sys/src/cmd/9660srv/xfile.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <auth.h>
   4 #include <fcall.h>
   5 #include "dat.h"
   6 #include "fns.h"
   7
   8 static Xfile*   clean(Xfile*);
   9
  10 #define FIDMOD  127     /* prime */
  11
  12 static Xdata*   xhead;
  13 static Xfile*   xfiles[FIDMOD];
  14 static Xfile*   freelist;
  15
  16 Xdata*
  17 getxdata(char *name)
  18 {
  19         int fd;
  20         Dir *dir;
  21         Xdata *xf, *fxf;
  22         int flag;
  23
  24         if(name[0] == 0)
  25                 name = deffile;
  26         if(name == 0)
  27                 error(Enofile);
  28         flag = (access(name, 6) == 0) ? ORDWR : OREAD;
  29         fd = open(name, flag);
  30         if(fd < 0)
  31                 error(Enonexist);
  32         dir = nil;
  33         if(waserror()){
  34                 close(fd);
  35                 free(dir);
  36                 nexterror();
  37         }
  38         if((dir = dirfstat(fd)) == nil)
  39                 error("I/O error");
  40         if((dir->qid.type & ~QTTMP) != QTFILE)
  41                 error("attach name not a plain file");
  42         for(fxf=0,xf=xhead; xf; xf=xf->next){
  43                 if(xf->name == 0){
  44                         if(fxf == 0)
  45                                 fxf = xf;
  46                         continue;
  47                 }
  48                 if(xf->qid.path != dir->qid.path || xf->qid.vers != dir->qid.vers)
  49                         continue;
  50                 if(xf->type != dir->type || xf->fdev != dir->dev)
  51                         continue;
  52                 xf->ref++;
  53                 chat("incref=%d, \"%s\", dev=%d...", xf->ref, xf->name, xf->dev);
  54                 close(fd);
  55                 poperror();
  56                 free(dir);
  57                 return xf;
  58         }
  59         if(fxf==0){
  60                 fxf = ealloc(sizeof(Xfs));
  61                 fxf->next = xhead;
  62                 xhead = fxf;
  63         }
  64         chat("alloc \"%s\", dev=%d...", name, fd);
  65         fxf->ref = 1;
  66         fxf->name = strcpy(ealloc(strlen(name)+1), name);
  67         fxf->qid = dir->qid;
  68         fxf->type = dir->type;
  69         fxf->fdev = dir->dev;
  70         fxf->dev = fd;
  71         free(dir);
  72         poperror();
  73         return fxf;
  74 }
  75
  76 static void
  77 putxdata(Xdata *d)
  78 {
  79         if(d->ref <= 0)
  80                 panic(0, "putxdata");
  81         d->ref--;
  82         chat("decref=%d, \"%s\", dev=%d...", d->ref, d->name, d->dev);
  83         if(d->ref == 0){
  84                 chat("purgebuf...");
  85                 purgebuf(d);
  86                 close(d->dev);
  87                 free(d->name);
  88                 d->name = 0;
  89         }
  90 }
  91
  92 void
  93 refxfs(Xfs *xf, int delta)
  94 {
  95         xf->ref += delta;
  96         if(xf->ref == 0){
  97                 if(xf->d)
  98                         putxdata(xf->d);
  99                 if(xf->ptr)
 100                         free(xf->ptr);
 101                 free(xf);
 102         }
 103 }
 104
 105 Xfile*
 106 xfile(int fid, int flag)
 107 {
 108         int k = fid%FIDMOD;
 109         Xfile **hp=&xfiles[k], *f, *pf;
 110
 111         for(f=*hp,pf=0; f; pf=f,f=f->next)
 112                 if(f->fid == fid)
 113                         break;
 114         if(f && pf){
 115                 pf->next = f->next;
 116                 f->next = *hp;
 117                 *hp = f;
 118         }
 119         switch(flag){
 120         default:
 121                 panic(0, "xfile");
 122         case Asis:
 123                 if(f == 0)
 124                         error("unassigned fid");
 125                 return f;
 126         case Clean:
 127                 break;
 128         case Clunk:
 129                 if(f){
 130                         *hp = f->next;
 131                         clean(f);
 132                         f->next = freelist;
 133                         freelist = f;
 134                 }
 135                 return 0;
 136         }
 137         if(f)
 138                 return clean(f);
 139         if(f = freelist)        /* assign = */
 140                 freelist = f->next;
 141         else
 142                 f = ealloc(sizeof(Xfile));
 143         f->next = *hp;
 144         *hp = f;
 145         f->xf = 0;
 146         f->fid = fid;
 147         f->flags = 0;
 148         f->qid = (Qid){0,0,0};
 149         f->len = 0;
 150         f->ptr = 0;
 151         return f;
 152 }
 153
 154 static Xfile *
 155 clean(Xfile *f)
 156 {
 157         if(f->xf){
 158                 refxfs(f->xf, -1);
 159                 f->xf = 0;
 160         }
 161         if(f->len){
 162                 free(f->ptr);
 163                 f->len = 0;
 164         }
 165         f->ptr = 0;
 166         f->flags = 0;
 167         f->qid = (Qid){0,0,0};
 168         return f;
 169 }
 170