1 files changed, 81 insertions, 0 deletions
diff --git a/plug/src/harness_adapter.c b/plug/src/harness_adapter.c
new file mode 100644
index 0000000..24b813c
--- /dev/null
+++ b/plug/src/harness_adapter.c
@@ -0,0 +1,81 @@
+// This file provides functions for the wetterhorn harness that are not
+// expressible directly in haskell.
+//
+// Currently these functions exclusively enable/disable the Haskell runtime.
+
+#include "HsFFI.h"
+#include "plugin_interface.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+const char *plugin_name = "Wetterhorn";
+
+void* foreign_interface;
+
+void* get_foreign_interface()
+{
+  return foreign_interface;
+}
+
+extern void performMajorGC();
+
+void plugin_metaload(int argc, char** argv)
+{
+  // hs_init(&argc, &argv);
+}
+
+void plugin_load(int argc, char **argv, foreign_interface_t* fintf) {
+  hs_init(&argc, &argv);
+  foreign_interface = fintf;
+}
+
+void plugin_teardown(opqst_t st) {
+  hs_exit();
+}
+
+void shell_exec(const char* cmd) {
+  if (fork() == 0) {
+    execl("/bin/sh", "/bin/sh", "-c", cmd, NULL);
+    exit(1);
+  }
+}
+
+static const char msg[] =
+    "Wetterhorn Plugin v 0.01\n\n"
+    "Welcome, and thank you for your interest.\n\n"
+    "This is merely a plugin to the Wetterhorn Compositor and not meant to be\n"
+    "executed as a standalone binary. This plugin requires a harness to run\n"
+    "To use this file, please use './wtr_harness [full-path-to-wtr.so]'\n"
+    "That will allow you to see how this compositor works in all its glory!\n";
+static const int msg_sz = sizeof(msg);
+
+/*
+ * Implemens a basic _start that prints inforamtion and exits for users on an
+ * x86_64 system.
+ */
+__attribute__((naked)) void _start()
+{
+
+  // Make system call to print the message
+  asm(
+      // Load the address of the string into rsi
+      "mov %0, %%rsi\n"
+      // Load the string length into edx
+      "mov %1, %%edx\n"
+      // Load the file descriptor for stdout into edi
+      "mov $1, %%edi\n"
+      // Load the syscall number for sys_write into eax
+      "mov $1, %%eax\n"
+      // Make the syscall
+      "syscall\n"
+
+      // Exit the program.
+      "mov $0, %%rdi\n"
+      "mov $60, %%rax\n"
+      "syscall\n"
+      :
+      : "r"(msg), "r"(msg_sz)  // Input: address of msg
+      : "%rsi", "%edx", "%edi" // Clobbered registers
+  );
+}