common/stdio/fgets.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped

#include "stdhdr.h"

extern char*
_stdgets(Sfio_t* f, char* us, int n, int isgets)
{
    int     p;
    unsigned char*  is;
    unsigned char*  ps;

    if(n <= 0 || !us || (f->mode != SF_READ && _sfmode(f,SF_READ,0) < 0))
        return NIL(char*);

    SFLOCK(f,0);

    n -= 1;
    is = (uchar*)us;

    while(n)
    {   /* peek the read buffer for data */
        if((p = f->endb - (ps = f->next)) <= 0 )
        {   f->getr = '\n';
            f->mode |= SF_RC;
            if(SFRPEEK(f,ps,p) <= 0)
                break;
        }

        if(p > n)
            p = n;

#if _lib_memccpy
        if((ps = (uchar*)memccpy((char*)is,(char*)ps,'\n',p)) != NIL(uchar*))
            p = ps-is;
        is += p;
        ps  = f->next+p;
#else
        if(!(f->flags&(SF_BOTH|SF_MALLOC)))
        {   while(p-- && (*is++ = *ps++) != '\n')
                ;
            p = ps-f->next;
        }
        else
        {   reg int c = ps[p-1];
            if(c != '\n')
                ps[p-1] = '\n';
            while((*is++ = *ps++) != '\n')
                ;
            if(c != '\n')
            {   f->next[p-1] = c;
                if((ps-f->next) >= p)
                    is[-1] = c;
            }
        }
#endif

        /* gobble up read data and continue */
        f->next = ps;
        if(is[-1] == '\n')
            break;
        else if(n > 0)
            n -= p;
    }

    if((_Sfi = is - ((uchar*)us)) <= 0)
        us = NIL(char*);
    else if(isgets && is[-1] == '\n')
    {   is[-1] = '\0';
        _Sfi -= 1;
    }
    else    *is = '\0';

    SFOPEN(f,0);
    return us;
}

char*
fgets(char* s, int n, Sfio_t* f)
{
    STDIO_PTR(f, "fgets", char*, (char*, int, Sfio_t*), (s, n, f))

    return _stdgets(f, s, n, 0);
}

char*
gets(char* s)
{
    return _stdgets(sfstdin, s, BUFSIZ, 1);
}