use .\scrcpy.exe -M error

[17ayst]

Environment

• OS: win10
• scrcpy version: 2.4
• device model: Nexus_6P
• Android version: 8.1.0

Describe the bug
.\scrcpy.exe -M error

On errors, please provide the output of the console (and adb logcat if relevant).

java.io.IOException: android.system.ErrnoException: write failed: ENOTSUP (Operation not supported on transport endpoint)
        at com.genymobile.scrcpy.UhidManager.open(UhidManager.java:66)
        at com.genymobile.scrcpy.Controller.handleEvent(Controller.java:208)
        at com.genymobile.scrcpy.Controller.control(Controller.java:97)
        at com.genymobile.scrcpy.Controller.lambda$start$0$com-genymobile-scrcpy-Controller(Controller.java:105)
        at com.genymobile.scrcpy.Controller$$ExternalSyntheticLambda1.run(Unknown Source:4)
        at java.lang.Thread.run(Thread.java:764)
Caused by: android.system.ErrnoException: write failed: ENOTSUP (Operation not supported on transport endpoint)
        at libcore.io.Linux.writeBytes(Native Method)
        at libcore.io.Linux.write(Linux.java:288)
        at libcore.io.BlockGuardOs.write(BlockGuardOs.java:345)
        at android.system.Os.write(Os.java:621)
        at com.genymobile.scrcpy.UhidManager.open(UhidManager.java:58)
        ... 5 more
[server] ERROR: Failed to close uhid: close failed: EBADF (Bad file descriptor)
INFO: Renderer: direct3d
WARN: Demuxer 'audio': stream explicitly disabled by the device
ERROR: Demuxer 'video': stream disabled due to connection error
ERROR: Demuxer error

[17ayst]

The reason is that the Android version is too low

[anotheruserofgithub]

@17ayst What's the output of adb shell cat /ueventd.rc, if this file exists on your device?

I have a (custom ROM and rooted) 8.1.0 device and uhid is available (but uinput requires root access):

/dev/uhid                 0660   uhid       uhid
/dev/uinput               0660   system     bluetooth

See also #4473 (comment).

[17ayst]

like this:

subsystem adf
    devname uevent_devname

subsystem graphics
    devname uevent_devpath
    dirname /dev/graphics

subsystem drm
    devname uevent_devpath
    dirname /dev/dri

subsystem oncrpc
    devname uevent_devpath
    dirname /dev/oncrpc

subsystem adsp
    devname uevent_devpath
    dirname /dev/adsp

subsystem msm_camera
    devname uevent_devpath
    dirname /dev/msm_camera

subsystem input
    devname uevent_devpath
    dirname /dev/input

subsystem mtd
    devname uevent_devpath
    dirname /dev/mtd

subsystem sound
    devname uevent_devpath
    dirname /dev/snd

# ueventd can only set permissions on device nodes and their associated
# sysfs attributes, not on arbitrary paths.
#
# format for /dev rules: devname mode uid gid
# format for /sys rules: nodename attr mode uid gid
# shortcut: "mtd@NN" expands to "/dev/mtd/mtdNN"

/dev/null                 0666   root       root
/dev/zero                 0666   root       root
/dev/full                 0666   root       root
/dev/ptmx                 0666   root       root
/dev/tty                  0666   root       root
/dev/random               0666   root       root
/dev/urandom              0666   root       root
# Make HW RNG readable by group system to let EntropyMixer read it.
/dev/hw_random            0440   root       system
/dev/ashmem               0666   root       root
/dev/binder               0666   root       root
/dev/hwbinder             0666   root       root
/dev/vndbinder            0666   root       root

/dev/pmsg0                0222   root       log

# the msm hw3d client device node is world writable/readable.
/dev/msm_hw3dc            0666   root       root

# gpu driver for adreno200 is globally accessible
/dev/kgsl                 0666   root       root

# kms driver for drm based gpu
/dev/dri/*                0666   root       graphics

# these should not be world writable
/dev/diag                 0660   radio      radio
/dev/diag_arm9            0660   radio      radio
/dev/ttyMSM0              0600   bluetooth  bluetooth
/dev/uhid                 0660   uhid       uhid
/dev/uinput               0660   system     bluetooth
/dev/alarm                0664   system     radio
/dev/rtc0                 0640   system     system
/dev/tty0                 0660   root       system
/dev/graphics/*           0660   root       graphics
/dev/msm_hw3dm            0660   system     graphics
/dev/input/*              0660   root       input
/dev/eac                  0660   root       audio
/dev/cam                  0660   root       camera
/dev/pmem                 0660   system     graphics
/dev/pmem_adsp*           0660   system     audio
/dev/pmem_camera*         0660   system     camera
/dev/oncrpc/*             0660   root       system
/dev/adsp/*               0660   system     audio
/dev/snd/*                0660   system     audio
/dev/mt9t013              0660   system     system
/dev/msm_camera/*         0660   system     system
/dev/akm8976_daemon       0640   compass    system
/dev/akm8976_aot          0640   compass    system
/dev/akm8973_daemon       0640   compass    system
/dev/akm8973_aot          0640   compass    system
/dev/bma150               0640   compass    system
/dev/cm3602               0640   compass    system
/dev/akm8976_pffd         0640   compass    system
/dev/lightsensor          0640   system     system
/dev/msm_pcm_out*         0660   system     audio
/dev/msm_pcm_in*          0660   system     audio
/dev/msm_pcm_ctl*         0660   system     audio
/dev/msm_snd*             0660   system     audio
/dev/msm_mp3*             0660   system     audio
/dev/audience_a1026*      0660   system     audio
/dev/tpa2018d1*           0660   system     audio
/dev/msm_audpre           0660   system     audio
/dev/msm_audio_ctl        0660   system     audio
/dev/htc-acoustic         0660   system     audio
/dev/vdec                 0660   system     audio
/dev/q6venc               0660   system     audio
/dev/snd/dsp              0660   system     audio
/dev/snd/dsp1             0660   system     audio
/dev/snd/mixer            0660   system     audio
/dev/smd0                 0640   radio      radio
/dev/qmi                  0640   radio      radio
/dev/qmi0                 0640   radio      radio
/dev/qmi1                 0640   radio      radio
/dev/qmi2                 0640   radio      radio
/dev/bus/usb/*            0660   root       usb
/dev/mtp_usb              0660   root       mtp
/dev/usb_accessory        0660   root       usb
/dev/tun                  0660   system     vpn

# CDMA radio interface MUX
/dev/ts0710mux*           0640   radio      radio
/dev/ppp                  0660   radio      vpn

# sysfs properties
/sys/devices/platform/trusty.*      trusty_version        0440  root   log
/sys/devices/virtual/input/input*   enable      0660  root   input
/sys/devices/virtual/input/input*   poll_delay  0660  root   input
/sys/devices/virtual/usb_composite/*   enable      0664  root   system
/sys/devices/system/cpu/cpu*   cpufreq/scaling_max_freq   0664  system system
/sys/devices/system/cpu/cpu*   cpufreq/scaling_min_freq   0664  system system

# DVB API device nodes
/dev/dvb*                 0660   root       system

[anotheruserofgithub]

Thanks! So the question is whether you user is granted the uhid group permission. What is the output of adb shell groups?

[yume-chan]

Or maybe the Linux kernel doesn't support new UHID commands. The stack trace shows open was successful but write wasn't.

if the event ID is not supported, it will return -EOPNOTSUPP.

https://www.kernel.org/doc/html/v5.14/hid/uhid.html

Copilot says the new commands were added in version 4.17.

[anotheruserofgithub]

Or maybe the Linux kernel doesn't support new UHID commands. The stack trace shows open was successful but write wasn't.

Fair enough! :)

Copilot says the new commands were added in version 4.17.

Although they seem to exist since v3.15 (2014): torvalds/linux@4522643

@17ayst What is the kernel version of your device?

[17ayst]

Sorry for the delay, I was quite busy and forgot to respond earlier. kernel version is 3.10.73-yesimxev.

[17ayst]

It seems the issue lies here; the version is less than v3.15.

[anotheruserofgithub]

Yes that makes sense. Thanks for your replies! :)