Convert depfixer.Elf class into a context manager.

This allows for automatic closing of its internal file handle.

mesonbuild/scripts/depfixer.py

@@ -115,11 +115,21 @@ class Elf(DataSizes):
         self.bfile = bfile
         self.verbose = verbose
         self.bf = open(bfile, 'r+b')
+        try:
             (self.ptrsize, self.is_le) = self.detect_elf_type()
             super().__init__(self.ptrsize, self.is_le)
             self.parse_header()
             self.parse_sections()
             self.parse_dynamic()
+        except:
+            self.bf.close()
+            raise
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.bf.close()
 
     def detect_elf_type(self):
         data = self.bf.read(6)
@@ -308,7 +318,7 @@ def run(args):
         print('Don\'t run this unless you know what you are doing.')
         print('%s: <binary file> <prefix>' % sys.argv[0])
         exit(1)
-    e = Elf(args[0])
+    with Elf(args[0]) as e:
         if len(args) == 1:
             e.print_rpath()
             e.print_runpath()