1 files changed, 17 insertions, 1 deletions
diff --git a/stdlib/setenv.c b/stdlib/setenv.c
index b60c4f0151..184a8cdd07 100644
--- a/stdlib/setenv.c
+++ b/stdlib/setenv.c
@@ -19,6 +19,13 @@
 # include <config.h>
 #endif
 
+/* Pacify GCC; see the commentary about VALLEN below.  This is needed
+   at least through GCC 4.9.2.  Pacify GCC for the entire file, as
+   there seems to be no way to pacify GCC selectively, only for the
+   place where it's needed.  Do not use DIAG_IGNORE_NEEDS_COMMENT
+   here, as it's not defined yet.  */
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+
 #include <errno.h>
 #if !_LIBC
 # if !defined errno && !defined HAVE_ERRNO_DECL
@@ -114,8 +121,17 @@ __add_to_environ (name, value, combined, replace)
 {
   char **ep;
   size_t size;
+
+  /* Compute lengths before locking, so that the critical section is
+     less of a performance bottleneck.  VALLEN is needed only if
+     COMBINED is null (unfortunately GCC is not smart enough to deduce
+     this; see the #pragma at the start of this file).  Testing
+     COMBINED instead of VALUE causes setenv (..., NULL, ...)  to dump
+     core now instead of corrupting memory later.  */
   const size_t namelen = strlen (name);
-  const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
+  size_t vallen;
+  if (combined == NULL)
+    vallen = strlen (value) + 1;
 
   LOCK;