Add samsung specific changes

avb_boot_img.bzl

@@ -0,0 +1,75 @@
+def sign_boot_img(ctx):
+    inputs = []
+    inputs += ctx.files.artifacts
+    inputs += ctx.files.avbtool
+    inputs += ctx.files.key
+
+    outputs = ctx.actions.declare_file("{}/boot.img".format(ctx.label.name))
+
+    for artifact in ctx.files.artifacts:
+        if artifact.basename == "boot.img":
+            boot_img = artifact
+            break
+
+    if not boot_img:
+        fail("artifacts must include file named \"boot.img\"")
+
+    proplist = " ".join(["--prop {}".format(x) for x in ctx.attr.props])
+
+    command = """
+    cp {boot_img} {boot_dir}/{boot_name}
+    {tool} add_hash_footer --image {boot_dir}/{boot_name} --algorithm SHA256_RSA4096 \
+            --key {key} --partition_size 100663296 --partition_name boot \
+            {proplist}
+    """.format(
+        boot_img = boot_img.path,
+        tool = ctx.file.avbtool.path,
+        key = ctx.file.key.path,
+        boot_dir = outputs.dirname,
+        boot_name = outputs.basename,
+        boot_partition_size = ctx.attr.boot_partition_size,
+        proplist = proplist,
+    )
+
+    ctx.actions.run_shell(
+        mnemonic = "SignBootImg",
+        inputs = inputs,
+        outputs = [outputs],
+        command = command,
+        progress_message = "Signing boot image from artifacts",
+    )
+
+    return [
+        DefaultInfo(
+            files = depset([outputs]),
+        ),
+    ]
+
+avb_sign_boot_image = rule(
+    implementation = sign_boot_img,
+    doc = "Sign the boot image present in artifacts",
+    attrs = {
+        "artifacts": attr.label(
+            mandatory = True,
+            allow_files = True,
+        ),
+        "avbtool": attr.label(
+            mandatory = True,
+            allow_single_file = True,
+        ),
+        "key": attr.label(
+            mandatory = True,
+            allow_single_file = True,
+        ),
+        "boot_partition_size": attr.int(
+            mandatory = False,
+            default = 0x6000000,  # bytes, = 98304 kb
+            doc = "Final size of boot.img desired",
+        ),
+        "props": attr.string_list(
+            mandatory = True,
+            allow_empty = False,
+            doc = "List of key:value pairs",
+        ),
+    },
+)