- struct mdesc mtemp;
- xbt_mheap_t mdp;
- void *mbase;
- struct stat sbuf;
-
- /* First check to see if FD is a valid file descriptor, and if so, see
- if the file has any current contents (size > 0). If it does, then
- attempt to reuse the file. If we can't reuse the file, either
- because it isn't a valid mmalloc produced file, was produced by an
- obsolete version, or any other reason, then we fail to attach to
- this file. */
-
- if (fd >= 0) {
- if (fstat(fd, &sbuf) < 0)
- return (NULL);
-
- else if (sbuf.st_size > 0) {
- /* We were given an valid file descriptor on an open file, so try to remap
- it into the current process at the same address to which it was previously
- mapped. It naturally have to pass some sanity checks for that.
-
- Note that we have to update the file descriptor number in the malloc-
- descriptor read from the file to match the current valid one, before
- trying to map the file in, and again after a successful mapping and
- after we've switched over to using the mapped in malloc descriptor
- rather than the temporary one on the stack.
-
- Once we've switched over to using the mapped in malloc descriptor, we
- have to update the pointer to the morecore function, since it almost
- certainly will be at a different address if the process reusing the
- mapped region is from a different executable.
-
- Also note that if the heap being remapped previously used the mmcheckf()
- routines, we need to update the hooks since their target functions
- will have certainly moved if the executable has changed in any way.
- We do this by calling mmcheckf() internally.
-
- Returns a pointer to the malloc descriptor if successful, or NULL if
- unsuccessful for some reason. */
-
- struct mdesc newmd;
- struct mdesc *mdptr = NULL, *mdptemp = NULL;
-
- if (lseek(fd, 0L, SEEK_SET) != 0)
- return NULL;
- if (read(fd, (char *) &newmd, sizeof(newmd)) != sizeof(newmd))
- return NULL;
- if (newmd.headersize != sizeof(newmd))
- return NULL;
- if (strcmp(newmd.magic, MMALLOC_MAGIC) != 0)
- return NULL;
- if (newmd.version > MMALLOC_VERSION)
- return NULL;
-
- newmd.fd = fd;
- if (__mmalloc_remap_core(&newmd) == newmd.base) {
- mdptr = (struct mdesc *) newmd.base;
- mdptr->fd = fd;
- if(!mdptr->refcount){
- pthread_mutex_init(&mdptr->mutex, NULL);
- mdptr->refcount++;
- }
- }
-
- /* Add the new heap to the linked list of heaps attached by mmalloc */
- mdptemp = __mmalloc_default_mdp;
- while(mdptemp->next_mdesc)
- mdptemp = mdptemp->next_mdesc;
-
- LOCK(mdptemp);
- mdptemp->next_mdesc = mdptr;
- UNLOCK(mdptemp);
-
- return mdptr;
- }
- }
-
- /* NULL is not a valid baseaddr as we cannot map anything there.
- C'mon, user. Think! */