releasetools: Add --oem_no_mount option.

We may have devices with OEM-specific properties but without an OEM
partition (e.g. the properties might be set by init based on hardware
SKUs). For such devices, we supply --oem_no_mount to skip mounting the
OEM partition in the updater-script. The option is only meaningful when
-o (--oem_settings) is specified.

Bug: 27359929
Change-Id: Ic08396e478a82be4188e980e704b33b4f704a8d7
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
index f57360a..57f8cda 100644
--- a/tools/releasetools/edify_generator.py
+++ b/tools/releasetools/edify_generator.py
@@ -83,11 +83,17 @@
       raise ValueError("must specify an OEM property")
     if not value:
       raise ValueError("must specify the OEM value")
-    cmd = ('file_getprop("/oem/oem.prop", "{name}") == "{value}" || '
-           'abort("This package expects the value \\"{value}\\" for '
-           '\\"{name}\\" on the OEM partition; this has value \\"" + '
-           'file_getprop("/oem/oem.prop", "{name}") + "\\".");').format(
-               name=name, value=value)
+    if common.OPTIONS.oem_no_mount:
+      cmd = ('getprop("{name}") == "{value}" || '
+             'abort("This package expects the value \\"{value}\\" for '
+             '\\"{name}\\"; this has value \\"" + '
+             'getprop("{name}") + "\\".");').format(name=name, value=value)
+    else:
+      cmd = ('file_getprop("/oem/oem.prop", "{name}") == "{value}" || '
+             'abort("This package expects the value \\"{value}\\" for '
+             '\\"{name}\\" on the OEM partition; this has value \\"" + '
+             'file_getprop("/oem/oem.prop", "{name}") + "\\".");').format(
+                 name=name, value=value)
     self.script.append(cmd)
 
   def AssertSomeFingerprint(self, *fp):
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 73f7e33..f51920a 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -54,6 +54,12 @@
       Use the file to specify the expected OEM-specific properties
       on the OEM partition of the intended device.
 
+  --oem_no_mount
+      For devices with OEM-specific properties but without an OEM partition,
+      do not mount the OEM partition in the updater-script. This should be
+      very rarely used, since it's expected to have a dedicated OEM partition
+      for OEM-specific properties. Only meaningful when -o is specified.
+
   -w  (--wipe_user_data)
       Generate an OTA package that will wipe the user data partition
       when installed.
@@ -144,6 +150,7 @@
 OPTIONS.block_based = False
 OPTIONS.updater_binary = None
 OPTIONS.oem_source = None
+OPTIONS.oem_no_mount = False
 OPTIONS.fallback_to_full = True
 OPTIONS.full_radio = False
 OPTIONS.full_bootloader = False
@@ -526,7 +533,8 @@
   if oem_props is not None and len(oem_props) > 0:
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
-    script.Mount("/oem", recovery_mount_options)
+    if not OPTIONS.oem_no_mount:
+      script.Mount("/oem", recovery_mount_options)
     oem_dict = common.LoadDictionaryFromLines(
         open(OPTIONS.oem_source).readlines())
 
@@ -777,7 +785,8 @@
   if oem_props is not None and len(oem_props) > 0:
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
-    script.Mount("/oem", recovery_mount_options)
+    if not OPTIONS.oem_no_mount:
+      script.Mount("/oem", recovery_mount_options)
     oem_dict = common.LoadDictionaryFromLines(
         open(OPTIONS.oem_source).readlines())
 
@@ -1062,7 +1071,8 @@
   if oem_props is not None and len(oem_props) > 0:
     if OPTIONS.oem_source is None:
       raise common.ExternalError("OEM source required for this build")
-    script.Mount("/oem", recovery_mount_options)
+    if not OPTIONS.oem_no_mount:
+      script.Mount("/oem", recovery_mount_options)
     oem_dict = common.LoadDictionaryFromLines(
         open(OPTIONS.oem_source).readlines())
 
@@ -1821,6 +1831,8 @@
       OPTIONS.wipe_user_data = True
     elif o in ("-o", "--oem_settings"):
       OPTIONS.oem_source = a
+    elif o == "--oem_no_mount":
+      OPTIONS.oem_no_mount = True
     elif o in ("-e", "--extra_script"):
       OPTIONS.extra_script = a
     elif o in ("-a", "--aslr_mode"):
@@ -1879,6 +1891,7 @@
                                  "block",
                                  "binary=",
                                  "oem_settings=",
+                                 "oem_no_mount",
                                  "verify",
                                  "no_fallback_to_full",
                                  "stash_threshold=",