[PATCH libinput v2] Fix to avoid use of undefined pointer values.

[Jon A. Cruz]

If asprintf fails for any reason, the contents of the pointer
are undefined. While some platforms set it to NULL, there is no
guarantee that all will.

This change adds a simple wrapper to ensure proper NULL results
on failure.

Signed-off-by: Jon A. Cruz <jonc at osg.samsung.com>
---
 src/evdev-middle-button.c           |  2 ++
 src/evdev-mt-touchpad-buttons.c     |  2 ++
 src/evdev-mt-touchpad-edge-scroll.c |  2 ++
 src/libinput-util.h                 | 30 ++++++++++++++++++++++++++++++
 src/timer.c                         |  2 ++
 test/litest.c                       |  2 +-
 tools/libinput-list-devices.c       | 14 +++++++-------
 7 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/src/evdev-middle-button.c b/src/evdev-middle-button.c
index 903fa4d..c989486 100644
--- a/src/evdev-middle-button.c
+++ b/src/evdev-middle-button.c
@@ -20,6 +20,8 @@
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include <stdint.h>
 
 #include "evdev.h"
diff --git a/src/evdev-mt-touchpad-buttons.c b/src/evdev-mt-touchpad-buttons.c
index 64e9d28..4b1d6ab 100644
--- a/src/evdev-mt-touchpad-buttons.c
+++ b/src/evdev-mt-touchpad-buttons.c
@@ -20,6 +20,8 @@
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include <errno.h>
 #include <limits.h>
 #include <math.h>
diff --git a/src/evdev-mt-touchpad-edge-scroll.c b/src/evdev-mt-touchpad-edge-scroll.c
index 585c764..2302d2c 100644
--- a/src/evdev-mt-touchpad-edge-scroll.c
+++ b/src/evdev-mt-touchpad-edge-scroll.c
@@ -20,6 +20,8 @@
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include <errno.h>
 #include <limits.h>
 #include <math.h>
diff --git a/src/libinput-util.h b/src/libinput-util.h
index 732f813..7d5651a 100644
--- a/src/libinput-util.h
+++ b/src/libinput-util.h
@@ -26,6 +26,8 @@
 
 #include <unistd.h>
 #include <math.h>
+#include <stdarg.h>
+#include <stdio.h>
 #include <string.h>
 #include <time.h>
 
@@ -230,6 +232,34 @@ matrix_to_farray6(const struct matrix *m, float out[6])
 	out[5] = m->val[1][2];
 }
 
+/**
+ * Simple wrapper for asprintf that ensures the passed in pointer is set
+ * to NULL upon error.
+ * The standard asprintf() call does not guarantee the passed in pointer
+ * will be NULL'ed upon failure, whereas this wrapper does.
+ *
+ * @param strp pointer to set to newly allocated string.
+ * This pointer should be passed to free() to release when done.
+ * @param fmt the format string to use for printing.
+ * @return The number of bytes printed (excluding the null byte terminator)
+ * upon success or -1 upon failure. In the case of failure the pointer is set
+ * to NULL.
+ */
+static inline int
+xasprintf(char **strp, const char *fmt, ...)
+{
+	int rc = 0;
+	va_list args;
+
+	va_start(args, fmt);
+	rc = vasprintf(strp, fmt, args);
+	va_end(args);
+	if ((rc == -1) && strp)
+		*strp = NULL;
+
+	return rc;
+}
+
 enum ratelimit_state {
 	RATELIMIT_EXCEEDED,
 	RATELIMIT_THRESHOLD,
diff --git a/src/timer.c b/src/timer.c
index dbd3894..1e507df 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -20,6 +20,8 @@
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include <assert.h>
 #include <errno.h>
 #include <inttypes.h>
diff --git a/test/litest.c b/test/litest.c
index 53c441b..b3410bd 100644
--- a/test/litest.c
+++ b/test/litest.c
@@ -876,7 +876,7 @@ litest_init_udev_rules(struct litest_test_device *dev)
 		ck_abort_msg("Failed to create udev rules directory (%s)\n",
 			     strerror(errno));
 
-	rc = asprintf(&path,
+	rc = xasprintf(&path,
 		      "%s/%s%s.rules",
 		      UDEV_RULES_D,
 		      UDEV_RULE_PREFIX,
diff --git a/tools/libinput-list-devices.c b/tools/libinput-list-devices.c
index 6625173..68ddb61 100644
--- a/tools/libinput-list-devices.c
+++ b/tools/libinput-list-devices.c
@@ -120,17 +120,17 @@ calibration_default(struct libinput_device *device)
 	float calibration[6];
 
 	if (!libinput_device_config_calibration_has_matrix(device)) {
-		asprintf(&str, "n/a");
+		xasprintf(&str, "n/a");
 		return str;
 	}
 
 	if (libinput_device_config_calibration_get_default_matrix(device,
 						  calibration) == 0) {
-		asprintf(&str, "identity matrix");
+		xasprintf(&str, "identity matrix");
 		return str;
 	}
 
-	asprintf(&str,
+	xasprintf(&str,
 		 "%.2f %.2f %.2f %.2f %.2f %.2f",
 		 calibration[0],
 		 calibration[1],
@@ -150,13 +150,13 @@ scroll_defaults(struct libinput_device *device)
 
 	scroll_methods = libinput_device_config_scroll_get_methods(device);
 	if (scroll_methods == LIBINPUT_CONFIG_SCROLL_NO_SCROLL) {
-		asprintf(&str, "none");
+		xasprintf(&str, "none");
 		return str;
 	}
 
 	method = libinput_device_config_scroll_get_default_method(device);
 
-	asprintf(&str,
+	xasprintf(&str,
 		 "%s%s%s%s%s%s",
 		 (method == LIBINPUT_CONFIG_SCROLL_2FG) ? "*" : "",
 		 (scroll_methods & LIBINPUT_CONFIG_SCROLL_2FG) ? "two-finger " : "",
@@ -176,12 +176,12 @@ click_defaults(struct libinput_device *device)
 
 	click_methods = libinput_device_config_click_get_methods(device);
 	if (click_methods == LIBINPUT_CONFIG_CLICK_METHOD_NONE) {
-		asprintf(&str, "none");
+		xasprintf(&str, "none");
 		return str;
 	}
 
 	method = libinput_device_config_click_get_default_method(device);
-	asprintf(&str,
+	xasprintf(&str,
 		 "%s%s%s%s",
 		 (method == LIBINPUT_CONFIG_CLICK_METHOD_BUTTON_AREAS) ? "*" : "",
 		 (click_methods & LIBINPUT_CONFIG_CLICK_METHOD_BUTTON_AREAS) ? "button-areas " : "",
-- 
2.1.0