From 5a224b981ee32d7cf59aaa9e2c101af65a275edc Mon Sep 17 00:00:00 2001
From: Julien Lepiller <julien@lepiller.eu>
Date: Mon, 20 Feb 2023 19:14:12 +0100
Subject: [PATCH] Dynamically allocate the alternate signal stack.

This patch is a backport of https://github.com/ocaml/ocaml/pull/10266.
---
 asmrun/signals_asm.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/asmrun/signals_asm.c b/asmrun/signals_asm.c
index 3895d75..7e2abe8 100644
--- a/asmrun/signals_asm.c
+++ b/asmrun/signals_asm.c
@@ -182,7 +182,6 @@ DECLARE_SIGNAL_HANDLER(trap_handler)
 #ifdef HAS_STACK_OVERFLOW_DETECTION
 
 static char * system_stack_top;
-static char sig_alt_stack[SIGSTKSZ];
 
 #if defined(SYS_linux)
 /* PR#4746: recent Linux kernels with support for stack randomization
@@ -274,15 +273,19 @@ void caml_init_signals(void)
 #ifdef HAS_STACK_OVERFLOW_DETECTION
   {
     stack_t stk;
-    struct sigaction act;
-    stk.ss_sp = sig_alt_stack;
+    stk.ss_sp = malloc(SIGSTKSZ);
     stk.ss_size = SIGSTKSZ;
     stk.ss_flags = 0;
-    SET_SIGACT(act, segv_handler);
-    act.sa_flags |= SA_ONSTACK | SA_NODEFER;
-    sigemptyset(&act.sa_mask);
-    system_stack_top = (char *) &act;
-    if (sigaltstack(&stk, NULL) == 0) { sigaction(SIGSEGV, &act, NULL); }
+    if (stk.ss_sp != NULL) {
+      if (sigaltstack(&stk, NULL) != -1) {                                     
+        struct sigaction act;                                                  
+        SET_SIGACT(act, segv_handler);                                         
+        act.sa_flags |= SA_ONSTACK | SA_NODEFER;                               
+        sigemptyset(&act.sa_mask);                                             
+        system_stack_top = (char *) &act;                                      
+        sigaction(SIGSEGV, &act, NULL);                                        
+      }
+    }
   }
 #endif
 }
-- 
2.38.1

ubmit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=049d53ee393abb072af9208ce37ec29e57c8fe96'>root</a>/<a href='/guix/log/gnu?id=049d53ee393abb072af9208ce37ec29e57c8fe96'>gnu</a>/<a href='/guix/log/gnu/installer?id=049d53ee393abb072af9208ce37ec29e57c8fe96'>installer</a>/<a href='/guix/log/gnu/installer/proxy.scm?id=049d53ee393abb072af9208ce37ec29e57c8fe96'>proxy.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/proxy.scm?id=049d53ee393abb072af9208ce37ec29e57c8fe96&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/proxy.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-04-08 10:24:02 +0200'>2020-04-08</span></td><td><a href='/guix/commit/gnu/installer/proxy.scm?id=ee0ad7803c82383ac1bced073d8670bc407797e7'>installer: Add proxy support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/proxy.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer/newt/parameters.scm (run-proxy-page): New procedure,
(run-parameters-page): add the previous procedure to the parameters menu.
</span></span></td><td>Mathieu Othacehe</td></tr>