#966: catch IOError: [Errno 19] No such device

2 files changed, 6 insertions, 7 deletions

diff --git a/docs/index.rst b/docs/index.rst
index 0d998913..2c4c87ed 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -655,7 +655,8 @@ Sensors
 .. function:: sensors_battery()
 
   Return battery status information as a namedtuple including the following
-  values. If no battery is installed returns ``None``.
+  values. If no battery is installed or metrics can't be determined returns
+  ``None``.
 
   - **percent**: battery power left as a percentage.
   - **secsleft**: a rough approximation of how many seconds are left before the
diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index a06ee73f..2b724fd3 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -282,14 +282,12 @@ def set_scputimes_ntuple(procfs_path):
 def cat(fname, fallback=_DEFAULT, binary=True):
     """Return file content."""
     try:
-        f = open_binary(fname) if binary else open_text(fname)
+        with open_binary(fname) if binary else open_text(fname) as f:
+            return f.read().strip()
     except IOError:
         if fallback != _DEFAULT:
             return fallback
         raise
-    else:
-        with f:
-            return f.read().strip()
 
 
 try:
@@ -1110,8 +1108,8 @@ def sensors_battery():
     null = object()
 
     def multi_cat(*paths):
-        """Read content of multiple files which may not exist.
-        # If none of them exist returns None.
+        """Attempt to read the content of multiple files which may
+        not exist. If none of them exist return None.
         """
         for path in paths:
             ret = cat(path, fallback=null)