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Add __cxa_atexit() support for gcc3. This provides support for shared object destructors called at dlclose() time. Inspired by similar changes in FreeBSD and NetBSD.

OPENBSD_4_3
millert 17 years ago
parent
commit
7726c7baf2
4 changed files with 108 additions and 30 deletions
  1. +6
    -3
      src/lib/libc/stdlib/abort.c
  2. +84
    -9
      src/lib/libc/stdlib/atexit.c
  3. +12
    -2
      src/lib/libc/stdlib/atexit.h
  4. +6
    -16
      src/lib/libc/stdlib/exit.c

+ 6
- 3
src/lib/libc/stdlib/abort.c View File

@ -1,4 +1,4 @@
/* $OpenBSD: abort.c,v 1.14 2005/08/08 08:05:36 espie Exp $ */
/* $OpenBSD: abort.c,v 1.15 2007/09/03 14:40:16 millert Exp $ */
/* /*
* Copyright (c) 1985 Regents of the University of California. * Copyright (c) 1985 Regents of the University of California.
* All rights reserved. * All rights reserved.
@ -54,11 +54,14 @@ abort(void)
* POSIX requires we flush stdio buffers on abort * POSIX requires we flush stdio buffers on abort
*/ */
if (cleanup_called == 0) { if (cleanup_called == 0) {
/* the cleanup routine lives in fns[0] on the last page */
while (p != NULL && p->next != NULL) while (p != NULL && p->next != NULL)
p = p->next; p = p->next;
if (p != NULL && p->fns[0] != NULL) {
/* the check for fn_dso == NULL is mostly paranoia */
if (p != NULL && p->fns[0].fn_dso == NULL &&
p->fns[0].fn_ptr.std_func != NULL) {
cleanup_called = 1; cleanup_called = 1;
(*p->fns[0])();
(*p->fns[0].fn_ptr.std_func)();
} }
} }


+ 84
- 9
src/lib/libc/stdlib/atexit.c View File

@ -1,4 +1,4 @@
/* $OpenBSD: atexit.c,v 1.12 2006/02/22 07:16:32 otto Exp $ */
/* $OpenBSD: atexit.c,v 1.13 2007/09/03 14:40:16 millert Exp $ */
/* /*
* Copyright (c) 2002 Daniel Hartmeier * Copyright (c) 2002 Daniel Hartmeier
* All rights reserved. * All rights reserved.
@ -45,17 +45,22 @@ struct atexit *__atexit;
* function pointer in the first allocated page (the last one in * function pointer in the first allocated page (the last one in
* the linked list) is reserved for the cleanup function. * the linked list) is reserved for the cleanup function.
* *
* Outside the following two functions, all pages are mprotect()'ed
* Outside the following functions, all pages are mprotect()'ed
* to prevent unintentional/malicious corruption. * to prevent unintentional/malicious corruption.
*/ */
/* /*
* Register a function to be performed at exit.
* 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 int
atexit(void (*fn)(void))
__cxa_atexit(void (*func)(void *), void *arg, void *dso)
{ {
struct atexit *p;
struct atexit *p = __atexit;
struct atexit_fn *fnp;
int pgsize = getpagesize(); int pgsize = getpagesize();
int ret = -1; int ret = -1;
@ -75,7 +80,7 @@ atexit(void (*fn)(void))
if (p == MAP_FAILED) if (p == MAP_FAILED)
goto unlock; goto unlock;
if (__atexit == NULL) { if (__atexit == NULL) {
p->fns[0] = NULL;
memset(&p->fns[0], 0, sizeof(p->fns[0]));
p->ind = 1; p->ind = 1;
} else } else
p->ind = 0; p->ind = 0;
@ -86,7 +91,10 @@ atexit(void (*fn)(void))
if (__atexit_invalid) if (__atexit_invalid)
__atexit_invalid = 0; __atexit_invalid = 0;
} }
p->fns[p->ind++] = fn;
fnp = &p->fns[p->ind++];
fnp->fn_ptr.cxa_func = func;
fnp->fn_arg = arg;
fnp->fn_dso = dso;
if (mprotect(p, pgsize, PROT_READ)) if (mprotect(p, pgsize, PROT_READ))
goto unlock; goto unlock;
ret = 0; ret = 0;
@ -95,11 +103,76 @@ unlock:
return (ret); return (ret);
} }
/*
* Register a function to be performed at exit.
*/
int
atexit(void (*func)(void))
{
return (__cxa_atexit((void (*)(void *))func, NULL, NULL));
}
/*
* 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;
if (__atexit_invalid)
return;
call_depth++;
for (p = __atexit; p != NULL; p = p->next) {
for (n = p->ind; --n >= 0;) {
if (p->fns[n].fn_ptr.cxa_func == 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.cxa_func = NULL;
mprotect(p, pgsize, PROT_READ);
}
if (dso != NULL)
(*fn.fn_ptr.cxa_func)(fn.fn_arg);
else
(*fn.fn_ptr.std_func)();
}
}
/*
* 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;
}
}
/* /*
* Register the cleanup function * Register the cleanup function
*/ */
void void
__atexit_register_cleanup(void (*fn)(void))
__atexit_register_cleanup(void (*func)(void))
{ {
struct atexit *p; struct atexit *p;
int pgsize = getpagesize(); int pgsize = getpagesize();
@ -126,7 +199,9 @@ __atexit_register_cleanup(void (*fn)(void))
if (mprotect(p, pgsize, PROT_READ | PROT_WRITE)) if (mprotect(p, pgsize, PROT_READ | PROT_WRITE))
goto unlock; goto unlock;
} }
p->fns[0] = fn;
p->fns[0].fn_ptr.std_func = func;
p->fns[0].fn_arg = NULL;
p->fns[0].fn_dso = NULL;
mprotect(p, pgsize, PROT_READ); mprotect(p, pgsize, PROT_READ);
unlock: unlock:
_ATEXIT_UNLOCK(); _ATEXIT_UNLOCK();


+ 12
- 2
src/lib/libc/stdlib/atexit.h View File

@ -1,4 +1,4 @@
/* $OpenBSD: atexit.h,v 1.6 2003/07/31 07:08:42 deraadt Exp $ */
/* $OpenBSD: atexit.h,v 1.7 2007/09/03 14:40:16 millert Exp $ */
/* /*
* Copyright (c) 2002 Daniel Hartmeier * Copyright (c) 2002 Daniel Hartmeier
@ -34,8 +34,18 @@ struct atexit {
struct atexit *next; /* next in list */ struct atexit *next; /* next in list */
int ind; /* next index in this table */ int ind; /* next index in this table */
int max; /* max entries >= ATEXIT_SIZE */ int max; /* max entries >= ATEXIT_SIZE */
void (*fns[1])(void); /* the table itself */
struct atexit_fn {
union {
void (*std_func)(void);
void (*cxa_func)(void *);
} fn_ptr;
void *fn_arg; /* argument for CXA callback */
void *fn_dso; /* shared module handle */
} fns[1]; /* the table itself */
}; };
extern int __atexit_invalid; extern int __atexit_invalid;
extern struct atexit *__atexit; /* points to head of LIFO stack */ extern struct atexit *__atexit; /* points to head of LIFO stack */
int __cxa_atexit(void (*)(void *), void *, void *);
void __cxa_finalize(void *);

+ 6
- 16
src/lib/libc/stdlib/exit.c View File

@ -1,4 +1,4 @@
/* $OpenBSD: exit.c,v 1.11 2005/08/08 08:05:36 espie Exp $ */
/* $OpenBSD: exit.c,v 1.12 2007/09/03 14:40:16 millert Exp $ */
/*- /*-
* Copyright (c) 1990 The Regents of the University of California. * Copyright (c) 1990 The Regents of the University of California.
* All rights reserved. * All rights reserved.
@ -50,20 +50,10 @@ int __isthreaded = 0;
void void
exit(int status) exit(int status)
{ {
struct atexit *p, *q;
int n, pgsize = getpagesize();
if (!__atexit_invalid) {
p = __atexit;
while (p != NULL) {
for (n = p->ind; --n >= 0;)
if (p->fns[n] != NULL)
(*p->fns[n])();
q = p;
p = p->next;
munmap(q, pgsize);
}
}
/* cleanup, if registered, was called through fns[0] in the last page */
/*
* Call functions registered by atexit() or _cxa_atexit()
* (including the stdio cleanup routine) and then _exit().
*/
__cxa_finalize(NULL);
_exit(status); _exit(status);
} }

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