c++tools: Fix memory leak

The allocated memory is not freed when returning early due to an error.

c++tools/ChangeLog:

	* resolver.cc (module_resolver::read_tuple_file): Use unique_ptr
	to ensure memory is freed before returning.

c++tools/resolver.cc

@@ -23,6 +23,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "resolver.h"
 // C++
 #include <algorithm>
+#include <memory>
 // C
 #include <cstring>
 // OS
@@ -114,10 +115,17 @@ module_resolver::read_tuple_file (int fd, char const *prefix, bool force)
   buffer = mmap (nullptr, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
   if (buffer == MAP_FAILED)
     return -errno;
+  struct Deleter {
+    void operator()(void* p) const { munmap(p, size); }
+    size_t size;
+  };
+  std::unique_ptr<void, Deleter> guard(buffer, Deleter{(size_t)stat.st_size});
 #else
   buffer = xmalloc (stat.st_size);
   if (!buffer)
     return -errno;
+  struct Deleter { void operator()(void* p) const { free(p); } };
+  std::unique_ptr<void, Deleter> guard(buffer);
   if (read (fd, buffer, stat.st_size) != stat.st_size)
     return -errno;
 #endif
@@ -179,12 +187,6 @@ module_resolver::read_tuple_file (int fd, char const *prefix, bool force)
 	}
     }
 
-#if MAPPED_READING
-  munmap (buffer, stat.st_size);
-#else
-  free (buffer);
-#endif
-
   return 0;
 }