commit 2c21f7101b5beb38d443ba2e2fbba594d70989e8
author David Brown <david.brown@linaro.org> Thu Jun 08 10:03:42 2017 -0600
committer David Brown <david.brown@linaro.org> Tue Jun 13 15:54:45 2017 -0400
tree bbaeeadab521026f370d892f3b9765cee8dc9bb4
parent b119424aa878e0e3329a9b24fc8c3e64a1373b9f

imgtool: Make "included header" optional

The imgtool.py program has been assuming that the input image for
signing has a zero padded place for the header at the beginning of the
image.  This is only true for some platforms.

Instead, make this included header space optional.  By default, prepend
the header to the image.  If `--included-header` is specified to the
sign command, consider the bytes at the beginning of the image to be
padded space for the header.  This option is required for Zephyr builds.

doc/imgtool.md

diff --git a/doc/imgtool.md b/doc/imgtool.md
index f881d57..309364e 100644
--- a/doc/imgtool.md
+++ b/doc/imgtool.md
@@ -66,6 +66,7 @@
       --align ALIGN
       -v VERSION, --version VERSION
       -H HEADER_SIZE, --header-size HEADER_SIZE
+      --included-header     Image has gap for header
       --pad PAD             Pad image to this many bytes, adding trailer magic
       --rsa-pkcs1-15        Use old PKCS#1 v1.5 signature algorithm
 
@@ -75,8 +76,10 @@
 
 The header size depends on the operating system and the particular
 flash device.  For Zephyr, it will be configured as part of the build,
-and will be a small power of two.  The generated image should start
-with zero bytes of this length (and the script will check this).
+and will be a small power of two.  By default, the header will be
+prepended to the image.  If `--included-header` is given, the image
+must start with header-size bytes of zeros, and the header will be
+overwritten over these bytes.
 
 The optional --pad argument will place a trailer on the image that
 indicates that the image should be considered an upgrade.  Writing

scripts/imgtool.py

diff --git a/scripts/imgtool.py b/scripts/imgtool.py
index fb09f96..70fdc97 100755
--- a/scripts/imgtool.py
+++ b/scripts/imgtool.py
@@ -34,6 +34,7 @@
         keys.sign_rsa_pss = False
     img = image.Image.load(args.infile, version=args.version,
             header_size=args.header_size,
+            included_header=args.included_header,
             pad=args.pad)
     key = keys.load(args.key)
     img.sign(key)
@@ -79,6 +80,8 @@
     sign.add_argument("--align", type=alignment_value, required=True)
     sign.add_argument("-v", "--version", type=version.decode_version, required=True)
     sign.add_argument("-H", "--header-size", type=intparse, required=True)
+    sign.add_argument("--included-header", default=False, action='store_true',
+            help='Image has gap for header')
     sign.add_argument("--pad", type=intparse,
             help='Pad image to this many bytes, adding trailer magic')
     sign.add_argument("--rsa-pkcs1-15", help='Use old PKCS#1 v1.5 signature algorithm',

scripts/imgtool/image.py

diff --git a/scripts/imgtool/image.py b/scripts/imgtool/image.py
index c4bedfe..b6a572d 100644
--- a/scripts/imgtool/image.py
+++ b/scripts/imgtool/image.py
@@ -55,12 +55,17 @@
 
 class Image():
     @classmethod
-    def load(cls, path, **kwargs):
+    def load(cls, path, included_header=False, **kwargs):
         """Load an image from a given file"""
         with open(path, 'rb') as f:
             payload = f.read()
         obj = cls(**kwargs)
         obj.payload = payload
+
+        # Add the image header if needed.
+        if not included_header and obj.header_size > 0:
+            obj.payload = (b'\000' * obj.header_size) + obj.payload
+
         obj.check()
         return obj