FindFiles.cpp

//////////////////////////////////////////////////////////////////////////
//
//
// Copyright (c) 2007, Algin Technology LLC
// Written by Alan Klietz 
// Distributed under GNU General Public License version 2.
//
// $Id: FindFiles.cpp,v 1.5 2008/08/28 22:44:31 cvsalan Exp $
//

// _aefindfirsti64() and _aefindnexti64()

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <ole2.h>

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

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <mbstring.h>
#include <time.h>

#include <errno.h>
#include <io.h> // for _finddatai64_t
#include <system.h> // for alloca()

//
// Stupid MSVC doesn't define __STDC__
//
#ifndef __STDC__
# define __STDC__ 1
#endif

#include "more.h"

#define NEED_DIRENT_H
#include "windows-support.h"
#include "xalloc.h"
#include "xmbrtowc.h" // for get_codepage()
#include "ls.h"
#include "FindFiles.h"

#undef strrchr
#define strrchr _mbsrchr // use the multibyte version of strrchr

#pragma warning(disable: 4057) // ignore unsigned char* vs char*

//
// BUG: _tfindfirsti64() wrongly uses FileSystemToLocalFileTime, which
// does not handle DST correctly when the filedate is standard time
// and the current time is daylight-savings time, or vice versa.
//
// It ought to use SystemTimeToTzSpecificLocalTime if running
// on NT or later.
//
// The bug is fixed on Windows Vista.  (Yes, Microsoft modified the legacy
// MSVCRT.DLL even though they promised they wouldn't change it on Vista.) 
// So we have to check if we are running on Vista.
//
// The reverse function (TzSpecificLocalTimeToSystemTime) requires 
// Windows XP or later.
//
// WORKAROUND: Convert from FILETIME to time_t directly, without
// involving DST.
// 
// DESIGN BUG: FAT filesystems store dates as UTC-5 during CDT and UTC-6
// during CST.  This is because FAT filesystems store the local time on disk,
// not the UTC time.
// 
// DESIGN BUG: FileTimeToLocalFileTime uses today's CDT/CST, not the date's
// CDT/CST.
// 
// SystemTimeToTzSpecificLocalTime subtracts UTC by -5 if the date is in CDT
// and by -6 if date is in CST.  Thus it always shows the correct local time
// for NTFS (and for all stored UTC dates in general).
// 
// Note: SystemTimeToTzSpecificLocalTime is not available on Win9x.
//
extern "C" time_t ConvertFileTimeToTimeT(PFILETIME pft)
{
    LARGE_INTEGER llFileDate, ll1970;

	static BOOL gbInitDst, gbIsDst;
	static TIME_ZONE_INFORMATION tzi;

	typedef BOOL (WINAPI *PFNSYSTEMTIMETOTZSPECIFICLOCALTIME)(
        IN     LPTIME_ZONE_INFORMATION lpTimeZoneInformation,
        IN     LPSYSTEMTIME lpUniversalTime,
   	    OUT    LPSYSTEMTIME lpLocalTime
    );

	static PFNSYSTEMTIMETOTZSPECIFICLOCALTIME pfnSystemTimeToTzSpecificLocalTime;

    time_t timFail = (time_t)-1;

	if (!gbInitDst) {
		gbInitDst = TRUE;
		gbIsDst = (GetTimeZoneInformation(&tzi) == TIME_ZONE_ID_DAYLIGHT);
	}


    if (pft->dwLowDateTime == 0 && pft->dwHighDateTime == 0) {
        return timFail;
    }

    llFileDate.LowPart = pft->dwLowDateTime;
    llFileDate.HighPart = pft->dwHighDateTime;

    //
    // 100ns intervals between Jan 1 1600 and Jan 1 1970
    //
    ll1970.LowPart = 0xD53E8000;
    ll1970.HighPart = 0x019DB1DE;

    if (llFileDate.QuadPart < ll1970.QuadPart) { // if before Jan 1 1970
        return timFail;
    }

	//
    // Convert from 100ns intervals since Jan 1 1600
	// to 100ns intervals since Jan 1 1970
	//
    llFileDate.QuadPart -= ll1970.QuadPart;
	//
    // Convert from 100ns intervals to seconds
	//
    llFileDate.QuadPart /= 10000000;

	//
	// BUG: localtime() wrongly uses the current DST, not the DST of 
	// the timestamp.
	//
	// WORKAROUND:
	// Use SystemTimeToTzSpecificLocalTime to adjust for DST.  Not available
	// on Win9x.
	//
	// Bug is fixed on Vista.
	//
	// Note: While SystemTimeToTzSpecificLocalTime is available on NT/W2K,
	// TzSpecificLocalTimeToSystemTime is only available on XP or later.
	//
	if (!IsVista) { // UNDOCUMENTED: localtime is fixed in MSVCRT.DLL in Vista

	  if (DynaLoad("KERNEL32.DLL", "SystemTimeToTzSpecificLocalTime",
			(PPFN)&pfnSystemTimeToTzSpecificLocalTime)) {
		//
		// Convert the UTC FILETIME to UTC SYSTEMTIME
		//
		SYSTEMTIME stmUTC, stmDate1, stmDate2;
		FileTimeToSystemTime(pft, &stmUTC);
		//
		// See if the file time is in DST by converting it twice,
		// once using the normal DST rules, and once using a bogus
		// "no DST" rule.
		//
		TIME_ZONE_INFORMATION tzNoDst;
		memset(&tzNoDst, 0, sizeof(tzNoDst));
    	tzNoDst.Bias = tzi.Bias; // non-DST bias only

		(*pfnSystemTimeToTzSpecificLocalTime)(NULL, &stmUTC, &stmDate1);
		(*pfnSystemTimeToTzSpecificLocalTime)(&tzNoDst, &stmUTC, &stmDate2);

		// 
		// Note: Some countries shift by 1/2 hour, so check both hours and
		// minutes.
		//
		BOOL bFileDst = (stmDate1.wHour != stmDate2.wHour
			|| stmDate1.wMinute != stmDate2.wMinute);

		//
		// BUG: This is wrong if the country uses a 1/2 hour bias,
		// e.g., Afghanistan.
		//
		if (!bFileDst && gbIsDst) {
			//
			// The file date is not in DST, and the current time is in DST.
			//
			// stftime wrongly uses DST: Add 1 hour to compensate
			//
			llFileDate.QuadPart += 3600;
		} else if (bFileDst && !gbIsDst) {
			//
			// The file date is in DST, and the current time is not in DST.
			//
			// localtime wrongly uses non-DST: Subtract 1 hour to compensate
			//
			llFileDate.QuadPart -= 3600;
		}
	  }
	}

	//
	// BUG: In the year 2038 we need to use __time64_t instead of time_t.
	//
	// There is no MSVCRT support for __time64_t in legacy operating
	// systems.  Coding it ourselves is too hard, so we punt.
	//
	// Hopefully by 2038 nobody will be running Win9x/NT/W2K, and we
	// can use the native __time64_t.
	//
	// TODO: Return (__time64_t)llFileDate.QuadPart;
	//
    return (time_t)llFileDate.QuadPart;
}


long _aefindfirsti64(const char* szWild,
    struct _finddatai64_t * pfd)
{
    HANDLE hFile;
    DWORD dwError;
    WIN32_FIND_DATA wfd;

    if ((hFile = FindFirstFile(szWild, &wfd)) == INVALID_HANDLE_VALUE) {
        switch (dwError = GetLastError()) {
            case ERROR_FILE_NOT_FOUND:
            case ERROR_PATH_NOT_FOUND:
            case ERROR_NO_MORE_FILES:
                errno = ENOENT;
                break;

            case ERROR_NOT_ENOUGH_MEMORY:
                errno = ENOMEM;
                break;

            default:
                errno = EINVAL;
                break;
        }
        return -1;
    }

    pfd->attrib = (wfd.dwFileAttributes == FILE_ATTRIBUTE_NORMAL)
                      ? 0 : wfd.dwFileAttributes;

#ifdef UNDEFINED
printf("low=%08X, high=%08X, file=%s\n",
wfd.ftLastWriteTime.dwLowDateTime,
wfd.ftLastWriteTime.dwHighDateTime, szWild);
#endif

    pfd->time_create  = ConvertFileTimeToTimeT(&wfd.ftCreationTime);
    pfd->time_access  = ConvertFileTimeToTimeT(&wfd.ftLastAccessTime);
    pfd->time_write   = ConvertFileTimeToTimeT(&wfd.ftLastWriteTime);

    pfd->size = ((__int64)(wfd.nFileSizeHigh)) * (0x100000000i64) +
                 (__int64)(wfd.nFileSizeLow);

    strcpy(pfd->name, wfd.cFileName);

    return (long)hFile;
}


int _aefindnexti64(long hFile, struct _finddatai64_t * pfd)
{
    WIN32_FIND_DATA wfd;
    DWORD dwError;

    if (!FindNextFile((HANDLE)hFile, &wfd)) {
        switch (dwError = GetLastError()) {
            case ERROR_FILE_NOT_FOUND:
            case ERROR_PATH_NOT_FOUND:
            case ERROR_NO_MORE_FILES:
                errno = ENOENT;
                break;

            case ERROR_NOT_ENOUGH_MEMORY:
                errno = ENOMEM;
                break;

            default:
                errno = EINVAL;
                break;
        }
        return -1;
    }

    pfd->attrib = (wfd.dwFileAttributes == FILE_ATTRIBUTE_NORMAL)
                      ? 0 : wfd.dwFileAttributes;

    pfd->time_create  = ConvertFileTimeToTimeT(&wfd.ftCreationTime);
    pfd->time_access  = ConvertFileTimeToTimeT(&wfd.ftLastAccessTime);
    pfd->time_write   = ConvertFileTimeToTimeT(&wfd.ftLastWriteTime);

    pfd->size = ((__int64)(wfd.nFileSizeHigh)) * (0x100000000i64) +
                 (__int64)(wfd.nFileSizeLow);

    strcpy(pfd->name, wfd.cFileName);

    return 0;
}

/*
vim:tabstop=4:shiftwidth=4:noexpandtab
*/