posix: getcwd now expects buf not null

Author: alfreb

src/posix/unistd.cpp

@@ -229,7 +229,9 @@ int chdir(const char *path)
 
 char *getcwd(char *buf, size_t size)
 {
-  assert(cwd.front() == '/');
+  Expects(cwd.front() == '/');
+  Expects(buf != nullptr);
+
   if (size == 0)
   {
     errno = EINVAL;

test/posix/integration/stat/stat_tests.cpp

@@ -142,21 +142,33 @@ void stat_tests()
   }
   CHECKSERT(res == 0, "chdir to subfolder of cwd is ok");
 
+  /**
+     If buf is a null pointer, the behavior of getcwd() is unspecified.
+     http://pubs.opengroup.org/onlinepubs/9699919799/functions/getcwd.html
+
+     Changed behavior of getcwd to Expect buf isn't nullptr.
+
+     TODO: It's nice to have these test cases in there, but it will require
+     the test to throw on contract violation
+  **/
+
+  /**
   char* nullcwd = getcwd(nullbuf, 0);
   printf("getcwd result (nullptr, size 0): %s\n", nullcwd == nullptr ? "NULL" : nullcwd);
   if (nullcwd == nullptr)
-  {
-    printf("getcwd error: %s\n", strerror(errno));
-  }
+    {
+      printf("getcwd error: %s\n", strerror(errno));
+    }
   CHECKSERT(nullcwd == nullptr && errno == EINVAL, "getcwd() with 0-size buffer should fail with EINVAL");
 
   nullcwd = getcwd(nullptr, 1024);
   printf("getcwd result (nullptr): %s\n", nullcwd == nullptr ? "NULL" : nullcwd);
   if (nullcwd == nullptr)
-  {
-    printf("getcwd error: %s\n", strerror(errno));
-  }
+    {
+      printf("getcwd error: %s\n", strerror(errno));
+    }
   CHECKSERT(nullcwd == nullptr, "getcwd() with nullptr buffer should fail");
+  **/
 
   char* shortcwd = getcwd(shortbuf, 4);
   printf("getcwd result (small buffer): %s\n", shortcwd == nullptr ? "NULL" : shortcwd);

test/posix/integration/stat/test.py

@@ -25,8 +25,8 @@ def increment(line):
   print "num_outputs after increment: ", num_outputs
 
 def check_num_outputs(line):
-  assert(num_outputs == 20)
-  vmrunner.vms[0].exit(0, "SUCCESS")
+  assert(num_outputs == 18)
+  vmrunner.vms[0].exit(0, "All tests passed", keep_running = True)
 
 vm.on_output("stat\(\) with nullptr buffer fails with EFAULT", increment)
 vm.on_output("stat\(\) of folder that exists is ok", increment)