From 04952f15df1bc81d1878833533d344a6b1d1326c Mon Sep 17 00:00:00 2001
From: Nicholas Marriott <nicholas.marriott@gmail.com>
Date: Tue, 8 Mar 2022 11:35:06 +0000
Subject: Use getpeerucred if available (not tested).

---
 compat/getpeereid.c | 19 +++++++++++++++++++
 configure.ac        |  6 ++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/compat/getpeereid.c b/compat/getpeereid.c
index 722f14a2..5a593c07 100644
--- a/compat/getpeereid.c
+++ b/compat/getpeereid.c
@@ -19,6 +19,10 @@
 
 #include <stdio.h>
 
+#ifdef HAVE_UCRED_H
+#include <ucred.h>
+#endif
+
 #include "compat.h"
 
 int
@@ -33,6 +37,21 @@ getpeereid(int s, uid_t *uid, gid_t *gid)
 	*uid = uc.uid;
 	*gid = uc.gid;
 	return (0);
+#elif defined(HAVE_GETPEERUCRED)
+int
+getpeereid(int s, uid_t *uid, gid_t *gid)
+{
+        ucred_t *ucred = NULL;
+
+        if (getpeerucred(s, &ucred) == -1)
+                return (-1);
+        if ((*uid = ucred_geteuid(ucred)) == -1)
+                return (-1);
+        if ((*gid = ucred_getrgid(ucred)) == -1)
+                return (-1);
+        ucred_free(ucred);
+        return (0);
+}
 #else
 	errno = EOPNOTSUPP;
 	return (-1);
diff --git a/configure.ac b/configure.ac
index 6ca86ea4..e473f141 100644
--- a/configure.ac
+++ b/configure.ac
@@ -128,6 +128,7 @@ AC_CHECK_HEADERS([ \
 	sys/dir.h \
 	sys/ndir.h \
 	sys/tree.h \
+	ucred.h \
 	util.h \
 ])
 
@@ -146,7 +147,8 @@ AC_CHECK_FUNCS([ \
 	flock \
 	prctl \
 	proc_pidinfo \
-	sysconf
+	getpeerucred \
+	sysconf \
 ])
 
 # Check for functions with a compatibility implementation.
@@ -170,7 +172,7 @@ AC_REPLACE_FUNCS([ \
 	strlcat \
 	strlcpy \
 	strndup \
-	strsep
+	strsep \
 ])
 AC_FUNC_STRNLEN
 
-- 
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