Fix crash from possible null return from getcwd.

lib/Interpreter/CIFactory.cpp

@@ -852,10 +852,11 @@ namespace {
     // directories (see ROOT-7114). By asking for $PWD (and not ".") it will
     // be registered as $PWD instead, which is stable even after chdirs.
     char cwdbuf[2048];
-    const clang::DirectoryEntry* DE
-      = FM.getDirectory(getcwd_func(cwdbuf, sizeof(cwdbuf)));
-    (void)DE;
-    assert(!strcmp(DE->getName(), cwdbuf) && "Unexpected name for $PWD");
+    if (!getcwd_func(cwdbuf, sizeof(cwdbuf))) {
+      // getcwd can fail, but that shouldn't mean we have to.
+      ::perror("Could not get current working directory");
+    } else
+      FM.getDirectory(cwdbuf);
 
     // Build the virtual file, Give it a name that's likely not to ever
     // be #included (so we won't get a clash in clangs cache).

test/Driver/CurrentDir.C

@@ -9,22 +9,32 @@
 // Test runing a file in the same directory `cling CurrentDir.C`
 // More info in CIFactory.cpp createCIImpl (line ~850)
 
-// RUN: cd %S && %cling -Xclang -verify CurrentDir.C | FileCheck %s
-// Test CurrentDir
+// RUN: cd %S && %cling -Xclang -verify CurrentDir.C 2>&1 | FileCheck %s
+// RUN: mkdir %T/Remove && cd %T/Remove && rm -rf %T/Remove && %cling -DTEST_CWDRETURN %s -Xclang -verify 2>&1 | FileCheck --check-prefix CHECK --check-prefix CHECKcwd %s
+// Test testCurrentDir
 
 extern "C" {
   int printf(const char*, ...);
   char* getcwd(char *buf, std::size_t size);
 }
 
+#ifdef TEST_CWDRETURN
+  // Make sure include still works
+  #include <string.h>
+  #include <vector>
+#endif
+
 void CurrentDir() {
-  char thisDir[1024];
-  getcwd(thisDir, sizeof(thisDir));
-  /*
-    This would be nice, but doesn't work
-    printf("We are here: %s\n", thisDir);
-    -CHECK: We are here: %S
-  */
+ #ifdef TEST_CWDRETURN
+    char thisDir[1024];
+    const char *rslt = getcwd(thisDir, sizeof(thisDir));
+    // Make sure cling reported the error
+    // CHECKcwd: Could not get current working directory: {{.*}}
+
+    if (rslt)
+      printf("Working directory exists\n");
+    // CHECK-NOT: Working directory exists
+ #endif
 
   printf("Script ran\n");
   // CHECK: Script ran