"env process" dumps two coredumps instead of one when killed

[Ecordonnier]

This used to work correctly with 0.0.16, but it stopped working after #4011 was merged (shortly after the 0.0.16 release):

Killing a process started using env should cause one coredump, not two:
With version 0.0.27 "env" generates its own coredump:

ecordonnier@lj8k2dq3:~/dev/coreutils$ ./target/release/coreutils env --version
uu_env 0.0.27
ecordonnier@lj8k2dq3:~/dev/coreutils$ ./target/release/coreutils env sleep 100 &
[1] 3724248
ecordonnier@lj8k2dq3:~/dev/coreutils$ pidof coreutils
3724248
ecordonnier@lj8k2dq3:~/dev/coreutils$ pidof sleep
3724252
ecordonnier@lj8k2dq3:~/dev/coreutils$ kill -11 $(pidof sleep)
ecordonnier@lj8k2dq3:~/dev/coreutils$ 
[1]+  Segmentation fault      (core dumped) ./target/release/coreutils env sleep 100
ecordonnier@lj8k2dq3:~/dev/coreutils$ 

/# coredumpctl list
TIME                         PID UID GID SIG     COREFILE EXE                 SIZE
Tue 2024-10-01 13:58:07 CEST 3724252 23274 23274 SIGSEGV present  /usr/bin/sleep                                                                           24.5K
Tue 2024-10-01 13:58:07 CEST 3724248 23274 23274 SIGSEGV present  /home/ecordonnier/dev/coreutils/target/release/coreutils                                 95.1K

See behavior of GNU coreutils where only one coredump is generated in this case:

ecordonnier@lj8k2dq3:~$ env --version
env (GNU coreutils) 9.4
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Richard Mlynarik, David MacKenzie, and Assaf Gordon.
ecordonnier@lj8k2dq3:~$ env sleep 100 &
[1] 3676807
ecordonnier@lj8k2dq3:~$ pidof sleep
3676807
ecordonnier@lj8k2dq3:~$ pidof env
ecordonnier@lj8k2dq3:~$ kill -11 $(pidof sleep)
ecordonnier@lj8k2dq3:~$ 
[1]+  Segmentation fault      (core dumped) env sleep 100
    
ecordonnier@lj8k2dq3:~$ coredumpctl list
Hint: You are currently not seeing messages from other users and the system.
      Users in groups 'adm', 'systemd-journal' can see all messages.
      Pass -q to turn off this notice.
TIME                             PID   UID   GID SIG     COREFILE EXE                                                                                       SIZE
Tue 2024-10-01 13:50:43 CEST 3676807 23274 23274 SIGSEGV present  /usr/bin/sleep                                                                           24.4K

[samueltardieu]

This is probably due to the non-use of exec*() functions, as describe in the env.rs file:

        /*
         * On Unix-like systems Command::status either ends up calling either fork or posix_spawnp
         * (which ends up calling clone). Keep using the current process would be ideal, but the
         * standard library contains many checks and fail-safes to ensure the process ends up being
         * created. This is much simpler than dealing with the hassles of calling execvp directly.
         */

GNU coreutils reuses the same process by calling exec*() as your pidof env empty output shows.