usr/src/lib/libc/stdio/flags.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)flags.c     5.1 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/file.h>
#include <stdio.h>
#include <errno.h>

/*
 * Return the (stdio) flags for a given mode.  Store the flags
 * to be passed to an open() syscall through *optr.
 * Return 0 on error.
 */
__sflags(mode, optr)
        register char *mode;
        int *optr;
{
        register int ret, m, o;

        switch (*mode++) {

        case 'r':       /* open for reading */
                ret = __SRD;
                m = O_RDONLY;
                o = 0;
                break;

        case 'w':       /* open for writing */
                ret = __SWR;
                m = O_WRONLY;
                o = O_CREAT | O_TRUNC;
                break;

        case 'a':       /* open for appending */
                ret = __SWR;
                m = O_WRONLY;
                o = O_CREAT | O_APPEND;
                break;

        default:        /* illegal mode */
                errno = EINVAL;
                return (0);
        }

        /* [rwa]\+ or [rwa]b\+ means read and write */
        if (*mode == '+' || (*mode == 'b' && mode[1] == '+')) {
                ret = __SRW;
                m = O_RDWR;
        }
        *optr = m | o;
        return (ret);
}