sendmail/libsm/fget.c

/*
 * Copyright (c) 2000-2001, 2013 Proofpoint, 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 1.26 2013-11-22 20:51:42 ca 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: number of characters
**      failure: -1
**      timeout: -1 and errno set to EAGAIN
**
**  Side Effects:
**      may move the file pointer
*/

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

    SM_REQUIRE_ISA(fp, SmFileMagic);
    if (n <= 0)     /* sanity check */
        return -1;

    s = buf;
    n--;            /* leave space for NUL */
    r = 0;
    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 -1;
                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;
            r += len;
            fp->f_r -= len;
            fp->f_p = t;
            (void) memcpy((void *) s, (void *) p, len);
            s[len] = 0;
            return r;
        }
        fp->f_r -= len;
        fp->f_p += len;
        (void) memcpy((void *) s, (void *) p, len);
        s += len;
        r += len;
        n -= len;
    }
    *s = 0;
    return r;
}