset
+                # (used later for setting current_block_offset).
+                relative_offset = r.offset + r.adjust
 
                 # Set the absolute offset inside the target file
-                r.offset = block_start + r.offset
+                r.offset = block_start + relative_offset
 
                 # Provide an instance of the current file object
                 r.file = fp