-/* Initialization for access to a mmap'd malloc managed region.
- Copyright 1992, 2000 Free Software Foundation, Inc.
-
- Contributed by Fred Fish at Cygnus Support. fnf@cygnus.com
-
-This file is part of the GNU C Library.
-
-The GNU C Library is free software; you can redistribute it and/or
-modify it under the terms of the GNU Library General Public License as
-published by the Free Software Foundation; either version 2 of the
-License, or (at your option) any later version.
-
-The GNU C Library is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-Library General Public License for more details.
-
-You should have received a copy of the GNU Library General Public
-License along with the GNU C Library; see the file COPYING.LIB. If
-not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
-
-#include <sys/types.h>
-#include <fcntl.h> /* After sys/types.h, at least for dpx/2. */
-#include <sys/stat.h>
-#include <string.h>
-#ifdef HAVE_UNISTD_H
-#include <unistd.h> /* Prototypes for lseek */
-#endif
-#include "mmprivate.h"
-#include "xbt/ex.h"
-
-#ifndef SEEK_SET
-#define SEEK_SET 0
-#endif
-
-
-/* Forward declarations/prototypes for local functions */
-
-static struct mdesc *reuse(int fd);
-
-/* Initialize access to a mmalloc managed region.
-
- If FD is a valid file descriptor for an open file then data for the
- mmalloc managed region is mapped to that file, otherwise an anonymous
- map is used if supported by the underlying OS. In case of running in
- an OS without support of anonymous mappings then "/dev/zero" is used
- and in both cases the data will not exist in any filesystem object.
-
- If the open file corresponding to FD is from a previous use of
- mmalloc and passes some basic sanity checks to ensure that it is
- compatible with the current mmalloc package, then its data is
- mapped in and is immediately accessible at the same addresses in
- the current process as the process that created the file (ignoring
- the BASEADDR parameter).
-
- For non valid FDs or empty files ones the mapping is established
- starting at the specified address BASEADDR in the process address
- space.
-
- The provided BASEADDR should be choosed carefully in order to avoid
- bumping into existing mapped regions or future mapped regions.
-
- On success, returns a "malloc descriptor" which is used in subsequent
- calls to other mmalloc package functions. It is explicitly "void *"
- so that users of the package don't have to worry about the actual
- implementation details.
-
- On failure returns NULL. */
-
-xbt_mheap_t mmalloc_attach(int fd, void *baseaddr)
-{
- 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)
- return ((void *) reuse(fd));
- }
-
- /* If the user provided NULL BASEADDR then fail */
- if (baseaddr == NULL)
- return (NULL);
-
- /* We start off with the malloc descriptor allocated on the stack, until
- we build it up enough to call _mmalloc_mmap_morecore() to allocate the
- first page of the region and copy it there. Ensure that it is zero'd and
- then initialize the fields that we know values for. */
-
- mdp = &mtemp;
- memset((char *) mdp, 0, sizeof(mtemp));
- strncpy(mdp->magic, MMALLOC_MAGIC, MMALLOC_MAGIC_SIZE);
- mdp->headersize = sizeof(mtemp);
- mdp->version = MMALLOC_VERSION;
- mdp->fd = fd;
- mdp->base = mdp->breakval = mdp->top = baseaddr;
- mdp->next_mdesc = NULL;
- mdp->refcount = 1;
-
- /* If we have not been passed a valid open file descriptor for the file
- to map to, then we go for an anonymous map */
-
- if (mdp->fd < 0){
- mdp->flags |= MMALLOC_ANONYMOUS;
- sem_init(&mdp->sem, 0, 1);
- }else{
- sem_init(&mdp->sem, 1, 1);
- }
-
- /* If we have not been passed a valid open file descriptor for the file
- to map to, then open /dev/zero and use that to map to. */
-
- /* Now try to map in the first page, copy the malloc descriptor structure
- there, and arrange to return a pointer to this new copy. If the mapping
- fails, then close the file descriptor if it was opened by us, and arrange
- to return a NULL. */
-
- if ((mbase = mmorecore(mdp, sizeof(mtemp))) != NULL) {
- memcpy(mbase, mdp, sizeof(mtemp));
- } else {
- THROWF(system_error,0,"morecore failed to get some memory!");
- }
-
- /* Add the new heap to the linked list of heaps attached by mmalloc */
- if(__mmalloc_default_mdp){
- mdp = __mmalloc_default_mdp;
- while(mdp->next_mdesc)
- mdp = mdp->next_mdesc;
-
- LOCK(mdp);
- mdp->next_mdesc = (struct mdesc *)mbase;
- UNLOCK(mdp);
- }
-
- return mbase;
-}
-
-/* Given an valid file descriptor on an open file, test to see if that file
- is a valid mmalloc produced file, and if so, attempt to remap it into the
- current process at the same address to which it was previously mapped.
-
- 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. */
-
-static struct mdesc *reuse(int fd)
-{
- struct mdesc mtemp;
- struct mdesc *mdp = NULL, *mdptemp = NULL;
-
- if (lseek(fd, 0L, SEEK_SET) != 0)
- return NULL;
- if (read(fd, (char *) &mtemp, sizeof(mtemp)) != sizeof(mtemp))
- return NULL;
- if (mtemp.headersize != sizeof(mtemp))
- return NULL;
- if (strcmp(mtemp.magic, MMALLOC_MAGIC) != 0)
- return NULL;
- if (mtemp.version > MMALLOC_VERSION)
- return NULL;
-
- mtemp.fd = fd;
- if (__mmalloc_remap_core(&mtemp) == mtemp.base) {
- mdp = (struct mdesc *) mtemp.base;
- mdp->fd = fd;
- if(!mdp->refcount){
- sem_init(&mdp->sem, 1, 1);
- mdp->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 = mdp;
- UNLOCK(mdptemp);
-
- return (mdp);
-}
