Revision 9cf85473209ea8ae2b56c13145c4704d12ee1374 authored by Filip Hejsek on 28 January 2024, 04:09:17 UTC, committed by Johannes Schindelin on 17 April 2024, 20:30:01 UTC
While it is expected to have several git dirs within the `.git/modules/` tree, it is important that they do not interfere with each other. For example, if one submodule was called "captain" and another submodule "captain/hooks", their respective git dirs would clash, as they would be located in `.git/modules/captain/` and `.git/modules/captain/hooks/`, respectively, i.e. the latter's files could clash with the actual Git hooks of the former. To prevent these clashes, and in particular to prevent hooks from being written and then executed as part of a recursive clone, we introduced checks as part of the fix for CVE-2019-1387 in a8dee3ca61 (Disallow dubiously-nested submodule git directories, 2019-10-01). It is currently possible to bypass the check for clashing submodule git dirs in two ways: 1. parallel cloning 2. checkout --recurse-submodules Let's check not only before, but also after parallel cloning (and before checking out the submodule), that the git dir is not clashing with another one, otherwise fail. This addresses the parallel cloning issue. As to the parallel checkout issue: It requires quite a few manual steps to create clashing git dirs because Git itself would refuse to initialize the inner one, as demonstrated by the test case. Nevertheless, let's teach the recursive checkout (namely, the `submodule_move_head()` function that is used by the recursive checkout) to be careful to verify that it does not use a clashing git dir, and if it does, disable it (by deleting the `HEAD` file so that subsequent Git calls won't recognize it as a git dir anymore). Note: The parallel cloning test case contains a `cat err` that proved to be highly useful when analyzing the racy nature of the operation (the operation can fail with three different error messages, depending on timing), and was left on purpose to ease future debugging should the need arise. Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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list.h
/*
* Copyright (C) 2002 Free Software Foundation, Inc.
* (originally part of the GNU C Library and Userspace RCU)
* Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
*
* Copyright (C) 2009 Pierre-Marc Fournier
* Conversion to RCU list.
* Copyright (C) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see
* <http://www.gnu.org/licenses/>.
*/
#ifndef LIST_H
#define LIST_H 1
/*
* The definitions of this file are adopted from those which can be
* found in the Linux kernel headers to enable people familiar with the
* latter find their way in these sources as well.
*/
/* Basic type for the double-link list. */
struct list_head {
struct list_head *next, *prev;
};
/* avoid conflicts with BSD-only sys/queue.h */
#undef LIST_HEAD
/* Define a variable with the head and tail of the list. */
#define LIST_HEAD(name) \
struct list_head name = { &(name), &(name) }
/* Initialize a new list head. */
#define INIT_LIST_HEAD(ptr) \
(ptr)->next = (ptr)->prev = (ptr)
#define LIST_HEAD_INIT(name) { \
.next = &(name), \
.prev = &(name), \
}
/* Add new element at the head of the list. */
static inline void list_add(struct list_head *newp, struct list_head *head)
{
head->next->prev = newp;
newp->next = head->next;
newp->prev = head;
head->next = newp;
}
/* Add new element at the tail of the list. */
static inline void list_add_tail(struct list_head *newp, struct list_head *head)
{
head->prev->next = newp;
newp->next = head;
newp->prev = head->prev;
head->prev = newp;
}
/* Remove element from list. */
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
next->prev = prev;
prev->next = next;
}
/* Remove element from list. */
static inline void list_del(struct list_head *elem)
{
__list_del(elem->prev, elem->next);
}
/* Remove element from list, initializing the element's list pointers. */
static inline void list_del_init(struct list_head *elem)
{
list_del(elem);
INIT_LIST_HEAD(elem);
}
/* Delete from list, add to another list as head. */
static inline void list_move(struct list_head *elem, struct list_head *head)
{
__list_del(elem->prev, elem->next);
list_add(elem, head);
}
/* Replace an old entry. */
static inline void list_replace(struct list_head *old, struct list_head *newp)
{
newp->next = old->next;
newp->prev = old->prev;
newp->prev->next = newp;
newp->next->prev = newp;
}
/* Join two lists. */
static inline void list_splice(struct list_head *add, struct list_head *head)
{
/* Do nothing if the list which gets added is empty. */
if (add != add->next) {
add->next->prev = head;
add->prev->next = head->next;
head->next->prev = add->prev;
head->next = add->next;
}
}
/* Get typed element from list at a given position. */
#define list_entry(ptr, type, member) \
((type *) ((char *) (ptr) - offsetof(type, member)))
/* Get first entry from a list. */
#define list_first_entry(ptr, type, member) \
list_entry((ptr)->next, type, member)
/* Iterate forward over the elements of the list. */
#define list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
/*
* Iterate forward over the elements list. The list elements can be
* removed from the list while doing this.
*/
#define list_for_each_safe(pos, p, head) \
for (pos = (head)->next, p = pos->next; \
pos != (head); \
pos = p, p = pos->next)
/* Iterate backward over the elements of the list. */
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev; pos != (head); pos = pos->prev)
/*
* Iterate backwards over the elements list. The list elements can be
* removed from the list while doing this.
*/
#define list_for_each_prev_safe(pos, p, head) \
for (pos = (head)->prev, p = pos->prev; \
pos != (head); \
pos = p, p = pos->prev)
static inline int list_empty(struct list_head *head)
{
return head == head->next;
}
static inline void list_replace_init(struct list_head *old,
struct list_head *newp)
{
struct list_head *head = old->next;
list_del(old);
list_add_tail(newp, head);
INIT_LIST_HEAD(old);
}
/*
* This is exactly the same as a normal list_head, except that it can be
* declared volatile (e.g., if you have a list that may be accessed from signal
* handlers).
*/
struct volatile_list_head {
volatile struct volatile_list_head *next, *prev;
};
#define VOLATILE_LIST_HEAD(name) \
volatile struct volatile_list_head name = { &(name), &(name) }
static inline void __volatile_list_del(volatile struct volatile_list_head *prev,
volatile struct volatile_list_head *next)
{
next->prev = prev;
prev->next = next;
}
static inline void volatile_list_del(volatile struct volatile_list_head *elem)
{
__volatile_list_del(elem->prev, elem->next);
}
static inline int volatile_list_empty(volatile struct volatile_list_head *head)
{
return head == head->next;
}
static inline void volatile_list_add(volatile struct volatile_list_head *newp,
volatile struct volatile_list_head *head)
{
head->next->prev = newp;
newp->next = head->next;
newp->prev = head;
head->next = newp;
}
#endif /* LIST_H */
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