Linux: Handle single- and two-digit kernel versions like 3.0 and 4

The code has been tested with various version strings.

[stuge: Remove bogus string length check and optimize for newer kernels]

1 files changed, 21 insertions, 13 deletions

diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index ca75779..69a2773 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -220,25 +220,33 @@ static clockid_t find_monotonic_clock(void)
 static int check_flag_bulk_continuation(void)
 {
 	struct utsname uts;
-	int major, minor, sublevel;
+	int atoms, major, minor, sublevel;
 
 	if (uname(&uts) < 0)
 		return -1;
-	if (strlen(uts.release) < 4)
+	atoms = sscanf(uts.release, "%d.%d.%d", &major, &minor, &sublevel);
+	if (atoms < 1)
+		return -1;
+
+	if (major > 2)
+		return 1;
+	if (major < 2)
 		return 0;
-	if (sscanf(uts.release, "%d.%d.%d", &major, &minor, &sublevel) != 3)
+
+	if (atoms < 2)
 		return 0;
-	if (major < 2)
+
+	/* major == 2 */
+	if (minor < 6)
 		return 0;
-	if (major == 2) {
-		if (minor < 6)
-			return 0;
-		if (minor == 6) {
-			if (sublevel < 32)
-				return 0;
-		}
-	}
-	return 1;
+	if (minor > 6) /* Does not exist, just here for correctness */
+		return 1;
+
+	/* 2.6.x */
+	if (3 == atoms && sublevel >= 32)
+		return 1;
+
+	return 0;
 }
 
 /* Return 1 if filename exists inside dirname in sysfs.