src/libfs/write.c

/* Copyright (C) 2003 Russ Cox, Massachusetts Institute of Technology */
/* See COPYRIGHT */

#include <u.h>
#include <libc.h>
#include <fcall.h>
#include <fs.h>
#include "fsimpl.h"

static long
_fspwrite(Fid *fid, void *buf, long n, vlong offset)
{
	Fcall tx, rx;
	void *freep;

	tx.type = Twrite;
	tx.fid = fid->fid;
	if(offset == -1){
		qlock(&fid->lk);
		tx.offset = fid->offset;
		qunlock(&fid->lk);
	}else
		tx.offset = offset;
	tx.count = n;
	tx.data = buf;

	if(fsrpc(fid->fs, &tx, &rx, &freep) < 0)
		return -1;
	if(rx.type == Rerror){
		werrstr("%s", rx.ename);
		free(freep);
		return -1;
	}
	if(offset == -1 && rx.count){
		qlock(&fid->lk);
		fid->offset += rx.count;
		qunlock(&fid->lk);
	}
	free(freep);
	return rx.count;
}

long
fspwrite(Fid *fid, void *buf, long n, vlong offset)
{
	long tot, want, got, first;
	uint msize;

	msize = fid->fs->msize - IOHDRSZ;
	tot = 0;
	first = 1;
	while(tot < n || first){
		want = n - tot;
		if(want > msize)
			want = msize;
		got = _fspwrite(fid, buf, want, offset);
		first = 0;
		if(got < 0){
			if(tot == 0)
				return got;
			break;
		}
		tot += got;
		if(offset != -1)
			offset += got;
	}
	return tot;
}

long
fswrite(Fid *fid, void *buf, long n)
{
	return fspwrite(fid, buf, n, -1);
}