If errno is zero strerror_r does not modify the buffer, leaving it unterminated.

This causes garbage to be printed out after error messages.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20165 91177308-0d34-0410-b5e6-96231b3b80d8

lib/System/Unix/Unix.h

@@ -68,14 +68,17 @@
 
 inline void ThrowErrno(const std::string& prefix) {
     char buffer[MAXPATHLEN];
+    buffer[0] = 0;
 #ifdef HAVE_STRERROR_R
     // strerror_r is thread-safe.
-    strerror_r(errno,buffer,MAXPATHLEN-1);
+    if (errno)
+      strerror_r(errno,buffer,MAXPATHLEN-1);
 #elif HAVE_STRERROR
     // Copy the thread un-safe result of strerror into
     // the buffer as fast as possible to minimize impact
     // of collision of strerror in multiple threads.
-    strncpy(buffer,strerror(errno),MAXPATHLEN-1);
+    if (Errno)
+      strncpy(buffer,strerror(errno),MAXPATHLEN-1);
     buffer[MAXPATHLEN-1] = 0;
 #else
     // Strange that this system doesn't even have strerror