From 36bac92cd2ef4a8719f62de9b4bde659a8682463 Mon Sep 17 00:00:00 2001
From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Mon, 2 Jun 2025 23:29:49 +0200
Subject: [PATCH] tools: Enforce default handling of SIGCHLD

Ignoring SIGCHLD gets passed to child processes. Doing that has
influence on waitpid, namely that zombie processes won't be
created. This means that a status can never be read.

We can't enforce this in library, but libarchive's tools can be
protected against this by enforcing default handling.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
---
 cat/bsdcat.c     | 13 +++++++++++++
 cpio/cpio.c      | 12 ++++++++++--
 tar/bsdtar.c     |  5 +++++
 unzip/bsdunzip.c | 13 +++++++++++++
 4 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/cat/bsdcat.c b/cat/bsdcat.c
index 731621fa9..40fdd0436 100644
--- a/cat/bsdcat.c
+++ b/cat/bsdcat.c
@@ -7,6 +7,9 @@
 
 #include "bsdcat_platform.h"
 
+#ifdef HAVE_SIGNAL_H
+#include <signal.h>
+#endif
 #include <stdio.h>
 #ifdef HAVE_STDLIB_H
 #include <stdlib.h>
@@ -105,6 +108,16 @@ main(int argc, char **argv)
 	bsdcat = &bsdcat_storage;
 	memset(bsdcat, 0, sizeof(*bsdcat));
 
+#if defined(HAVE_SIGACTION) && defined(SIGCHLD)
+	{ /* Do not ignore SIGCHLD. */
+		struct sigaction sa;
+		sa.sa_handler = SIG_DFL;
+		sigemptyset(&sa.sa_mask);
+		sa.sa_flags = 0;
+		sigaction(SIGCHLD, &sa, NULL);
+	}
+#endif
+
 	lafe_setprogname(*argv, "bsdcat");
 
 	bsdcat->argv = argv;
diff --git a/cpio/cpio.c b/cpio/cpio.c
index 2bf1bfa29..cd88d416e 100644
--- a/cpio/cpio.c
+++ b/cpio/cpio.c
@@ -124,13 +124,21 @@ main(int argc, char *argv[])
 	cpio->buff_size = sizeof(buff);
 
 
-#if defined(HAVE_SIGACTION) && defined(SIGPIPE)
-	{ /* Ignore SIGPIPE signals. */
+#if defined(HAVE_SIGACTION)
+	{
 		struct sigaction sa;
 		sigemptyset(&sa.sa_mask);
 		sa.sa_flags = 0;
+#ifdef SIGPIPE
+		/* Ignore SIGPIPE signals. */
 		sa.sa_handler = SIG_IGN;
 		sigaction(SIGPIPE, &sa, NULL);
+#endif
+#ifdef SIGCHLD
+		/* Do not ignore SIGCHLD. */
+		sa.sa_handler = SIG_DFL;
+		sigaction(SIGCHLD, &sa, NULL);
+#endif
 	}
 #endif
 
diff --git a/tar/bsdtar.c b/tar/bsdtar.c
index 53ac135f0..c80c1a1b6 100644
--- a/tar/bsdtar.c
+++ b/tar/bsdtar.c
@@ -182,6 +182,11 @@ main(int argc, char **argv)
 		/* Ignore SIGPIPE signals. */
 		sa.sa_handler = SIG_IGN;
 		sigaction(SIGPIPE, &sa, NULL);
+#endif
+#ifdef SIGCHLD
+		/* Do not ignore SIGCHLD. */
+		sa.sa_handler = SIG_DFL;
+		sigaction(SIGCHLD, &sa, NULL);
 #endif
 	}
 #endif
diff --git a/unzip/bsdunzip.c b/unzip/bsdunzip.c
index 621afbeb9..0559a0ddc 100644
--- a/unzip/bsdunzip.c
+++ b/unzip/bsdunzip.c
@@ -29,6 +29,9 @@
 #ifdef HAVE_LOCALE_H
 #include <locale.h>
 #endif
+#ifdef HAVE_SIGNAL_H
+#include <signal.h>
+#endif
 #ifdef HAVE_STDARG_H
 #include <stdarg.h>
 #endif
@@ -1187,6 +1190,16 @@ main(int argc, char *argv[])
 	const char *zipfile;
 	int nopts;
 
+#if defined(HAVE_SIGACTION) && defined(SIGCHLD)
+	{ /* Do not ignore SIGCHLD. */
+		struct sigaction sa;
+		sa.sa_handler = SIG_DFL;
+		sigemptyset(&sa.sa_mask);
+		sa.sa_flags = 0;
+		sigaction(SIGCHLD, &sa, NULL);
+	}
+#endif
+
 	lafe_setprogname(*argv, "bsdunzip");
 
 #if HAVE_SETLOCALE
-- 
2.47.2