/*
    cpjit.C -- c portable jit in time compiler
    Copyright (C) 2005      Marc Lehmann <cpjit@schmorp.de>
 
    This file is part of libcpjit.

    libcpjit is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with gvpe; if not, write to the Free Software
    Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "config.h"

#include "cpjit.h"

#include <cassert>
#include <cstdlib>
#include <cstdarg>
#include <cstdio>
#include <cstring>
#include <cerrno>

#include <sstream>
#include <fstream>
#include <stdexcept>
#include <iomanip>

#include <unistd.h>
#include <fcntl.h> // for locking

#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>

#include "md5.h"

#include <dlfcn.h>

#define STR_(str) #str
#define STR(str) STR_(str)

namespace cpjit
{

const char typestr<U8   >::str[] = "unsigned " STR(TYPE_INT8);
const char typestr<U16  >::str[] = "unsigned " STR(TYPE_INT16);
const char typestr<U32  >::str[] = "unsigned " STR(TYPE_INT32);
const char typestr<U64  >::str[] = "unsigned " STR(TYPE_INT64);
const char typestr<I8   >::str[] = "signed "   STR(TYPE_INT8);
const char typestr<I16  >::str[] =             STR(TYPE_INT16);
const char typestr<I32  >::str[] =             STR(TYPE_INT32);
const char typestr<I64  >::str[] =             STR(TYPE_INT64);
const char typestr<FLT  >::str[] = "float";
const char typestr<DBL  >::str[] = "double";

const char typestr<PTR  >::str[] = "void"                      " *";

const char typestr<U8  *>::str[] = "unsigned " STR(TYPE_INT8)  " *";
const char typestr<U16 *>::str[] = "unsigned " STR(TYPE_INT16) " *";
const char typestr<U32 *>::str[] = "unsigned " STR(TYPE_INT32) " *";
const char typestr<U64 *>::str[] = "unsigned " STR(TYPE_INT64) " *";
const char typestr<I8  *>::str[] = "signed "   STR(TYPE_INT8)  " *";
const char typestr<I16 *>::str[] =             STR(TYPE_INT16) " *";
const char typestr<I32 *>::str[] =             STR(TYPE_INT32) " *";
const char typestr<I64 *>::str[] =             STR(TYPE_INT64) " *";
const char typestr<FLT *>::str[] = "float"                     " *";
const char typestr<DBL *>::str[] = "double"                    " *";

struct digest
{
  unsigned char data[16];

  digest (const std::string &str);
  operator std::string();
};

digest::digest (const std::string &str)
{
  MD5_CTX ctx;
  MD5Init (&ctx);
  MD5Update (&ctx, (const unsigned char *)str.c_str (), str.size ());
  MD5Final (&ctx);

  memcpy (data, ctx.digest, sizeof (data));
}

digest::operator std::string ()
{
  std::ostringstream s;

  for (int i = 0; i < 15; i++)
    s << std::setfill ('0') << std::hex << std::setw (2) << (int)data [i];

  return s.str ();
}

static inline bool
is_null (const std::string &s)
{
  return s.empty ();
}

// error exception builder
struct error : std::ostringstream
{
  ~error ()
  {
    throw std::runtime_error (str ());
  }
};

#define FATAL(msg) do { error o; o << msg << std::endl; } while (0)
#define ERRNO " (" << strerror (errno) << ")"

env::env (const std::string &path, bool temporary)
: path(path), temporary(temporary)
{
  if (is_null (path))
    {
      this->path = tmpnam (0);

      if (mkdir (this->path.c_str (), 0777))
        FATAL ("error while creating libcpjit temporary directory" << ERRNO);
  
      temporary = true;
    }

  std::string index = this->path + "/libcpjit.idx";

  idxfd = open (index.c_str (), O_RDWR|O_CREAT, 0666);

  if (idxfd < 0)
    FATAL (path << ": unable to open index file" << index);

  lock ();
  load_index ();
  unlock ();

  nextid = 0;
}

env::~env ()
{
  if (temporary)
    {
      DIR *dir = opendir (path.c_str ());

      if (dir)
        {
          struct dirent *de;
          while ((de = readdir (dir)))
            {
              if (de->d_name [0] == '.')
                continue;

              std::string f = path + "/" + de->d_name;
              unlink (f.c_str ());
            }

          closedir (dir);
        }

      if (rmdir (path.c_str ()))
        FATAL (path << ": unable to remove libcpjit temporary directory" << ERRNO);
    }
}

void env::dolock (bool lock)
{
  struct flock fl;

  fl.l_type   = lock ? F_WRLCK : F_UNLCK;
  fl.l_whence = SEEK_SET;
  fl.l_start  = 0;
  fl.l_len    = 0;

  while (fcntl (idxfd, F_SETLKW, &fl) < 0)
    if (errno != EINTR)
      FATAL (path << ": unable to lock index file" << ERRNO);
}

void env::lock ()
{
  dolock (true);
}

void env::unlock ()
{
  dolock (false);
}

void
env::load_index ()
{
  std::ifstream f ((this->path + "/libcpjit.idx").c_str ());
  assert (("not a cpjit directory", f));
  f.close ();
}

std::string
env::genid ()
{
  std::ostringstream os;

  os << "i" << ++nextid;
  return os.str ();
}

fun::fun (env &e, const idstr &id)
: e(e), id(id), funptr(0)
{
}

void fun::set_source (const std::string source)
{
  this->source = source;
}

void *fun::ptr ()
{
  if (!funptr)
    {
      std::string base = e.path + "/" + (std::string) digest (source);

      std::string fc  = base + ".c";
      std::string fo  = base + ".o";
      std::string fso = base + ".so";
      std::string fa  = base + ".a";

      std::ofstream f (fc.c_str ());
      f << source;
      f.close ();

      system (("gcc -O6 -c -o " + fo + " " + fc).c_str ());

      unlink (fc.c_str ());

      system (("gcc -O6 -nostdlib -lgcc -shared -o " + fso + " " + fo).c_str ());

      printf ("%s\n", fso.c_str ());
      sleep (10);

      void *so = dlopen (fso.c_str (), RTLD_LAZY);
      assert (so);

      funptr = dlsym (so, id.c_str ());
      assert (funptr);
    }

  return funptr;
}

funbuild::funbuild (env &e, const idstr &id, const char *rettype, ...)
: e(e), id(id)
{
  std::ostringstream hdrs;

  if (is_null (id))
    this->id = e.genid ();

  hdrs << rettype << " " << this->id << "(";

  va_list ap;
  va_start (ap, rettype);

  int args = 0;
  while ((rettype = va_arg (ap, const char *)))
    {
      if (args++)
        hdrs << ", ";

      hdrs << rettype << " a" << args;
    }

  va_end (ap);

  hdrs << ")\n{\n";

  hdr = hdrs.str ();
}

std::string
funbuild::finish ()
{
  *this << "\n}\n";

  return hdr + str ();
}

}