From 158efe6cc8d8a6e3d8e7b9b4a909c890bd88cf7e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Sat, 6 Sep 2025 16:32:19 +0200
Subject: [PATCH] Remove unused function setChildSignalMask()

(cherry picked from commit a44dcbff13b7c70aaefd9e99517b30c0546f36d9)
---
 .../unix/include/nix/util/signals-impl.hh     |  9 ---------
 src/libutil/unix/signals.cc                   | 20 -------------------
 2 files changed, 29 deletions(-)

diff --git a/src/libutil/unix/include/nix/util/signals-impl.hh b/src/libutil/unix/include/nix/util/signals-impl.hh
index 1bcc90cdf..2456119be 100644
--- a/src/libutil/unix/include/nix/util/signals-impl.hh
+++ b/src/libutil/unix/include/nix/util/signals-impl.hh
@@ -42,13 +42,6 @@ extern thread_local std::function<bool()> interruptCheck;
 
 void _interrupted();
 
-/**
- * Sets the signal mask. Like saveSignalMask() but for a signal set that doesn't
- * necessarily match the current thread's mask.
- * See saveSignalMask() to set the saved mask to the current mask.
- */
-void setChildSignalMask(sigset_t * sigs);
-
 /**
  * Start a thread that handles various signals. Also block those signals
  * on the current thread (and thus any threads created by it).
@@ -60,8 +53,6 @@ void startSignalHandlerThread();
 /**
  * Saves the signal mask, which is the signal mask that nix will restore
  * before creating child processes.
- * See setChildSignalMask() to set an arbitrary signal mask instead of the
- * current mask.
  */
 void saveSignalMask();
 
diff --git a/src/libutil/unix/signals.cc b/src/libutil/unix/signals.cc
index 8a94cc2b1..d6efd6aa7 100644
--- a/src/libutil/unix/signals.cc
+++ b/src/libutil/unix/signals.cc
@@ -99,26 +99,6 @@ void unix::triggerInterrupt()
 static sigset_t savedSignalMask;
 static bool savedSignalMaskIsSet = false;
 
-void unix::setChildSignalMask(sigset_t * sigs)
-{
-    assert(sigs); // C style function, but think of sigs as a reference
-
-#if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 1) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE) \
-    || (defined(_POSIX_SOURCE) && _POSIX_SOURCE)
-    sigemptyset(&savedSignalMask);
-    // There's no "assign" or "copy" function, so we rely on (math) idempotence
-    // of the or operator: a or a = a.
-    sigorset(&savedSignalMask, sigs, sigs);
-#else
-    // Without sigorset, our best bet is to assume that sigset_t is a type that
-    // can be assigned directly, such as is the case for a sigset_t defined as
-    // an integer type.
-    savedSignalMask = *sigs;
-#endif
-
-    savedSignalMaskIsSet = true;
-}
-
 void unix::saveSignalMask()
 {
     if (sigprocmask(SIG_BLOCK, nullptr, &savedSignalMask))