Merge branch '17-swap-module-fix-etc-fstab-entry-problem' into 'master'

Resolve "Swap module -> fix /etc/fstab entry problem"

Closes #17

See merge request icaotix/linux-tools!12

modules/swap/module.py

@@ -1,8 +1,14 @@
 import subprocess
+from typing import List
+
 from AbstractModule import AbstractModule
 from PyInquirer import prompt
 
 
+def _run_shell_command(cmd: List[str]) -> str:
+    return subprocess.check_output(cmd).decode("UTF-8").strip()
+
+
 class SwapModule(AbstractModule):
 
     def __init__(self):
@@ -17,7 +23,8 @@ class SwapModule(AbstractModule):
             "Get swap location": self._get_swap_location,
             "Get swap size": self._get_swap_size,
             "Show swapiness": self._show_swapiness,
-            "Adjust temp. swapiness": self._adjust_swapiness_temp
+            "Adjust temp. swapiness": self._adjust_swapiness_temp,
+            "Check fstab for entry": self._fstab_entry_exists
         }
         menu = [
             {
@@ -35,7 +42,7 @@ class SwapModule(AbstractModule):
         self._make_swap_persistent()
 
     def _get_swap_location(self):
-        output_swaps = subprocess.check_output(['cat', '/proc/swaps']).decode("UTF-8")
+        output_swaps = _run_shell_command(["cat", "/proc/swaps"])
         try:
             swap_location = output_swaps.split()[5]
             print("Swap is located here:", swap_location)
@@ -45,7 +52,7 @@ class SwapModule(AbstractModule):
             return None
 
     def _get_swap_size(self):
-        swap_size = subprocess.check_output(['swapon', '--show']).decode("UTF-8")
+        swap_size = _run_shell_command(['swapon', '--show'])
         try:
             swap_size = swap_size.split()[7]
             print("Swap is {}b big!".format(swap_size))
@@ -53,10 +60,9 @@ class SwapModule(AbstractModule):
             print("Swap file doesn´t exist!")
 
     def _create_resize_swap(self):
-        output_swapon = subprocess.check_output(['swapon', '--show']).decode("UTF-8")
+        output_swapon = _run_shell_command(['swapon', '--show'])
-        if output_swapon:
+        if output_swapon is not "":
-            swap_size = subprocess.check_output(['swapon', '--show']).decode("UTF-8")
+            swap_size = output_swapon.split()[7]
-            swap_size = swap_size.split()[7]
             print("")
             print("Swap already installed! You can resize it!")
             print("Curr. swap size: {}b".format(swap_size))
@@ -66,7 +72,7 @@ class SwapModule(AbstractModule):
                               "sudo mkswap /swapfile && " + \
                               "sudo swapon /swapfile"
             subprocess.call(resize_swapfile, shell=True)
-            output_free = subprocess.check_output(['free', '-h']).decode("UTF-8")
+            output_free = _run_shell_command(["free", "-h"])
             print(output_free.strip())
 
         else:
@@ -77,7 +83,7 @@ class SwapModule(AbstractModule):
                               "sudo swapon /swapfile"
             subprocess.call(create_swapfile, shell=True)
 
-            output_free = subprocess.check_output(['free', '-h']).decode("UTF-8")
+            output_free = _run_shell_command(["free", "-h"])
             print(output_free.strip())
 
     def _make_swap_persistent(self):
@@ -87,13 +93,15 @@ class SwapModule(AbstractModule):
             return
         backup_fstab = "sudo cp /etc/fstab /etc/fstab.bak"
         enable_persistence = "echo '{} none swap sw 0 0' | sudo tee -a /etc/fstab".format(swap_location)
-        subprocess.call(backup_fstab, shell=True)
+        if self._fstab_entry_exists():
-        subprocess.call(enable_persistence, shell=True)
+            print("Swap is already persistent!")
-        print("Swap is now persistent!")
+        else:
+            subprocess.call(backup_fstab, shell=True)
+            subprocess.call(enable_persistence, shell=True)
+            print("Swap is now persistent!")
 
     def _show_swapiness(self):
-        get_swapiness = "cat /proc/sys/vm/swappiness"
+        print(_run_shell_command(["cat", "/proc/sys/vm/swappiness"]))
-        subprocess.call(get_swapiness, shell=True)
 
     def _adjust_swapiness_temp(self):
         options = {
@@ -121,9 +129,30 @@ class SwapModule(AbstractModule):
             return
         disable_swapfile = "sudo swapoff {} && ".format(swap_location) + \
                            "sudo rm {}".format(swap_location)
+        if self._fstab_entry_exists():
+            with open("/etc/fstab", "r") as fstab_out:
+                content = fstab_out.readlines()
+            with open("/etc/fstab", "w") as fstab_in:
+                content = content[:-1]
+                for line in content:
+                    fstab_in.write(line)
+        else:
+            print("No entry in /etc/fstab!")
         subprocess.call(disable_swapfile, shell=True)
-        output_swapon = subprocess.check_output(['swapon', '--show']).decode("UTF-8")
+        output_swapon = _run_shell_command(['swapon', '--show'])
-        output_free = subprocess.check_output(['free', '-h']).decode("UTF-8")
+        output_free = _run_shell_command(["free", "-h"])
         if not output_swapon:
             print("Swap deleted!")
             print(output_free.strip())
+
+    def _fstab_entry_exists(self):
+        swap_location = self._get_swap_location()
+        fstab_entry = "{} none swap sw 0 0\n".format(swap_location)
+        with open("/etc/fstab", "r") as fstab_file:
+            line = fstab_file.readlines()[-1]
+            if line != fstab_entry:
+                print("No entry in /etc/fstab")
+                return False
+            else:
+                print("fstab entry:", line.strip())
+                return True