Bug#876261: PathModified in path activation propagates to containing directory when file is deleted

[Enrico Zini]

Package: systemd
Version: 232-25+deb9u1
Severity: normal

Hello,

given this setup:

   # cat beeponce.service 
   [Unit]
   Description=Beeps
   
   [Service]
   Type=oneshot
   ExecStart=/usr/bin/aplay /tmp/beep.wav
   
   
   # cat beeponce.path 
   [Unit]
   Description=Monitor /tmp/zz
   
   [Path]
   PathModified=/tmp/zz


This happens:

   touch /tmp/zz   # BEEP!   (ok)
   rm /tmp/zz      # BEEP!   (ok)
   touch /tmp/foo  # BEEP!   (What??)
   touch /tmp/foo  # silence (ok)
   touch /tmp/zz   # BEEP!   (ok)
   touch /tmp/foo  # silence (ok)

It looks like systemd is listening to events in the containing directory to
catch if the file is created, and after removing the file it accidentally
triggers on a directory event even if it's not about the file being monitored.


Enrico

-- Package-specific info:

-- System Information:
Debian Release: 9.1
  APT prefers stable-debug
  APT policy: (500, 'stable-debug'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.9.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages systemd depends on:
ii  adduser         3.115
ii  libacl1         2.2.52-3+b1
ii  libapparmor1    2.11.0-3
ii  libaudit1       1:2.6.7-2
ii  libblkid1       2.29.2-1
ii  libc6           2.24-11+deb9u1
ii  libcap2         1:2.25-1
ii  libcryptsetup4  2:1.7.3-4
ii  libgcrypt20     1.7.6-2+deb9u2
ii  libgpg-error0   1.26-2
ii  libidn11        1.33-1
ii  libip4tc0       1.6.0+snapshot20161117-6
ii  libkmod2        23-2
ii  liblz4-1        0.0~r131-2+b1
ii  liblzma5        5.2.2-1.2+b1
ii  libmount1       2.29.2-1
ii  libpam0g        1.1.8-3.6
ii  libseccomp2     2.3.1-2.1
ii  libselinux1     2.6-3+b1
ii  libsystemd0     232-25+deb9u1
ii  mount           2.29.2-1
ii  procps          2:3.3.12-3
ii  util-linux      2.29.2-1

Versions of packages systemd recommends:
ii  dbus            1.10.18-1
ii  libpam-systemd  232-25+deb9u1

Versions of packages systemd suggests:
ii  policykit-1        0.105-18
ii  systemd-container  232-25+deb9u1
ii  systemd-ui         3-4+b1

Versions of packages systemd is related to:
pn  dracut           <none>
ii  initramfs-tools  0.130
ii  udev             232-25+deb9u1

-- no debconf information