Fix the return value of pal

src/pal/pal.c

@@ -306,7 +306,7 @@ int SGX_CDECL main(int argc, const char *argv[])
     if (argc < 2) {
         printf("ERROR: at least one argument must be provided\n\n");
         printf("Usage: pal <executable> <arg1> <arg2>...\n");
-        return -1;
+        return EXIT_FAILURE;
     }
     const char* executable_path = argv[1];
 
@@ -314,7 +314,7 @@ int SGX_CDECL main(int argc, const char *argv[])
     if (initialize_enclave() < 0){
         printf("Enter a character before exit ...\n");
         getchar();
-        return -1;
+        return EXIT_FAILURE;
     }
 
     // First ecall do a lot initializations.
@@ -326,7 +326,10 @@ int SGX_CDECL main(int argc, const char *argv[])
     sgx_ret = libos_boot(global_eid, &status, executable_path, &argv[2]);
     if (sgx_ret != SGX_SUCCESS) {
         print_error_message(sgx_ret);
-        return status;
+        return EXIT_FAILURE;
+    }
+    if (status != 0) {
+        return EXIT_FAILURE;
     }
 
     // TODO: exit all tasks gracefully, instead of killing all remaining