Magisk Alpha su doesn't support -c option

[CECoffee]

Environment

• Magisk version: b1dc47a0-alpha (29001)
• termux-sudo version: 1.2.0

Details

When I execute sudo xxx, it always throws out the following error:

~ $ sudo nmap -O 1.1.1.1
No 'su' binary found that supports the '-c', '--shell', '--preserve-environment' and '--mount-master' options
SU_SEARCH_PATHS: /system/bin/su /debug_ramdisk/su /system/xbin/su /sbin/su /sbin/bin/su /system/sbin/su /su/xbin/su /su/bin/su /magisk/.core/bin/su
sudo requires a 'su' binary that supports the '-c', '--shell', '--preserve-environment' and '--mount-master' options

Further, I executed sudo -vv su:

~ $ sudo -vv su

Running sudo

Running sudo_set_su_variables
A su binary found at '/debug_ramdisk/su'
The su binary found does not support '-c' option, continuing search
No 'su' binary found that supports the '-c', '--shell', '--preserve-environment' and '--mount-master' options
SU_SEARCH_PATHS: /system/bin/su /debug_ramdisk/su /system/xbin/su /sbin/su /sbin/bin/su /system/sbin/su /su/xbin/su /su/bin/su /magisk/.core/bin/su
sudo requires a 'su' binary that supports the '-c', '--shell', '--preserve-environment' and '--mount-master' options

Obviously, magisk su mounted at /debug_ramdisk/su is correctly recognized.
sudo says it doesn't receive necessary params like '-c', but it's actually fine if I directly run /debug_ramdisk/su -c 'ls -a' in MT terminal:

#/ /debug_ramdisk/su -c 'ls -a'
.                          mi_ext
..                         mnt
acct                       odm
apex                       odm_dlkm
bin                        oem
bootstrap-apex             opconfig
bugreports                 opcust
cache                      postinstall
config                     proc
cust                       product
d                          sdcard
data                       second_stage_resources
data_mirror                storage
debug_ramdisk              sys
dev                        system
etc                        system_dlkm
init                       system_ext
init.environ.rc            tmp
init.recovery.hardware.rc  vendor
linkerconfig               vendor_dlkm
metadata

[agnostic-apollo]

What's the output of su --help and su --version?

[CECoffee]

~ $ su --help
MagiskSU

Usage: su [options] [--] [user [argument...]]

Options:
  -s, --shell SHELL             Use SHELL instead of the default /system/bin/sh
  -i, --interactive             Force pseudo-terminal allocation
  -g, --group GROUP             Specify the primary group
  -G, --supp-group GROUP        Specify a supplementary group
                                The first specified supplementary group is also used
                                as a primary group if the option -g is not specified
  -Z, --context CONTEXT         Change SELinux context
  -t, --target PID              PID to take mount namespace from
                                pid 0 means magisk global mount namespace
  -d, --drop-cap                Drop all Linux capabilities
  -m, -p,
  --preserve-environment        Preserve the entire environment
  -v, --version                 Display version number and exit
  -V                            Display version code and exit
  -h, --help                    Display this help message and exit

--: Force stop options parsing, and also stop when an unknown option is found
User: The user to switch to (default root), it can be name or uid
Argument: Pass it to the shell as is

~ $ su --version
b1dc47a0-alpha:MAGISKSU

[agnostic-apollo]

Where is this line in your build? Install official magisk and latest build.

https://github.com/topjohnwu/Magisk/blob/b1dc47a047f134f87943eb424309356d22091db5/native/src/core/su/su.cpp#L41

[CECoffee]

su -c is deprecated in Magisk Alpha. Magisk#9003

[agnostic-apollo]

No, you just need to pass --interactive along with -c for tty allocation, and that was fixed in 746ba74

[CECoffee]

When a TTY is required, using su -c is incorrect, as this option is intended for executing non-interactive commands and should not be used to launch a shell.
The -c parameter is merely a legacy compatibility measure: it was designed to indicate the command content to be forwarded to the remote shell. In theory, all remaining arguments should be forwarded to the remote shell, which would then parse -c itself. Unfortunately, due to historical reasons, -c does not provide a TTY.
Therefore, do not use -ic to specify a shell. Instead, use the long-existing -s option.

su -ic is a compatibility feature. Instead, use the -s option is expected in Magisk Alpha, which aligns with the behavior of su on Linux.
Though su -ic still exists in Magisk, it has been deprecated in Alpha. Hope that sudo could adapt to the latter.

[agnostic-apollo]

-s, --shell SHELL Use SHELL instead of the default /system/bin/sh

-s is to set shell used, which is already set to bash by sudo. -c and -i are completely different options about passing commands to the shell started, or starting tty. -c option is necessary to exist to pass commands and removing it will break 10-15 years of user scripts.

[CECoffee]

It's not removed, but is passed and resolved by remote shell, just like shown previously, /debug_ramdisk/su -c 'ls -a' executed correctly. Magisk Pull#9017

[agnostic-apollo]

I see, that should work too, but the --help output should still have some reference of -c, if even at the end describing this behavior so that clients can match this, even if su itself does not handle the option itself anymore. The current -c, --command output can also be kept with additional info that this will be handled with the shell set by --shell, as otherwise users will also wonder where the -c option went. And that it should be passed after other su options.

[CECoffee]

@vvb2060

[agnostic-apollo]

For reference

sudo/sudo

Lines 836 to 838 in 50b2ec4

	# If '-c' option is not supported, then continue searching
	if [[ "$su_help" != *"-c,"* ]] && [[ "$su_help" != *"-c "* ]]; then
	sudo_log 3 "The su binary found does not support '-c' option, continuing search"

[vvb2060]

https://cs.android.com/android/platform/superproject/+/android-latest-release:system/extras/su/su.cpp

[agnostic-apollo]

Yes, I am aware of that, adb root su is not supported by sudo (nor is it normally callable by apps), and that's why those checks exist. And in addition to -c, it also doesn't support --shell, --preserve-environment and --mount-master.

• https://github.com/agnostic-apollo/sudo/blob/master/site/pages/en/projects/docs/usage/index.md#su-search-paths

[vvb2060]

su should not have -c, that is a feature of sh, not su. Parsing help output is unstable, you should use su -V and -v