build/file_utils: Newline for mapping files
Previous behaviour:
Test: Set `PRODUCT_PUBLIC_SEPOLICY_DIRS`, causing
`product_sepolicy.cil` and `product_mapping_file` to
be generated. Do not use any `type` declarations that
would require a mapping in product sepolicy, e.g. only
define macros.
Run `make selinux_policy`, observe error:
```
FAILED: out/target/product/mydevice/obj/ETC/plat_pub_versioned.cil_intermediates/plat_pub_versioned.cil
/bin/bash -c "(out/host/linux-x86/bin/version_policy -b out/target/product/mydevice/obj/FAKE/sepolicy_neverallows_intermediates/pub_policy.cil -t out/target/product/mydevice/obj/FAKE/sepolicy_neverallows_intermediates/pub_policy.cil -n 10000.0 -o out/target/product/mydevice/obj/ETC/plat_pub_versioned.cil_intermediates/plat_pub_versioned.cil ) && (out/host/linux-x86/bin/secilc -m -M true -G -N -c 30 out/target/product/mydevice/obj/ETC/plat_sepolicy.cil_intermediates/plat_sepolicy.cil out/target/product/mydevice/obj/ETC/product_sepolicy.cil_intermediates/product_sepolicy.cil out/target/product/mydevice/obj/ETC/plat_mapping_file_intermediates/10000.0.cil out/target/product/mydevice/obj/ETC/product_mapping_file_intermediates/10000.0.cil out/target/product/mydevice/obj/ETC/plat_pub_versioned.cil_intermediates/plat_pub_versioned.cil -o /dev/null -f /dev/null )"
Failure reading file: out/target/product/mydevice/obj/ETC/product_mapping_file_intermediates/10000.0.cil
```
This is caused by `secilc.c` trying to read the empty file:
```
rc = fread(buffer, file_size, 1, file);
```
Fix: Append a newline to make sure any file processed by
`filter_out` is still readable by secilc.
After:
Test: `make selinux_policy` with same preconditions.
Signed-off-by: Felix <google@ix5.org>
Change-Id: I6dcfcccdfa83121bbdc09632f7a2b609ef932fc9
diff --git a/build/file_utils.py b/build/file_utils.py
index 1559a9b..9f95f52 100644
--- a/build/file_utils.py
+++ b/build/file_utils.py
@@ -43,6 +43,9 @@
with open(input_file, 'r') as in_file:
tmp_output.writelines(line for line in in_file.readlines()
if line not in patterns)
+ # Append empty line because a completely empty file
+ # will trip up secilc later on:
+ tmp_output.write("\n")
tmp_output.flush()
# Replaces the input_file.