Stackable IRT

src/untrusted/nacl/nacl_irt.c

Index: src/untrusted/nacl/nacl_irt.c
diff --git a/src/untrusted/nacl/nacl_irt.c b/src/untrusted/nacl/nacl_irt.c
index 888f38d6b32ea3ce804ec46c7e43b961245e0ea9..3202f1009252dac7e21a1a4909bdbadf38fe6209 100644
--- a/src/untrusted/nacl/nacl_irt.c
+++ b/src/untrusted/nacl/nacl_irt.c
@@ -7,6 +7,9 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "native_client/src/include/elf_auxv.h"
+#include "native_client/src/include/elf32.h"
+#include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/untrusted/irt/irt_interfaces.h"
 #include "native_client/src/untrusted/nacl/nacl_irt.h"
 
@@ -43,6 +46,7 @@ static int stub_getdents(int fd, struct dirent *dirent, size_t count,
   return ENOSYS;
 }
 
+struct nacl_irt_instance __libnacl_irt_instance;
 struct nacl_irt_basic __libnacl_irt_basic;
 struct nacl_irt_memory __libnacl_irt_memory;
 struct nacl_irt_tls __libnacl_irt_tls;
@@ -65,6 +69,43 @@ struct nacl_irt_fdio __libnacl_irt_fdio = {
 
 TYPE_nacl_irt_query __nacl_irt_query;
 
+struct nacl_interface_table {
+  const char *name;
+  void *table;
+  size_t size;
+};
+
+static const struct nacl_interface_table irt_interfaces[] = {
+  { NACL_IRT_INSTANCE_v0_1, &__libnacl_irt_instance, sizeof(__libnacl_irt_instance) },
+  { NACL_IRT_BASIC_v0_1, &__libnacl_irt_basic, sizeof(__libnacl_irt_basic) },
+  { NACL_IRT_DEV_FDIO_v0_1, &__libnacl_irt_fdio, sizeof(__libnacl_irt_fdio) },
+  { NACL_IRT_FILENAME_v0_1, &__libnacl_irt_dev_filename, sizeof(struct nacl_irt_filename) },
+  { NACL_IRT_DEV_FILENAME_v0_2, &__libnacl_irt_dev_filename, sizeof(__libnacl_irt_dev_filename) },
+  { NACL_IRT_MEMORY_v0_1, &__libnacl_irt_memory, sizeof(struct nacl_irt_memory_v0_1) },
+  { NACL_IRT_MEMORY_v0_2, &__libnacl_irt_memory, sizeof(struct nacl_irt_memory_v0_2) },
+  { NACL_IRT_MEMORY_v0_3, &__libnacl_irt_memory, sizeof(struct nacl_irt_memory) },
+  { NACL_IRT_TLS_v0_1, &__libnacl_irt_tls, sizeof(__libnacl_irt_tls) },
+  { NACL_IRT_CLOCK_v0_1, &__libnacl_irt_clock, sizeof(__libnacl_irt_clock) },
+  { NACL_IRT_DEV_GETPID_v0_1, &__libnacl_irt_dev_getpid,
+    sizeof(__libnacl_irt_dev_getpid) },
+};
+
+int nacl_irt_interface_set(const char *interface_ident,
+                           void *table, size_t tablesize, void *old_table) {
+  int i;
+  for (i = 0; i < NACL_ARRAY_SIZE(irt_interfaces); ++i) {
+    if (0 == strcmp(interface_ident, irt_interfaces[i].name)) {
+      const size_t size = irt_interfaces[i].size;
+      if (size <= tablesize) {
+        memcpy(old_table, irt_interfaces[i].table, size);
+        memcpy(irt_interfaces[i].table, table, size);
+        return size;
+      }
+      break;
+    }
+  }
+  return 0;
+}
 
 /*
  * Avoid a dependency on libc's strlen function.
@@ -106,7 +147,6 @@ static void __libnacl_fatal(const char* message) {
 
 }
 
-
 int __libnacl_irt_query(const char *interface,
                         void *table, size_t table_size) {
   if (NULL == __nacl_irt_query) {
@@ -125,9 +165,6 @@ void __libnacl_mandatory_irt_query(const char *interface,
   }
 }
 
-/*
- * Used to lazily initialize an IRT interface function.
- */
 int __libnacl_irt_init_fn(void *interface_field, void (*init)(void)) {
   if (*((void **) interface_field) == NULL) {
     init();