bug#32083: 26.1.50; temacs bootstrap execs itself forever on alpha-unknown-linux-gnu

[Paul Eggert <eggert@cs.ucla.edu>]

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Thanks for the bug report. Please try the attached patch; if it works around the 
bug for you, I'll install it on the emacs-26 branch and it should appear in the 
next Emacs release.

It would also be helpful to file a bug report with the Alpha Linux kernel folks, 
as there does seem to be a kernel bug here (or at least, an unexpected 
inconsistency with x86-64 with respect to how process personalities survive exec).

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From 13726cbac681e442649de1dfd73fcc7f889e87d9 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 7 Jul 2018 10:59:22 -0700
Subject: [PATCH] Fix bootstrap infloop in GNU/Linux alpha

* src/emacs.c (main): Do not re-exec if EMACS_HEAP_EXEC
is already set (Bug#32083).
---
 src/emacs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/emacs.c b/src/emacs.c
index 017c62308c..f5e47428ef 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -707,10 +707,12 @@ main (int argc, char **argv)
   bool disable_aslr = dumping;
 # endif
 
-  if (disable_aslr && disable_address_randomization ())
+  if (disable_aslr && disable_address_randomization ()
+      && !getenv ("EMACS_HEAP_EXEC"))
     {
       /* Set this so the personality will be reverted before execs
-	 after this one.  */
+	 after this one, and to work around an re-exec loop on buggy
+	 kernels (Bug#32083).  */
       xputenv ("EMACS_HEAP_EXEC=true");
 
       /* Address randomization was enabled, but is now disabled.
-- 
2.17.1