tools/llvm-stub/llvm-stub.c

/*===- llvm-stub.c - Stub executable to run llvm bitcode files ------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tool is used by the gccld program to enable transparent execution of
// bitcode files by the user.  Specifically, gccld outputs two files when asked
// to compile a <program> file:
//    1. It outputs the LLVM bitcode file to <program>.bc
//    2. It outputs a stub executable that runs lli on <program>.bc
//
// This allows the end user to just say ./<program> and have the JIT executed
// automatically.  On unix, the stub executable emitted is actually a bourne
// shell script that does the forwarding.  Windows does not like #!/bin/sh
// programs in .exe files, so we make it an actual program, defined here.
//
//===----------------------------------------------------------------------===*/

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

#include "llvm/Config/config.h"

#if defined(HAVE_UNISTD_H) && !defined(_MSC_VER)
#include <unistd.h>
#endif

#ifdef _WIN32
#include <process.h>
#include <io.h>
#endif

int main(int argc, char** argv) {
  const char *Interp = getenv("LLVMINTERP");
  const char **Args;
  if (Interp == 0) Interp = "lli";

  /* Set up the command line options to pass to the JIT. */
  Args = (const char**)malloc(sizeof(char*) * (argc+2));
  /* argv[0] is the JIT */
  Args[0] = Interp;

#ifdef LLVM_ON_WIN32
  {
    int len = strlen(argv[0]);
    if (len < 4 || strcmp(argv[0] + len - 4, ".exe") != 0) {
      /* .exe suffix is stripped off of argv[0] if the executable was run on the
       * command line without one. Put it back on.
       */
      argv[0] = strcat(strcpy((char*)malloc(len + 5), argv[0]), ".exe");
    }
  }
#endif

  /* argv[1] is argv[0] + ".bc". */
  Args[1] = strcat(strcpy((char*)malloc(strlen(argv[0])+4), argv[0]), ".bc");

  /* The rest of the args are as before. */
  memcpy((char **)Args+2, argv+1, sizeof(char*)*argc);

  /* Run the JIT. */
#if !defined(_WIN32) || defined(__MINGW64__)
  execvp(Interp, (char **)Args); /* POSIX execvp takes a char *const[]. */
#else
  execvp(Interp, Args); /* windows execvp takes a const char *const *. */
#endif
  /* if _execv returns, the JIT could not be started. */
  fprintf(stderr, "Could not execute the LLVM JIT.  Either add 'lli' to your"
          " path, or set the\ninterpreter you want to use in the LLVMINTERP "
          "environment variable.\n");
  return 1;
}