[wimlib] / src / win32_apply.c

/*
 * win32_apply.c - Windows-specific code for applying files from a WIM image.
 */

/*
 * Copyright (C) 2013 Eric Biggers
 *
 * This file is part of wimlib, a library for working with WIM files.
 *
 * wimlib 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; either version 3 of the License, or (at your option)
 * any later version.
 *
 * wimlib 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 wimlib; if not, see http://www.gnu.org/licenses/.
 */

#ifdef __WIN32__

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "wimlib/win32_common.h"

#include "wimlib/apply.h"
#include "wimlib/dentry.h"
#include "wimlib/endianness.h"
#include "wimlib/error.h"
#include "wimlib/lookup_table.h"
#include "wimlib/metadata.h"
#include "wimlib/reparse.h"
#include "wimlib/security.h"

#define MAX_CREATE_HARD_LINK_WARNINGS 5
#define MAX_CREATE_SOFT_LINK_WARNINGS 5

#define MAX_SET_SD_ACCESS_DENIED_WARNINGS 1
#define MAX_SET_SACL_PRIV_NOTHELD_WARNINGS 1

static const wchar_t *apply_access_denied_msg =
L"If you are not running this program as the administrator, you may\n"
 "          need to do so, so that all data and metadata can be extracted\n"
 "          exactly as the origignal copy.  However, if you do not care that\n"
 "          the security descriptors are extracted correctly, you could run\n"
 "          `wimlib-imagex apply' with the --no-acls flag instead.\n"
 ;


static int
win32_extract_try_rpfix(u8 *rpbuf,
                        u16 *rpbuflen_p,
                        const wchar_t *extract_root_realpath,
                        unsigned extract_root_realpath_nchars)
{
        struct reparse_data rpdata;
        wchar_t *target;
        size_t target_nchars;
        size_t stripped_nchars;
        wchar_t *stripped_target;
        wchar_t stripped_target_nchars;
        int ret;

        utf16lechar *new_target;
        utf16lechar *new_print_name;
        size_t new_target_nchars;
        size_t new_print_name_nchars;
        utf16lechar *p;

        ret = parse_reparse_data(rpbuf, *rpbuflen_p, &rpdata);
        if (ret)
                return ret;

        if (extract_root_realpath[0] == L'\0' ||
            extract_root_realpath[1] != L':' ||
            extract_root_realpath[2] != L'\\')
        {
                ERROR("Can't understand full path format \"%ls\".  "
                      "Try turning reparse point fixups off...",
                      extract_root_realpath);
                return WIMLIB_ERR_REPARSE_POINT_FIXUP_FAILED;
        }

        ret = parse_substitute_name(rpdata.substitute_name,
                                    rpdata.substitute_name_nbytes,
                                    rpdata.rptag);
        if (ret < 0)
                return 0;
        stripped_nchars = ret;
        target = rpdata.substitute_name;
        target_nchars = rpdata.substitute_name_nbytes / sizeof(utf16lechar);
        stripped_target = target + stripped_nchars;
        stripped_target_nchars = target_nchars - stripped_nchars;

        new_target = alloca((6 + extract_root_realpath_nchars +
                             stripped_target_nchars) * sizeof(utf16lechar));

        p = new_target;
        if (stripped_nchars == 6) {
                /* Include \??\ prefix if it was present before */
                p = wmempcpy(p, L"\\??\\", 4);
        }

        /* Print name excludes the \??\ if present. */
        new_print_name = p;
        if (stripped_nchars != 0) {
                /* Get drive letter from real path to extract root, if a drive
                 * letter was present before. */
                *p++ = extract_root_realpath[0];
                *p++ = extract_root_realpath[1];
        }
        /* Copy the rest of the extract root */
        p = wmempcpy(p, extract_root_realpath + 2, extract_root_realpath_nchars - 2);

        /* Append the stripped target */
        p = wmempcpy(p, stripped_target, stripped_target_nchars);
        new_target_nchars = p - new_target;
        new_print_name_nchars = p - new_print_name;

        if (new_target_nchars * sizeof(utf16lechar) >= REPARSE_POINT_MAX_SIZE ||
            new_print_name_nchars * sizeof(utf16lechar) >= REPARSE_POINT_MAX_SIZE)
        {
                ERROR("Path names too long to do reparse point fixup!");
                return WIMLIB_ERR_REPARSE_POINT_FIXUP_FAILED;
        }
        rpdata.substitute_name = new_target;
        rpdata.substitute_name_nbytes = new_target_nchars * sizeof(utf16lechar);
        rpdata.print_name = new_print_name;
        rpdata.print_name_nbytes = new_print_name_nchars * sizeof(utf16lechar);
        return make_reparse_buffer(&rpdata, rpbuf, rpbuflen_p);
}

/* Wrapper around the FSCTL_SET_REPARSE_POINT ioctl to set the reparse data on
 * an extracted reparse point. */
static int
win32_set_reparse_data(HANDLE h,
                       const struct wim_inode *inode,
                       const struct wim_lookup_table_entry *lte,
                       const wchar_t *path,
                       struct apply_args *args)
{
        int ret;
        u8 rpbuf[REPARSE_POINT_MAX_SIZE] _aligned_attribute(8);
        DWORD bytesReturned;
        u16 rpbuflen;

        DEBUG("Setting reparse data on \"%ls\"", path);

        ret = wim_inode_get_reparse_data(inode, rpbuf, &rpbuflen);
        if (ret)
                return ret;

        if (args->extract_flags & WIMLIB_EXTRACT_FLAG_RPFIX &&
            (inode->i_reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
             inode->i_reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT) &&
            !inode->i_not_rpfixed)
        {
                ret = win32_extract_try_rpfix(rpbuf,
                                              &rpbuflen,
                                              args->target_realpath,
                                              args->target_realpath_len);
                if (ret)
                        return WIMLIB_ERR_REPARSE_POINT_FIXUP_FAILED;
        }

        /* Set the reparse data on the open file using the
         * FSCTL_SET_REPARSE_POINT ioctl.
         *
         * There are contradictions in Microsoft's documentation for this:
         *
         * "If hDevice was opened without specifying FILE_FLAG_OVERLAPPED,
         * lpOverlapped is ignored."
         *
         * --- So setting lpOverlapped to NULL is okay since it's ignored.
         *
         * "If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an
         * operation returns no output data and lpOutBuffer is NULL,
         * DeviceIoControl makes use of lpBytesReturned. After such an
         * operation, the value of lpBytesReturned is meaningless."
         *
         * --- So lpOverlapped not really ignored, as it affects another
         *  parameter.  This is the actual behavior: lpBytesReturned must be
         *  specified, even though lpBytesReturned is documented as:
         *
         *  "Not used with this operation; set to NULL."
         */
        if (!DeviceIoControl(h, FSCTL_SET_REPARSE_POINT, rpbuf,
                             rpbuflen,
                             NULL, 0,
                             &bytesReturned /* lpBytesReturned */,
                             NULL /* lpOverlapped */))
        {
                DWORD err = GetLastError();
                if (err == ERROR_ACCESS_DENIED || err == ERROR_PRIVILEGE_NOT_HELD)
                {
                        args->num_soft_links_failed++;
                        if (args->num_soft_links_failed <= MAX_CREATE_SOFT_LINK_WARNINGS) {
                                WARNING("Can't set reparse data on \"%ls\": Access denied!\n"
                                        "          You may be trying to extract a symbolic "
                                        "link without the\n"
                                        "          SeCreateSymbolicLink privilege, which by "
                                        "default non-Administrator\n"
                                        "          accounts do not have.", path);
                        }
                        if (args->num_hard_links_failed == MAX_CREATE_HARD_LINK_WARNINGS) {
                                WARNING("Suppressing further warnings regarding failure to extract\n"
                                        "          reparse points due to insufficient privileges...");
                        }
                } else {
                        ERROR("Failed to set reparse data on \"%ls\"", path);
                        win32_error(err);
                        if (inode->i_reparse_tag == WIM_IO_REPARSE_TAG_SYMLINK ||
                            inode->i_reparse_tag == WIM_IO_REPARSE_TAG_MOUNT_POINT)
                                return WIMLIB_ERR_LINK;
                        else
                                return WIMLIB_ERR_WRITE;
                }
        }
        return 0;
}

/* Wrapper around the FSCTL_SET_COMPRESSION ioctl to change the
 * FILE_ATTRIBUTE_COMPRESSED flag of a file or directory. */
static int
win32_set_compression_state(HANDLE hFile, USHORT format, const wchar_t *path)
{
        DWORD bytesReturned;
        if (!DeviceIoControl(hFile, FSCTL_SET_COMPRESSION,
                             &format, sizeof(USHORT),
                             NULL, 0,
                             &bytesReturned, NULL))
        {
                /* Could be a warning only, but we only call this if the volume
                 * supports compression.  So I'm calling this an error. */
                DWORD err = GetLastError();
                ERROR("Failed to set compression flag on \"%ls\"", path);
                win32_error(err);
                if (err == ERROR_ACCESS_DENIED || err == ERROR_PRIVILEGE_NOT_HELD)
                        return WIMLIB_ERR_INSUFFICIENT_PRIVILEGES_TO_EXTRACT;
                else
                        return WIMLIB_ERR_WRITE;
        }
        return 0;
}

/* Wrapper around FSCTL_SET_SPARSE ioctl to set a file as sparse. */
static int
win32_set_sparse(HANDLE hFile, const wchar_t *path)
{
        DWORD bytesReturned;
        if (!DeviceIoControl(hFile, FSCTL_SET_SPARSE,
                             NULL, 0,
                             NULL, 0,
                             &bytesReturned, NULL))
        {
                /* Could be a warning only, but we only call this if the volume
                 * supports sparse files.  So I'm calling this an error. */
                DWORD err = GetLastError();
                WARNING("Failed to set sparse flag on \"%ls\"", path);
                win32_error(err);
                if (err == ERROR_ACCESS_DENIED || err == ERROR_PRIVILEGE_NOT_HELD)
                        return WIMLIB_ERR_INSUFFICIENT_PRIVILEGES_TO_EXTRACT;
                else
                        return WIMLIB_ERR_WRITE;
        }
        return 0;
}

/*
 * Sets the security descriptor on an extracted file.
 */
static int
win32_set_security_data(const struct wim_inode *inode,
                        HANDLE hFile,
                        const wchar_t *path,
                        struct apply_args *args)
{
        PSECURITY_DESCRIPTOR descriptor;
        unsigned long n;
        DWORD err;
        const struct wim_security_data *sd;
        SECURITY_INFORMATION securityInformation;

        securityInformation = OWNER_SECURITY_INFORMATION |
                              GROUP_SECURITY_INFORMATION |
                              DACL_SECURITY_INFORMATION  |
                              SACL_SECURITY_INFORMATION;

        sd = wim_const_security_data(args->wim);
        descriptor = sd->descriptors[inode->i_security_id];

again:
        /* We could use SetSecurityInfo() here if it wasn't horribly broken.  */
        if (SetFileSecurity(path, securityInformation, descriptor))
                return 0;
        err = GetLastError();
        if (args->extract_flags & WIMLIB_EXTRACT_FLAG_STRICT_ACLS)
                goto fail;
        switch (err) {
        case ERROR_PRIVILEGE_NOT_HELD:
                if (securityInformation & SACL_SECURITY_INFORMATION) {
                        n = args->num_set_sacl_priv_notheld++;
                        securityInformation &= ~SACL_SECURITY_INFORMATION;
                        if (n < MAX_SET_SACL_PRIV_NOTHELD_WARNINGS) {
                                WARNING(
"We don't have enough privileges to set the full security\n"
"          descriptor on \"%ls\"!\n", path);
                                if (args->num_set_sd_access_denied +
                                    args->num_set_sacl_priv_notheld == 1)
                                {
                                        WARNING("%ls", apply_access_denied_msg);
                                }
                                WARNING("Re-trying with SACL omitted.\n", path);
                        } else if (n == MAX_SET_SACL_PRIV_NOTHELD_WARNINGS) {
                                WARNING(
"Suppressing further 'privileges not held' error messages when setting\n"
"          security descriptors.");
                        }
                        goto again;
                }
                /* Fall through */
        case ERROR_INVALID_OWNER:
        case ERROR_ACCESS_DENIED:
                n = args->num_set_sd_access_denied++;
                if (n < MAX_SET_SD_ACCESS_DENIED_WARNINGS) {
                        WARNING("Failed to set security descriptor on \"%ls\": "
                                "Access denied!\n", path);
                        if (args->num_set_sd_access_denied +
                            args->num_set_sacl_priv_notheld == 1)
                        {
                                WARNING("%ls", apply_access_denied_msg);
                        }
                } else if (n == MAX_SET_SD_ACCESS_DENIED_WARNINGS) {
                        WARNING(
"Suppressing further access denied error messages when setting\n"
"          security descriptors");
                }
                return 0;
        default:
fail:
                ERROR("Failed to set security descriptor on \"%ls\"", path);
                win32_error(err);
                if (err == ERROR_ACCESS_DENIED || err == ERROR_PRIVILEGE_NOT_HELD)
                        return WIMLIB_ERR_INSUFFICIENT_PRIVILEGES_TO_EXTRACT;
                else
                        return WIMLIB_ERR_WRITE;
        }
}


static int
win32_extract_chunk(const void *buf, size_t len, void *arg)
{
        HANDLE hStream = arg;

        DWORD nbytes_written;
        wimlib_assert(len <= 0xffffffff);

        if (!WriteFile(hStream, buf, len, &nbytes_written, NULL) ||
            nbytes_written != len)
        {
                DWORD err = GetLastError();
                ERROR("WriteFile(): write error");
                win32_error(err);
                return WIMLIB_ERR_WRITE;
        }
        return 0;
}

static int
do_win32_extract_stream(HANDLE hStream, const struct wim_lookup_table_entry *lte)
{
        return extract_wim_resource(lte, wim_resource_size(lte),
                                    win32_extract_chunk, hStream);
}

struct win32_encrypted_extract_ctx {
        const struct wim_lookup_table_entry *lte;
        u64 offset;
};

static DWORD WINAPI
win32_encrypted_import_cb(unsigned char *data, void *_ctx,
                          unsigned long *len_p)
{
        struct win32_encrypted_extract_ctx *ctx = _ctx;
        unsigned long len = *len_p;
        const struct wim_lookup_table_entry *lte = ctx->lte;

        len = min(len, wim_resource_size(lte) - ctx->offset);

        if (read_partial_wim_resource_into_buf(lte, len, ctx->offset, data))
                return ERROR_READ_FAULT;

        ctx->offset += len;
        *len_p = len;
        return ERROR_SUCCESS;
}

/* Create an encrypted file and extract the raw encrypted data to it.
 *
 * @path:  Path to encrypted file to create.
 * @lte:   WIM lookup_table entry for the raw encrypted data.
 *
 * This is separate from do_win32_extract_stream() because the WIM is supposed
 * to contain the *raw* encrypted data, which needs to be extracted ("imported")
 * using the special APIs OpenEncryptedFileRawW(), WriteEncryptedFileRaw(), and
 * CloseEncryptedFileRaw().
 *
 * Returns 0 on success; nonzero on failure.
 */
static int
do_win32_extract_encrypted_stream(const wchar_t *path,
                                  const struct wim_lookup_table_entry *lte)
{
        void *file_ctx;
        int ret;

        DEBUG("Opening file \"%ls\" to extract raw encrypted data", path);

        ret = OpenEncryptedFileRawW(path, CREATE_FOR_IMPORT, &file_ctx);
        if (ret) {
                ERROR("Failed to open \"%ls\" to write raw encrypted data", path);
                win32_error(ret);
                return WIMLIB_ERR_OPEN;
        }

        if (lte) {
                struct win32_encrypted_extract_ctx ctx;

                ctx.lte = lte;
                ctx.offset = 0;
                ret = WriteEncryptedFileRaw(win32_encrypted_import_cb, &ctx, file_ctx);
                if (ret == ERROR_SUCCESS) {
                        ret = 0;
                } else {
                        ret = WIMLIB_ERR_WRITE;
                        ERROR("Failed to extract encrypted file \"%ls\"", path);
                }
        }
        CloseEncryptedFileRaw(file_ctx);
        return ret;
}

static inline DWORD
win32_mask_attributes(DWORD i_attributes)
{
        return i_attributes & ~(FILE_ATTRIBUTE_SPARSE_FILE |
                                FILE_ATTRIBUTE_COMPRESSED |
                                FILE_ATTRIBUTE_REPARSE_POINT |
                                FILE_ATTRIBUTE_DIRECTORY |
                                FILE_ATTRIBUTE_ENCRYPTED |
                                FILE_FLAG_DELETE_ON_CLOSE |
                                FILE_FLAG_NO_BUFFERING |
                                FILE_FLAG_OPEN_NO_RECALL |
                                FILE_FLAG_OVERLAPPED |
                                FILE_FLAG_RANDOM_ACCESS |
                                /*FILE_FLAG_SESSION_AWARE |*/
                                FILE_FLAG_SEQUENTIAL_SCAN |
                                FILE_FLAG_WRITE_THROUGH);
}

static inline DWORD
win32_get_create_flags_and_attributes(DWORD i_attributes)
{
        /*
         * Some attributes cannot be set by passing them to CreateFile().  In
         * particular:
         *
         * FILE_ATTRIBUTE_DIRECTORY:
         *   CreateDirectory() must be called instead of CreateFile().
         *
         * FILE_ATTRIBUTE_SPARSE_FILE:
         *   Needs an ioctl.
         *   See: win32_set_sparse().
         *
         * FILE_ATTRIBUTE_COMPRESSED:
         *   Not clear from the documentation, but apparently this needs an
         *   ioctl as well.
         *   See: win32_set_compressed().
         *
         * FILE_ATTRIBUTE_REPARSE_POINT:
         *   Needs an ioctl, with the reparse data specified.
         *   See: win32_set_reparse_data().
         *
         * In addition, clear any file flags in the attributes that we don't
         * want, but also specify FILE_FLAG_OPEN_REPARSE_POINT and
         * FILE_FLAG_BACKUP_SEMANTICS as we are a backup application.
         */
        return win32_mask_attributes(i_attributes) |
                FILE_FLAG_OPEN_REPARSE_POINT |
                FILE_FLAG_BACKUP_SEMANTICS;
}

/* Set compression and/or sparse attributes on a stream, if supported by the
 * volume. */
static int
win32_set_special_stream_attributes(HANDLE hFile, const struct wim_inode *inode,
                                    struct wim_lookup_table_entry *unnamed_stream_lte,
                                    const wchar_t *path, unsigned vol_flags)
{
        int ret;

        if (inode->i_attributes & FILE_ATTRIBUTE_COMPRESSED) {
                if (vol_flags & FILE_FILE_COMPRESSION) {
                        ret = win32_set_compression_state(hFile,
                                                          COMPRESSION_FORMAT_DEFAULT,
                                                          path);
                        if (ret)
                                return ret;
                } else {
                        DEBUG("Cannot set compression attribute on \"%ls\": "
                              "volume does not support transparent compression",
                              path);
                }
        }

        if (inode->i_attributes & FILE_ATTRIBUTE_SPARSE_FILE) {
                if (vol_flags & FILE_SUPPORTS_SPARSE_FILES) {
                        DEBUG("Setting sparse flag on \"%ls\"", path);
                        ret = win32_set_sparse(hFile, path);
                        if (ret)
                                return ret;
                } else {
                        DEBUG("Cannot set sparse attribute on \"%ls\": "
                              "volume does not support sparse files",
                              path);
                }
        }
        return 0;
}

/* Pre-create directories; extract encrypted streams */
static int
win32_begin_extract_unnamed_stream(const struct wim_inode *inode,
                                   const struct wim_lookup_table_entry *lte,
                                   const wchar_t *path,
                                   DWORD *creationDisposition_ret,
                                   unsigned int vol_flags)
{
        DWORD err;
        int ret;

        /* Directories must be created with CreateDirectoryW().  Then the call
         * to CreateFileW() will merely open the directory that was already
         * created rather than creating a new file. */
        if (inode->i_attributes & FILE_ATTRIBUTE_DIRECTORY) {
                if (!win32_path_is_root_of_drive(path)) {
                        if (!CreateDirectoryW(path, NULL)) {
                                err = GetLastError();
                                if (err != ERROR_ALREADY_EXISTS) {
                                        ERROR("Failed to create directory \"%ls\"",
                                              path);
                                        win32_error(err);
                                        return WIMLIB_ERR_MKDIR;
                                }
                        }
                        DEBUG("Created directory \"%ls\"", path);
                }
                *creationDisposition_ret = OPEN_EXISTING;
        }
        if (inode->i_attributes & FILE_ATTRIBUTE_ENCRYPTED &&
            vol_flags & FILE_SUPPORTS_ENCRYPTION)
        {
                if (inode->i_attributes & FILE_ATTRIBUTE_DIRECTORY) {
                        unsigned remaining_sharing_violations = 100;
                        while (!EncryptFile(path)) {
                                if (remaining_sharing_violations &&
                                    err == ERROR_SHARING_VIOLATION)
                                {
                                        WARNING("Couldn't encrypt directory \"%ls\" "
                                                "due to sharing violation; re-trying "
                                                "after 100 ms", path);
                                        Sleep(100);
                                        remaining_sharing_violations--;
                                } else {
                                        err = GetLastError();
                                        ERROR("Failed to encrypt directory \"%ls\"",
                                              path);
                                        win32_error(err);
                                        return WIMLIB_ERR_WRITE;
                                }
                        }
                } else {
                        ret = do_win32_extract_encrypted_stream(path, lte);
                        if (ret)
                                return ret;
                        DEBUG("Extracted encrypted file \"%ls\"", path);
                }
                *creationDisposition_ret = OPEN_EXISTING;
        }

        /* Set file attributes if we created the file.  Otherwise, we haven't
         * created the file set and we will set the attributes in the call to
         * CreateFileW().
         *
         * The FAT filesystem does not let you change the attributes of the root
         * directory, so treat that as a special case and do not set attributes.
         * */
        if (*creationDisposition_ret == OPEN_EXISTING &&
            !win32_path_is_root_of_drive(path))
        {
                if (!SetFileAttributesW(path,
                                        win32_mask_attributes(inode->i_attributes)))
                {
                        err = GetLastError();
                        ERROR("Failed to set attributes on \"%ls\"", path);
                        win32_error(err);
                        return WIMLIB_ERR_WRITE;
                }
        }
        return 0;
}

/* Set security descriptor and extract stream data or reparse data (skip the
 * unnamed data stream of encrypted files, which was already extracted). */
static int
win32_finish_extract_stream(HANDLE h, const struct wim_dentry *dentry,
                            const struct wim_lookup_table_entry *lte,
                            const wchar_t *stream_path,
                            const wchar_t *stream_name_utf16,
                            struct apply_args *args)
{
        int ret = 0;
        const struct wim_inode *inode = dentry->d_inode;
        if (stream_name_utf16 == NULL) {
                /* Unnamed stream. */

                /* Handle reparse points.  The data for them needs to be set
                 * using a special ioctl.  Note that the reparse point may have
                 * been created using CreateFileW() in the case of
                 * non-directories or CreateDirectoryW() in the case of
                 * directories; but the ioctl works either way.  Also, it is
                 * only this step that actually sets the
                 * FILE_ATTRIBUTE_REPARSE_POINT, as it is not valid to set it
                 * using SetFileAttributesW() or CreateFileW().
                 *
                 * If the volume does not support reparse points we simply
                 * ignore the reparse data.  (N.B. the code currently doesn't
                 * actually reach this case because reparse points are skipped
                 * entirely on such volumes.) */
                if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
                        if (args->vol_flags & FILE_SUPPORTS_REPARSE_POINTS) {
                                ret = win32_set_reparse_data(h, inode,
                                                             lte, stream_path,
                                                             args);
                                if (ret)
                                        return ret;
                        } else {
                                DEBUG("Cannot set reparse data on \"%ls\": volume "
                                      "does not support reparse points", stream_path);
                        }
                } else if (lte != NULL &&
                           !(args->vol_flags & FILE_SUPPORTS_ENCRYPTION &&
                             inode->i_attributes & FILE_ATTRIBUTE_ENCRYPTED))
                {
                        /* Extract the data of the unnamed stream, unless the
                         * lookup table entry is NULL (indicating an empty
                         * stream for which no data needs to be extracted), or
                         * the stream is encrypted and therefore was already
                         * extracted as a special case. */
                        ret = do_win32_extract_stream(h, lte);
                        if (ret)
                                return ret;
                }

                if (dentry_has_short_name(dentry) && !dentry->dos_name_invalid)
                        SetFileShortNameW(h, dentry->short_name);
                else if (running_on_windows_7_or_later())
                        SetFileShortNameW(h, L"");

                /* Set security descriptor, unless the extract_flags indicate
                 * not to or the volume does not supported it.  Note that this
                 * is only done when the unnamed stream is being extracted, as
                 * security descriptors are per-file and not per-stream. */
                if (inode->i_security_id >= 0 &&
                    !(args->extract_flags & WIMLIB_EXTRACT_FLAG_NO_ACLS)
                    && (args->vol_flags & FILE_PERSISTENT_ACLS))
                {
                        ret = win32_set_security_data(inode, h, stream_path, args);
                        if (ret)
                                return ret;
                }
        } else {
                /* Extract the data for a named data stream. */
                if (lte != NULL) {
                        DEBUG("Extracting named data stream \"%ls\" (len = %"PRIu64")",
                              stream_path, wim_resource_size(lte));
                        ret = do_win32_extract_stream(h, lte);
                }
        }
        return ret;
}

static int
win32_decrypt_file(HANDLE open_handle, const wchar_t *path)
{
        DWORD err;
        /* We cannot call DecryptFileW() while there is an open handle to the
         * file.  So close it first. */
        if (!CloseHandle(open_handle)) {
                err = GetLastError();
                ERROR("Failed to close handle for \"%ls\"", path);
                win32_error(err);
                return WIMLIB_ERR_WRITE;
        }
        if (!DecryptFileW(path, 0 /* reserved parameter; set to 0 */)) {
                err = GetLastError();
                ERROR("Failed to decrypt file \"%ls\"", path);
                win32_error(err);
                return WIMLIB_ERR_WRITE;
        }
        return 0;
}

/*
 * Create and extract a stream to a file, or create a directory, using the
 * Windows API.
 *
 * This handles reparse points, directories, alternate data streams, encrypted
 * files, compressed files, etc.
 *
 * @dentry: WIM dentry for the file or directory being extracted.
 *
 * @path:  Path to extract the file to.
 *
 * @stream_name_utf16:
 *         Name of the stream, or NULL if the stream is unnamed.  This will
 *         be called with a NULL stream_name_utf16 before any non-NULL
 *         stream_name_utf16's.
 *
 * @lte:   WIM lookup table entry for the stream.  May be NULL to indicate
 *         a stream of length 0.
 *
 * @args:  Additional apply context, including flags indicating supported
 *         volume features.
 *
 * Returns 0 on success; nonzero on failure.
 */
static int
win32_extract_stream(const struct wim_dentry *dentry,
                     const wchar_t *path,
                     const wchar_t *stream_name_utf16,
                     struct wim_lookup_table_entry *lte,
                     struct apply_args *args)
{
        wchar_t *stream_path;
        HANDLE h;
        int ret;
        DWORD err;
        DWORD creationDisposition = CREATE_ALWAYS;
        DWORD requestedAccess;
        BY_HANDLE_FILE_INFORMATION file_info;
        unsigned remaining_sharing_violations = 1000;
        const struct wim_inode *inode = dentry->d_inode;

        if (stream_name_utf16) {
                /* Named stream.  Create a buffer that contains the UTF-16LE
                 * string [.\]path:stream_name_utf16.  This is needed to
                 * create and open the stream using CreateFileW().  I'm not
                 * aware of any other APIs to do this.  Note: the '$DATA' suffix
                 * seems to be unneeded.  Additional note: a ".\" prefix needs
                 * to be added when the path is a 1-character long relative path
                 * to avoid ambiguity with drive letters. */
                size_t stream_path_nchars;
                size_t path_nchars;
                size_t stream_name_nchars;
                const wchar_t *prefix;

                path_nchars = wcslen(path);
                stream_name_nchars = wcslen(stream_name_utf16);
                stream_path_nchars = path_nchars + 1 + stream_name_nchars;
                if (path_nchars == 1 && !is_any_path_separator(path[0])) {
                        static const wchar_t _prefix[] =
                                {L'.', OS_PREFERRED_PATH_SEPARATOR, L'\0'};
                        prefix = _prefix;
                        stream_path_nchars += 2;
                } else {
                        prefix = L"";
                }
                stream_path = alloca((stream_path_nchars + 1) * sizeof(wchar_t));
                swprintf(stream_path, L"%ls%ls:%ls",
                         prefix, path, stream_name_utf16);
        } else {
                /* Unnamed stream; its path is just the path to the file itself.
                 * */
                stream_path = (wchar_t*)path;

                ret = win32_begin_extract_unnamed_stream(inode, lte, path,
                                                         &creationDisposition,
                                                         args->vol_flags);
                if (ret)
                        goto fail;
        }

        DEBUG("Opening \"%ls\"", stream_path);
        requestedAccess = GENERIC_READ | GENERIC_WRITE;
        /* DELETE access is needed for SetFileShortNameW(), for some reason.
         * But don't request it for the extraction root, for the following
         * reasons:
         *
         * - Requesting DELETE access on the extraction root will cause a
         *   sharing violation if the extraction root is the current working
         *   directory (".").
         * - The extraction root may be extracted to a different name than given
         *   in the WIM file, in which case the DOS name, if given, would not be
         *   meaningful.
         * - For full-image extractions, the root dentry is supposed to be
         *   unnamed anyway.
         * - Microsoft's ImageX does not extract the root directory.
         */
        if (dentry != args->extract_root)
                requestedAccess |= DELETE;

        /* SetFileSecurity() opens its own handle so doesn't need the following
         * access rights.  */
#if 0
        /* If file has a security descriptor, set extra permissions needed for
         * SetSecurityInfo() not implied by GENERIC_WRITE.  */
        if (inode->i_security_id != -1)
                requestedAccess |= WRITE_OWNER | WRITE_DAC | ACCESS_SYSTEM_SECURITY;
#endif

try_open_again:
        /* Open the stream to be extracted.  Depending on what we have set
         * creationDisposition to, we may be creating this for the first time,
         * or we may be opening on existing stream we already created using
         * CreateDirectoryW() or OpenEncryptedFileRawW(). */
        h = CreateFileW(stream_path,
                        requestedAccess,
                        FILE_SHARE_READ,
                        NULL,
                        creationDisposition,
                        win32_get_create_flags_and_attributes(inode->i_attributes),
                        NULL);
        if (h == INVALID_HANDLE_VALUE) {
                err = GetLastError();
                if (err == ERROR_ACCESS_DENIED &&
                    win32_path_is_root_of_drive(stream_path))
                {
                        ret = 0;
                        goto out;
                }
                if ((err == ERROR_PRIVILEGE_NOT_HELD ||
                     err == ERROR_ACCESS_DENIED) &&
                    (requestedAccess & ACCESS_SYSTEM_SECURITY))
                {
                        /* Try opening the file again without privilege to
                         * modify SACL. */
                        requestedAccess &= ~ACCESS_SYSTEM_SECURITY;
                        goto try_open_again;
                }
                if (err == ERROR_SHARING_VIOLATION &&
                    (inode->i_attributes & (FILE_ATTRIBUTE_ENCRYPTED |
                                            FILE_ATTRIBUTE_DIRECTORY)) ==
                        (FILE_ATTRIBUTE_ENCRYPTED | FILE_ATTRIBUTE_DIRECTORY))
                {
                        if (remaining_sharing_violations) {
                                --remaining_sharing_violations;
                                /* This can happen when restoring encrypted directories
                                 * for some reason.  Probably a bug in EncryptFile(). */
                                WARNING("Couldn't open \"%ls\" due to sharing violation; "
                                        "re-trying after 100ms", stream_path);
                                Sleep(100);
                                goto try_open_again;
                        } else {
                                ERROR("Too many sharing violations; giving up...");
                        }
                }
                if (creationDisposition == OPEN_EXISTING)
                        ERROR("Failed to open \"%ls\"", stream_path);
                else
                        ERROR("Failed to create \"%ls\"", stream_path);
                win32_error(err);
                ret = WIMLIB_ERR_OPEN;
                goto fail;
        }

        /* Check the attributes of the file we just opened, and remove
         * encryption or compression if either was set by default but is not
         * supposed to be set based on the WIM inode attributes. */
        if (!GetFileInformationByHandle(h, &file_info)) {
                err = GetLastError();
                ERROR("Failed to get attributes of \"%ls\"", stream_path);
                win32_error(err);
                ret = WIMLIB_ERR_STAT;
                goto fail_close_handle;
        }

        /* Remove encryption? */
        if (file_info.dwFileAttributes & FILE_ATTRIBUTE_ENCRYPTED &&
            !(inode->i_attributes & FILE_ATTRIBUTE_ENCRYPTED))
        {
                /* File defaulted to encrypted due to being in an encrypted
                 * directory, but is not actually supposed to be encrypted.
                 *
                 * This is a workaround, because I'm not aware of any way to
                 * directly (e.g. with CreateFileW()) create an unencrypted file
                 * in a directory with FILE_ATTRIBUTE_ENCRYPTED set. */
                ret = win32_decrypt_file(h, stream_path);
                if (ret)
                        goto fail; /* win32_decrypt_file() closed the handle. */
                creationDisposition = OPEN_EXISTING;
                goto try_open_again;
        }

        /* Remove compression? */
        if (file_info.dwFileAttributes & FILE_ATTRIBUTE_COMPRESSED &&
            !(inode->i_attributes & FILE_ATTRIBUTE_COMPRESSED))
        {
                /* Similar to the encrypted case, above, if the file defaulted
                 * to compressed due to being in an compressed directory, but is
                 * not actually supposed to be compressed, explicitly set the
                 * compression format to COMPRESSION_FORMAT_NONE. */
                ret = win32_set_compression_state(h, COMPRESSION_FORMAT_NONE,
                                                  stream_path);
                if (ret)
                        goto fail_close_handle;
        }

        /* Set compression and/or sparse attributes if needed */
        ret = win32_set_special_stream_attributes(h, inode, lte, path,
                                                  args->vol_flags);

        if (ret)
                goto fail_close_handle;

        /* At this point we have at least created the needed stream with the
         * appropriate attributes.  We have yet to set the appropriate security
         * descriptor and actually extract the stream data (other than for
         * extracted files, which were already extracted).
         * win32_finish_extract_stream() handles these additional steps. */
        ret = win32_finish_extract_stream(h, dentry, lte, stream_path,
                                          stream_name_utf16, args);
        if (ret)
                goto fail_close_handle;

        /* Done extracting the stream.  Close the handle and return. */
        DEBUG("Closing \"%ls\"", stream_path);
        if (!CloseHandle(h)) {
                err = GetLastError();
                ERROR("Failed to close \"%ls\"", stream_path);
                win32_error(err);
                ret = WIMLIB_ERR_WRITE;
                goto fail;
        }
        ret = 0;
        goto out;
fail_close_handle:
        CloseHandle(h);
fail:
        ERROR("Error extracting \"%ls\"", stream_path);
out:
        return ret;
}

/*
 * Creates a file, directory, or reparse point and extracts all streams to it
 * (unnamed data stream and/or reparse point stream, plus any alternate data
 * streams).  Handles sparse, compressed, and/or encrypted files.
 *
 * @dentry:     WIM dentry for this file or directory.
 * @path:       UTF-16LE external path to extract the inode to.
 * @args:       Additional extraction context.
 *
 * Returns 0 on success; nonzero on failure.
 */
static int
win32_extract_streams(const struct wim_dentry *dentry,
                      const wchar_t *path, struct apply_args *args)
{
        struct wim_lookup_table_entry *unnamed_lte;
        int ret;
        const struct wim_inode *inode = dentry->d_inode;

        /* First extract the unnamed stream. */

        unnamed_lte = inode_unnamed_lte_resolved(inode);
        ret = win32_extract_stream(dentry, path, NULL, unnamed_lte, args);
        if (ret)
                goto out;

        /* Extract any named streams, if supported by the volume. */

        if (!(args->vol_flags & FILE_NAMED_STREAMS))
                goto out;
        for (u16 i = 0; i < inode->i_num_ads; i++) {
                const struct wim_ads_entry *ads_entry = &inode->i_ads_entries[i];

                /* Skip the unnamed stream if it's in the ADS entries (we
                 * already extracted it...) */
                if (ads_entry->stream_name_nbytes == 0)
                        continue;

                /* Skip special UNIX data entries (see documentation for
                 * WIMLIB_ADD_FLAG_UNIX_DATA) */
                if (ads_entry->stream_name_nbytes == WIMLIB_UNIX_DATA_TAG_UTF16LE_NBYTES
                    && !memcmp(ads_entry->stream_name,
                               WIMLIB_UNIX_DATA_TAG_UTF16LE,
                               WIMLIB_UNIX_DATA_TAG_UTF16LE_NBYTES))
                        continue;

                /* Extract the named stream */
                ret = win32_extract_stream(dentry,
                                           path,
                                           ads_entry->stream_name,
                                           ads_entry->lte,
                                           args);
                if (ret)
                        break;
        }
out:
        return ret;
}

static int
dentry_clear_inode_visited(struct wim_dentry *dentry, void *_ignore)
{
        dentry->d_inode->i_visited = 0;
        return 0;
}

static int
dentry_get_features(struct wim_dentry *dentry, void *_features_p)
{
        DWORD features = 0;
        DWORD *features_p = _features_p;
        struct wim_inode *inode = dentry->d_inode;

        if (inode->i_visited) {
                features |= FILE_SUPPORTS_HARD_LINKS;
        } else {
                inode->i_visited = 1;
                if (inode->i_attributes & FILE_ATTRIBUTE_SPARSE_FILE)
                        features |= FILE_SUPPORTS_SPARSE_FILES;
                if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT)
                        features |= FILE_SUPPORTS_REPARSE_POINTS;
                for (unsigned i = 0; i < inode->i_num_ads; i++)
                        if (inode->i_ads_entries[i].stream_name_nbytes)
                                features |= FILE_NAMED_STREAMS;
                if (inode->i_attributes & FILE_ATTRIBUTE_ENCRYPTED)
                        features |= FILE_SUPPORTS_ENCRYPTION;
                if (inode->i_attributes & FILE_ATTRIBUTE_COMPRESSED)
                        features |= FILE_FILE_COMPRESSION;
                if (inode->i_security_id != -1)
                        features |= FILE_PERSISTENT_ACLS;
        }
        *features_p |= features;
        return 0;
}

/* If not done already, load the supported feature flags for the volume onto
 * which the image is being extracted, and warn the user about any missing
 * features that could be important. */
static int
win32_check_vol_flags(const wchar_t *output_path,
                      struct wim_dentry *root, struct apply_args *args)
{
        DWORD dentry_features = 0;
        DWORD missing_features;

        if (args->have_vol_flags)
                return 0;

        for_dentry_in_tree(root, dentry_clear_inode_visited, NULL);
        for_dentry_in_tree(root, dentry_get_features, &dentry_features);

        win32_get_vol_flags(output_path, &args->vol_flags);
        args->have_vol_flags = true;

        missing_features = dentry_features & ~args->vol_flags;

        /* Warn the user about data that may not be extracted. */
        if (missing_features & FILE_SUPPORTS_SPARSE_FILES)
                WARNING("Volume does not support sparse files!\n"
                        "          Sparse files will be extracted as non-sparse.");
        if (missing_features & FILE_SUPPORTS_REPARSE_POINTS)
                WARNING("Volume does not support reparse points!\n"
                        "          Reparse point data will not be extracted.");
        if (missing_features & FILE_NAMED_STREAMS) {
                WARNING("Volume does not support named data streams!\n"
                        "          Named data streams will not be extracted.");
        }
        if (missing_features & FILE_SUPPORTS_ENCRYPTION) {
                WARNING("Volume does not support encryption!\n"
                        "          Encrypted files will be extracted as raw data.");
        }
        if (missing_features & FILE_FILE_COMPRESSION) {
                WARNING("Volume does not support transparent compression!\n"
                        "          Compressed files will be extracted as non-compressed.");
        }
        if (missing_features & FILE_PERSISTENT_ACLS) {
                if (args->extract_flags & WIMLIB_EXTRACT_FLAG_STRICT_ACLS) {
                        ERROR("Strict ACLs requested, but the volume does not "
                              "support ACLs!");
                        return WIMLIB_ERR_VOLUME_LACKS_FEATURES;
                } else {
                        WARNING("Volume does not support persistent ACLS!\n"
                                "          File permissions will not be extracted.");
                }
        }
        if (running_on_windows_7_or_later() &&
            (missing_features & FILE_SUPPORTS_HARD_LINKS))
        {
                WARNING("Volume does not support hard links!\n"
                        "          Hard links will be extracted as duplicate files.");
        }
        return 0;
}

/*
 * Try extracting a hard link.
 *
 * @output_path:  Path to link to be extracted.
 *
 * @inode:        WIM inode that the link is to; inode->i_extracted_file
 *                the path to a name of the file that has already been
 *                extracted (we use this to create the hard link).
 *
 * @args:         Additional apply context, used here to keep track of
 *                the number of times creating a hard link failed due to
 *                ERROR_INVALID_FUNCTION.  This error should indicate that hard
 *                links are not supported by the volume, and we would like to
 *                warn the user a few times, but not too many times.
 *
 * Returns 0 if the hard link was successfully extracted.  Returns
 * WIMLIB_ERR_LINK (> 0) if an error occurred, other than hard links possibly
 * being unsupported by the volume.  Returns a negative value if creating the
 * hard link failed due to ERROR_INVALID_FUNCTION.
 */
static int
win32_try_hard_link(const wchar_t *output_path, const struct wim_inode *inode,
                    struct apply_args *args)
{
        DWORD err;

        /* There is a volume flag for this (FILE_SUPPORTS_HARD_LINKS),
         * but it's only available on Windows 7 and later.
         *
         * Otherwise, CreateHardLinkW() will apparently return
         * ERROR_INVALID_FUNCTION if the volume does not support hard links. */

        DEBUG("Creating hard link \"%ls => %ls\"",
              output_path, inode->i_extracted_file);

        if (running_on_windows_7_or_later() &&
            !(args->vol_flags & FILE_SUPPORTS_HARD_LINKS))
                goto hard_links_unsupported;

        if (CreateHardLinkW(output_path, inode->i_extracted_file, NULL))
                return 0;

        err = GetLastError();
        if (err != ERROR_INVALID_FUNCTION) {
                ERROR("Can't create hard link \"%ls => %ls\"",
                      output_path, inode->i_extracted_file);
                win32_error(err);
                return WIMLIB_ERR_LINK;
        }
hard_links_unsupported:
        args->num_hard_links_failed++;
        if (args->num_hard_links_failed <= MAX_CREATE_HARD_LINK_WARNINGS) {
                if (running_on_windows_7_or_later())
                {
                        WARNING("Extracting duplicate copy of \"%ls\" "
                                "rather than hard link", output_path);
                } else {
                        WARNING("Can't create hard link \"%ls\" => \"%ls\":\n"
                                "          Volume does not support hard links!\n"
                                "          Falling back to extracting a copy of the file.",
                                output_path, inode->i_extracted_file);
                }
        }
        if (args->num_hard_links_failed == MAX_CREATE_HARD_LINK_WARNINGS)
                WARNING("Suppressing further hard linking warnings...");
        return -1;
}

/* Extract a file, directory, reparse point, or hard link to an
 * already-extracted file using the Win32 API */
int
win32_do_apply_dentry(const wchar_t *output_path,
                      size_t output_path_num_chars,
                      struct wim_dentry *dentry,
                      struct apply_args *args)
{
        int ret;
        struct wim_inode *inode = dentry->d_inode;

        ret = win32_check_vol_flags(output_path, dentry, args);
        if (ret)
                return ret;
        if (inode->i_nlink > 1 && inode->i_extracted_file != NULL) {
                /* Linked file, with another name already extracted.  Create a
                 * hard link. */
                ret = win32_try_hard_link(output_path, inode, args);
                if (ret >= 0)
                        return ret;
                /* Negative return value from win32_try_hard_link() indicates
                 * that hard links are probably not supported by the volume.
                 * Fall back to extracting a copy of the file. */
        }

        /* If this is a reparse point and the volume does not support reparse
         * points, just skip it completely. */
        if (inode->i_attributes & FILE_ATTRIBUTE_REPARSE_POINT &&
            !(args->vol_flags & FILE_SUPPORTS_REPARSE_POINTS))
        {
                WARNING("Not extracting reparse point \"%ls\"", output_path);
                dentry->not_extracted = 1;
        } else {
                /* Create the file, directory, or reparse point, and extract the
                 * data streams. */
                ret = win32_extract_streams(dentry, output_path, args);
                if (ret)
                        return ret;
        }
        if (inode->i_extracted_file == NULL) {
                const struct wim_lookup_table_entry *lte;

                /* Tally bytes extracted, including all alternate data streams,
                 * unless we extracted a hard link (or, at least extracted a
                 * name that was supposed to be a hard link) */
                for (unsigned i = 0; i <= inode->i_num_ads; i++) {
                        lte = inode_stream_lte_resolved(inode, i);
                        if (lte)
                                args->progress.extract.completed_bytes +=
                                                        wim_resource_size(lte);
                }
                if (inode->i_nlink > 1) {
                        /* Save extracted path for a later call to
                         * CreateHardLinkW() if this inode has multiple links.
                         * */
                        inode->i_extracted_file = WCSDUP(output_path);
                        if (!inode->i_extracted_file)
                                return WIMLIB_ERR_NOMEM;
                }
        }
        return 0;
}

/* Set timestamps on an extracted file using the Win32 API */
int
win32_do_apply_dentry_timestamps(const wchar_t *path,
                                 size_t path_num_chars,
                                 struct wim_dentry *dentry,
                                 struct apply_args *args)
{
        DWORD err;
        HANDLE h;
        const struct wim_inode *inode = dentry->d_inode;

        /* Windows doesn't let you change the timestamps of the root directory
         * (at least on FAT, which is dumb but expected since FAT doesn't store
         * any metadata about the root directory...) */
        if (win32_path_is_root_of_drive(path))
                return 0;

        DEBUG("Opening \"%ls\" to set timestamps", path);
        h = win32_open_existing_file(path, FILE_WRITE_ATTRIBUTES);
        if (h == INVALID_HANDLE_VALUE) {
                err = GetLastError();
                goto fail;
        }

        FILETIME creationTime = {.dwLowDateTime = inode->i_creation_time & 0xffffffff,
                                 .dwHighDateTime = inode->i_creation_time >> 32};
        FILETIME lastAccessTime = {.dwLowDateTime = inode->i_last_access_time & 0xffffffff,
                                  .dwHighDateTime = inode->i_last_access_time >> 32};
        FILETIME lastWriteTime = {.dwLowDateTime = inode->i_last_write_time & 0xffffffff,
                                  .dwHighDateTime = inode->i_last_write_time >> 32};

        DEBUG("Calling SetFileTime() on \"%ls\"", path);
        if (!SetFileTime(h, &creationTime, &lastAccessTime, &lastWriteTime)) {
                err = GetLastError();
                CloseHandle(h);
                goto fail;
        }
        DEBUG("Closing \"%ls\"", path);
        if (!CloseHandle(h)) {
                err = GetLastError();
                goto fail;
        }
        goto out;
fail:
        /* Only warn if setting timestamps failed; still return 0. */
        WARNING("Can't set timestamps on \"%ls\"", path);
        win32_error(err);
out:
        return 0;
}

#endif /* __WIN32__ */