Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/stdlib/atexit.c	Lines:	61	87	70.1 %
Date:	2017-11-13	Branches:	32	74	43.2 %


/*	$OpenBSD: atexit.c,v 1.24 2015/11/10 04:14:03 guenther Exp $ */
/*
 * Copyright (c) 2002 Daniel Hartmeier
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *    - Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    - Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials provided
 *      with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <sys/types.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "atexit.h"
#include "atfork.h"
#include "thread_private.h"

struct atexit *__atexit;
static int restartloop;

/* define and initialize the list */
struct atfork_listhead _atfork_list = TAILQ_HEAD_INITIALIZER(_atfork_list);


/*
 * Function pointers are stored in a linked list of pages. The list
 * is initially empty, and pages are allocated on demand. The first
 * function pointer in the first allocated page (the last one in
 * the linked list) is reserved for the cleanup function.
 *
 * Outside the following functions, all pages are mprotect()'ed
 * to prevent unintentional/malicious corruption.
 */

/*
 * Register a function to be performed at exit or when a shared object
 * with the given dso handle is unloaded dynamically.  Also used as
 * the backend for atexit().  For more info on this API, see:
 *
 *	http://www.codesourcery.com/cxx-abi/abi.html#dso-dtor
 */
int
__cxa_atexit(void (*func)(void *), void *arg, void *dso)
{
	struct atexit *p = __atexit;
	struct atexit_fn *fnp;
	int pgsize = getpagesize();
	int ret = -1;

	if (pgsize < sizeof(*p))
		return (-1);
	_ATEXIT_LOCK();
	p = __atexit;
	if (p != NULL) {
		if (p->ind + 1 >= p->max)
			p = NULL;
		else if (mprotect(p, pgsize, PROT_READ | PROT_WRITE))
			goto unlock;
	}
	if (p == NULL) {
		p = mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
		    MAP_ANON | MAP_PRIVATE, -1, 0);
		if (p == MAP_FAILED)
			goto unlock;
		if (__atexit == NULL) {
			memset(&p->fns[0], 0, sizeof(p->fns[0]));
			p->ind = 1;
		} else
			p->ind = 0;
		p->max = (pgsize - ((char *)&p->fns[0] - (char *)p)) /
		    sizeof(p->fns[0]);
		p->next = __atexit;
		__atexit = p;
	}
	fnp = &p->fns[p->ind++];
	fnp->fn_ptr = func;
	fnp->fn_arg = arg;
	fnp->fn_dso = dso;
	if (mprotect(p, pgsize, PROT_READ))
		goto unlock;
	restartloop = 1;
	ret = 0;
unlock:
	_ATEXIT_UNLOCK();
	return (ret);
}
DEF_STRONG(__cxa_atexit);

/*
 * Copy of atexit() used by libc and anything staticly linked into the
 * executable.  This passes NULL for the dso, so the callbacks are only
 * invoked by exit() and not dlclose()
 */
int
atexit(void (*fn)(void))
{
	return (__cxa_atexit((void (*)(void *))fn, NULL, NULL));
}
DEF_STRONG(atexit);

/*
 * Call all handlers registered with __cxa_atexit() for the shared
 * object owning 'dso'.
 * Note: if 'dso' is NULL, then all remaining handlers are called.
 */
void
__cxa_finalize(void *dso)
{
	struct atexit *p, *q;
	struct atexit_fn fn;
	int n, pgsize = getpagesize();
	static int call_depth;

	_ATEXIT_LOCK();
	call_depth++;

restart:
	restartloop = 0;
	for (p = __atexit; p != NULL; p = p->next) {
		for (n = p->ind; --n >= 0;) {
			if (p->fns[n].fn_ptr == NULL)
				continue;	/* already called */
			if (dso != NULL && dso != p->fns[n].fn_dso)
				continue;	/* wrong DSO */

			/*
			 * Mark handler as having been already called to avoid
			 * dupes and loops, then call the appropriate function.
			 */
			fn = p->fns[n];
			if (mprotect(p, pgsize, PROT_READ | PROT_WRITE) == 0) {
				p->fns[n].fn_ptr = NULL;
				mprotect(p, pgsize, PROT_READ);
			}
			_ATEXIT_UNLOCK();
			(*fn.fn_ptr)(fn.fn_arg);
			_ATEXIT_LOCK();
			if (restartloop)
				goto restart;
		}
	}

	call_depth--;

	/*
	 * If called via exit(), unmap the pages since we have now run
	 * all the handlers.  We defer this until calldepth == 0 so that
	 * we don't unmap things prematurely if called recursively.
	 */
	if (dso == NULL && call_depth == 0) {
		for (p = __atexit; p != NULL; ) {
			q = p;
			p = p->next;
			munmap(q, pgsize);
		}
		__atexit = NULL;
	}
	_ATEXIT_UNLOCK();

	/*
	 * If unloading a DSO, unregister any atfork handlers registered
	 * by it.  Skip the locking if the list is currently empty.
	 */
	if (dso != NULL && TAILQ_FIRST(&_atfork_list) != NULL) {
		struct atfork_fn *af, *afnext;

		_ATFORK_LOCK();
		TAILQ_FOREACH_SAFE(af, &_atfork_list, fn_next, afnext)
			if (af->fn_dso == dso) {
				TAILQ_REMOVE(&_atfork_list, af, fn_next);
				free(af);
			}
		_ATFORK_UNLOCK();

	}
}
DEF_STRONG(__cxa_finalize);

/*
 * Register the cleanup function
 */
void
__atexit_register_cleanup(void (*func)(void))
{
	struct atexit *p;
	int pgsize = getpagesize();

	if (pgsize < sizeof(*p))
		return;
	_ATEXIT_LOCK();
	p = __atexit;
	while (p != NULL && p->next != NULL)
		p = p->next;
	if (p == NULL) {
		p = mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
		    MAP_ANON | MAP_PRIVATE, -1, 0);
		if (p == MAP_FAILED)
			goto unlock;
		p->ind = 1;
		p->max = (pgsize - ((char *)&p->fns[0] - (char *)p)) /
		    sizeof(p->fns[0]);
		p->next = NULL;
		__atexit = p;
	} else {
		if (mprotect(p, pgsize, PROT_READ | PROT_WRITE))
			goto unlock;
	}
	p->fns[0].fn_ptr = (void (*)(void *))func;
	p->fns[0].fn_arg = NULL;
	p->fns[0].fn_dso = NULL;
	mprotect(p, pgsize, PROT_READ);
	restartloop = 1;
unlock:
	_ATEXIT_UNLOCK();
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: atexit.c,v 1.24 2015/11/10 04:14:03 guenther Exp $ */
2			/*
3			* Copyright (c) 2002 Daniel Hartmeier
4			* All rights reserved.
5			*
6			* Redistribution and use in source and binary forms, with or without
7			* modification, are permitted provided that the following conditions
8			* are met:
9			*
10			* - Redistributions of source code must retain the above copyright
11			* notice, this list of conditions and the following disclaimer.
12			* - Redistributions in binary form must reproduce the above
13			* copyright notice, this list of conditions and the following
14			* disclaimer in the documentation and/or other materials provided
15			* with the distribution.
16			*
17			* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18			* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19			* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20			* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
21			* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22			* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23			* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24			* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25			* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
27			* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28			* POSSIBILITY OF SUCH DAMAGE.
29			*
30			*/
31
32			#include <sys/types.h>
33			#include <sys/mman.h>
34			#include <stdlib.h>
35			#include <string.h>
36			#include <unistd.h>
37			#include "atexit.h"
38			#include "atfork.h"
39			#include "thread_private.h"
40
41			struct atexit *__atexit;
42			static int restartloop;
43
44			/* define and initialize the list */
45			struct atfork_listhead _atfork_list = TAILQ_HEAD_INITIALIZER(_atfork_list);
46
47
48			/*
49			* Function pointers are stored in a linked list of pages. The list
50			* is initially empty, and pages are allocated on demand. The first
51			* function pointer in the first allocated page (the last one in
52			* the linked list) is reserved for the cleanup function.
53			*
54			* Outside the following functions, all pages are mprotect()'ed
55			* to prevent unintentional/malicious corruption.
56			*/
57
58			/*
59			* Register a function to be performed at exit or when a shared object
60			* with the given dso handle is unloaded dynamically. Also used as
61			* the backend for atexit(). For more info on this API, see:
62			*
63			* http://www.codesourcery.com/cxx-abi/abi.html#dso-dtor
64			*/
65			int
66			__cxa_atexit(void (func)(void ), void arg, void dso)
67			{
68			struct atexit *p = __atexit;
69			struct atexit_fn *fnp;
70		1179786	int pgsize = getpagesize();
71			int ret = -1;
72
73	✗✓	589893	if (pgsize < sizeof(*p))
74			return (-1);
75	✗✓	589893	_ATEXIT_LOCK();
76		589893	p = __atexit;
77	✓✓	589893	if (p != NULL) {
78	✓✓	589878	if (p->ind + 1 >= p->max)
79		3483	p = NULL;
80	✓✗	586395	else if (mprotect(p, pgsize, PROT_READ \| PROT_WRITE))
81			goto unlock;
82			}
83	✓✓	589893	if (p == NULL) {
84		3498	p = mmap(NULL, pgsize, PROT_READ \| PROT_WRITE,
85			MAP_ANON \| MAP_PRIVATE, -1, 0);
86	✓✗	3498	if (p == MAP_FAILED)
87			goto unlock;
88	✓✓	3498	if (__atexit == NULL) {
89		15	memset(&p->fns[0], 0, sizeof(p->fns[0]));
90			p->ind = 1;
91		15	} else
92			p->ind = 0;
93		3498	p->max = (pgsize - ((char )&p->fns[0] - (char )p)) /
94			sizeof(p->fns[0]);
95		3498	p->next = __atexit;
96		3498	__atexit = p;
97		3498	}
98		589893	fnp = &p->fns[p->ind++];
99		589893	fnp->fn_ptr = func;
100		589893	fnp->fn_arg = arg;
101		589893	fnp->fn_dso = dso;
102	✓✗	589893	if (mprotect(p, pgsize, PROT_READ))
103			goto unlock;
104		589893	restartloop = 1;
105		589893	ret = 0;
106			unlock:
107	✗✓	589893	_ATEXIT_UNLOCK();
108		589893	return (ret);
109		589893	}
110			DEF_STRONG(__cxa_atexit);
111
112			/*
113			* Copy of atexit() used by libc and anything staticly linked into the
114			* executable. This passes NULL for the dso, so the callbacks are only
115			* invoked by exit() and not dlclose()
116			*/
117			int
118			atexit(void (*fn)(void))
119			{
120		1179786	return (__cxa_atexit((void ()(void ))fn, NULL, NULL));
121			}
122			DEF_STRONG(atexit);
123
124			/*
125			* Call all handlers registered with __cxa_atexit() for the shared
126			* object owning 'dso'.
127			* Note: if 'dso' is NULL, then all remaining handlers are called.
128			*/
129			void
130			__cxa_finalize(void *dso)
131			{
132			struct atexit p, q;
133			struct atexit_fn fn;
134		30	int n, pgsize = getpagesize();
135			static int call_depth;
136
137	✗✓	15	_ATEXIT_LOCK();
138		15	call_depth++;
139
140			restart:
141		15	restartloop = 0;
142	✓✗	6996	for (p = __atexit; p != NULL; p = p->next) {
143	✓✓	1186692	for (n = p->ind; --n >= 0;) {
144	✗✓	589863	if (p->fns[n].fn_ptr == NULL)
145			continue; /* already called */
146	✗✓✗✗	589863	if (dso != NULL && dso != p->fns[n].fn_dso)
147			continue; /* wrong DSO */
148
149			/*
150			* Mark handler as having been already called to avoid
151			* dupes and loops, then call the appropriate function.
152			*/
153		589863	fn = p->fns[n];
154	✓✗	589863	if (mprotect(p, pgsize, PROT_READ \| PROT_WRITE) == 0) {
155		589863	p->fns[n].fn_ptr = NULL;
156		589863	mprotect(p, pgsize, PROT_READ);
157		589863	}
158	✗✓	589863	_ATEXIT_UNLOCK();
159		589848	(*fn.fn_ptr)(fn.fn_arg);
160	✗✓	589848	_ATEXIT_LOCK();
161	✗✓	589848	if (restartloop)
162			goto restart;
163			}
164			}
165
166			call_depth--;
167
168			/*
169			* If called via exit(), unmap the pages since we have now run
170			* all the handlers. We defer this until calldepth == 0 so that
171			* we don't unmap things prematurely if called recursively.
172			*/
173			if (dso == NULL && call_depth == 0) {
174			for (p = __atexit; p != NULL; ) {
175			q = p;
176			p = p->next;
177			munmap(q, pgsize);
178			}
179			__atexit = NULL;
180			}
181			_ATEXIT_UNLOCK();
182
183			/*
184			* If unloading a DSO, unregister any atfork handlers registered
185			* by it. Skip the locking if the list is currently empty.
186			*/
187			if (dso != NULL && TAILQ_FIRST(&_atfork_list) != NULL) {
188			struct atfork_fn af, afnext;
189
190			_ATFORK_LOCK();
191			TAILQ_FOREACH_SAFE(af, &_atfork_list, fn_next, afnext)
192			if (af->fn_dso == dso) {
193			TAILQ_REMOVE(&_atfork_list, af, fn_next);
194			free(af);
195			}
196			_ATFORK_UNLOCK();
197
198			}
199			}
200			DEF_STRONG(__cxa_finalize);
201
202			/*
203			* Register the cleanup function
204			*/
205			void
206			__atexit_register_cleanup(void (*func)(void))
207			{
208			struct atexit *p;
209		36	int pgsize = getpagesize();
210
211	✗✓	18	if (pgsize < sizeof(*p))
212			return;
213	✗✓	18	_ATEXIT_LOCK();
214		18	p = __atexit;
215	✓✗✓✓	4716	while (p != NULL && p->next != NULL)
216		1161	p = p->next;
217	✗✓	18	if (p == NULL) {
218			p = mmap(NULL, pgsize, PROT_READ \| PROT_WRITE,
219			MAP_ANON \| MAP_PRIVATE, -1, 0);
220			if (p == MAP_FAILED)
221			goto unlock;
222			p->ind = 1;
223			p->max = (pgsize - ((char )&p->fns[0] - (char )p)) /
224			sizeof(p->fns[0]);
225			p->next = NULL;
226			__atexit = p;
227			} else {
228	✓✗	18	if (mprotect(p, pgsize, PROT_READ \| PROT_WRITE))
229			goto unlock;
230			}
231		18	p->fns[0].fn_ptr = (void ()(void ))func;
232		18	p->fns[0].fn_arg = NULL;
233		18	p->fns[0].fn_dso = NULL;
234		18	mprotect(p, pgsize, PROT_READ);
235		18	restartloop = 1;
236			unlock:
237	✗✓	18	_ATEXIT_UNLOCK();
238		36	}