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| author | Paul Eggert <eggert@cs.ucla.edu> | 2011-06-20 14:59:13 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2011-06-20 15:14:58 -0700 |
| commit | 3c4ad6125cf33faf3cc090b4232d35f3866b9799 (patch) | |
| tree | ee2ab39310dbfab4e2a1f9ee9a97f5beeec9c4ca /lib/c-stack.c | |
| parent | d80aff0ae74993962a24f205a356ffae59eab5be (diff) | |
| download | gnulib-3c4ad6125cf33faf3cc090b4232d35f3866b9799.tar.gz | |
c-stack: stop worrying about stack direction
* lib/c-stack.c (find_stack_direction): Remove.
(segv_handler): Don't worry about stack direction growth, as it's
too much of a pain to configure this correctly, given how compilers
are optimizing-away our stack-growth detection code. Instead, assume
that any access to just before or just after the stack is OK.
* m4/c-stack.m4 (AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC):
Don't require AC_FUNC_ALLOCA; no longer needed.
Diffstat (limited to 'lib/c-stack.c')
| -rw-r--r-- | lib/c-stack.c | 25 |
1 files changed, 3 insertions, 22 deletions
diff --git a/lib/c-stack.c b/lib/c-stack.c index 7f0f488456..e48b97c3b7 100644 --- a/lib/c-stack.c +++ b/lib/c-stack.c @@ -223,22 +223,6 @@ c_stack_action (void (*action) (int)) #elif HAVE_SIGALTSTACK && HAVE_DECL_SIGALTSTACK && HAVE_STACK_OVERFLOW_HANDLING -/* Direction of the C runtime stack. This function is - async-signal-safe. */ - -# if STACK_DIRECTION -# define find_stack_direction(ptr) STACK_DIRECTION -# else -# if ! SIGINFO_WORKS || HAVE_XSI_STACK_OVERFLOW_HEURISTIC -static int -find_stack_direction (char const *addr) -{ - char dummy; - return ! addr ? find_stack_direction (&dummy) : addr < &dummy ? 1 : -1; -} -# endif -# endif - # if SIGINFO_WORKS /* Handle a segmentation violation and exit. This function is @@ -266,17 +250,14 @@ segv_handler (int signo, siginfo_t *info, if (0 < info->si_code) { /* If the faulting address is within the stack, or within one - page of the stack end, assume that it is a stack - overflow. */ + page of the stack, assume that it is a stack overflow. */ ucontext_t const *user_context = context; char const *stack_base = user_context->uc_stack.ss_sp; size_t stack_size = user_context->uc_stack.ss_size; char const *faulting_address = info->si_addr; - size_t s = faulting_address - stack_base; size_t page_size = sysconf (_SC_PAGESIZE); - if (find_stack_direction (NULL) < 0) - s += page_size; - if (s < stack_size + page_size) + size_t s = faulting_address - stack_base + page_size; + if (s < stack_size + 2 * page_size) signo = 0; # if DEBUG |