fastboot driver: repack vendor boot ramdisk

When a user issues `fastboot flash vendor_boot:foo ramdisk.img`, the fastboot driver
fetches the vendor_boot image from the device,
determines if `foo` is a valid vendor ramdisk fragment,
repacks a new vendor boot image, then
flash the vendor boot image back.
This requires vendor boot header V4.

As a convinent alias, `fastboot flash vendor_boot:default ramdisk.img`
flashes the whole vendor ramdisk image. This works on vendor boot header
V3 & 4.

Fixes: 173654501
Test: pass

Change-Id: I42b2483a736ea8aa9fd9372b960502a642934cdc
diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 720810d..3c4269b 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -55,6 +55,7 @@
         "tcp.cpp",
         "udp.cpp",
         "util.cpp",
+        "vendor_boot_img_utils.cpp",
         "fastboot_driver.cpp",
     ],
 
@@ -75,6 +76,7 @@
     ],
 
     header_libs: [
+        "avb_headers",
         "bootimg_headers",
         "libstorage_literals_headers",
     ],
@@ -270,6 +272,7 @@
         "tcp.cpp",
         "udp.cpp",
         "util.cpp",
+        "vendor_boot_img_utils.cpp",
         "fastboot_driver.cpp",
     ],
 
@@ -277,6 +280,7 @@
     use_version_lib: false,
     static_libs: ["libbuildversion"],
     header_libs: [
+        "avb_headers",
         "libstorage_literals_headers",
     ],
 
@@ -370,3 +374,33 @@
         },
     },
 }
+
+cc_test_host {
+    name: "fastboot_vendor_boot_img_utils_test",
+    srcs: ["vendor_boot_img_utils_test.cpp"],
+    static_libs: [
+        "libbase",
+        "libc++fs",
+        "libfastboot",
+        "libgmock",
+        "liblog",
+    ],
+    header_libs: [
+        "avb_headers",
+        "bootimg_headers",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    data: [
+        ":fastboot_test_dtb",
+        ":fastboot_test_bootconfig",
+        ":fastboot_test_vendor_ramdisk_none",
+        ":fastboot_test_vendor_ramdisk_platform",
+        ":fastboot_test_vendor_ramdisk_replace",
+        ":fastboot_test_vendor_boot_v3",
+        ":fastboot_test_vendor_boot_v4_without_frag",
+        ":fastboot_test_vendor_boot_v4_with_frag"
+    ],
+}