[glibc] hurd: Prevent the final file_exec_paths call from signals

[Samuel Thibault <sthibaul@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=49b308a26e2a9e02ef396f67f59c462ad4171ea4

commit 49b308a26e2a9e02ef396f67f59c462ad4171ea4
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Mon Nov 20 19:19:50 2023 +0100

    hurd: Prevent the final file_exec_paths call from signals
    
    Otherwise if the exec server started thrashing the old task,
    we won't be able to restart the exec.
    
    This notably fixes building ghc.

Diff:
---
 hurd/hurdexec.c            | 12 ++++++++++++
 sysdeps/mach/hurd/spawni.c | 16 +++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/hurd/hurdexec.c b/hurd/hurdexec.c
index e358d846c8..317d7ea0ad 100644
--- a/hurd/hurdexec.c
+++ b/hurd/hurdexec.c
@@ -362,6 +362,7 @@ retry:
   if (!err)
     {
       int flags;
+      sigset_t old, new;
 
       if (pdp)
 	{
@@ -420,6 +421,15 @@ retry:
       if (__sigismember (&_hurdsig_traced, SIGKILL))
 	flags |= EXEC_SIGTRAP;
 #endif
+
+     /* Avoid getting interrupted while exec(), notably not after the exec
+        server has committed to the exec and started thrashing us.
+
+        TODO Rather add proper interrupt support to the exec server, that
+        avoids interrupts in that period.  */
+      __sigfillset (&new);
+      __sigprocmask (SIG_SETMASK, &new, &old);
+
       err = __file_exec_paths (file, task, flags,
 			       path ? path : "",
 			       abspath ? abspath : "",
@@ -440,6 +450,8 @@ retry:
 			   ints, INIT_INT_MAX,
 			   please_dealloc, pdp - please_dealloc,
 			   portnames, nportnames);
+
+      __sigprocmask (SIG_SETMASK, &old, NULL);
     }
 
   /* Release references to the standard ports.  */
diff --git a/sysdeps/mach/hurd/spawni.c b/sysdeps/mach/hurd/spawni.c
index 9516001817..58a89b45f3 100644
--- a/sysdeps/mach/hurd/spawni.c
+++ b/sysdeps/mach/hurd/spawni.c
@@ -812,6 +812,18 @@ retry:
 
     inline error_t exec (file_t file)
       {
+	sigset_t old, new;
+
+	/* Avoid getting interrupted while exec(), notably not after the exec
+	   server has committed to the exec and started thrashing the task.
+
+	   Various issues otherwise show up when building e.g. ghc.
+
+	   TODO Rather add proper interrupt support to the exec server, that
+	   avoids interrupts in that period.  */
+	__sigfillset(&new);
+	__sigprocmask (SIG_SETMASK, &new, &old);
+
 	error_t err = __file_exec_paths
 	  (file, task,
 	   __sigismember (&_hurdsig_traced, SIGKILL) ? EXEC_SIGTRAP : 0,
@@ -824,7 +836,7 @@ retry:
 	/* Fallback for backwards compatibility.  This can just be removed
 	   when __file_exec goes away.  */
 	if (err == MIG_BAD_ID)
-	  return __file_exec (file, task,
+	  err = __file_exec (file, task,
 			      (__sigismember (&_hurdsig_traced, SIGKILL)
 			      ? EXEC_SIGTRAP : 0),
 			      args, argslen, env, envlen,
@@ -833,6 +845,8 @@ retry:
 			      ints, INIT_INT_MAX,
 			      NULL, 0, NULL, 0);
 
+	__sigprocmask (SIG_SETMASK, &old, NULL);
+
 	return err;
       }