sfwrite.c revision 34f9b3eef6fdadbda0a846aa4d68691ac40eace5
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2009 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> *
* *
***********************************************************************/
#include "sfhdr.h"
/* Write data out to the file system
**
** Written by Kiem-Phong Vo.
*/
#if __STD_C
ssize_t sfwrite(Sfio_t* f, const Void_t* buf, size_t n)
#else
ssize_t sfwrite(f,buf,n)
Sfio_t* f; /* write to this stream. */
Void_t* buf; /* buffer to be written. */
size_t n; /* number of bytes. */
#endif
{
reg uchar *s, *begs, *next;
reg ssize_t w;
reg int local;
SFMTXDECL(f);
SFMTXENTER(f, (ssize_t)(-1));
GETLOCAL(f,local);
if(!buf)
SFMTXRETURN(f, (ssize_t)(n == 0 ? 0 : -1) );
/* release peek lock */
if(f->mode&SF_PEEK)
{ if(!(f->mode&SF_WRITE) && (f->flags&SF_RDWR) != SF_RDWR)
SFMTXRETURN(f, (ssize_t)(-1));
if((uchar*)buf != f->next &&
(!f->rsrv || f->rsrv->data != (uchar*)buf) )
SFMTXRETURN(f, (ssize_t)(-1));
f->mode &= ~SF_PEEK;
if(f->mode&SF_PKRD)
{ /* read past peeked data */
char buf[16];
reg ssize_t r;
for(w = n; w > 0; )
{ if((r = w) > sizeof(buf))
r = sizeof(buf);
if((r = sysreadf(f->file,buf,r)) <= 0)
{ n -= w;
break;
}
else w -= r;
}
f->mode &= ~SF_PKRD;
f->endb = f->data + n;
f->here += n;
}
if((f->mode&SF_READ) && f->proc)
f->next += n;
}
s = begs = (uchar*)buf;
for(;; f->mode &= ~SF_LOCK)
{ /* check stream mode */
if(SFMODE(f,local) != SF_WRITE && _sfmode(f,SF_WRITE,local) < 0 )
{ w = s > begs ? s-begs : -1;
SFMTXRETURN(f,w);
}
SFLOCK(f,local);
w = f->endb - f->next;
if(s == f->next) /* after sfreserve */
{ if(w > (ssize_t)n)
w = (ssize_t)n;
f->next = (s += w);
n -= w;
break;
}
/* attempt to create space in buffer */
if(w == 0 || ((f->flags&SF_WHOLE) && w < (ssize_t)n) )
{ if(f->flags&SF_STRING) /* extend buffer */
{ (void)SFWR(f, s, n-w, f->disc);
if((w = f->endb - f->next) < (ssize_t)n)
{ if(!(f->flags&SF_STRING)) /* maybe sftmp */
{ if(f->next > f->data)
goto fls_buf;
}
else if(w == 0)
break;
}
}
else if(f->next > f->data)
{ fls_buf:
(void)SFFLSBUF(f, -1);
if((w = f->endb - f->next) < (ssize_t)n &&
(f->flags&SF_WHOLE) && f->next > f->data )
break;
}
}
if(!(f->flags&SF_STRING) && f->next == f->data &&
(((f->flags&SF_WHOLE) && w <= n) || SFDIRECT(f,n)) )
{ /* bypass buffering */
if((w = SFWR(f,s,n,f->disc)) <= 0 )
break;
}
else
{ if(w > (ssize_t)n)
w = (ssize_t)n;
if(w <= 0) /* no forward progress possible */
break;
memcpy(f->next, s, w);
f->next += w;
}
s += w;
if((n -= w) <= 0)
break;
}
/* always flush buffer for share streams */
if(f->extent < 0 && (f->flags&SF_SHARE) && !(f->flags&SF_PUBLIC) )
(void)SFFLSBUF(f,-1);
/* check to see if buffer should be flushed */
else if(n == 0 && (f->flags&SF_LINE) && !(f->flags&SF_STRING))
{ if((ssize_t)(n = f->next-f->data) > (w = s-begs))
n = w;
if(n > 0 && n < HIFORLINE)
{ for(next = f->next-1; n > 0; --n, --next)
{ if(*next == '\n')
{ n = HIFORLINE;
break;
}
}
}
if(n >= HIFORLINE)
(void)SFFLSBUF(f,-1);
}
SFOPEN(f,local);
w = s-begs;
SFMTXRETURN(f,w);
}