os_unlink.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: os_unlink.c,v 12.7 2005/10/20 18:57:08 bostic Exp $
 */

#include "db_config.h"

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <string.h>
#endif

#include "db_int.h"

/*
 * __os_region_unlink --
 *      Remove a shared memory object file.
 */
int
__os_region_unlink(dbenv, path)
        DB_ENV *dbenv;
        const char *path;
{
        if (F_ISSET(dbenv, DB_ENV_OVERWRITE))
                (void)__db_file_multi_write(dbenv, path);

        return (__os_unlink(dbenv, path));
}

/*
 * __os_unlink --
 *      Remove a file.
 *
 * PUBLIC: int __os_unlink __P((DB_ENV *, const char *));
 */
int
__os_unlink(dbenv, path)
        DB_ENV *dbenv;
        const char *path;
{
        HANDLE h;
        _TCHAR *tpath, *orig_tpath, buf[MAXPATHLEN];
        u_int32_t id;
        int ret;

        if (DB_GLOBAL(j_unlink) != NULL) {
                ret = DB_GLOBAL(j_unlink)(path);
                goto done;
        }

        TO_TSTRING(dbenv, path, tpath, ret);
        if (ret != 0)
                return (ret);
        orig_tpath = tpath;

        /*
         * Windows NT and its descendents allow removal of open files, but the
         * DeleteFile Win32 system call isn't equivalent to a POSIX unlink.
         * Firstly, it only succeeds if FILE_SHARE_DELETE is set when the file
         * is opened.  Secondly, it leaves the file in a "zombie" state, where
         * it can't be opened again, but a new file with the same name can't be
         * created either.
         *
         * Since we depend on being able to recreate files (during recovery,
         * say), we have to first rename the file, and then delete it.  It
         * still hangs around, but with a name we don't care about.  The rename
         * will fail if the file doesn't exist, which isn't a problem, but if
         * it fails for some other reason, we need to know about it or a
         * subsequent open may fail for no apparent reason.
         */
        if (__os_is_winnt()) {
                __os_unique_id(dbenv, &id);
                _sntprintf(buf, MAXPATHLEN, _T("%s.del.%010u"), tpath, id);
                if (MoveFile(tpath, buf))
                        tpath = buf;
                else if (__os_get_errno() != ENOENT)
                        __db_err(dbenv,
                            "unlink: rename %s to temporary file failed", path);

                /*
                 * Try removing the file using the delete-on-close flag.  This
                 * plays nicer with files that are still open than DeleteFile.
                 */
                h = CreateFile(tpath, 0, FILE_SHARE_READ, NULL, OPEN_EXISTING,
                    FILE_FLAG_DELETE_ON_CLOSE, 0);
                if (h != INVALID_HANDLE_VALUE) {
                        (void)CloseHandle (h);
                        if (GetFileAttributes(tpath) == INVALID_FILE_ATTRIBUTES)
                                goto skipdel;
                }
        }

        RETRY_CHK((!DeleteFile(tpath)), ret);

skipdel:
        FREE_STRING(dbenv, orig_tpath);

        /*
         * XXX
         * We shouldn't be testing for an errno of ENOENT here, but ENOENT
         * signals that a file is missing, and we attempt to unlink things
         * (such as v. 2.x environment regions, in DB_ENV->remove) that we
         * are expecting not to be there.  Reporting errors in these cases
         * is annoying.
         */
done:   if (ret != 0 && ret != ENOENT)
                __db_err(dbenv, "unlink: %s: %s", path, strerror(ret));

        return (ret);
}

---