Add dlwrap.c to binutils to simulate dlopen/dlsym for gold plugin

binutils-2.20/dlwrap.c

+#include <stdio.h>
+#include <string.h>
+

[sehr (please use chromium), 2012/02/15 19:47:57]

Please add explicitly a comment that this is a hack to get a windows pnacl
toolchain working.

+/* This must match RTLD_NOW in dlwrap.h */
+#define PNACL_RTLD_NOW   0x2
+
+static int dummy;
+static int haserr = 0;
+static char errmsg[200];
+
+/* This is not the real signature of this function,
+ * but we just need the symbol address.
+ */
+#ifdef HAS_LLVM_PLUGIN
+void llvm_plugin_onload();
+#endif
+
+void *pnacl_dlopen(const char *filename, int flag) {
+  void *ret;
+  if (flag != 0 && flag != PNACL_RTLD_NOW) {
+    sprintf(errmsg, "Error: Unknown flag to pnacl_dlopen: %d\n", flag);
+    haserr = 1;
+    return NULL;
+  }
+  if (strstr(filename, "LLVMgold") == NULL) {
+    sprintf(errmsg, "Error: Unexpected pnacl_dlopen: %s\n", filename);
+    haserr = 1;
+    return NULL;
+  }
+  return (void*)&dummy;
+}
+
+char *pnacl_dlerror(void) {
+  if (haserr) {
+    haserr = 0;
+    return errmsg;
+  }
+  return NULL;
+}
+
+void *pnacl_dlsym(void *handle, const char *symbol) {
+  if (handle != (void*)&dummy) {
+    sprintf(errmsg, "Error: Unexpected pnacl_dlsym handle\n");
+    haserr = 1;
+    return NULL;
+  }
+
+  if (strcmp(symbol, "onload") != 0) {
+    sprintf(errmsg, "Error: Unexpected pnacl_dlsym symbol: %s\n", symbol);
+    haserr = 1;
+    return NULL;
+  }
+#ifdef HAS_LLVM_PLUGIN
+  return (void*)&llvm_plugin_onload;
+#else
+  sprintf(errmsg, "Error: LLVM plugin not available\n");
+  haserr = 1;
+  return NULL;
+#endif
+}
+
+int pnacl_dlclose(void *handle) {
+  return 0;
+}