PNaCl dynamic linking: Build an initial dynamically-linked newlib-based libc

src/untrusted/pll_loader/pll_loader_main.cc

+// Copyright (c) 2016 The Native Client Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include "native_client/src/include/elf32.h"
+#include "native_client/src/include/elf_auxv.h"
+#include "native_client/src/untrusted/nacl/nacl_irt.h"
+#include "native_client/src/untrusted/pll_loader/pll_loader.h"
+
+
+typedef void (*start_func_t)(int argc, char **argv, char **envp,
+                             Elf32_auxv_t *auxv);
+
+int main(int argc, char **argv, char **envp) {
+  // The PLL format does not include module dependencies yet, so all the
+  // modules must be specified on the command line.
+  if (argc <= 2) {
+    fprintf(stderr, "Usage: pll_loader <ELF file>...\n");
+    return 1;
+  }
+
+  ModuleSet modset;
+  for (int i = 1; i < argc; i++) {
+    modset.AddByFilename(argv[i]);
+  }
+  modset.ResolveRefs();
+
+  Elf32_auxv_t auxv[2];
+  auxv[0].a_type = AT_SYSINFO;
+  auxv[0].a_un.a_val = (uintptr_t) __nacl_irt_query;
+  auxv[1].a_type = AT_NULL;
+  auxv[1].a_un.a_val = 0;
+
+  start_func_t start_func =
+    (start_func_t) (uintptr_t) modset.GetSym("__libc_start");
+  if (start_func == NULL) {
+    fprintf(stderr, "Entry point symbol \"__libc_start\" not defined\n");
+    return 1;
+  }
+  start_func(argc, argv, envp, auxv);
+
+  return 0;
+}