os_errno.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1999-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: os_errno.c,v 12.1 2005/06/16 20:23:23 bostic Exp $
 */

#include "db_config.h"

#include "db_int.h"

/*
 * __os_get_errno_ret_zero --
 *      Return the value of errno, even if it's zero.
 *
 * PUBLIC: int __os_get_errno_ret_zero __P((void));
 */
int
__os_get_errno_ret_zero()
{
        /* This routine must be able to return the same value repeatedly. */
        return (errno);
}

/*
 * __os_get_errno --
 *      Return the value of errno, or EAGAIN if errno is zero.
 *
 * PUBLIC: int __os_get_errno __P((void));
 */
int
__os_get_errno()
{
        /*
         * This routine must be able to return the same value repeatedly.
         *
         * We've seen cases where system calls failed but errno was never set.
         * This version of __os_get_errno() sets errno to EAGAIN if it's not
         * already set, to work around that problem.  For obvious reasons, we
         * can only call this function if we know an error has occurred, that
         * is, we can't test errno for a non-zero value after this call.
         */
        if (errno == 0)
                __os_set_errno(EAGAIN);

        return (errno);
}

/*
 * __os_set_errno --
 *      Set the value of errno.
 *
 * PUBLIC: void __os_set_errno __P((int));
 */
void
__os_set_errno(evalue)
        int evalue;
{
        /*
         * This routine is called by the compatibility interfaces (DB 1.85,
         * dbm and hsearch).  Force values > 0, that is, not one of DB 2.X
         * and later's public error returns.  If something bad has happened,
         * default to EFAULT -- a nasty return.  Otherwise, default to EINVAL.
         * As the compatibility APIs aren't included on Windows, the Windows
         * version of this routine doesn't need this behavior.
         */
        errno =
            evalue >= 0 ? evalue : (evalue == DB_RUNRECOVERY ? EFAULT : EINVAL);
}

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