1 files changed, 46 insertions, 3 deletions

diff --git a/libgcc/libgcov-driver-system.c b/libgcc/libgcov-driver-system.c
index 4e3b244c7c..5cfc950ab0 100644
--- a/libgcc/libgcov-driver-system.c
+++ b/libgcc/libgcov-driver-system.c
@@ -1,6 +1,6 @@
 /* Routines required for instrumenting a program.  */
 /* Compile this one with gcc.  */
-/* Copyright (C) 1989-2016 Free Software Foundation, Inc.
+/* Copyright (C) 1989-2017 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -23,19 +23,62 @@ a copy of the GCC Runtime Library Exception along with this program;
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */
 
-/* A utility function for outputing errors.  */
+#if !IN_GCOV_TOOL
+/* Configured via the GCOV_ERROR_FILE environment variable;
+   it will either be stderr, or a file of the user's choosing.
+   Non-static to prevent multiple gcov-aware shared objects from
+   instantiating their own copies. */
+FILE *__gcov_error_file = NULL;
+#endif
+
+/* A utility function to populate the __gcov_error_file pointer.
+   This should NOT be called outside of the gcov system driver code. */
+
+static FILE *
+get_gcov_error_file (void)
+{
+#if IN_GCOV_TOOL
+  return stderr;
+#else
+  if (!__gcov_error_file)
+    {
+      const char *gcov_error_filename = getenv ("GCOV_ERROR_FILE");
+
+      if (gcov_error_filename)
+	__gcov_error_file = fopen (gcov_error_filename, "a");
+      if (!__gcov_error_file)
+	__gcov_error_file = stderr;
+    }
+  return __gcov_error_file;
+#endif
+}
+
+/* A utility function for outputting errors.  */
 
 static int __attribute__((format(printf, 1, 2)))
 gcov_error (const char *fmt, ...)
 {
   int ret;
   va_list argp;
+
   va_start (argp, fmt);
-  ret = vfprintf (stderr, fmt, argp);
+  ret = vfprintf (get_gcov_error_file (), fmt, argp);
   va_end (argp);
   return ret;
 }
 
+#if !IN_GCOV_TOOL
+static void
+gcov_error_exit (void)
+{
+  if (__gcov_error_file && __gcov_error_file != stderr)
+    {
+      fclose (__gcov_error_file);
+      __gcov_error_file = NULL;
+    }
+}
+#endif
+
 /* Make sure path component of the given FILENAME exists, create
    missing directories. FILENAME must be writable.
    Returns zero on success, or -1 if an error occurred.  */