sys/src/libndb/ndbgetval.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include "ndb.h"
   5
   6 /*
   7  *  search for a tuple that has the given 'attr=val' and also 'rattr=x'.
   8  *  copy 'x' into 'buf' and return the whole tuple.
   9  *
  10  *  return 0 if not found.
  11  */
  12 char*
  13 ndbgetvalue(Ndb *db, Ndbs *s, char *attr, char *val, char *rattr, Ndbtuple **pp)
  14 {
  15         Ndbtuple *t, *nt;
  16         char *rv;
  17         Ndbs temps;
  18
  19         if(s == nil)
  20                 s = &temps;
  21         if(pp)
  22                 *pp = nil;
  23         t = ndbsearch(db, s, attr, val);
  24         while(t){
  25                 /* first look on same line (closer binding) */
  26                 nt = s->t;
  27                 for(;;){
  28                         if(strcmp(rattr, nt->attr) == 0){
  29                                 rv = strdup(nt->val);
  30                                 if(pp != nil)
  31                                         *pp = t;
  32                                 else
  33                                         ndbfree(t);
  34                                 return rv;
  35                         }
  36                         nt = nt->line;
  37                         if(nt == s->t)
  38                                 break;
  39                 }
  40                 /* search whole tuple */
  41                 for(nt = t; nt; nt = nt->entry){
  42                         if(strcmp(rattr, nt->attr) == 0){
  43                                 rv = strdup(nt->val);
  44                                 if(pp != nil)
  45                                         *pp = t;
  46                                 else
  47                                         ndbfree(t);
  48                                 return rv;
  49                         }
  50                 }
  51                 ndbfree(t);
  52                 t = ndbsnext(s, attr, val);
  53         }
  54         return nil;
  55 }
  56
  57 Ndbtuple*
  58 ndbgetval(Ndb *db, Ndbs *s, char *attr, char *val, char *rattr, char *buf)
  59 {
  60         Ndbtuple *t;
  61         char *p;
  62
  63         p = ndbgetvalue(db, s, attr, val, rattr, &t);
  64         if(p == nil){
  65                 if(buf != nil)
  66                         *buf = 0;
  67         } else {
  68                 if(buf != nil){
  69                         strncpy(buf, p, Ndbvlen-1);
  70                         buf[Ndbvlen-1] = 0;
  71                 }
  72                 free(p);
  73         }
  74         ndbsetmalloctag(t, getcallerpc(&db));
  75         return t;
  76 }