1 files changed, 130 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/path/RTPathCalcRelative.cpp b/src/VBox/Runtime/common/path/RTPathCalcRelative.cpp
new file mode 100644
index 00000000..fbb6b64c
--- /dev/null
+++ b/src/VBox/Runtime/common/path/RTPathCalcRelative.cpp
@@ -0,0 +1,130 @@
+/* $Id: RTPathCalcRelative.cpp $ */
+/** @file
+ * IPRT - RTPathCreateRelative.
+ */
+
+/*
+ * Copyright (C) 2013 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE 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.
+ */
+
+
+/*******************************************************************************
+*   Header Files                                                               *
+*******************************************************************************/
+#include "internal/iprt.h"
+#include <iprt/path.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/string.h>
+#include "internal/path.h"
+
+
+
+RTDECL(int) RTPathCalcRelative(char *pszPathDst, size_t cbPathDst,
+                               const char *pszPathFrom,
+                               const char *pszPathTo)
+{
+    int rc = VINF_SUCCESS;
+
+    AssertPtrReturn(pszPathDst, VERR_INVALID_POINTER);
+    AssertReturn(cbPathDst, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszPathFrom, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszPathTo, VERR_INVALID_POINTER);
+    AssertReturn(RTPathStartsWithRoot(pszPathFrom), VERR_INVALID_PARAMETER);
+    AssertReturn(RTPathStartsWithRoot(pszPathTo), VERR_INVALID_PARAMETER);
+    AssertReturn(RTStrCmp(pszPathFrom, pszPathTo), VERR_INVALID_PARAMETER);
+
+    /*
+     * Check for different root specifiers (drive letters), creating a relative path doesn't work here.
+     * @todo: How to handle case insensitive root specifiers correctly?
+     */
+    size_t offRootFrom = rtPathRootSpecLen(pszPathFrom);
+    size_t offRootTo   = rtPathRootSpecLen(pszPathTo);
+
+    if (   offRootFrom != offRootTo
+        || RTStrNCmp(pszPathFrom, pszPathTo, offRootFrom))
+        return VERR_NOT_SUPPORTED;
+
+    /* Filter out the parent path which is equal to both paths. */
+    while (   *pszPathFrom == *pszPathTo
+           && *pszPathFrom != '\0'
+           && *pszPathTo != '\0')
+    {
+        pszPathFrom++;
+        pszPathTo++;
+    }
+
+    /*
+     * Because path components can start with an equal string but differ afterwards we
+     * need to go back to the beginning of the current component.
+     */
+    while (!RTPATH_IS_SEP(*pszPathFrom))
+        pszPathFrom--;
+
+    pszPathFrom++; /* Skip path separator. */
+
+    while (!RTPATH_IS_SEP(*pszPathTo))
+        pszPathTo--;
+
+    pszPathTo++; /* Skip path separator. */
+
+    /* Paths point to the first non equal component now. */
+    char aszPathTmp[RTPATH_MAX + 1];
+    unsigned offPathTmp = 0;
+
+    /* Create the part to go up from pszPathFrom. */
+    while (*pszPathFrom != '\0')
+    {
+        while (   !RTPATH_IS_SEP(*pszPathFrom)
+               && *pszPathFrom != '\0')
+            pszPathFrom++;
+
+        if (RTPATH_IS_SEP(*pszPathFrom))
+        {
+            if (offPathTmp + 3 >= sizeof(aszPathTmp) - 1)
+                return VERR_FILENAME_TOO_LONG;
+            aszPathTmp[offPathTmp++] = '.';
+            aszPathTmp[offPathTmp++] = '.';
+            aszPathTmp[offPathTmp++] = RTPATH_SLASH;
+            pszPathFrom++;
+        }
+    }
+
+    aszPathTmp[offPathTmp] = '\0';
+
+    /* Now append the rest of pszPathTo to the final path. */
+    char *pszPathTmp = &aszPathTmp[offPathTmp];
+    size_t cbPathTmp = sizeof(aszPathTmp) - offPathTmp - 1;
+    rc = RTStrCatP(&pszPathTmp, &cbPathTmp, pszPathTo);
+    if (RT_SUCCESS(rc))
+    {
+        *pszPathTmp = '\0';
+
+        size_t cchPathTmp = strlen(aszPathTmp);
+        if (cchPathTmp >= cbPathDst)
+           return VERR_BUFFER_OVERFLOW;
+        memcpy(pszPathDst, aszPathTmp, cchPathTmp + 1);
+    }
+    else
+        rc = VERR_FILENAME_TOO_LONG;
+
+    return rc;
+}
+