1 files changed, 70 insertions, 0 deletions
diff --git a/src/util/open_as.c b/src/util/open_as.c
new file mode 100644
index 0000000..0fa84b7
--- /dev/null
+++ b/src/util/open_as.c
@@ -0,0 +1,70 @@
+/*++
+/* NAME
+/*	open_as 3
+/* SUMMARY
+/*	open file as user
+/* SYNOPSIS
+/*	#include <fcntl.h>
+/*	#include <open_as.h>
+/*
+/*	int	open_as(path, flags, mode, euid, egid)
+/*	const char *path;
+/*	int	mode;
+/*	uid_t	euid;
+/*	gid_t	egid;
+/* DESCRIPTION
+/*	open_as() opens the named \fIpath\fR with the named \fIflags\fR
+/*	and \fImode\fR, and with the effective rights specified by \fIeuid\fR
+/*	and \fIegid\fR.  A -1 result means the open failed.
+/* DIAGNOSTICS
+/*	Fatal error: no permission to change privilege level.
+/* SEE ALSO
+/*	set_eugid(3) switch effective rights
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* Utility library. */
+
+#include "msg.h"
+#include "set_eugid.h"
+#include "open_as.h"
+
+/* open_as - open file as user */
+
+int     open_as(const char *path, int flags, int mode, uid_t euid, gid_t egid)
+{
+    uid_t   saved_euid = geteuid();
+    gid_t   saved_egid = getegid();
+    int     fd;
+
+    /*
+     * Switch to the target user privileges.
+     */
+    set_eugid(euid, egid);
+
+    /*
+     * Open that file.
+     */
+    fd = open(path, flags, mode);
+
+    /*
+     * Restore saved privileges.
+     */
+    set_eugid(saved_euid, saved_egid);
+
+    return (fd);
+}