xsetwacom: Add ability to read args from stdin for fuzzing

Add a new "--enable-fuzz-interface" configuration option which will
cause xsetwacom to read NUL-separated arguments from stdin (for
example: `echo -en 'list\0devices' | xsetwacom`). This makes it
easier to plug into fuzzing software for debugging.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>

3 files changed, 57 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index ec04a2e..2244d16 100644
--- a/configure.ac
+++ b/configure.ac
@@ -106,6 +106,12 @@ AC_ARG_WITH([xorg-conf-dir],
 AC_SUBST(configdir)
 AM_CONDITIONAL(HAS_XORG_CONF_DIR, [test "x$configdir" != "x"])
 
+AC_ARG_ENABLE(fuzz-interface, AS_HELP_STRING([--enable-fuzz-interface],
+                          [Enable xsetwacom to take NUL-separated commands from stdin (default: no)]),
+                          [FUZZINTERFACE=$enableval],
+                          [FUZZINTERFACE=no])
+AM_CONDITIONAL(FUZZINTERFACE, [test "x$FUZZINTERFACE" = xyes])
+
 AC_ARG_ENABLE(unit-tests, AS_HELP_STRING([--enable-unit-tests],
                           [Enable unit-tests (default: auto)]),
                           [UNITTESTS=$enableval],
diff --git a/tools/Makefile.am b/tools/Makefile.am
index 5622362..28c2fcd 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -35,6 +35,10 @@ xsetwacom_SOURCES = xsetwacom.c
 xsetwacom_CFLAGS = $(X11_CFLAGS)
 xsetwacom_LDADD = $(X11_LIBS)
 
+if FUZZINTERFACE
+xsetwacom_CFLAGS += -DBUILD_FUZZINTERFACE
+endif
+
 if UNITTESTS
 check_PROGRAMS = xsetwacom-test
 xsetwacom_test_SOURCES=xsetwacom.c
diff --git a/tools/xsetwacom.c b/tools/xsetwacom.c
index 1fd70c8..e9d455b 100644
--- a/tools/xsetwacom.c
+++ b/tools/xsetwacom.c
@@ -2697,6 +2697,49 @@ static void get_param(Display *dpy, XDevice *dev, param_t *param, int argc, char
 
 
 #ifndef BUILD_TEST
+
+#ifdef BUILD_FUZZINTERFACE
+void argsfromstdin(int *argc, char ***argv)
+{
+	const int READSIZE = 256;
+	char *buf = strdup((*argv)[0]);
+	size_t len = strlen(buf)+1;
+
+	while (1) {
+		char *p = realloc(buf, len + READSIZE);
+		size_t n;
+
+		if (!p)
+			exit(1);
+		buf = p;
+
+		n = fread(buf+len, 1, READSIZE, stdin);
+		if (n > 0) {
+			len += n;
+		}
+		else {
+			buf[len] = '\0';
+			len++;
+			break;
+		}
+	}
+
+	*argc = 0;
+	*argv = NULL;
+	while (len) {
+		char **p = realloc(*argv, (*argc + 1) * sizeof(char**));
+		if (!p)
+			exit(1);
+		*argv = p;
+		(*argv)[*argc] = buf;
+		(*argc)++;
+
+		len -= strlen(buf) + 1;
+		buf += strlen(buf) + 1;
+	}
+}
+#endif /* BUILD_FUZZINTERFACE */
+
 int main (int argc, char **argv)
 {
 	int c;
@@ -2719,6 +2762,10 @@ int main (int argc, char **argv)
 		{NULL, 0, NULL, 0}
 	};
 
+#ifdef BUILD_FUZZINTERFACE
+	argsfromstdin(&argc, &argv);
+#endif /* BUILD FUZZINTERFACE */
+
 	if (argc < 2)
 	{
 		usage();