cleaner way to keep files open for lsof

tests/profiles/lsof/task.yaml

@@ -1,14 +1,5 @@
 summary: stress test for the lsof profile
 execute: |
-  ### Trivial test cases                                                 
-  #lsof /usr/bin/bash | MATCH '/usr/bin/bash' #initial basic test        
-  # lsof >/dev/null 2>&1                                                 
-  # test $? -eq 0$                                                       
-
-  #if debugging necessary, run spread with '-vv' and  '-debugging' and uncomment below
-  #lsof | tee /var/tmp/lsof_no_denials.txt                               
-
-  # Create block and character devices only if they don't exist         
   ###########
   ## SETUP ##
   ###########
@@ -17,7 +8,7 @@ execute: |
   # make sure we can run lsof -d mem later
   sudo chmod 660 /dev/mem
 
-  # Create loopback test device (chck it doesn't exist either!)          
+  # Create loopback test device (check it doesn't exist either!)
   [ -e /dev/loop10 ] || sudo mknod /dev/loop10 b 7 10  # major 1 -> loopback device; #minor10 -> instance 10 of device driver; shouldn't be in use.
   dd if=/dev/zero of=/tmp/test.img bs=1M count=10  # Fill /tmp/test.img with 10MB of 0's
   sudo losetup /dev/loop10 /tmp/test.img  # mount /tmp/test.img on /dev/loop10 so it looks like a block device
@@ -32,7 +23,7 @@ execute: |
 
   # List all open files attached to /, recursively
   # sudo lsof +D /
-  # these 2 could be combined in one (-i -U) to list all UNIX sockets and network files$$$$
+  # these 2 could be combined in one (-i -U) to list all UNIX sockets and network files
   sudo lsof -i
   sudo lsof -U
   # these 5 could be combined ( -d mem,mmap,txt,CHR,BLK) for mapped, memory-mapped, binaries, character & block devices)
@@ -42,8 +33,9 @@ execute: |
   sudo lsof -d CHR
   sudo lsof -d BLK
 
-  # ##########################################################################
+  #############################
   # Test Deleted but Open Files
+  #############################
   # Create a test file and open it in the background
   echo "test data" > /tmp/deleted-file
   sleep 1
@@ -60,8 +52,9 @@ execute: |
   kill $TAIL_PID
 
 
-  # #######################################################
+  ##############################
   # Start a temporary web server
+  ##############################
   python3 -m http.server 8080 &
   PYTHON_PID=$!
   sleep 2
@@ -71,26 +64,23 @@ execute: |
   # Cleanup
   kill $PYTHON_PID
 
-  # ########################################################
+  ####################
   # Test Named Pipe
+  ####################
   # Open a named pipe
   mkfifo /tmp/testpipe
-  cat /tmp/testpipe &  # Open for reading in the background
+  # open the pipe for r/w so that it remains open
-  CAT_PID=$!
+  exec 3<> /tmp/testpipe
-  sleep 2
-  echo "test" > /tmp/testpipe #so that grep doesn't hang
-  sleep 1
   # Check lsof dislays open pipe
   sudo lsof +E | tee /tmp/lsof.log | grep /tmp/testpipe || grep FIFO /tmp/lsof.log
   # Cleanup
-  #kill $CAT_PID 2>/dev/null #in case cat terminates as soon as it outputs the redirected input from echoi
+  exec 3<&-  # Close fd 3
   rm /tmp/testpipe
-  # 
-  # 
 
-  # cat /tmp/script_debug.log
+
-  # ###########################
+  #####################
   # Open network sockets
+  #####################
   # Start a temporary web server
   python3 -m http.server 8080 &
   sleep 1
@@ -119,30 +109,31 @@ execute: |
   kill $SCRIPT_PID 2>/dev/null
 
 
-  # ###################################
+  #################
-  # #Zombie process
+  # Zombie process
-  # ## Create a process that turns into a zombie
+  #################
+  # Create a process that turns into a zombie
   bash -c 'sleep 10 & wait $!' &
   PARENT_PID=$!
 
-  # # Wait a moment and check for zombies
+  # Wait a moment and check for zombies
   sleep 2
   ps -ef | grep defunct
   sudo lsof -p $PARENT_PID
 
-  # # Cleanup
+  # Cleanup
   kill $PARENT_PID 2>/dev/null
 
-
+  ###########################
-  # #########################################
+  # Encrypted loopback device
-  # #Encrypted loopback device
+  ###########################
   # Create an encrypted loopback device
   dd if=/dev/zero of=/tmp/encrypted.img bs=1M count=30
   sudo losetup /dev/loop20 /tmp/encrypted.img
   echo "securest passphrase" | sudo cryptsetup luksFormat /dev/loop20 --key-file=-
   echo "securest passphrase" | sudo cryptsetup luksOpen /dev/loop20 encdev --key-file=-
 
-  # # Mount it and check open files
+  # Mount it and check open files
   sudo mkfs.ext4 /dev/mapper/encdev
   mkdir -p /mnt/encrypted
   sudo mount /dev/mapper/encdev /mnt/encrypted
@@ -154,55 +145,57 @@ execute: |
   sudo lsof /mnt/encrypted
   exec 3<&-  # Close file descriptor after lsof
 
-  # # Cleanup
+  # Cleanup
   sudo umount /mnt/encrypted
   sudo cryptsetup luksClose encdev
   sudo losetup -d /dev/loop20
   rm /tmp/encrypted.img
 
-  # #############################################
+  ########
   #Try SMB
+  ########
   #Install SMB and Mount SMB share 
   sudo apt update && sudo apt install -y samba
   sleep 1
   sudo mkdir -p /srv/samba/share
   sudo chmod 777 /srv/samba/share  # Allow all users to access (for testing)
+  # Inline the 'testshare' entry to the samba config file
   printf "\n[testshare]\npath = /srv/samba/share\nbrowseable = yes\nread only = no\nguest ok = yes\nforce user = nobody\n" | sudo tee -a /etc/samba/smb.conf
 
   sleep 1
   sudo systemctl restart smbd nmbd
 
-  sudo ss -tulnp | grep smbd
+  # sudo ss -tulnp | grep smbd  # uncomment if need to troubleshoot SMB.
 
   sudo modprobe cifs
 
 
-  #testparm
-  
   sleep 1
   sudo mkdir -p /mnt/smb
   sudo mount -t cifs //127.0.0.1/testshare /mnt/smb -o guest
 
-  # Try open file from mounted sharew
+  # Try open file from mounted share
   echo "test content" | sudo tee /srv/samba/share/testfile.txt
-  sudo sync #sync samba or no content is cat'd
+  sudo sync  # sync samba to update testfile.txt
-  cat /mnt/smb/testfile.txt &
+  # Open shared file for reading ans assign fd 3. Opoen for r/w can be tricky in smb, this does the trick.
-  CAT_PID=$!
+  exec 3</mnt/smb/testfile.txt
   sleep 2
   #lsof on open share
-  #sudo lsof  /mnt/smb
   sudo lsof -c smbd
 
-  #kill $CAT_PID
+  # Cleanup
+  exec 3<&-  # Close fd 3
   sudo umount /mnt/smb
 
-  ##############################################
+  #########
   # Try NFS
+  #########
   #mount NFS
   sudo apt install -y nfs-kernel-server
   sleep 1
   sudo mkdir -p /srv/nfs/share
   sudo chmod 777 /srv/nfs/share  # Allow all users for testing
+  # Update nfs share config
   echo '/srv/nfs/share 127.0.0.1(rw,sync,no_subtree_check,no_root_squash)' | sudo tee -a /etc/exports
   sudo exportfs -a
   sudo systemctl restart nfs-kernel-server
@@ -210,3 +203,4 @@ execute: |
   sudo mount -t nfs 127.0.0.1:/srv/nfs/share /mnt/nfs
   sudo lsof -c nfsd
 
+  sudo umount /mnt/nfs