1 files changed, 112 insertions, 0 deletions
diff --git a/src/util/exec_command.c b/src/util/exec_command.c
new file mode 100644
index 0000000..8629b0c
--- /dev/null
+++ b/src/util/exec_command.c
@@ -0,0 +1,112 @@
+/*++
+/* NAME
+/*	exec_command 3
+/* SUMMARY
+/*	execute command
+/* SYNOPSIS
+/*	#include <exec_command.h>
+/*
+/*	NORETURN exec_command(command)
+/*	const char *command;
+/* DESCRIPTION
+/*	\fIexec_command\fR() replaces the current process by an instance
+/*	of \fIcommand\fR. This routine uses a simple heuristic to avoid
+/*	the overhead of running a command shell interpreter.
+/* DIAGNOSTICS
+/*	This routine never returns. All errors are fatal.
+/* 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 <unistd.h>
+#include <string.h>
+#ifdef USE_PATHS_H
+#include <paths.h>
+#endif
+#include <errno.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <argv.h>
+#include <exec_command.h>
+
+/* Application-specific. */
+
+#define SPACE_TAB	" \t"
+
+/* exec_command - exec command */
+
+NORETURN exec_command(const char *command)
+{
+    ARGV   *argv;
+
+    /*
+     * Character filter. In this particular case, we allow space and tab in
+     * addition to the regular character set.
+     */
+    static char ok_chars[] = "1234567890!@%-_=+:,./\
+abcdefghijklmnopqrstuvwxyz\
+ABCDEFGHIJKLMNOPQRSTUVWXYZ" SPACE_TAB;
+
+    /*
+     * See if this command contains any shell magic characters.
+     */
+    if (command[strspn(command, ok_chars)] == 0
+	&& command[strspn(command, SPACE_TAB)] != 0) {
+
+	/*
+	 * No shell meta characters found, so we can try to avoid the overhead
+	 * of running a shell. Just split the command on whitespace and exec
+	 * the result directly.
+	 */
+	argv = argv_split(command, SPACE_TAB);
+	(void) execvp(argv->argv[0], argv->argv);
+
+	/*
+	 * Auch. Perhaps they're using some shell built-in command.
+	 */
+	if (errno != ENOENT || strchr(argv->argv[0], '/') != 0)
+	    msg_fatal("execvp %s: %m", argv->argv[0]);
+
+	/*
+	 * Not really necessary, but...
+	 */
+	argv_free(argv);
+    }
+
+    /*
+     * Pass the command to a shell.
+     */
+    (void) execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
+    msg_fatal("execl %s: %m", _PATH_BSHELL);
+}
+
+#ifdef TEST
+
+ /*
+  * Yet another proof-of-concept test program.
+  */
+#include <vstream.h>
+#include <msg_vstream.h>
+
+int     main(int argc, char **argv)
+{
+    msg_vstream_init(argv[0], VSTREAM_ERR);
+    if (argc != 2)
+	msg_fatal("usage: %s 'command'", argv[0]);
+    exec_command(argv[1]);
+}
+
+#endif