win7compat.c

#include <windows.h>
#include "win7compat.h"

/* 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;
    }
}

static BOOL is_drive_spec( const WCHAR *str )
{
    return ((str[0] >= 'A' && str[0] <= 'Z') || (str[0] >= 'a' && str[0] <= 'z')) && str[1] == ':';
}

static BOOL is_prefixed_unc(const WCHAR *string)
{
    return !_wcsnicmp(string, L"\\\\?\\UNC\\", 8 );
}

static BOOL is_prefixed_volume(const WCHAR *string)
{
    const WCHAR *guid;
    INT i = 0;

    if (_wcsnicmp( string, L"\\\\?\\Volume", 10 )) return FALSE;

    guid = string + 10;

    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 (!isxdigit(guid[i])) return FALSE;
            break;
        }
        i++;
    }

    return TRUE;
}

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

    length = lstrlenW(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;
}

static BOOL is_prefixed_disk(const WCHAR *string)
{
    return !wcsncmp(string, L"\\\\?\\", 4) && is_drive_spec( string + 4 );
}

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

/* 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 (is_drive_spec( path ))
        return path[2] == '\\' ? path + 2 : path + 1;
    else
        return NULL;
}

HRESULT WINAPI PathCchStripPrefix(WCHAR *path, SIZE_T size)
{
    if (!path || !size || size > PATHCCH_MAX_CCH) return E_INVALIDARG;

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

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;

    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 = lstrlenW(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 (is_drive_spec( dst ) && dst[2]!= '\\')
            {
                dst[2] = '\\';
                dst[3] = 0;
            }
            dst = buffer + lstrlenW(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 not surrounded by \ */
                if ((src[2] != '\\' && src[2]) || (dst > buffer && dst[-1] != '\\'))
                {
                    *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 not surrounded by \ */
                if ((src[1] != '\\' && src[1]) || (dst > buffer && 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 (is_drive_spec( buffer ) && 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;

    /* Strip multiple trailing . */
    if (!(flags & PATHCCH_DO_NOT_NORMALIZE_SEGMENTS))
    {
        while (dst > buffer && dst[-1] == '.')
        {
            /* Keep a . after * */
            if (dst - 1 > buffer && dst[-2] == '*')
                break;
            /* If . follow a : at the second character, remove the . and add a \ */
            else if (dst - 1 > buffer && dst[-2] == ':' && dst - 2 == buffer + 1)
                *--dst = '\\';
            else
                *--dst = 0;
        }
    }

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

    /* Extend the path if needed */
    length = lstrlenW(buffer);
    if (((length + 1 > MAX_PATH && is_drive_spec( buffer ))
         || (is_drive_spec( buffer ) && 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 PathCchSkipRoot(const WCHAR *path, const WCHAR **root_end)
{
    if (!path || !path[0] || !root_end
        || (!_wcsnicmp(path, L"\\\\?", 3) && !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 PathCchCanonicalizeEx(WCHAR *out, SIZE_T size, const WCHAR *in, DWORD flags)
{
    WCHAR *buffer;
    SIZE_T length;
    HRESULT hr;

    if (!size) return E_INVALIDARG;

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

    length = lstrlenW(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] == '\\' || (is_drive_spec( in ) && 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 (is_drive_spec( out ) && !out[2] && size > 3)
        {
            out[2] = '\\';
            out[3] = 0;
        }
    }

    LocalFree(buffer);
    return hr;
}

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

    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 ((SIZE_T)(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 ((SIZE_T)(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;
}

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;

    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 (is_drive_spec( path2 ) || (path2[0] == '\\' && path2[1] == '\\'))
    {
        path1 = path2;
        path2 = NULL;
        from_path2 = TRUE;
    }

    length2 = path2 ? lstrlenW(path2) : 0;
    /* path1 length + path2 length + possible backslash + NULL */
    combined_length = lstrlenW(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 PathCchCombineEx(WCHAR *out, SIZE_T size, const WCHAR *path1, const WCHAR *path2, DWORD flags)
{
    HRESULT hr;
    WCHAR *buffer;
    SIZE_T length;

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

    hr = PathAllocCombine(path1, path2, flags, &buffer);
    if (FAILED(hr))
    {
        out[0] = 0;
        return hr;
    }

    length = lstrlenW(buffer);
    if (length + 1 > size)
    {
        out[0] = 0;
        LocalFree(buffer);
        return STRSAFE_E_INSUFFICIENT_BUFFER;
    }
    else
    {
        memcpy(out, buffer, (length + 1) * sizeof(WCHAR));
        LocalFree(buffer);
        return S_OK;
    }
}