add test for longjump with 0 as return value

Signed-off-by: Gao Jiawei <gaojiawei@xiaomi.com>

testing/ostest/setjmp.c

@@ -32,25 +32,56 @@
  * Public Functions
  ****************************************************************************/
 
-void setjmp_test(void)
+void jump_with_retval(jmp_buf buf, int ret)
 {
+  volatile bool did_jump = false;
   int value;
-  jmp_buf buf;
-
-  printf("setjmp_test: Initializing jmp_buf\n");
 
   if ((value = setjmp(buf)) == 0)
     {
       printf("setjmp_test: Try jump\n");
-      longjmp(buf, 123);
+
+      if (did_jump)
+        {
+          ASSERT(!"setjmp retutns zero after calling longjmp");
+        }
+
+      did_jump = true;
+      printf("setjmp_test: About to jump, longjmp with ret val: %d\n", ret);
+      longjmp(buf, ret);
 
       /* Unreachable */
 
       ASSERT(0);
     }
   else
     {
-      ASSERT(value == 123);
+      /* If we provide 0 as the return value to longjmp()
+       * we expect it substitute to 1 for us.
+       */
+
+      if (ret == 0)
+        {
+          ret = 1;
+        }
+
+      ASSERT(value == ret);
       printf("setjmp_test: Jump succeed\n");
     }
 }
+
+void setjmp_test(void)
+{
+  jmp_buf buf;
+
+  printf("setjmp_test: Initializing jmp_buf\n");
+
+  jump_with_retval(buf, 123);
+
+  /* Pls ref to:
+   * the longjmp should never make setjmp returns 0
+   * https://pubs.opengroup.org/onlinepubs/009604599/functions/longjmp.html
+   */
+
+  jump_with_retval(buf, 0);
+}