Marcus Meissner
7a657f6c9c
- gnulib-c-stack.patch: c-stack: stop using SIGSTKSZ OBS-URL: https://build.opensuse.org/request/show/907134 OBS-URL: https://build.opensuse.org/package/show/Base:System/m4?expand=0&rev=44
123 lines
4.5 KiB
Diff
123 lines
4.5 KiB
Diff
From f9e2b20a12a230efa30f1d479563ae07d276a94b Mon Sep 17 00:00:00 2001
|
||
From: Paul Eggert <eggert@cs.ucla.edu>
|
||
Date: Wed, 30 Sep 2020 13:50:36 -0700
|
||
Subject: [PATCH] c-stack: stop using SIGSTKSZ
|
||
MIME-Version: 1.0
|
||
Content-Type: text/plain; charset=UTF-8
|
||
Content-Transfer-Encoding: 8bit
|
||
|
||
It’s been proposed to stop making SIGSTKSZ an integer constant:
|
||
https://sourceware.org/pipermail/libc-alpha/2020-September/118028.html
|
||
Also, using SIGSTKSZ in #if did not conform to current POSIX.
|
||
Also, avoiding SIGSTKSZ makes the code simpler and easier to grok.
|
||
* lib/c-stack.c (SIGSTKSZ): Remove.
|
||
(alternate_signal_stack): Now a 64 KiB array, for simplicity.
|
||
All uses changed.
|
||
---
|
||
ChangeLog | 9 +++++++++
|
||
lib/c-stack.c | 42 ++++++++++++++++++------------------------
|
||
lib/c-stack.h | 2 +-
|
||
3 files changed, 28 insertions(+), 25 deletions(-)
|
||
|
||
Index: m4-1.4.18/lib/c-stack.c
|
||
===================================================================
|
||
--- m4-1.4.18.orig/lib/c-stack.c
|
||
+++ m4-1.4.18/lib/c-stack.c
|
||
@@ -50,15 +50,6 @@
|
||
#if ! HAVE_STACK_T && ! defined stack_t
|
||
typedef struct sigaltstack stack_t;
|
||
#endif
|
||
-#ifndef SIGSTKSZ
|
||
-# define SIGSTKSZ 16384
|
||
-#elif HAVE_LIBSIGSEGV && SIGSTKSZ < 16384
|
||
-/* libsigsegv 2.6 through 2.8 have a bug where some architectures use
|
||
- more than the Linux default of an 8k alternate stack when deciding
|
||
- if a fault was caused by stack overflow. */
|
||
-# undef SIGSTKSZ
|
||
-# define SIGSTKSZ 16384
|
||
-#endif
|
||
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
@@ -89,6 +80,16 @@ typedef struct sigaltstack stack_t;
|
||
# endif
|
||
#endif
|
||
|
||
+/* Storage for the alternate signal stack.
|
||
+ 64 KiB is not too large for Gnulib-using apps, and is large enough
|
||
+ for all known platforms. Smaller sizes may run into trouble.
|
||
+ For example, libsigsegv 2.6 through 2.8 have a bug where some
|
||
+ architectures use more than the Linux default of an 8 KiB alternate
|
||
+ stack when deciding if a fault was caused by stack overflow. */
|
||
+static max_align_t alternate_signal_stack[(64 * 1024
|
||
+ + sizeof (max_align_t) - 1)
|
||
+ / sizeof (max_align_t)];
|
||
+
|
||
/* The user-specified action to take when a SEGV-related program error
|
||
or stack overflow occurs. */
|
||
static void (* volatile segv_action) (int);
|
||
@@ -128,19 +129,6 @@ die (int signo)
|
||
#if (HAVE_SIGALTSTACK && HAVE_DECL_SIGALTSTACK \
|
||
&& HAVE_STACK_OVERFLOW_HANDLING) || HAVE_LIBSIGSEGV
|
||
|
||
-/* Storage for the alternate signal stack. */
|
||
-static union
|
||
-{
|
||
- char buffer[SIGSTKSZ];
|
||
-
|
||
- /* These other members are for proper alignment. There's no
|
||
- standard way to guarantee stack alignment, but this seems enough
|
||
- in practice. */
|
||
- long double ld;
|
||
- long l;
|
||
- void *p;
|
||
-} alternate_signal_stack;
|
||
-
|
||
static void
|
||
null_action (int signo __attribute__ ((unused)))
|
||
{
|
||
@@ -205,8 +193,8 @@ c_stack_action (void (*action) (int))
|
||
|
||
/* Always install the overflow handler. */
|
||
if (stackoverflow_install_handler (overflow_handler,
|
||
- alternate_signal_stack.buffer,
|
||
- sizeof alternate_signal_stack.buffer))
|
||
+ alternate_signal_stack,
|
||
+ sizeof alternate_signal_stack))
|
||
{
|
||
errno = ENOTSUP;
|
||
return -1;
|
||
@@ -279,14 +267,14 @@ c_stack_action (void (*action) (int))
|
||
stack_t st;
|
||
struct sigaction act;
|
||
st.ss_flags = 0;
|
||
+ st.ss_sp = alternate_signal_stack;
|
||
+ st.ss_size = sizeof alternate_signal_stack;
|
||
# if SIGALTSTACK_SS_REVERSED
|
||
/* Irix mistakenly treats ss_sp as the upper bound, rather than
|
||
lower bound, of the alternate stack. */
|
||
- st.ss_sp = alternate_signal_stack.buffer + SIGSTKSZ - sizeof (void *);
|
||
- st.ss_size = sizeof alternate_signal_stack.buffer - sizeof (void *);
|
||
-# else
|
||
- st.ss_sp = alternate_signal_stack.buffer;
|
||
- st.ss_size = sizeof alternate_signal_stack.buffer;
|
||
+ st.ss_size -= sizeof (void *);
|
||
+ char *ss_sp = st.ss_sp;
|
||
+ st.ss_sp = ss_sp + st.ss_size;
|
||
# endif
|
||
r = sigaltstack (&st, NULL);
|
||
if (r != 0)
|
||
Index: m4-1.4.18/lib/c-stack.h
|
||
===================================================================
|
||
--- m4-1.4.18.orig/lib/c-stack.h
|
||
+++ m4-1.4.18/lib/c-stack.h
|
||
@@ -34,7 +34,7 @@
|
||
A null ACTION acts like an action that does nothing.
|
||
|
||
ACTION must be async-signal-safe. ACTION together with its callees
|
||
- must not require more than SIGSTKSZ bytes of stack space. Also,
|
||
+ must not require more than 64 KiB of stack space. Also,
|
||
ACTION should not call longjmp, because this implementation does
|
||
not guarantee that it is safe to return to the original stack.
|
||
|