Ctrl-C with cmd /c weirdness

[simonbuchan]

Possibly related to #1569 or #1583.

I see Ctrl-C effectively "background" windows apps launched with cmd.exe /c, that is, it returns to the prompt, but the app continues:

0 app-tester 130 % strace -o node-full.strace /mnt/c/Windows/System32/cmd.exe /c 'node -e "setTimeout(() => console.log(`done`), 3000)"'
done
0 app-tester 0 % strace -o node-intr.strace /mnt/c/Windows/System32/cmd.exe /c 'node -e "setTimeout(() => console.log(`done`), 3000)"'
^C
0 app-tester 130 % done

As far as I can tell, the straces seem as expected?

--- node-full.strace    2017-01-26 12:10:14.746717500 +1300
+++ node-intr.strace    2017-01-26 12:10:23.762533400 +1300
@@ -1,56 +1,53 @@
 execve("/mnt/c/Windows/System32/cmd.exe", ["/mnt/c/Windows/System32/cmd.exe", "/c", "node -e \"setTimeout(() => consol"...], [/* 21 vars */]) = 0
-brk(NULL)                               = 0x7fffd5421000
+brk(NULL)                               = 0x7fffbb78c000
 access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
-mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ffb2ab30000
+mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3b8aaf0000
 access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
 fstat(3, {st_mode=S_IFREG|0644, st_size=37347, ...}) = 0
-mmap(NULL, 37347, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ffb2ab26000
+mmap(NULL, 37347, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3b8aae6000
 close(3)                                = 0
 access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
 read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\t\2\0\0\0\0\0"..., 832) = 832
 fstat(3, {st_mode=S_IFREG|0755, st_size=1864888, ...}) = 0
-mmap(NULL, 3967392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7ffb2a430000
-mprotect(0x7ffb2a5ef000, 2097152, PROT_NONE) = 0
-mmap(0x7ffb2a7ef000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bf000) = 0x7ffb2a7ef000
-mmap(0x7ffb2a7f5000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7ffb2a7f5000
+mmap(NULL, 3967392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f3b8a430000
+mprotect(0x7f3b8a5ef000, 2097152, PROT_NONE) = 0
+mmap(0x7f3b8a7ef000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bf000) = 0x7f3b8a7ef000
+mmap(0x7f3b8a7f5000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f3b8a7f5000
 close(3)                                = 0
-mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ffb2ab20000
-mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ffb2ab10000
-mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7ffb2ab00000
-arch_prctl(ARCH_SET_FS, 0x7ffb2ab10700) = 0
-mprotect(0x7ffb2a7ef000, 16384, PROT_READ) = 0
-mprotect(0x7ffb2ae09000, 4096, PROT_READ) = 0
-mprotect(0x7ffb2aa25000, 4096, PROT_READ) = 0
-munmap(0x7ffb2ab26000, 37347)           = 0
-getpid()                                = 788
-brk(NULL)                               = 0x7fffd5421000
-brk(0x7fffd5442000)                     = 0x7fffd5442000
+mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3b8aae0000
+mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3b8aad0000
+mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3b8aac0000
+arch_prctl(ARCH_SET_FS, 0x7f3b8aad0700) = 0
+mprotect(0x7f3b8a7ef000, 16384, PROT_READ) = 0
+mprotect(0x7f3b8ae09000, 4096, PROT_READ) = 0
+mprotect(0x7f3b8aa25000, 4096, PROT_READ) = 0
+munmap(0x7f3b8aae6000, 37347)           = 0
+getpid()                                = 799
+brk(NULL)                               = 0x7fffbb78c000
+brk(0x7fffbb7ad000)                     = 0x7fffbb7ad000
 open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
 fstat(3, {st_mode=S_IFREG|0644, st_size=1668976, ...}) = 0
-mmap(NULL, 1668976, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7ffb2a88d000
+mmap(NULL, 1668976, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3b8a88d000
 close(3)                                = 0
 getcwd("/mnt/c/code/player/app-tester", 4096) = 30
 open("/dev/lxssclient", O_RDWR)         = 3
-ioctl(3, _IOC(0, 0x00, 0x2f, 0x22), 0x7fffdd76eb20) = 0
+ioctl(3, _IOC(0, 0x00, 0x2f, 0x22), 0x7fffc3650210) = 0
 open("/mnt/c/Windows/System32/cmd.exe", O_RDONLY) = 5
-ioctl(3, _IOC(0, 0x00, 0x3f, 0x22), 0x7fffdd76e9e8) = 0
+ioctl(3, _IOC(0, 0x00, 0x3f, 0x22), 0x7fffc36500d8) = 0
 close(5)                                = 0
 open("/mnt/c/code/player/app-tester", O_RDONLY) = 5
-ioctl(3, _IOC(0, 0x00, 0x3f, 0x22), 0x7fffdd76e9e8) = 0
+ioctl(3, _IOC(0, 0x00, 0x3f, 0x22), 0x7fffc36500d8) = 0
 close(5)                                = 0
-ioctl(4, _IOC(0, 0x00, 0x97, 0x22), 0x7fffdd76ea80) = 0
-ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffdd76ea78) = 0
-ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffdd76ea78) = 0
-ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffdd76ea78) = 0
-write(4, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0O\0\0\0\0\0\0\0"..., 223) = 223
-read(4, "\0\0\0\0\0\0\0\0;\0\0\0\0\0\0\0", 16) = 16
-ioctl(4, _IOC(0, 0x00, 0x9b, 0x22), 0x7fffdd76eb18) = 0
-write(4, "\0\0\0\0\0\0\0\0;\0\0\0\0\0\0\0", 16) = 16
-ioctl(5, _IOC(0, 0x00, 0xbf, 0x22), 0x7fffdd76eb10) = 0
-close(3)                                = 0
-close(4)                                = 0
-close(5)                                = 0
-exit_group(0)                           = ?
-+++ exited with 0 +++
+ioctl(4, _IOC(0, 0x00, 0x97, 0x22), 0x7fffc3650170) = 0
+ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffc3650168) = 0
+ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffc3650168) = 0
+ioctl(4, _IOC(0, 0x00, 0xb7, 0x22), 0x7fffc3650168) = 0
+write(4, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0R\0\0\0\0\0\0\0"..., 223) = 223
+read(4, "\0\0\0\0\0\0\0\0=\0\0\0\0\0\0\0", 16) = 16
+ioctl(4, _IOC(0, 0x00, 0x9b, 0x22), 0x7fffc3650208) = 0
+write(4, "\0\0\0\0\0\0\0\0=\0\0\0\0\0\0\0", 16) = 16
+ioctl(5, _IOC(0, 0x00, 0xbf, 0x22), 0x7fffc3650200) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
+--- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
++++ killed by SIGINT +++

I'm on 15014, and Ctrl-C works as expected with native linux commands.

I also noticed while doing some testing that cmd /c pause doesn't... pause, and cmd /c timeout ... doesn't work at all, but I don't know if that's expected:

0 app-tester 0 % cmd /c pause
Press any key to continue . . . # no keypress!
0 app-tester 0 % cmd /c timeout 1
ERROR: Input redirection is not supported, exiting the process immediately.
0 app-tester 1 %

[benhillis]

Thanks for posting - This is a duplicate of #1614.

[simonbuchan]

@benhillis OK, cool. I did search, but the #1614's title wasn't particularly suggestive of this :) I should probably include closed issues too in the future, which would have found #1574 and saved me some time :)

[benhillis]

Good call, I've modified #1614's title to include ctrl-c.