From ea72182faa98806557ba6170604b3ce6ca5c9eda Mon Sep 17 00:00:00 2001 From: "Todd C. Miller" Date: Mon, 3 Sep 2007 14:40:17 +0000 Subject: 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. --- lib/libc/stdlib/abort.c | 9 +++-- lib/libc/stdlib/atexit.c | 93 +++++++++++++++++++++++++++++++++++++++++++----- lib/libc/stdlib/atexit.h | 14 ++++++-- lib/libc/stdlib/exit.c | 22 ++++-------- 4 files changed, 108 insertions(+), 30 deletions(-) (limited to 'lib/libc/stdlib') diff --git a/lib/libc/stdlib/abort.c b/lib/libc/stdlib/abort.c index 072a9fa8c11..244e3b28aa2 100644 --- a/lib/libc/stdlib/abort.c +++ b/lib/libc/stdlib/abort.c @@ -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. * All rights reserved. @@ -54,11 +54,14 @@ abort(void) * POSIX requires we flush stdio buffers on abort */ if (cleanup_called == 0) { + /* the cleanup routine lives in fns[0] on the last page */ while (p != NULL && p->next != NULL) 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; - (*p->fns[0])(); + (*p->fns[0].fn_ptr.std_func)(); } } diff --git a/lib/libc/stdlib/atexit.c b/lib/libc/stdlib/atexit.c index 50f8ec93728..ebf5f8775c7 100644 --- a/lib/libc/stdlib/atexit.c +++ b/lib/libc/stdlib/atexit.c @@ -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 * All rights reserved. @@ -45,17 +45,22 @@ struct atexit *__atexit; * function pointer in the first allocated page (the last one in * 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. */ /* - * 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 -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 ret = -1; @@ -75,7 +80,7 @@ atexit(void (*fn)(void)) if (p == MAP_FAILED) goto unlock; if (__atexit == NULL) { - p->fns[0] = NULL; + memset(&p->fns[0], 0, sizeof(p->fns[0])); p->ind = 1; } else p->ind = 0; @@ -86,7 +91,10 @@ atexit(void (*fn)(void)) if (__atexit_invalid) __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)) goto unlock; ret = 0; @@ -95,11 +103,76 @@ unlock: 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 */ void -__atexit_register_cleanup(void (*fn)(void)) +__atexit_register_cleanup(void (*func)(void)) { struct atexit *p; int pgsize = getpagesize(); @@ -126,7 +199,9 @@ __atexit_register_cleanup(void (*fn)(void)) if (mprotect(p, pgsize, PROT_READ | PROT_WRITE)) 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); unlock: _ATEXIT_UNLOCK(); diff --git a/lib/libc/stdlib/atexit.h b/lib/libc/stdlib/atexit.h index 21b0c2e5327..1b23565dd06 100644 --- a/lib/libc/stdlib/atexit.h +++ b/lib/libc/stdlib/atexit.h @@ -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 @@ -34,8 +34,18 @@ struct atexit { struct atexit *next; /* next in list */ int ind; /* next index in this table */ 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 struct atexit *__atexit; /* points to head of LIFO stack */ + +int __cxa_atexit(void (*)(void *), void *, void *); +void __cxa_finalize(void *); diff --git a/lib/libc/stdlib/exit.c b/lib/libc/stdlib/exit.c index 90b7d5adc2d..83fe3d2de56 100644 --- a/lib/libc/stdlib/exit.c +++ b/lib/libc/stdlib/exit.c @@ -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. * All rights reserved. @@ -50,20 +50,10 @@ int __isthreaded = 0; void 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); } -- cgit v1.2.3