mdw@git.distorted.org.uk Git - qmail/blob - cdb_seek.c

   1 #include <sys/types.h>
   2 #include <errno.h>
   3 extern int errno;
   4 #include "cdb.h"
   5
   6 #ifndef SEEK_SET
   7 #define SEEK_SET 0
   8 #endif
   9
  10 int cdb_bread(fd,buf,len)
  11 int fd;
  12 char *buf;
  13 int len;
  14 {
  15   int r;
  16   while (len > 0) {
  17     do
  18       r = read(fd,buf,len);
  19     while ((r == -1) && (errno == EINTR));
  20     if (r == -1) return -1;
  21     if (r == 0) { errno = EIO; return -1; }
  22     buf += r;
  23     len -= r;
  24   }
  25   return 0;
  26 }
  27
  28 static int match(fd,key,len)
  29 int fd;
  30 char *key;
  31 unsigned int len;
  32 {
  33   char buf[32];
  34   int n;
  35   int i;
  36
  37   while (len > 0) {
  38     n = sizeof(buf);
  39     if (n > len) n = len;
  40     if (cdb_bread(fd,buf,n) == -1) return -1;
  41     for (i = 0;i < n;++i) if (buf[i] != key[i]) return 0;
  42     key += n;
  43     len -= n;
  44   }
  45   return 1;
  46 }
  47
  48 int cdb_seek(fd,key,len,dlen)
  49 int fd;
  50 char *key;
  51 unsigned int len;
  52 uint32 *dlen;
  53 {
  54   char packbuf[8];
  55   uint32 pos;
  56   uint32 h;
  57   uint32 lenhash;
  58   uint32 h2;
  59   uint32 loop;
  60   uint32 poskd;
  61
  62   h = cdb_hash(key,len);
  63
  64   pos = 8 * (h & 255);
  65   if (lseek(fd,(off_t) pos,SEEK_SET) == -1) return -1;
  66
  67   if (cdb_bread(fd,packbuf,8) == -1) return -1;
  68
  69   pos = cdb_unpack(packbuf);
  70   lenhash = cdb_unpack(packbuf + 4);
  71
  72   if (!lenhash) return 0;
  73   h2 = (h >> 8) % lenhash;
  74
  75   for (loop = 0;loop < lenhash;++loop) {
  76     if (lseek(fd,(off_t) (pos + 8 * h2),SEEK_SET) == -1) return -1;
  77     if (cdb_bread(fd,packbuf,8) == -1) return -1;
  78     poskd = cdb_unpack(packbuf + 4);
  79     if (!poskd) return 0;
  80     if (cdb_unpack(packbuf) == h) {
  81       if (lseek(fd,(off_t) poskd,SEEK_SET) == -1) return -1;
  82       if (cdb_bread(fd,packbuf,8) == -1) return -1;
  83       if (cdb_unpack(packbuf) == len)
  84         switch(match(fd,key,len)) {
  85           case -1:
  86             return -1;
  87           case 1:
  88             *dlen = cdb_unpack(packbuf + 4);
  89             return 1;
  90         }
  91     }
  92     if (++h2 == lenhash) h2 = 0;
  93   }
  94   return 0;
  95 }