sys/src/libndb/csgetval.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include <ndb.h>
   5 #include <ndbhf.h>
   6
   7 /*
   8  *  search for a tuple that has the given 'attr=val' and also 'rattr=x'.
   9  *  copy 'x' into 'buf' and return the whole tuple.
  10  *
  11  *  return 0 if not found.
  12  */
  13 char*
  14 csgetvalue(char *netroot, char *attr, char *val, char *rattr, Ndbtuple **pp)
  15 {
  16         Ndbtuple *t, *first, *last;
  17         int n, linefound;
  18         char line[1024];
  19         int fd;
  20         int oops = 0;
  21         char *rv;
  22
  23         if(pp)
  24                 *pp = nil;
  25         rv = nil;
  26
  27         if(netroot)
  28                 snprint(line, sizeof(line), "%s/cs", netroot);
  29         else
  30                 strcpy(line, "/net/cs");
  31         fd = open(line, ORDWR);
  32         if(fd < 0)
  33                 return 0;
  34         seek(fd, 0, 0);
  35         snprint(line, sizeof(line), "!%s=%s %s=*", attr, val, rattr);
  36         if(write(fd, line, strlen(line)) < 0){
  37                 close(fd);
  38                 return 0;
  39         }
  40         seek(fd, 0, 0);
  41
  42         first = last = 0;
  43         linefound = 0;
  44         for(;;){
  45                 n = read(fd, line, sizeof(line)-2);
  46                 if(n <= 0)
  47                         break;
  48                 line[n] = '\n';
  49                 line[n+1] = 0;
  50
  51                 t = _ndbparseline(line);
  52                 if(t == 0)
  53                         continue;
  54                 if(first)
  55                         last->entry = t;
  56                 else
  57                         first = t;
  58                 last = t;
  59
  60                 while(last->entry)
  61                         last = last->entry;
  62
  63                 for(; t; t = t->entry){
  64                         if(linefound == 0){
  65                                 if(strcmp(rattr, t->attr) == 0){
  66                                         linefound = 1;
  67                                         rv = strdup(t->val);
  68                                 }
  69                         }
  70                 }
  71         }
  72         close(fd);
  73
  74         if(oops){
  75                 werrstr("buffer too short");
  76                 ndbfree(first);
  77                 return nil;
  78         }
  79
  80         if(pp){
  81                 setmalloctag(first, getcallerpc(&netroot));
  82                 *pp = first;
  83         } else
  84                 ndbfree(first);
  85
  86         return rv;
  87 }
  88
  89 Ndbtuple*
  90 csgetval(char *netroot, char *attr, char *val, char *rattr, char *buf)
  91 {
  92         Ndbtuple *t;
  93         char *p;
  94
  95         p = csgetvalue(netroot, attr, val, rattr, &t);
  96         if(p == nil){
  97                 if(buf != nil)
  98                         *buf = 0;
  99         } else {
 100                 if(buf != nil){
 101                         strncpy(buf, p, Ndbvlen-1);
 102                         buf[Ndbvlen-1] = 0;
 103                 }
 104                 free(p);
 105         }
 106         ndbsetmalloctag(t, getcallerpc(&netroot));
 107         return t;
 108 }