Fix crash in `ReadFile` when the input file is empty.

When the internal ifstream is in a `fail()` state `tellg()` returns -1,
and passing that directly to `std::string::resize` causes it to throw an
exception. We can avoid the exception by checking `fail()` first.

Bug: 227657872
Test: Use with aosp/2048065
Change-Id: Ibb262c753ad90d044a0d8c28d439ea699a481b2b
Merged-In: Ibb262c753ad90d044a0d8c28d439ea699a481b2b

1 files changed, 4 insertions, 0 deletions

diff --git a/common/libs/utils/files.cpp b/common/libs/utils/files.cpp
index 833806ffc..b56c70111 100644
--- a/common/libs/utils/files.cpp
+++ b/common/libs/utils/files.cpp
@@ -104,6 +104,10 @@ std::string ReadFile(const std::string& file) {
   std::string contents;
   std::ifstream in(file, std::ios::in | std::ios::binary);
   in.seekg(0, std::ios::end);
+  if (in.fail()) {
+    // TODO(schuffelen): Return a failing Result instead
+    return "";
+  }
   contents.resize(in.tellg());
   in.seekg(0, std::ios::beg);
   in.read(&contents[0], contents.size());