/*
 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: fget.c,v 1.22 2001/08/27 18:54:14 gshapiro Exp $")
#include <stdlib.h>
#include <string.h>
#include <sm/io.h>
#include <sm/assert.h>
#include "local.h"

/*
**  SM_IO_FGETS -- get a string from a file
**
**  Read at most n-1 characters from the given file.
**  Stop when a newline has been read, or the count ('n') runs out.
**
**      Parameters:
**              fp -- the file to read from
**              timeout -- time to complete reading the string in milliseconds
**              buf -- buffer to place read string in
**              n -- size of 'buf'
**
**      Returns:
**              success: returns value of 'buf'
**              failure: NULL (no characters were read)
**              timeout: NULL and errno set to EAGAIN
**
**      Side Effects:
**              may move the file pointer
*/

char *
sm_io_fgets(fp, timeout, buf, n)
        register SM_FILE_T *fp;
        int timeout;
        char *buf;
        register int n;
{
        register int len;
        register char *s;
        register unsigned char *p, *t;

        SM_REQUIRE_ISA(fp, SmFileMagic);
        if (n <= 0)             /* sanity check */
                return NULL;

        s = buf;
        n--;                    /* leave space for NUL */
        while (n > 0)
        {
                /* If the buffer is empty, refill it. */
                if ((len = fp->f_r) <= 0)
                {

                        /*
                        **  Timeout is only passed if we can't get the data
                        **  from the buffer (which is counted as immediately).
                        */

                        if (sm_refill(fp, timeout) != 0)
                        {
                                /* EOF/error: stop with partial or no line */
                                if (s == buf)
                                        return NULL;
                                break;
                        }
                        len = fp->f_r;
                }
                p = fp->f_p;

                /*
                **  Scan through at most n bytes of the current buffer,
                **  looking for '\n'.  If found, copy up to and including
                **  newline, and stop.  Otherwise, copy entire chunk
                **  and loop.
                */

                if (len > n)
                        len = n;
                t = (unsigned char *) memchr((void *) p, '\n', len);
                if (t != NULL)
                {
                        len = ++t - p;
                        fp->f_r -= len;
                        fp->f_p = t;
                        (void) memcpy((void *) s, (void *) p, len);
                        s[len] = 0;
                        return buf;
                }
                fp->f_r -= len;
                fp->f_p += len;
                (void) memcpy((void *) s, (void *) p, len);
                s += len;
                n -= len;
        }
        *s = 0;
        return buf;
}