Add a function to create a the header

Signed-off-by: Joakim Bech <joakim.bech@linaro.org>

2 files changed, 23 insertions, 2 deletions

diff --git a/newtimg.py b/newtimg.py
index 8124f0b..ca55307 100644
--- a/newtimg.py
+++ b/newtimg.py
@@ -1,4 +1,4 @@
-IMAGE_MAGIC =			0x96f3b83
+IMAGE_MAGIC =			0x96f3b83c
 IMAGE_MAGIC_NONE =		0xffffffff
 
 #
@@ -21,6 +21,7 @@ IMAGE_TLV_RSA2048 =		2   # RSA2048 of hash output
 IMAGE_TLV_ECDSA224 =		3   # ECDSA of hash output
 
 
+OFFSET_VECTOR_TABLE = 0x80
 OFFSET_IH_MAGIC = 0
 OFFSET_IH_TLV_SIZE = 4
 OFFSET_IH_KEY_ID = 6
diff --git a/patch_mynewt_img.py b/patch_mynewt_img.py
index 7f407b6..6f0a0bc 100755
--- a/patch_mynewt_img.py
+++ b/patch_mynewt_img.py
@@ -7,6 +7,24 @@ import sys
 from newtimg import *
 from ctypes import *
 
+def create_header(img):
+    hdr = bytearray(struct.pack('I', IMAGE_MAGIC) +
+                    struct.pack('H', SHA256_DIGEST_SIZE + 4) + # TLV size
+                    struct.pack('B', 0) + # Key ID
+                    struct.pack('B', 0) + # PAD 1
+                    struct.pack('H', OFFSET_VECTOR_TABLE) + # New HDR SIZE
+                    struct.pack('H', 0) + # PAD 2
+                    struct.pack('I', 0xbabebabe) + # TODO img size
+                    struct.pack('I', IMAGE_F_SHA256) + # Flags
+                    struct.pack('B', 0) + # Major
+                    struct.pack('B', 0) + # Minor
+                    struct.pack('H', 0) + # Revision
+                    struct.pack('I', 0) + # Build number
+                    struct.pack('I', 0)) # PAD3
+    with open(img + ".hdr", "w+b") as f:
+        f.write(hdr)
+        f.close()
+
 def patch_header(img):
     """
     Patch the image with the new header size and with the new image size.
@@ -49,7 +67,8 @@ def extend_image(img, img_size):
         # Store the header, pad it and then store the image itself
         with open(img + ".img", "w+b") as f:
             f.write(hdr)
-            f.write(('\xFF' * (0x80 - IMAGE_HEADER_SIZE)))
+            # Pad the header up til where the image itself begins
+            f.write(('\xFF' * (OFFSET_VECTOR_TABLE - IMAGE_HEADER_SIZE)))
             f.write(image)
             f.close()
     except IOError:
@@ -84,6 +103,7 @@ def append_hash(img, digest):
 
 def main(img):
     # backup(img) # Backup original image
+    create_header(img)
     size = patch_header(img)
     extend_image(img, size)