/*
 * Copyright 2018 Nikolay Sivov
 * Copyright 2018 Zhiyi Zhang
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <stdarg.h>

#include "windef.h"
#include "winbase.h"
#include "pathcch.h"
#include "strsafe.h"

#include "wine/debug.h"
#include "wine/unicode.h"

WINE_DEFAULT_DEBUG_CHANNEL(path);

static SIZE_T strnlenW(const WCHAR *string, SIZE_T maxlen)
{
    SIZE_T i;

    for (i = 0; i < maxlen; i++)
        if (!string[i]) break;
    return i;
}

static BOOL is_prefixed_unc(const WCHAR *string)
{
    static const WCHAR prefixed_unc[] = {'\\', '\\', '?', '\\', 'U', 'N', 'C', '\\'};
    return !strncmpiW(string, prefixed_unc, ARRAY_SIZE(prefixed_unc));
}

static BOOL is_prefixed_disk(const WCHAR *string)
{
    static const WCHAR prefix[] = {'\\', '\\', '?', '\\'};
    return !strncmpW(string, prefix, ARRAY_SIZE(prefix)) && isalphaW(string[4]) && string[5] == ':';
}

static BOOL is_prefixed_volume(const WCHAR *string)
{
    static const WCHAR prefixed_volume[] = {'\\', '\\', '?', '\\', 'V', 'o', 'l', 'u', 'm', 'e'};
    const WCHAR *guid;
    INT i = 0;

    if (strncmpiW(string, prefixed_volume, ARRAY_SIZE(prefixed_volume))) return FALSE;

    guid = string + ARRAY_SIZE(prefixed_volume);

    while (i <= 37)
    {
        switch (i)
        {
        case 0:
            if (guid[i] != '{') return FALSE;
            break;
        case 9:
        case 14:
        case 19:
        case 24:
            if (guid[i] != '-') return FALSE;
            break;
        case 37:
            if (guid[i] != '}') return FALSE;
            break;
        default:
            if (!isalnumW(guid[i])) return FALSE;
            break;
        }
        i++;
    }

    return TRUE;
}

/* Get the next character beyond end of the segment.
   Return TRUE if the last segment ends with a backslash */
static BOOL get_next_segment(const WCHAR *next, const WCHAR **next_segment)
{
    while (*next && *next != '\\') next++;
    if (*next == '\\')
    {
        *next_segment = next + 1;
        return TRUE;
    }
    else
    {
        *next_segment = next;
        return FALSE;
    }
}

/* Find the last character of the root in a path, if there is one, without any segments */
static const WCHAR *get_root_end(const WCHAR *path)
{
    /* Find path root */
    if (is_prefixed_volume(path))
        return path[48] == '\\' ? path + 48 : path + 47;
    else if (is_prefixed_unc(path))
        return path + 7;
    else if (is_prefixed_disk(path))
        return path[6] == '\\' ? path + 6 : path + 5;
    /* \\ */
    else if (path[0] == '\\' && path[1] == '\\')
        return path + 1;
    /* \ */
    else if (path[0] == '\\')
        return path;
    /* X:\ */
    else if (isalphaW(path[0]) && path[1] == ':')
        return path[2] == '\\' ? path + 2 : path + 1;
    else
        return NULL;
}

HRESULT WINAPI PathAllocCanonicalize(const WCHAR *path_in, DWORD flags, WCHAR **path_out)
{
    WCHAR *buffer, *dst;
    const WCHAR *src;
    const WCHAR *root_end;
    SIZE_T buffer_size, length;

    TRACE("%s %#x %p\n", debugstr_w(path_in), flags, path_out);

    if (!path_in || !path_out
        || ((flags & PATHCCH_FORCE_ENABLE_LONG_NAME_PROCESS) && (flags & PATHCCH_FORCE_DISABLE_LONG_NAME_PROCESS))
        || (flags & (PATHCCH_FORCE_ENABLE_LONG_NAME_PROCESS | PATHCCH_FORCE_DISABLE_LONG_NAME_PROCESS)
            && !(flags & PATHCCH_ALLOW_LONG_PATHS))
        || ((flags & PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH) && (flags & PATHCCH_ALLOW_LONG_PATHS)))
    {
        if (path_out) *path_out = NULL;
        return E_INVALIDARG;
    }

    length = strlenW(path_in);
    if ((length + 1 > MAX_PATH && !(flags & (PATHCCH_ALLOW_LONG_PATHS | PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH)))
        || (length + 1 > PATHCCH_MAX_CCH))
    {
        *path_out = NULL;
        return HRESULT_FROM_WIN32(ERROR_FILENAME_EXCED_RANGE);
    }

    /* PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH implies PATHCCH_DO_NOT_NORMALIZE_SEGMENTS */
    if (flags & PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH) flags |= PATHCCH_DO_NOT_NORMALIZE_SEGMENTS;

    /* path length + possible \\?\ addition + possible \ addition + NUL */
    buffer_size = (length + 6) * sizeof(WCHAR);
    buffer = LocalAlloc(LMEM_ZEROINIT, buffer_size);
    if (!buffer)
    {
        *path_out = NULL;
        return E_OUTOFMEMORY;
    }

    src = path_in;
    dst = buffer;

    root_end = get_root_end(path_in);
    if (root_end) root_end = buffer + (root_end - path_in);

    /* Copy path root */
    if (root_end)
    {
        memcpy(dst, src, (root_end - buffer + 1) * sizeof(WCHAR));
        src += root_end - buffer + 1;
        if(PathCchStripPrefix(dst, length + 6) == S_OK)
        {
            /* Fill in \ in X:\ if the \ is missing */
            if(isalphaW(dst[0]) && dst[1] == ':' && dst[2]!= '\\')
            {
                dst[2] = '\\';
                dst[3] = 0;
            }
            dst = buffer + strlenW(buffer);
            root_end = dst;
        }
        else
            dst += root_end - buffer + 1;
    }

    while (*src)
    {
        if (src[0] == '.')
        {
            if (src[1] == '.')
            {
                /* Keep one . after * */
                if (dst > buffer && dst[-1] == '*')
                {
                    *dst++ = *src++;
                    continue;
                }

                /* Keep the . if one of the following is true:
                 * 1. PATHCCH_DO_NOT_NORMALIZE_SEGMENTS
                 * 2. in form of a..b
                 */
                if (dst > buffer
                    && (((flags & PATHCCH_DO_NOT_NORMALIZE_SEGMENTS) && dst[-1] != '\\')
                        || (dst[-1] != '\\' && src[2] != '\\' && src[2])))
                {
                    *dst++ = *src++;
                    *dst++ = *src++;
                    continue;
                }

                /* Remove the \ before .. if the \ is not part of root */
                if (dst > buffer && dst[-1] == '\\' && (!root_end || dst - 1 > root_end))
                {
                    *--dst = '\0';
                    /* Remove characters until a \ is encountered */
                    while (dst > buffer)
                    {
                        if (dst[-1] == '\\')
                        {
                            *--dst = 0;
                            break;
                        }
                        else
                            *--dst = 0;
                    }
                }
                /* Remove the extra \ after .. if the \ before .. wasn't deleted */
                else if (src[2] == '\\')
                    src++;

                src += 2;
            }
            else
            {
                /* Keep the . if one of the following is true:
                 * 1. PATHCCH_DO_NOT_NORMALIZE_SEGMENTS
                 * 2. in form of a.b, which is used in domain names
                 * 3. *.
                 */
                if (dst > buffer
                    && ((flags & PATHCCH_DO_NOT_NORMALIZE_SEGMENTS && dst[-1] != '\\')
                        || (dst[-1] != '\\' && src[1] != '\\' && src[1]) || (dst[-1] == '*')))
                {
                    *dst++ = *src++;
                    continue;
                }

                /* Remove the \ before . if the \ is not part of root */
                if (dst > buffer && dst[-1] == '\\' && (!root_end || dst - 1 > root_end)) dst--;
                /* Remove the extra \ after . if the \ before . wasn't deleted */
                else if (src[1] == '\\')
                    src++;

                src++;
            }

            /* If X:\ is not complete, then complete it */
            if (isalphaW(buffer[0]) && buffer[1] == ':' && buffer[2] != '\\')
            {
                root_end = buffer + 2;
                dst = buffer + 3;
                buffer[2] = '\\';
                /* If next character is \, use the \ to fill in */
                if (src[0] == '\\') src++;
            }
        }
        /* Copy over */
        else
            *dst++ = *src++;
    }
    /* End the path */
    *dst = 0;

    /* If result path is empty, fill in \ */
    if (!*buffer)
    {
        buffer[0] = '\\';
        buffer[1] = 0;
    }

    /* Extend the path if needed */
    length = strlenW(buffer);
    if (((length + 1 > MAX_PATH && isalphaW(buffer[0]) && buffer[1] == ':')
         || (isalphaW(buffer[0]) && buffer[1] == ':' && flags & PATHCCH_ENSURE_IS_EXTENDED_LENGTH_PATH))
        && !(flags & PATHCCH_FORCE_ENABLE_LONG_NAME_PROCESS))
    {
        memmove(buffer + 4, buffer, (length + 1) * sizeof(WCHAR));
        buffer[0] = '\\';
        buffer[1] = '\\';
        buffer[2] = '?';
        buffer[3] = '\\';
    }

    /* Add a trailing backslash to the path if needed */
    if (flags & PATHCCH_ENSURE_TRAILING_SLASH)
        PathCchAddBackslash(buffer, buffer_size);

    *path_out = buffer;
    return S_OK;
}

HRESULT WINAPI PathAllocCombine(const WCHAR *path1, const WCHAR *path2, DWORD flags, WCHAR **out)
{
    SIZE_T combined_length, length2;
    WCHAR *combined_path;
    BOOL from_path2 = FALSE;
    HRESULT hr;

    TRACE("%s %s %#x %p\n", wine_dbgstr_w(path1), wine_dbgstr_w(path2), flags, out);

    if ((!path1 && !path2) || !out)
    {
        if (out) *out = NULL;
        return E_INVALIDARG;
    }

    if (!path1 || !path2) return PathAllocCanonicalize(path1 ? path1 : path2, flags, out);

    /* If path2 is fully qualified, use path2 only */
    if (path2 && ((isalphaW(path2[0]) && path2[1] == ':') || (path2[0] == '\\' && path2[1] == '\\')))
    {
        path1 = path2;
        path2 = NULL;
        from_path2 = TRUE;
    }

    length2 = path2 ? strlenW(path2) : 0;
    /* path1 length + path2 length + possible backslash + NULL */
    combined_length = strlenW(path1) + length2 + 2;

    combined_path = HeapAlloc(GetProcessHeap(), 0, combined_length * sizeof(WCHAR));
    if (!combined_path)
    {
        *out = NULL;
        return E_OUTOFMEMORY;
    }

    lstrcpyW(combined_path, path1);
    PathCchStripPrefix(combined_path, combined_length);
    if (from_path2) PathCchAddBackslashEx(combined_path, combined_length, NULL, NULL);

    if (path2 && path2[0])
    {
        if (path2[0] == '\\' && path2[1] != '\\')
        {
            PathCchStripToRoot(combined_path, combined_length);
            path2++;
        }

        PathCchAddBackslashEx(combined_path, combined_length, NULL, NULL);
        lstrcatW(combined_path, path2);
    }

    hr = PathAllocCanonicalize(combined_path, flags, out);
    HeapFree(GetProcessHeap(), 0, combined_path);
    return hr;
}

HRESULT WINAPI PathCchAddBackslash(WCHAR *path, SIZE_T size)
{
    return PathCchAddBackslashEx(path, size, NULL, NULL);
}

HRESULT WINAPI PathCchAddBackslashEx(WCHAR *path, SIZE_T size, WCHAR **endptr, SIZE_T *remaining)
{
    BOOL needs_termination;
    SIZE_T length;

    TRACE("%s, %lu, %p, %p\n", debugstr_w(path), size, endptr, remaining);

    length = strlenW(path);
    needs_termination = size && length && path[length - 1] != '\\';

    if (length >= (needs_termination ? size - 1 : size))
    {
        if (endptr) *endptr = NULL;
        if (remaining) *remaining = 0;
        return STRSAFE_E_INSUFFICIENT_BUFFER;
    }

    if (!needs_termination)
    {
        if (endptr) *endptr = path + length;
        if (remaining) *remaining = size - length;
        return S_FALSE;
    }

    path[length++] = '\\';
    path[length] = 0;

    if (endptr) *endptr = path + length;
    if (remaining) *remaining = size - length;

    return S_OK;
}

HRESULT WINAPI PathCchAddExtension(WCHAR *path, SIZE_T size, const WCHAR *extension)
{
    const WCHAR *existing_extension, *next;
    SIZE_T path_length, extension_length, dot_length;
    BOOL has_dot;
    HRESULT hr;

    TRACE("%s %lu %s\n", wine_dbgstr_w(path), size, wine_dbgstr_w(extension));

    if (!path || !size || size > PATHCCH_MAX_CCH || !extension) return E_INVALIDARG;

    next = extension;
    while (*next)
    {
        if ((*next == '.' && next > extension) || *next == ' ' || *next == '\\') return E_INVALIDARG;
        next++;
    }

    has_dot = extension[0] == '.' ? TRUE : FALSE;

    hr = PathCchFindExtension(path, size, &existing_extension);
    if (FAILED(hr)) return hr;
    if (*existing_extension) return S_FALSE;

    path_length = strnlenW(path, size);
    dot_length = has_dot ? 0 : 1;
    extension_length = strlenW(extension);

    if (path_length + dot_length + extension_length + 1 > size) return STRSAFE_E_INSUFFICIENT_BUFFER;

    /* If extension is empty or only dot, return S_OK with path unchanged */
    if (!extension[0] || (extension[0] == '.' && !extension[1])) return S_OK;

    if (!has_dot)
    {
        path[path_length] = '.';
        path_length++;
    }

    strcpyW(path + path_length, extension);
    return S_OK;
}

HRESULT WINAPI PathCchCanonicalize(WCHAR *out, SIZE_T size, const WCHAR *in)
{
    TRACE("%p %lu %s\n", out, size, wine_dbgstr_w(in));

    /* Not X:\ and path > MAX_PATH - 4, return HRESULT_FROM_WIN32(ERROR_FILENAME_EXCED_RANGE) */
    if (strlenW(in) > MAX_PATH - 4 && !(isalphaW(in[0]) && in[1] == ':' && in[2] == '\\'))
        return HRESULT_FROM_WIN32(ERROR_FILENAME_EXCED_RANGE);

    return PathCchCanonicalizeEx(out, size, in, PATHCCH_NONE);
}

HRESULT WINAPI PathCchCanonicalizeEx(WCHAR *out, SIZE_T size, const WCHAR *in, DWORD flags)
{
    WCHAR *buffer;
    SIZE_T length;
    HRESULT hr;

    TRACE("%p %lu %s %#x\n", out, size, wine_dbgstr_w(in), flags);

    if (!size) return E_INVALIDARG;

    hr = PathAllocCanonicalize(in, flags, &buffer);
    if (FAILED(hr)) return hr;

    length = strlenW(buffer);
    if (size < length + 1)
    {
        /* No root and path > MAX_PATH - 4, return HRESULT_FROM_WIN32(ERROR_FILENAME_EXCED_RANGE) */
        if (length > MAX_PATH - 4 && !(in[0] == '\\' || (isalphaW(in[0]) && in[1] == ':' && in[2] == '\\')))
            hr = HRESULT_FROM_WIN32(ERROR_FILENAME_EXCED_RANGE);
        else
            hr = STRSAFE_E_INSUFFICIENT_BUFFER;
    }

    if (SUCCEEDED(hr))
    {
        memcpy(out, buffer, (length + 1) * sizeof(WCHAR));

        /* Fill a backslash at the end of X: */
        if (isalphaW(out[0]) && out[1] == ':' && !out[2] && size > 3)
        {
            out[2] = '\\';
            out[3] = 0;
        }
    }

    LocalFree(buffer);
    return hr;
}

HRESULT WINAPI PathCchFindExtension(const WCHAR *path, SIZE_T size, const WCHAR **extension)
{
    const WCHAR *lastpoint = NULL;
    SIZE_T counter = 0;

    TRACE("%s %lu %p\n", wine_dbgstr_w(path), size, extension);

    if (!path || !size || size > PATHCCH_MAX_CCH)
    {
        *extension = NULL;
        return E_INVALIDARG;
    }

    while (*path)
    {
        if (*path == '\\' || *path == ' ')
            lastpoint = NULL;
        else if (*path == '.')
            lastpoint = path;

        path++;
        counter++;
        if (counter == size || counter == PATHCCH_MAX_CCH)
        {
            *extension = NULL;
            return E_INVALIDARG;
        }
    }

    *extension = lastpoint ? lastpoint : path;
    return S_OK;
}

BOOL WINAPI PathCchIsRoot(const WCHAR *path)
{
    const WCHAR *root_end;
    const WCHAR *next;
    BOOL is_unc;

    TRACE("%s\n", wine_dbgstr_w(path));

    if (!path || !*path) return FALSE;

    root_end = get_root_end(path);
    if (!root_end) return FALSE;

    if ((is_unc = is_prefixed_unc(path)) || (path[0] == '\\' && path[1] == '\\' && path[2] != '?'))
    {
        next = root_end + 1;
        /* No extra segments */
        if ((is_unc && !*next) || (!is_unc && !*next)) return TRUE;

        /* Has first segment with an ending backslash but no remaining characters */
        if (get_next_segment(next, &next) && !*next) return FALSE;
        /* Has first segment with no ending backslash */
        else if (!*next)
            return TRUE;
        /* Has first segment with an ending backslash and has remaining characters*/
        else
        {
            next++;
            /* Second segment must have no backslash and no remaining characters */
            return !get_next_segment(next, &next) && !*next;
        }
    }
    else if (*root_end == '\\' && !root_end[1])
        return TRUE;
    else
        return FALSE;
}

HRESULT WINAPI PathCchRemoveBackslash(WCHAR *path, SIZE_T path_size)
{
    WCHAR *path_end;
    SIZE_T free_size;

    TRACE("%s %lu\n", debugstr_w(path), path_size);

    return PathCchRemoveBackslashEx(path, path_size, &path_end, &free_size);
}

HRESULT WINAPI PathCchRemoveBackslashEx(WCHAR *path, SIZE_T path_size, WCHAR **path_end, SIZE_T *free_size)
{
    const WCHAR *root_end;
    SIZE_T path_length;

    TRACE("%s %lu %p %p\n", debugstr_w(path), path_size, path_end, free_size);

    if (!path_size || !path_end || !free_size)
    {
        if (path_end) *path_end = NULL;
        if (free_size) *free_size = 0;
        return E_INVALIDARG;
    }

    path_length = strnlenW(path, path_size);
    if (path_length == path_size && !path[path_length]) return E_INVALIDARG;

    root_end = get_root_end(path);
    if (path_length > 0 && path[path_length - 1] == '\\')
    {
        *path_end = path + path_length - 1;
        *free_size = path_size - path_length + 1;
        /* If the last character is beyond end of root */
        if (!root_end || path + path_length - 1 > root_end)
        {
            path[path_length - 1] = 0;
            return S_OK;
        }
        else
            return S_FALSE;
    }
    else
    {
        *path_end = path + path_length;
        *free_size = path_size - path_length;
        return S_FALSE;
    }
}

HRESULT WINAPI PathCchRemoveExtension(WCHAR *path, SIZE_T size)
{
    const WCHAR *extension;
    WCHAR *next;
    HRESULT hr;

    TRACE("%s %lu\n", wine_dbgstr_w(path), size);

    if (!path || !size || size > PATHCCH_MAX_CCH) return E_INVALIDARG;

    hr = PathCchFindExtension(path, size, &extension);
    if (FAILED(hr)) return hr;

    next = path + (extension - path);
    while (next - path < size && *next) *next++ = 0;

    return next == extension ? S_FALSE : S_OK;
}

HRESULT WINAPI PathCchRemoveFileSpec(WCHAR *path, SIZE_T size)
{
    const WCHAR *root_end = NULL;
    SIZE_T length;
    WCHAR *last;

    TRACE("%s %lu\n", wine_dbgstr_w(path), size);

    if (!path || !size || size > PATHCCH_MAX_CCH) return E_INVALIDARG;

    if (PathCchIsRoot(path)) return S_FALSE;

    PathCchSkipRoot(path, &root_end);

    /* The backslash at the end of UNC and \\* are not considered part of root in this case */
    if (root_end && root_end > path && root_end[-1] == '\\'
        && (is_prefixed_unc(path) || (path[0] == '\\' && path[1] == '\\' && path[2] != '?')))
        root_end--;

    length = strlenW(path);
    last = path + length - 1;
    while (last >= path && (!root_end || last >= root_end))
    {
        if (last - path >= size) return E_INVALIDARG;

        if (*last == '\\')
        {
            *last-- = 0;
            break;
        }

        *last-- = 0;
    }

    return last != path + length - 1 ? S_OK : S_FALSE;
}

HRESULT WINAPI PathCchRenameExtension(WCHAR *path, SIZE_T size, const WCHAR *extension)
{
    HRESULT hr;

    TRACE("%s %lu %s\n", wine_dbgstr_w(path), size, wine_dbgstr_w(extension));

    hr = PathCchRemoveExtension(path, size);
    if (FAILED(hr)) return hr;

    hr = PathCchAddExtension(path, size, extension);
    return FAILED(hr) ? hr : S_OK;
}

HRESULT WINAPI PathCchSkipRoot(const WCHAR *path, const WCHAR **root_end)
{
    static const WCHAR unc_prefix[] = {'\\', '\\', '?'};

    TRACE("%s %p\n", debugstr_w(path), root_end);

    if (!path || !path[0] || !root_end
        || (!memicmpW(unc_prefix, path, ARRAY_SIZE(unc_prefix)) && !is_prefixed_volume(path) && !is_prefixed_unc(path)
            && !is_prefixed_disk(path)))
        return E_INVALIDARG;

    *root_end = get_root_end(path);
    if (*root_end)
    {
        (*root_end)++;
        if (is_prefixed_unc(path))
        {
            get_next_segment(*root_end, root_end);
            get_next_segment(*root_end, root_end);
        }
        else if (path[0] == '\\' && path[1] == '\\' && path[2] != '?')
        {
            /* Skip share server */
            get_next_segment(*root_end, root_end);
            /* If mount point is empty, don't skip over mount point */
            if (**root_end != '\\') get_next_segment(*root_end, root_end);
        }
    }

    return *root_end ? S_OK : E_INVALIDARG;
}

HRESULT WINAPI PathCchStripPrefix(WCHAR *path, SIZE_T size)
{
    TRACE("%s %lu\n", wine_dbgstr_w(path), size);

    if (!path || !size || size > PATHCCH_MAX_CCH) return E_INVALIDARG;

    if (is_prefixed_unc(path))
    {
        /* \\?\UNC\a -> \\a */
        if (size < strlenW(path + 8) + 3) return E_INVALIDARG;
        strcpyW(path + 2, path + 8);
        return S_OK;
    }
    else if (is_prefixed_disk(path))
    {
        /* \\?\C:\ -> C:\ */
        if (size < strlenW(path + 4) + 1) return E_INVALIDARG;
        strcpyW(path, path + 4);
        return S_OK;
    }
    else
        return S_FALSE;
}

HRESULT WINAPI PathCchStripToRoot(WCHAR *path, SIZE_T size)
{
    const WCHAR *root_end;
    WCHAR *segment_end;
    BOOL is_unc;

    TRACE("%s %lu\n", wine_dbgstr_w(path), size);

    if (!path || !*path || !size || size > PATHCCH_MAX_CCH) return E_INVALIDARG;

    /* \\\\?\\UNC\\* and \\\\* have to have at least two extra segments to be striped,
     * e.g. \\\\?\\UNC\\a\\b\\c -> \\\\?\\UNC\\a\\b
     *      \\\\a\\b\\c         -> \\\\a\\b         */
    if ((is_unc = is_prefixed_unc(path)) || (path[0] == '\\' && path[1] == '\\' && path[2] != '?'))
    {
        root_end = is_unc ? path + 8 : path + 3;
        if (!get_next_segment(root_end, &root_end)) return S_FALSE;
        if (!get_next_segment(root_end, &root_end)) return S_FALSE;

        if (root_end - path >= size) return E_INVALIDARG;

        segment_end = path + (root_end - path) - 1;
        *segment_end = 0;
        return S_OK;
    }
    else if (PathCchSkipRoot(path, &root_end) == S_OK)
    {
        if (root_end - path >= size) return E_INVALIDARG;

        segment_end = path + (root_end - path);
        if (!*segment_end) return S_FALSE;

        *segment_end = 0;
        return S_OK;
    }
    else
        return E_INVALIDARG;
}

BOOL WINAPI PathIsUNCEx(const WCHAR *path, const WCHAR **server)
{
    const WCHAR *result = NULL;

    TRACE("%s %p\n", wine_dbgstr_w(path), server);

    if (is_prefixed_unc(path))
        result = path + 8;
    else if (path[0] == '\\' && path[1] == '\\' && path[2] != '?')
        result = path + 2;

    if (server) *server = result;
    return result ? TRUE : FALSE;
}