/*
 *  R : A Computer Language for Statistical Data Analysis
 *  Copyright (C) 1995-1996 Robert Gentleman and Ross Ihaka
 *  Copyright (C) 1997-2023 The R Core Team
 *
 *  This program 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 this program; if not, a copy is available at
 *  https://www.R-project.org/Licenses/
 */

/*  Dynamic Loading Support: See ../main/Rdynload.c and ../include/Rdynpriv.h
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <string.h>
#include <stdlib.h>
#include <Defn.h>
#include <Rmath.h>
#define WIN32_LEAN_AND_MEAN 1

#include <direct.h>
#include <windows.h>

/* If called with a non-NULL argument it sets the argument to be
   the second item on the DLL search path (after the application
   launch directory).  This is removed if called with NULL.
 */

int setDLLSearchPath(const char *path)
{
    return SetDllDirectory(path);
}

#include <R_ext/Rdynload.h>
#include <Rdynpriv.h>


	/* Inserts the specified DLL at the head of the DLL list */
	/* Returns 1 if the library was successfully added */
	/* and returns 0 if the library table is full or */
	/* or if LoadLibrary fails for some reason. */

static void fixPath(char *path)
{
    char *p;
    for(p = path; *p != '\0'; p++) if(*p == '\\') *p = '/';
}

static HINSTANCE R_loadLibrary(const char *path, int asLocal, int now,
			       const char *search);
static DL_FUNC getRoutine(DllInfo *info, char const *name);

static void R_getDLLError(char *buf, int len);
static size_t
GetFullDLLPath(SEXP call, char *buf, size_t bufsize, const char *path);

static void closeLibrary(HINSTANCE handle)
{
    FreeLibrary(handle);
}

void InitFunctionHashing(void)
{
    R_osDynSymbol->loadLibrary = R_loadLibrary;
    R_osDynSymbol->dlsym = getRoutine;
    R_osDynSymbol->closeLibrary = closeLibrary;
    R_osDynSymbol->getError = R_getDLLError;

#ifdef CACHE_DLL_SYM
    R_osDynSymbol->deleteCachedSymbols = Rf_deleteCachedSymbols;
    R_osDynSymbol->lookupCachedSymbol = Rf_lookupCachedSymbol;
#endif

    R_osDynSymbol->fixPath = fixPath;
    R_osDynSymbol->getFullDLLPath = GetFullDLLPath;
}

#ifndef _MCW_EM
_CRTIMP unsigned int __cdecl
_controlfp (unsigned int unNew, unsigned int unMask);
_CRTIMP unsigned int __cdecl _clearfp (void);
/* Control word masks for unMask */
#define	_MCW_EM		0x0008001F	/* Error masks */
#define	_MCW_IC		0x00040000	/* Infinity */
#define	_MCW_RC		0x00000300	/* Rounding */
#define	_MCW_PC		0x00030000	/* Precision */
#endif

HINSTANCE R_loadLibrary(const char *path, int asLocal, int now,
			const char *search)
{
    HINSTANCE tdlh;
    unsigned int dllcw, rcw;
    int useSearch = search && search[0];

    rcw = _controlfp(0,0) & ~_MCW_IC;  /* Infinity control is ignored */
    _clearfp();
    if(useSearch) setDLLSearchPath(search);
    tdlh = LoadLibrary(path);
    if(useSearch) setDLLSearchPath(NULL);
    dllcw = _controlfp(0,0) & ~_MCW_IC;
    if (dllcw != rcw) {
	_controlfp(rcw, _MCW_EM | _MCW_IC | _MCW_RC | _MCW_PC);
	if (LOGICAL(GetOption1(install("warn.FPU")))[0])
	    warning(_("DLL attempted to change FPU control word from %x to %x"),
		    rcw,dllcw);
    }
    return(tdlh);
}

static DL_FUNC getRoutine(DllInfo *info, char const *name)
{
    DL_FUNC f;
    f = (DL_FUNC) GetProcAddress(info->handle, name);
    return(f);
}

static void R_getDLLError(char *buf, int len)
{
    LPSTR lpMsgBuf, p;
    char *q;
    FormatMessage(
	FORMAT_MESSAGE_ALLOCATE_BUFFER |
	FORMAT_MESSAGE_FROM_SYSTEM |
	FORMAT_MESSAGE_IGNORE_INSERTS,
	NULL,
	GetLastError(),
	MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
	(LPSTR) &lpMsgBuf,
	0,
	NULL
	);
    strcpy(buf, "LoadLibrary failure:  ");
    q = buf + strlen(buf);
    /* It seems that Win 7 returns error messages with CRLF terminators */
    for (p = lpMsgBuf; *p; p++) if (*p != '\r') *q++ = *p;
    LocalFree(lpMsgBuf);
}

/* Retuns the number of bytes (excluding the terminator) needed in buf.
   When bufsize is at least that + 1, buf contains the result
   with terminator. */
static size_t
GetFullDLLPath(SEXP call, char *buf, size_t bufsize, const char *path)
{
    /* NOTE: Unix version also expands ~ */

    size_t needed = strlen(path);
    if ((path[0] != '/') && (path[0] != '\\') && (path[1] != ':')) {
	needed ++; /* for separator */
	DWORD res = GetCurrentDirectory(bufsize, buf);
	if (!res)
	    errorcall(call, _("cannot get working directory"));
	needed += res;
	if (res >= bufsize)
	    return needed - 1; /* res here includes terminator */

	if (bufsize >= needed + 1) {
	    strcat(buf, "/");
	    strcat(buf, path);
	    /* fix slashes to allow inconsistent usage later */
	    fixPath(buf);
	}
    } else {
	if (bufsize >= needed + 1) {
	    strcpy(buf, path);
	    /* fix slashes to allow inconsistent usage later */
	    fixPath(buf);
	}
    }
    return needed;
}