libv4l: Also look for dmi info under /sys/class/dmi/id

From: Hans de Goede <hdegoede@redhat.com>

libv4l was looking for dmi strings in sysfs under /sys/devices/virtual/dmi/id
but with some kernel configurations this does not exist. It turns out that
the dmi strings do exist under /sys/class/dmi/id here. It seems that all
systems with dmi info in sysfs have /sys/class/dmi/id so default to using
that instead. To be sure fall back to /sys/devices/virtual/dmi/id
(the old behavor) when /sys/class/dmi/id is not found.

Priority: normal

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/v4l2-apps/libv4l/libv4lconvert/control/libv4lcontrol.c b/v4l2-apps/libv4l/libv4lconvert/control/libv4lcontrol.c
index 55ebf1b54..a20c114a1 100644
--- a/v4l2-apps/libv4l/libv4lconvert/control/libv4lcontrol.c
+++ b/v4l2-apps/libv4l/libv4lconvert/control/libv4lcontrol.c
@@ -169,11 +169,19 @@ static void v4lcontrol_get_dmi_string(const char *string, char *buf, int size)
   char *s, sysfs_name[512];
 
   snprintf(sysfs_name, sizeof(sysfs_name),
-	   "/sys/devices/virtual/dmi/id/%s", string);
+	   "/sys/class/dmi/id/%s", string);
   f = fopen(sysfs_name, "r");
   if (!f) {
-    buf[0] = 0;
-    return;
+    /* Try again with a different sysfs path, not sure if this is needed
+       but we used to look under /sys/devices/virtual/dmi/id in older
+       libv4l versions, but this did not work with some kernels */
+    snprintf(sysfs_name, sizeof(sysfs_name),
+	     "/sys/devices/virtual/dmi/id/%s", string);
+    f = fopen(sysfs_name, "r");
+    if (!f) {
+      buf[0] = 0;
+      return;
+    }
   }
 
   s = fgets(buf, size, f);