vlib: add cgo-friendly plugin registration support

[vpp.git] / src / vlib / unix / plugin.c

diff --git a/src/vlib/unix/plugin.c b/src/vlib/unix/plugin.c
index 0837ecd..a714c7c 100644 (file)
--- a/src/vlib/unix/plugin.c
+++ b/src/vlib/unix/plugin.c
@@ -81,22 +81,120 @@ extract (u8 * sp, u8 * ep)
   return rv;
 }
 
+/*
+ * If a plugin .so contains a ".vlib_plugin_r2" section,
+ * this function converts the vlib_plugin_r2_t to
+ * a vlib_plugin_registration_t.
+ */
+
+static clib_error_t *
+r2_to_reg (elf_main_t * em, vlib_plugin_r2_t * r2,
+          vlib_plugin_registration_t * reg)
+{
+  clib_error_t *error;
+  elf_section_t *section;
+  uword data_segment_offset;
+  u8 *data;
+
+  /* It turns out that the strings land in the ".data" section */
+  error = elf_get_section_by_name (em, ".data", &section);
+  if (error)
+    return error;
+  data = elf_get_section_contents (em, section->index, 1);
+
+  /*
+   * Offsets in the ".vlib_plugin_r2" section
+   * need to have the data section base subtracted from them.
+   * The offset is in the first 8 bytes of the ".data" section
+   */
+
+  data_segment_offset = *((uword *) data);
+
+  /* Relocate pointers, subtract data_segment_offset */
+#define _(a) r2->a.data_segment_offset -= data_segment_offset;
+  foreach_r2_string_field;
+#undef _
+
+  if (r2->version.length >= ARRAY_LEN (reg->version) - 1)
+    return clib_error_return (0, "Version string too long");
+
+  if (r2->version_required.length >= ARRAY_LEN (reg->version_required) - 1)
+    return clib_error_return (0, "Version-required string too long");
+
+  if (r2->overrides.length >= ARRAY_LEN (reg->overrides) - 1)
+    return clib_error_return (0, "Override string too long");
+
+  /* Compatibility with C-initializer */
+  memcpy ((void *) reg->version, data + r2->version.data_segment_offset,
+         r2->version.length);
+  memcpy ((void *) reg->version_required,
+         data + r2->version_required.data_segment_offset,
+         r2->version_required.length);
+  memcpy ((void *) reg->overrides, data + r2->overrides.data_segment_offset,
+         r2->overrides.length);
+
+  if (r2->early_init.length > 0)
+    {
+      u8 *ei = 0;
+      vec_validate (ei, r2->early_init.length + 1);
+      memcpy (ei, data + r2->early_init.data_segment_offset,
+             r2->early_init.length);
+      reg->early_init = (void *) ei;
+    }
+
+  if (r2->description.length > 0)
+    {
+      u8 *desc = 0;
+      vec_validate (desc, r2->description.length + 1);
+      memcpy (desc, data + r2->description.data_segment_offset,
+             r2->description.length);
+      reg->description = (void *) desc;
+    }
+  vec_free (data);
+  return 0;
+}
+
+
 static int
 load_one_plugin (plugin_main_t * pm, plugin_info_t * pi, int from_early_init)
 {
   void *handle;
+  int reread_reg = 1;
   clib_error_t *error;
   elf_main_t em = { 0 };
   elf_section_t *section;
   u8 *data;
   char *version_required;
   vlib_plugin_registration_t *reg;
+  vlib_plugin_r2_t *r2;
   plugin_config_t *pc = 0;
   uword *p;
 
   if (elf_read_file (&em, (char *) pi->filename))
     return -1;
 
+  /* New / improved (well, not really) registration structure? */
+  error = elf_get_section_by_name (&em, ".vlib_plugin_r2", &section);
+  if (error == 0)
+    {
+      data = elf_get_section_contents (&em, section->index, 1);
+      r2 = (vlib_plugin_r2_t *) data;
+      reg = clib_mem_alloc (sizeof (*reg));
+      memset (reg, 0, sizeof (*reg));
+
+      reg->default_disabled = r2->default_disabled != 0;
+      error = r2_to_reg (&em, r2, reg);
+      if (error)
+       {
+         PLUGIN_LOG_ERR ("Bad r2 registration: %s\n", (char *) pi->name);
+         return -1;
+       }
+      if (pm->plugins_default_disable)
+       reg->default_disabled = 1;
+      reread_reg = 0;
+      goto process_reg;
+    }
+
   error = elf_get_section_by_name (&em, ".vlib_plugin_registration",
                                   &section);
   if (error)
@@ -118,6 +216,7 @@ load_one_plugin (plugin_main_t * pm, plugin_info_t * pi, int from_early_init)
   if (pm->plugins_default_disable)
     reg->default_disabled = 1;
 
+process_reg:
   p = hash_get_mem (pm->config_index_by_name, pi->name);
   if (p)
     {
@@ -216,15 +315,8 @@ load_one_plugin (plugin_main_t * pm, plugin_info_t * pi, int from_early_init)
 
   pi->handle = handle;
 
-  reg = dlsym (pi->handle, "vlib_plugin_registration");
-
-  if (reg == 0)
-    {
-      /* This should never happen unless somebody changes registration macro */
-      PLUGIN_LOG_ERR ("Missing plugin registration in plugin '%s'", pi->name);
-      dlclose (pi->handle);
-      goto error;
-    }
+  if (reread_reg)
+    reg = dlsym (pi->handle, "vlib_plugin_registration");
 
   pi->reg = reg;
   pi->version = str_array_to_vec ((char *) &reg->version,