libv4lcontrol: Prefix sysfs root with environment variable value

If the LIBV4LCONTROL_SYSFS_PREFIX value is set it will be added
as a prefix to the sysfs root. This allows to fake USB and DMI
values to test upside down table entries.

Signed-off-by: Gregor Jasny <gjasny@googlemail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/lib/libv4lconvert/control/libv4lcontrol.c b/lib/libv4lconvert/control/libv4lcontrol.c
index d5269b1..087df26 100644 (file)
--- a/lib/libv4lconvert/control/libv4lcontrol.c
+++ b/lib/libv4lconvert/control/libv4lcontrol.c
@@ -689,20 +689,20 @@ static const struct v4lcontrol_flags_info v4lcontrol_flags[] = {
 
 static const struct v4l2_queryctrl fake_controls[];
 
-static void v4lcontrol_get_dmi_string(const char *string, char *buf, int size)
+static void v4lcontrol_get_dmi_string(const char *sysfs_prefix, const char *string, char *buf, int size)
 {
        FILE *f;
        char *s, sysfs_name[512];
 
        snprintf(sysfs_name, sizeof(sysfs_name),
-                       "/sys/class/dmi/id/%s", string);
+                       "%s/sys/class/dmi/id/%s", sysfs_prefix, string);
        f = fopen(sysfs_name, "r");
        if (!f) {
                /* 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);
+                               "%s/sys/devices/virtual/dmi/id/%s", sysfs_prefix, string);
                f = fopen(sysfs_name, "r");
                if (!f) {
                        buf[0] = 0;
@@ -717,6 +717,7 @@ static void v4lcontrol_get_dmi_string(const char *string, char *buf, int size)
 }
 
 static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
+               const char *sysfs_prefix,
                unsigned short *vendor_id, unsigned short *product_id,
                int *speed)
 {
@@ -732,7 +733,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
        /* <Sigh> find ourselve in sysfs */
        for (i = 0; i < 256; i++) {
                snprintf(sysfs_name, sizeof(sysfs_name),
-                        "/sys/class/video4linux/video%d/dev", i);
+                        "%s/sys/class/video4linux/video%d/dev", sysfs_prefix, i);
                f = fopen(sysfs_name, "r");
                if (!f)
                        continue;
@@ -749,7 +750,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
 
        /* Get vendor and product ID */
        snprintf(sysfs_name, sizeof(sysfs_name),
-                "/sys/class/video4linux/video%d/device/modalias", i);
+                "%s/sys/class/video4linux/video%d/device/modalias", sysfs_prefix, i);
        f = fopen(sysfs_name, "r");
        if (f) {
                s = fgets(buf, sizeof(buf), f);
@@ -760,7 +761,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
                        return 0; /* Not an USB device */
 
                snprintf(sysfs_name, sizeof(sysfs_name),
-                        "/sys/class/video4linux/video%d/device/../speed", i);
+                        "%s/sys/class/video4linux/video%d/device/../speed", sysfs_prefix, i);
        } else {
                /* Try again assuming the device link points to the usb
                   device instead of the usb interface (bug in older versions
@@ -768,7 +769,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
 
                /* Get vendor ID */
                snprintf(sysfs_name, sizeof(sysfs_name),
-                        "/sys/class/video4linux/video%d/device/idVendor", i);
+                        "%s/sys/class/video4linux/video%d/device/idVendor", sysfs_prefix, i);
                f = fopen(sysfs_name, "r");
                if (!f)
                        return 0; /* Not an USB device (or no sysfs) */
@@ -782,7 +783,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
 
                /* Get product ID */
                snprintf(sysfs_name, sizeof(sysfs_name),
-                        "/sys/class/video4linux/video%d/device/idProduct", i);
+                        "%s/sys/class/video4linux/video%d/device/idProduct", sysfs_prefix, i);
                f = fopen(sysfs_name, "r");
                if (!f)
                        return 0; /* Should never happen */
@@ -795,7 +796,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
                        return 0; /* Should never happen */
 
                snprintf(sysfs_name, sizeof(sysfs_name),
-                        "/sys/class/video4linux/video%d/device/speed", i);
+                        "%s/sys/class/video4linux/video%d/device/speed", sysfs_prefix, i);
        }
 
        f = fopen(sysfs_name, "r");
@@ -812,6 +813,7 @@ static int v4lcontrol_get_usb_info(struct v4lcontrol_data *data,
 }
 
 static void v4lcontrol_get_flags_from_db(struct v4lcontrol_data *data,
+               const char *sysfs_prefix,
                unsigned short vendor_id, unsigned short product_id)
 {
        char dmi_system_vendor[512], dmi_system_name[512], dmi_system_version[512];
@@ -819,18 +821,18 @@ static void v4lcontrol_get_flags_from_db(struct v4lcontrol_data *data,
        int i;
 
        /* Get DMI board and system strings */
-       v4lcontrol_get_dmi_string("sys_vendor", dmi_system_vendor,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "sys_vendor", dmi_system_vendor,
                        sizeof(dmi_system_vendor));
-       v4lcontrol_get_dmi_string("product_name", dmi_system_name,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "product_name", dmi_system_name,
                        sizeof(dmi_system_name));
-       v4lcontrol_get_dmi_string("product_version", dmi_system_version,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "product_version", dmi_system_version,
                        sizeof(dmi_system_version));
 
-       v4lcontrol_get_dmi_string("board_vendor", dmi_board_vendor,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "board_vendor", dmi_board_vendor,
                        sizeof(dmi_board_vendor));
-       v4lcontrol_get_dmi_string("board_name", dmi_board_name,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "board_name", dmi_board_name,
                        sizeof(dmi_board_name));
-       v4lcontrol_get_dmi_string("board_version", dmi_board_version,
+       v4lcontrol_get_dmi_string(sysfs_prefix, "board_version", dmi_board_version,
                        sizeof(dmi_board_version));
 
        for (i = 0; i < ARRAY_SIZE(v4lcontrol_flags); i++)
@@ -892,10 +894,14 @@ struct v4lcontrol_data *v4lcontrol_create(int fd, void *dev_ops_priv,
                        data->flags |= V4LCONTROL_VFLIPPED;
        }
 
-       got_usb_info = v4lcontrol_get_usb_info(data, &vendor_id, &product_id,
+       s = getenv("LIBV4LCONTROL_SYSFS_PREFIX");
+       if (!s)
+               s = "";
+
+       got_usb_info = v4lcontrol_get_usb_info(data, s, &vendor_id, &product_id,
                                               &speed);
        if (got_usb_info) {
-               v4lcontrol_get_flags_from_db(data, vendor_id, product_id);
+               v4lcontrol_get_flags_from_db(data, s, vendor_id, product_id);
                switch (speed) {
                case 12:
                        data->bandwidth = 1023 * 1000;