From f33f4c85581045ae493e7f12c6ba1bf5829d8192 Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Fri, 4 Apr 2025 13:50:04 +0200
Subject: [PATCH] lib: Prevent double inclusion of config.h through system.h

Files that include both <config.h> and "system.h" might include
config.h twice. Prevent that by adding a guard check in system.h
before including config.h.

       * lib/crc32.c: Use #ifdef HAVE_CONFIG_H instead of #if.
       * lib/error.h: Check HAVE_CONFIG_H before including config.h.
       * lib/system.h: Check both HAVE_CONFIG_H and whether
       EU_CONFIG_H is defined before including config.h.

Suggested-by: Dmitry V. Levin <ldv@strace.io>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 lib/crc32.c  | 2 +-
 lib/error.c  | 4 +++-
 lib/system.h | 7 ++++++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/crc32.c b/lib/crc32.c
index 758602ea0..eae658225 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -25,7 +25,7 @@
    the GNU Lesser General Public License along with this program.  If
    not, see <http://www.gnu.org/licenses/>.  */
 
-#if HAVE_CONFIG_H
+#ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif
 
diff --git a/lib/error.c b/lib/error.c
index 5186fc15e..75c9eafb5 100644
--- a/lib/error.c
+++ b/lib/error.c
@@ -26,7 +26,9 @@
    the GNU Lesser General Public License along with this program.  If
    not, see <http://www.gnu.org/licenses/>.  */
 
-#include <config.h>
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
 
 #if !defined(HAVE_ERROR_H) && defined(HAVE_ERR_H)
 #include <errno.h>
diff --git a/lib/system.h b/lib/system.h
index 0698e5ffb..c17e2aa0f 100644
--- a/lib/system.h
+++ b/lib/system.h
@@ -31,7 +31,12 @@
 #ifndef LIB_SYSTEM_H
 #define LIB_SYSTEM_H	1
 
-#include <config.h>
+/* Prevent double inclusion of config.h, config.h includes eu-config.h.  */
+#ifdef HAVE_CONFIG_H
+#ifndef EU_CONFIG_H
+# include <config.h>
+#endif
+#endif
 
 #include <errno.h>
 #include <stdbool.h>
-- 
2.47.2