1 /* _longjmp_unwind -- Clean up stack frames unwound by longjmp. Hurd version.
2 Copyright (C) 1995-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <jmpbuf-unwind.h>
20 #include <hurd/userlink.h>
21 #include <hurd/signal.h>
22 #include <hurd/sigpreempt.h>
23 #include <assert.h>
24 #include <stdint.h>
25
26
27 #ifndef _JMPBUF_UNWINDS
28 #error "<jmpbuf-unwind.h> fails to define _JMPBUF_UNWINDS"
29 #endif
30
31 static inline uintptr_t
demangle_ptr(uintptr_t x)32 demangle_ptr (uintptr_t x)
33 {
34 # ifdef PTR_DEMANGLE
35 PTR_DEMANGLE (x);
36 # endif
37 return x;
38 }
39
40 /* This function is called by `longjmp' (with its arguments) to restore
41 active resources to a sane state before the frames code using them are
42 jumped out of. */
43
44 void
_longjmp_unwind(jmp_buf env,int val)45 _longjmp_unwind (jmp_buf env, int val)
46 {
47 struct hurd_sigstate *ss = _hurd_self_sigstate ();
48 struct hurd_userlink *link;
49
50 /* All access to SS->active_resources must take place inside a critical
51 section where signal handlers cannot run. */
52 __spin_lock (&ss->lock);
53 assert (! __spin_lock_locked (&ss->critical_section_lock));
54 __spin_lock (&ss->critical_section_lock);
55
56 /* Remove local signal preemptors being unwound past. */
57 while (ss->preemptors
58 && _JMPBUF_UNWINDS (env[0].__jmpbuf, ss->preemptors, demangle_ptr))
59 ss->preemptors = ss->preemptors->next;
60
61 __spin_unlock (&ss->lock);
62
63 /* Iterate over the current thread's list of active resources.
64 Process the head portion of the list whose links reside
65 in stack frames being unwound by this jump. */
66
67 for (link = ss->active_resources;
68 link && _JMPBUF_UNWINDS (env[0].__jmpbuf, link, demangle_ptr);
69 link = link->thread.next)
70 /* Remove this link from the resource's users list,
71 since the frame using the resource is being unwound.
72 This call returns nonzero if that was the last user. */
73 if (_hurd_userlink_unlink (link))
74 /* One of the frames being unwound by the longjmp was the last user
75 of its resource. Call the cleanup function to deallocate it. */
76 (*link->cleanup) (link->cleanup_data, env, val);
77
78 _hurd_critical_section_unlock (ss);
79 }
80