twrite.c - plan9port - [fork] Plan 9 from user space
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       ---
       twrite.c (1267B)
       ---
            1 /* Copyright (C) 2003 Russ Cox, Massachusetts Institute of Technology */
            2 /* See COPYRIGHT */
            3 
            4 #include <u.h>
            5 #include <libc.h>
            6 #include <fcall.h>
            7 #include <9pclient.h>
            8 #include "fsimpl.h"
            9 
           10 static long
           11 _fspwrite(CFid *fid, void *buf, long n, vlong offset)
           12 {
           13         Fcall tx, rx;
           14         void *freep;
           15 
           16         tx.type = Twrite;
           17         tx.fid = fid->fid;
           18         if(offset == -1){
           19                 qlock(&fid->lk);
           20                 tx.offset = fid->offset;
           21                 qunlock(&fid->lk);
           22         }else
           23                 tx.offset = offset;
           24         tx.count = n;
           25         tx.data = buf;
           26 
           27         if(_fsrpc(fid->fs, &tx, &rx, &freep) < 0)
           28                 return -1;
           29         if(rx.type == Rerror){
           30                 werrstr("%s", rx.ename);
           31                 free(freep);
           32                 return -1;
           33         }
           34         if(offset == -1 && rx.count){
           35                 qlock(&fid->lk);
           36                 fid->offset += rx.count;
           37                 qunlock(&fid->lk);
           38         }
           39         free(freep);
           40         return rx.count;
           41 }
           42 
           43 long
           44 fspwrite(CFid *fid, void *buf, long n, vlong offset)
           45 {
           46         long tot, want, got, first;
           47         uint msize;
           48 
           49         msize = fid->fs->msize - IOHDRSZ;
           50         tot = 0;
           51         first = 1;
           52         while(tot < n || first){
           53                 want = n - tot;
           54                 if(want > msize)
           55                         want = msize;
           56                 got = _fspwrite(fid, (char*)buf+tot, want, offset);
           57                 first = 0;
           58                 if(got < 0){
           59                         if(tot == 0)
           60                                 return got;
           61                         break;
           62                 }
           63                 tot += got;
           64                 if(offset != -1)
           65                         offset += got;
           66         }
           67         return tot;
           68 }
           69 
           70 long
           71 fswrite(CFid *fid, void *buf, long n)
           72 {
           73         return fspwrite(fid, buf, n, -1);
           74 }