+static char *sun_prep(struct sockaddr_un *sun) {
+ const char *dir=getenv("UDP_PRELOAD_DIR");
+ if (!dir) { errno=ECHILD; return 0; }
+
+ memset(sun,0,sizeof(*sun));
+ sun->sun_family=AF_UNIX;
+ int dl = strlen(dir);
+ if (dl + 1 + ADDRPORTSTRLEN + 1 > sizeof(sun->sun_path)) {
+ errno=ENAMETOOLONG; return 0;
+ }
+ strcpy(sun->sun_path,dir);
+ char *p=sun->sun_path+dl;
+ *p++='/';
+ return p;
+}
+