mec1322: killing the white whale (removing temp files left behind)

This has been bothering me literally for years: once in a while there
would be tons of files in /tmp directory named tmpXXXXXX where XXXXXXX
is some random string.

Finally, it became clear that the files are generated when 'make
buildall -j' is called in the ec directory. Next step - it looks like
one of the culprits is building for board named 'chell'. Indeed, this
board uses its own version of cmd_obj_to_bin make function, which,
among other things invokes the pack_ec script to pack the image.

The script was creating temporary files and leaving them behind.

This patch makes the name pattern of the temp files better
recognizable, juts in case, and makes sure that the files are deleted
once they are not needed.

BRANCH=none
BUG=none
TEST=invoking 'make buildall -j' still succeeds but does not result in
     leaving temp files behind.

Change-Id: I50c511773caa87d4e92980c4c9a36768b0c3101f
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/310586
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

1 files changed, 17 insertions, 13 deletions

diff --git a/chip/mec1322/util/pack_ec.py b/chip/mec1322/util/pack_ec.py
index 236d364b2c..7fed5a8008 100755
--- a/chip/mec1322/util/pack_ec.py
+++ b/chip/mec1322/util/pack_ec.py
@@ -109,19 +109,23 @@ def BuildHeader(args, payload_len, rorofile):
   return header
 
 def SignByteArray(data, pem_file):
-  hash_file = tempfile.mkstemp()[1]
-  sign_file = tempfile.mkstemp()[1]
-  with open(hash_file, 'wb') as f:
-    hasher = hashlib.sha256()
-    hasher.update(data)
-    f.write(hasher.digest())
-  subprocess.check_call(['openssl', 'rsautl', '-sign', '-inkey', pem_file,
-                         '-keyform', 'PEM', '-in', hash_file,
-                         '-out', sign_file])
-  with open(sign_file, 'rb') as f:
-    signed = list(f.read())
-    signed.reverse()
-    return bytearray(''.join(signed))
+  hash_file = tempfile.mkstemp(prefix='pack_ec.')[1]
+  sign_file = tempfile.mkstemp(prefix='pack_ec.')[1]
+  try:
+      with open(hash_file, 'wb') as f:
+        hasher = hashlib.sha256()
+        hasher.update(data)
+        f.write(hasher.digest())
+      subprocess.check_call(['openssl', 'rsautl', '-sign', '-inkey', pem_file,
+                             '-keyform', 'PEM', '-in', hash_file,
+                             '-out', sign_file])
+      with open(sign_file, 'rb') as f:
+        signed = list(f.read())
+        signed.reverse()
+        return bytearray(''.join(signed))
+  finally:
+    os.remove(hash_file)
+    os.remove(sign_file)
 
 def BuildTag(args):
   tag = bytearray([(args.header_loc >> 8) & 0xff,