f-string-ify

Mostly-ish automated with https://github.com/ikamensh/flynt

Using f-strings means we will no longer support Python 3.5, which seems okay
since it went EOL over 3 years ago:
https://www.python.org/downloads/release/python-3510

.github/workflows/test_and_release.yml

@@ -41,7 +41,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python-version: ['3.5', '3.6', '3.7']
+        python-version: ['3.6', '3.7']
 
     steps:
     - uses: actions/checkout@v3

setup.py

@@ -31,7 +31,7 @@
         "setproctitle": ["setproctitle"],
         "dnspython": ["dnspython"],
     },
-    python_requires=">=3.5",
+    python_requires=">=3.6",
     license='GPL v3 or later',
     url="https://github.com/dlenski/vpn-slice",
     packages=["vpn_slice"],

vpn_slice/freebsd.py

@@ -6,14 +6,14 @@
 class ProcfsProvider(PosixProcessProvider):
     def pid2exe(self, pid):
         try:
-            return os.readlink('/proc/%d/file' % pid)
+            return os.readlink(f'/proc/{pid}/file')
         except OSError:
             return None
 
     def ppid_of(self, pid=None):
         if pid is None:
             return os.getppid()
         try:
-            return int(next(open('/proc/%d/status' % pid)).split()[3])
+            return int(next(open(f'/proc/{pid}/status')).split()[3])
         except (OSError, ValueError):
             return None

vpn_slice/linux.py

@@ -10,15 +10,15 @@
 class ProcfsProvider(PosixProcessProvider):
     def pid2exe(self, pid):
         try:
-            return os.readlink('/proc/%d/exe' % pid)
+            return os.readlink(f'/proc/{pid}/exe')
         except OSError:
             return None
 
     def ppid_of(self, pid=None):
         if pid is None:
             return os.getppid()
         try:
-            return int(next(open('/proc/%d/stat' % pid)).split()[3])
+            return int(next(open(f'/proc/{pid}/stat')).split()[3])
         except (OSError, ValueError):
             return None
 

vpn_slice/mac.py

@@ -119,14 +119,14 @@ def configure_domain_vpn_dns(self, domains, nameservers):
         if not os.path.exists('/etc/resolver'):
             os.makedirs('/etc/resolver')
         for domain in domains:
-            resolver_file_name = "/etc/resolver/{0}".format(domain)
+            resolver_file_name = f"/etc/resolver/{domain}"
             with open(resolver_file_name, "w") as resolver_file:
                 for nameserver in nameservers:
-                    resolver_file.write("nameserver {}\n".format(nameserver))
+                    resolver_file.write(f"nameserver {nameserver}\n")
 
     def deconfigure_domain_vpn_dns(self, domains, nameservers):
         for domain in domains:
-            resolver_file_name = "/etc/resolver/{0}".format(domain)
+            resolver_file_name = f"/etc/resolver/{domain}"
             if os.path.exists(resolver_file_name):
                 os.remove(resolver_file_name)
         if not len(os.listdir('/etc/resolver')):
@@ -167,10 +167,10 @@ def configure_firewall(self, device):
         if not enable_token:
             print("WARNING: failed to get pf enable reference token, packet filter might not shutdown correctly")
 
-        anchor = '{}/{}'.format(self._PF_ANCHOR, device)
+        anchor = f'{self._PF_ANCHOR}/{device}'
         # add anchor to generate rules with
         with open(self._PF_CONF_FILE, 'a') as file:
-            file.write('anchor "{}" # vpn-slice-{} AUTOCREATED {}\n'.format(anchor, device, enable_token))
+            file.write(f'anchor "{anchor}" # vpn-slice-{device} AUTOCREATED {enable_token}\n')
 
         # reload config file
         self._reload_conf()
@@ -191,7 +191,7 @@ def configure_firewall(self, device):
 
     def deconfigure_firewall(self, device):
         # disable anchor
-        anchor = '{}/{}'.format(self._PF_ANCHOR, device)
+        anchor = f'{self._PF_ANCHOR}/{device}'
         subprocess.check_call([self.pfctl, '-a', anchor, '-F', 'all'])
 
         with open(self._PF_CONF_FILE, 'r') as file:

vpn_slice/posix.py

@@ -20,7 +20,7 @@ def lookup_host(self, hostname, keep_going=True):
         search_domains = self.search_domains
 
         if not bind_addresses:
-            some_cls = [self.base_cl + ['@{!s}'.format(dns) for dns in dns_servers]]
+            some_cls = [self.base_cl + [f'@{dns!s}' for dns in dns_servers]]
             field_requests = [hostname, 'A', hostname, 'AAAA']
         else:
             some_cls = []
@@ -32,7 +32,7 @@ def lookup_host(self, hostname, keep_going=True):
                 field_requests.extend([hostname, ('AAAA' if bind.version == 6 else 'A')])
 
                 # We can only do a lookup via DNS-over-IPv[X] if we have an IPv[X] address to bind to.
-                matching_dns = ['@{!s}'.format(dns) for dns in dns_servers if dns.version == bind.version]
+                matching_dns = [f'@{dns!s}' for dns in dns_servers if dns.version == bind.version]
                 if matching_dns:
                     some_cls.append(self.base_cl + ['-b', str(bind)] + matching_dns)
 
@@ -43,7 +43,7 @@ def lookup_host(self, hostname, keep_going=True):
         all_cls = []
         if search_domains:
             for cl in some_cls:
-                all_cls.extend(cl + ['+domain={!s}'.format(sd)] + field_requests for sd in search_domains)
+                all_cls.extend(cl + [f'+domain={sd!s}'] + field_requests for sd in search_domains)
         else:
             for cl in some_cls:
                 all_cls.extend([cl + field_requests])
@@ -71,10 +71,10 @@ def lookup_srv(self, query):
         bind_addresses = self.bind_addresses
 
         if not bind_addresses:
-            all_cls = [self.base_cl + ['@{!s}'.format(dns) for dns in dns_servers] + [query, 'SRV']]
+            all_cls = [self.base_cl + [f'@{dns!s}' for dns in dns_servers] + [query, 'SRV']]
         else:
             all_cls = [self.base_cl + ['-b', str(bind)] +
-                       ['@{!s}'.format(n) for n in dns_servers if n.version == bind.version] +
+                       [f'@{n!s}' for n in dns_servers if n.version == bind.version] +
                        [query, 'SRV'] for bind in bind_addresses]
 
         result = set()
@@ -95,18 +95,18 @@ class HostsFileProvider(HostsProvider):
     def __init__(self, path):
         self.path = path
         if not os.access(path, os.R_OK | os.W_OK):
-            raise OSError('Cannot read/write {}'.format(path))
+            raise OSError(f'Cannot read/write {path}')
 
     def write_hosts(self, host_map, name):
-        tag = 'vpn-slice-{} AUTOCREATED'.format(name)
+        tag = f'vpn-slice-{name} AUTOCREATED'
         with open(self.path, 'r+') as hostf:
             fcntl.flock(hostf, fcntl.LOCK_EX)  # POSIX only, obviously
             lines = hostf.readlines()
-            keeplines = [l for l in lines if not l.endswith('# %s\n' % tag)]
+            keeplines = [l for l in lines if not l.endswith(f'# {tag}\n')]
             hostf.seek(0, 0)
             hostf.writelines(keeplines)
             for ip, names in host_map:
-                print('%s %s\t\t# %s' % (ip, ' '.join(names), tag), file=hostf)
+                print(f"{ip} {' '.join(names)}\t\t# {tag}", file=hostf)
             hostf.truncate()
         return len(host_map) or len(lines) - len(keeplines)
 

vpn_slice/util.py

@@ -6,7 +6,7 @@
 def get_executable(path):
     path = which(os.path.basename(path)) or path
     if not os.access(path, os.X_OK):
-        raise OSError('cannot execute {}'.format(path))
+        raise OSError(f'cannot execute {path}')
     return path