#include "dlfcn.h"
#include "string.h"
#include "stdio.h"

#define INCL_BASE
#include <os2.h>
#include <float.h>
#include <stdlib.h>

static ULONG retcode;
static char fail[300];

static ULONG dllHandle;
static int handle_found;
static int handle_loaded;
#ifdef PERL_CORE

#include "EXTERN.h"
#include "perl.h"

#else

char *os2error(int rc);

#endif

#ifdef DLOPEN_INITTERM
unsigned long _DLL_InitTerm(unsigned long modHandle, unsigned long flag)
{
    switch (flag) {
    case 0:     /* INIT */
        /* Save handle */
        dllHandle = modHandle;
	handle_found = 1;
        return TRUE;

    case 1:     /* TERM */
	handle_found = 0;
        dllHandle = (unsigned long)NULLHANDLE;
        return TRUE;
    }

    return FALSE;
}

#endif

HMODULE
find_myself(void)
{

  static APIRET APIENTRY (*pDosQueryModFromEIP) (HMODULE * hmod, ULONG * obj, ULONG BufLen, PCHAR Buf,
		    ULONG * Offset, ULONG Address);
  HMODULE doscalls_h, mod;
  static int failed;
  ULONG obj, offset, rc;
  char buf[260];

  if (failed)
	return 0;
  failed = 1;
  doscalls_h = (HMODULE)dlopen("DOSCALLS",0);
  if (!doscalls_h)
	return 0;
/*  {&doscalls_handle, NULL, 360}, */	/* DosQueryModFromEIP */
  rc = DosQueryProcAddr(doscalls_h, 360, 0, (PFN*)&pDosQueryModFromEIP);
  if (rc)
	return 0;
  rc = pDosQueryModFromEIP(&mod, &obj, sizeof(buf), buf, &offset, (ULONG)dlopen);
  if (rc)
	return 0;
  failed = 0;
  handle_found = 1;
  dllHandle = mod;
  return mod;
}

void *
dlopen(const char *path, int mode)
{
	HMODULE handle;
	char tmp[260];
	const char *beg, *dot;
	ULONG rc;
	unsigned fpflag = _control87(0,0);

	fail[0] = 0;
	if (!path) {			/* Our own handle. */
	    if (handle_found || find_myself()) {
		char dllname[260];

		if (handle_loaded)
		    return (void*)dllHandle;
		rc = DosQueryModuleName(dllHandle, sizeof(dllname), dllname);
		if (rc) {
	            strcpy(fail, "can't find my DLL name by the handle");
		    retcode = rc;
		    return 0;
		}
		rc = DosLoadModule(fail, sizeof fail, dllname, &handle);
		if (rc) {
	            strcpy(fail, "can't load my own DLL");
		    retcode = rc;
		    return 0;
		}
		handle_loaded = 1;
		goto ret;
	    }
	    retcode = ERROR_MOD_NOT_FOUND;
            strcpy(fail, "can't load from myself: compiled without -DDLOPEN_INITTERM");
	    return 0;
	}
	if ((rc = DosLoadModule(fail, sizeof fail, (char*)path, &handle)) == 0)
		goto ret;

	retcode = rc;

	if (strlen(path) >= sizeof(tmp))
	    return NULL;

	/* Not found. Check for non-FAT name and try truncated name. */
	/* Don't know if this helps though... */
	for (beg = dot = path + strlen(path);
	     beg > path && !strchr(":/\\", *(beg-1));
	     beg--)
		if (*beg == '.')
			dot = beg;
	if (dot - beg > 8) {
		int n = beg+8-path;

		memmove(tmp, path, n);
		memmove(tmp+n, dot, strlen(dot)+1);
		if (DosLoadModule(fail, sizeof fail, tmp, &handle) == 0)
		    goto ret;
	}
	handle = 0;

      ret:
	_control87(fpflag, MCW_EM); /* Some modules reset FP flags on load */
	return (void *)handle;
}

#define ERROR_WRONG_PROCTYPE 0xffffffff

void *
dlsym(void *handle, const char *symbol)
{
	ULONG rc, type;
	PFN addr;

	fail[0] = 0;
	rc = DosQueryProcAddr((HMODULE)handle, 0, symbol, &addr);
	if (rc == 0) {
		rc = DosQueryProcType((HMODULE)handle, 0, symbol, &type);
		if (rc == 0 && type == PT_32BIT)
			return (void *)addr;
		rc = ERROR_WRONG_PROCTYPE;
	}
	retcode = rc;
	return NULL;
}

char *
dlerror(void)
{
	static char buf[700];
	ULONG len;
	char *err;

	if (retcode == 0)
		return NULL;
	if (retcode == ERROR_WRONG_PROCTYPE)
	    err = "Wrong procedure type";
	else
	    err = os2error(retcode);
	len = strlen(err);
	if (len > sizeof(buf) - 1)
	    len = sizeof(buf) - 1;
	strncpy(buf, err, len+1);
	if (fail[0] && len + strlen(fail) < sizeof(buf) - 100)
	    sprintf(buf + len, ", possible problematic module: '%s'", fail);
	retcode = 0;
	return buf;
}

int
dlclose(void *handle)
{
	ULONG rc;

	if ((rc = DosFreeModule((HMODULE)handle)) == 0) return 0;

	retcode = rc;
	return 2;
}
