From 31d721301cd410079355e4ab2a46864d57818ce5 Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@fb.com>
Date: Thu, 9 Jan 2020 07:29:00 -0800
Subject: [PATCH] getdeps: dyndeps: gracefully handle empty files

Summary:
Don't error out if we can't read the ELF/MACH-O header; just treat
it is not an object.

Reviewed By: chadaustin, simpkins

Differential Revision: D19253434

fbshipit-source-id: c5ecc7f0bc7a20e2611b7e2ff754355155f095da
---
 build/fbcode_builder/getdeps/dyndeps.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/build/fbcode_builder/getdeps/dyndeps.py b/build/fbcode_builder/getdeps/dyndeps.py
index 47ff13766..abc02e7e9 100644
--- a/build/fbcode_builder/getdeps/dyndeps.py
+++ b/build/fbcode_builder/getdeps/dyndeps.py
@@ -251,7 +251,10 @@ class MachDeps(DepBase):
         with open(objfile, "rb") as f:
             # mach stores the magic number in native endianness,
             # so unpack as native here and compare
-            magic = unpack("I", f.read(4))[0]
+            header = f.read(4)
+            if len(header) != 4:
+                return False
+            magic = unpack("I", header)[0]
             return magic == MACH_MAGIC
 
     def list_dynamic_deps(self, objfile):