1 files changed, 60 insertions, 0 deletions
diff --git a/compat/setresuid.c b/compat/setresuid.c
new file mode 100644
index 0000000..a033d99
--- /dev/null
+++ b/compat/setresuid.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2004, 2005 Darren Tucker (dtucker at zip com au).
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+int
+setresuid(uid_t ruid, uid_t euid, uid_t suid)
+{
+	uid_t ouid;
+	int ret = -1;
+
+	/* Allow only the tested configuration. */
+
+	if (ruid != euid || euid != suid) {
+		errno = ENOSYS;
+		return -1;
+	}
+	ouid = getuid();
+
+	if ((ret = setreuid(euid, euid)) == -1)
+		return -1;
+
+	/*
+	 * When real, effective and saved uids are the same and we have
+	 * changed uids, sanity check that we cannot restore the old uid.
+	 */
+
+	if (ruid == euid && euid == suid && ouid != ruid &&
+	    setuid(ouid) != -1 && seteuid(ouid) != -1) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/*
+	 * Finally, check that the real and effective uids are what we
+	 * expect.
+	 */
+	if (getuid() != ruid || geteuid() != euid) {
+		errno = EACCES;
+		return -1;
+	}
+
+	return ret;
+}