File 0003-Enforce-use-of-setfsuid.patch of Package slang

From e73c4ca4aec9c2f3e3556d45f2330d8ed9edc7e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Klaus=20K=C3=A4mpf?= <kkaempf@gmail.com>
Date: Tue, 7 Jan 2025 17:44:24 +0100
Subject: [PATCH 3/3] Enforce use of setfsuid

---
 autoconf/configure.ac |  9 +++++++++
 src/config.hin        |  2 ++
 src/slinclud.h        |  4 ++++
 src/sltermin.c        | 28 ++++++++++++++++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 4f8d184..c027289 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -177,9 +177,18 @@ sys/socket.h \
 netinet/in.h \
 arpa/inet.h \
 sys/un.h \
+sys/fsuid.h \
 sys/resource.h \
 )
 
+AC_CHECK_FUNCS(setfsuid setfsgid)
+
+if test "${ac_cv_func_setfsuid}" != "yes" || test "${ac_cv_func_setfsgid}" != "yes"; then
+    AC_MSG_ERROR([
+*** setfsguid and setfsgid cannot be found!!!
+    These are needed to support setuid/setgid applications ***])
+fi
+
 AC_TYPE_MODE_T
 AC_TYPE_PID_T
 AC_TYPE_UID_T
diff --git a/src/config.hin b/src/config.hin
index 1348e89..f0748f0 100644
--- a/src/config.hin
+++ b/src/config.hin
@@ -202,6 +202,8 @@
 #undef HAVE_SYS_UN_H
 #undef socklen_t
 
+#undef HAVE_SYS_FSUID_H
+#undef HAVE_SETFSUID
 #undef HAVE_CONFSTR
 #undef HAVE_SYSCONF
 #undef HAVE_PATHCONF
diff --git a/src/slinclud.h b/src/slinclud.h
index 27bfc95..6ea1242 100644
--- a/src/slinclud.h
+++ b/src/slinclud.h
@@ -30,4 +30,8 @@
 # include <memory.h>
 #endif
 
+#ifdef HAVE_SYS_FSUID_H
+# include <sys/fsuid.h>
+#endif
+
 #endif				       /* _SLANG_INCLUDE_H_ */
diff --git a/src/sltermin.c b/src/sltermin.c
index 20784e2..dd01596 100644
--- a/src/sltermin.c
+++ b/src/sltermin.c
@@ -23,6 +23,9 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 USA.
 */
 
+#include <unistd.h>
+#include <sys/types.h>
+
 #include "slinclud.h"
 
 #include "slang.h"
@@ -168,7 +171,32 @@ static FILE *open_terminfo (char *file, SLterminfo_Type *h)
     * I will also look into the use of setreuid, seteuid and setregid, setegid.
     * FIXME: Priority=medium
     */
+   /* If your system lacks setfsuid/getfsuid either write
+      equivalent support or dont use slang to build setuid/setgid
+      apps like Mutt */
+
+   if(setfsuid(getuid())==-1)
+   {
+       perror("setfsuid");
+       return NULL;
+   }
+   if(setfsgid(getgid())==-1)
+   {
+       perror("setfsgid");
+       return NULL;
+   }
    fp = fopen (file, "rb");
+   if(setfsuid(geteuid())==-1)
+   {
+       perror("setfsuid");
+       return NULL;
+   }
+   if(setfsgid(getegid())==-1)
+   {
+       perror("setfsgid");
+       return NULL;
+   }
+
    if (fp == NULL) return NULL;
 
    if (12 != fread ((char *)buf, 1, 12, fp))
-- 
2.47.1