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/* $Id: RTPathCalcRelative.cpp $ */
/** @file
* IPRT - RTPathCreateRelative.
*/
/*
* Copyright (C) 2013-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* 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, in version 3 of the
* License.
*
* 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, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "internal/iprt.h"
#include <iprt/path.h>
#include <iprt/assert.h>
#include <iprt/errcore.h>
#include <iprt/string.h>
#if RTPATH_STYLE == RTPATH_STR_F_STYLE_DOS
# include <iprt/uni.h>
#endif
#include "internal/path.h"
#if RTPATH_STYLE == RTPATH_STR_F_STYLE_DOS
/** Helper for doing case insensitive comparison of a mismatching codepoint. */
DECLINLINE(bool) rtPathCalcRelativeEqualICaseCodepoint(const char *pszPathFromStart, const char *pszPathFrom,
const char *pszPathToStart, const char *pszPathTo)
{
RTUNICP ucFrom = RTStrGetCp(RTStrPrevCp(pszPathFromStart, pszPathFrom));
RTUNICP ucTo = RTStrGetCp(RTStrPrevCp(pszPathToStart, pszPathTo));
return ucFrom == ucTo
|| RTUniCpToLower(ucFrom) == RTUniCpToLower(ucTo)
|| RTUniCpToUpper(ucFrom) == RTUniCpToUpper(ucTo);
}
#endif
RTDECL(int) RTPathCalcRelative(char *pszPathDst, size_t cbPathDst,
const char *pszPathFrom, bool fFromFile,
const char *pszPathTo)
{
AssertPtrReturn(pszPathDst, VERR_INVALID_POINTER);
AssertReturn(cbPathDst, VERR_INVALID_PARAMETER);
AssertPtrReturn(pszPathFrom, VERR_INVALID_POINTER);
AssertPtrReturn(pszPathTo, VERR_INVALID_POINTER);
#if RTPATH_STYLE == RTPATH_STR_F_STYLE_DOS
const char * const pszPathFromStart = pszPathFrom;
const char * const pszPathToStart = pszPathTo;
#endif
/*
* Check for different root specifiers (drive letters), creating a relative path doesn't work here.
*/
size_t offRootFrom = rtPathRootSpecLen(pszPathFrom);
AssertReturn(offRootFrom > 0, VERR_INVALID_PARAMETER);
size_t offRootTo = rtPathRootSpecLen(pszPathTo);
AssertReturn(offRootTo > 0, VERR_INVALID_PARAMETER);
/** @todo correctly deal with extra root slashes! */
if (offRootFrom != offRootTo)
return VERR_NOT_SUPPORTED;
#if RTPATH_STYLE != RTPATH_STR_F_STYLE_DOS
if (RTStrNCmp(pszPathFrom, pszPathTo, offRootFrom))
return VERR_NOT_SUPPORTED;
#else
if (RTStrNICmp(pszPathFrom, pszPathTo, offRootFrom))
{
const char *pszFromCursor = pszPathFrom;
const char *pszToCursor = pszPathTo;
while ((size_t)(pszFromCursor - pszPathFrom) < offRootFrom)
{
RTUNICP ucFrom;
int rc = RTStrGetCpEx(&pszFromCursor, &ucFrom);
AssertRCReturn(rc, rc);
RTUNICP ucTo;
rc = RTStrGetCpEx(&pszToCursor, &ucTo);
AssertRCReturn(rc, rc);
if ( ucFrom != ucTo
&& RTUniCpToLower(ucFrom) != RTUniCpToLower(ucTo)
&& RTUniCpToUpper(ucFrom) != RTUniCpToUpper(ucTo)
&& (!RTPATH_IS_SLASH(ucFrom) || !RTPATH_IS_SLASH(ucTo)) )
return VERR_NOT_SUPPORTED;
}
}
#endif
pszPathFrom += offRootFrom;
pszPathTo += offRootTo;
/*
* Skip out the part of the path which is equal to both.
*/
const char *pszStartOfFromComp = pszPathFrom;
for (;;)
{
char const chFrom = *pszPathFrom;
char const chTo = *pszPathTo;
if (!RTPATH_IS_SLASH(chFrom))
{
if (chFrom == chTo)
{
if (chFrom)
{ /* likely */ }
else
{
/* Special case: The two paths are equal. */
if (fFromFile)
{
size_t cchComp = pszPathFrom - pszStartOfFromComp;
if (cchComp < cbPathDst)
{
memcpy(pszPathDst, pszStartOfFromComp, cchComp);
pszPathDst[cchComp] = '\0';
return VINF_SUCCESS;
}
}
else if (sizeof(".") <= cbPathDst)
{
memcpy(pszPathDst, ".", sizeof("."));
return VINF_SUCCESS;
}
return VERR_BUFFER_OVERFLOW;
}
}
#if RTPATH_STYLE == RTPATH_STR_F_STYLE_DOS
else if (rtPathCalcRelativeEqualICaseCodepoint(pszPathFromStart, pszPathFrom + 1, pszPathToStart, pszPathTo + 1))
{ /* if not likely, then simpler code structure wise. */ }
#endif
else if (chFrom != '\0' || !RTPATH_IS_SLASH(chTo) || fFromFile)
break;
else
{
pszStartOfFromComp = pszPathFrom;
do
pszPathTo++;
while (RTPATH_IS_SLASH(*pszPathTo));
break;
}
pszPathFrom++;
pszPathTo++;
}
else if (RTPATH_IS_SLASH(chTo))
{
/* Both have slashes. Skip any additional ones before taking down
the start of the component for rewinding purposes. */
do
pszPathTo++;
while (RTPATH_IS_SLASH(*pszPathTo));
do
pszPathFrom++;
while (RTPATH_IS_SLASH(*pszPathFrom));
pszStartOfFromComp = pszPathFrom;
}
else
break;
}
/* Rewind to the start of the current component. */
pszPathTo -= pszPathFrom - pszStartOfFromComp;
pszPathFrom = pszStartOfFromComp;
/* Paths point to the first non equal component now. */
/*
* Constructure the relative path.
*/
/* Create the part to go up from pszPathFrom. */
unsigned offDst = 0;
if (!fFromFile && *pszPathFrom != '\0')
{
if (offDst + 3 < cbPathDst)
{
pszPathDst[offDst++] = '.';
pszPathDst[offDst++] = '.';
pszPathDst[offDst++] = RTPATH_SLASH;
}
else
return VERR_BUFFER_OVERFLOW;
}
while (*pszPathFrom != '\0')
{
char ch;
while ( (ch = *pszPathFrom) != '\0'
&& !RTPATH_IS_SLASH(*pszPathFrom))
pszPathFrom++;
while ( (ch = *pszPathFrom) != '\0'
&& RTPATH_IS_SLASH(ch))
pszPathFrom++;
if (!ch)
break;
if (offDst + 3 < cbPathDst)
{
pszPathDst[offDst++] = '.';
pszPathDst[offDst++] = '.';
pszPathDst[offDst++] = RTPATH_SLASH;
}
else
return VERR_BUFFER_OVERFLOW;
}
/* Now append the rest of pszPathTo to the final path. */
size_t cchTo = strlen(pszPathTo);
if (offDst + cchTo <= cbPathDst)
{
memcpy(&pszPathDst[offDst], pszPathTo, cchTo);
pszPathDst[offDst + cchTo] = '\0';
return VINF_SUCCESS;
}
return VERR_BUFFER_OVERFLOW;
}
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