Fix duplicate comports listed with list_ports(include_links=True)

In case there are any symlinks which name matches any of the previously
checked globs then list_ports(include_links=True) will report them twice.
For example if there's a symlink named /dev/ttyUSB_mylink then it would
appear twice.

The problem is fixed by storing the found paths in a set instead of a list.
Documentation at https://pythonhosted.org/pyserial/tools.html#module-serial.tools.list_ports
already states that "Items are returned in no particular order" so there's
no need to do extra sorting before returning the results.

2 files changed, 25 insertions, 24 deletions

diff --git a/serial/tools/list_ports_linux.py b/serial/tools/list_ports_linux.py
index c8c1cfc..ec2e0ca 100644
--- a/serial/tools/list_ports_linux.py
+++ b/serial/tools/list_ports_linux.py
@@ -89,15 +89,16 @@ class SysFS(list_ports_common.ListPortInfo):
 
 
 def comports(include_links=False):
-    devices = glob.glob('/dev/ttyS*')           # built-in serial ports
-    devices.extend(glob.glob('/dev/ttyUSB*'))   # usb-serial with own driver
-    devices.extend(glob.glob('/dev/ttyXRUSB*')) # xr-usb-serial port exar (DELL Edge 3001)
-    devices.extend(glob.glob('/dev/ttyACM*'))   # usb-serial with CDC-ACM profile
-    devices.extend(glob.glob('/dev/ttyAMA*'))   # ARM internal port (raspi)
-    devices.extend(glob.glob('/dev/rfcomm*'))   # BT serial devices
-    devices.extend(glob.glob('/dev/ttyAP*'))    # Advantech multi-port serial controllers
+    devices = set()
+    devices.update(glob.glob('/dev/ttyS*'))     # built-in serial ports
+    devices.update(glob.glob('/dev/ttyUSB*'))   # usb-serial with own driver
+    devices.update(glob.glob('/dev/ttyXRUSB*')) # xr-usb-serial port exar (DELL Edge 3001)
+    devices.update(glob.glob('/dev/ttyACM*'))   # usb-serial with CDC-ACM profile
+    devices.update(glob.glob('/dev/ttyAMA*'))   # ARM internal port (raspi)
+    devices.update(glob.glob('/dev/rfcomm*'))   # BT serial devices
+    devices.update(glob.glob('/dev/ttyAP*'))    # Advantech multi-port serial controllers
     if include_links:
-        devices.extend(list_ports_common.list_links(devices))
+        devices.update(list_ports_common.list_links(devices))
     return [info
             for info in [SysFS(d) for d in devices]
             if info.subsystem != "platform"]    # hide non-present internal serial ports
diff --git a/serial/tools/list_ports_posix.py b/serial/tools/list_ports_posix.py
index 79bc8ed..b115754 100644
--- a/serial/tools/list_ports_posix.py
+++ b/serial/tools/list_ports_posix.py
@@ -37,63 +37,63 @@ elif plat == 'cygwin':       # cygwin/win32
     # (such as 'open' call, explicit 'ls'), but 'glob.glob'
     # and bare 'ls' do not; so use /dev/ttyS* instead
     def comports(include_links=False):
-        devices = glob.glob('/dev/ttyS*')
+        devices = set(glob.glob('/dev/ttyS*'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:7] == 'openbsd':    # OpenBSD
     def comports(include_links=False):
-        devices = glob.glob('/dev/cua*')
+        devices = set(glob.glob('/dev/cua*'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:3] == 'bsd' or plat[:7] == 'freebsd':
     def comports(include_links=False):
-        devices = glob.glob('/dev/cua*[!.init][!.lock]')
+        devices = set(glob.glob('/dev/cua*[!.init][!.lock]'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:6] == 'netbsd':   # NetBSD
     def comports(include_links=False):
         """scan for available ports. return a list of device names."""
-        devices = glob.glob('/dev/dty*')
+        devices = set(glob.glob('/dev/dty*'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:4] == 'irix':     # IRIX
     def comports(include_links=False):
         """scan for available ports. return a list of device names."""
-        devices = glob.glob('/dev/ttyf*')
+        devices = set(glob.glob('/dev/ttyf*'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:2] == 'hp':       # HP-UX (not tested)
     def comports(include_links=False):
         """scan for available ports. return a list of device names."""
-        devices = glob.glob('/dev/tty*p0')
+        devices = set(glob.glob('/dev/tty*p0'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:5] == 'sunos':    # Solaris/SunOS
     def comports(include_links=False):
         """scan for available ports. return a list of device names."""
-        devices = glob.glob('/dev/tty*c')
+        devices = set(glob.glob('/dev/tty*c'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 elif plat[:3] == 'aix':      # AIX
     def comports(include_links=False):
         """scan for available ports. return a list of device names."""
-        devices = glob.glob('/dev/tty*')
+        devices = set(glob.glob('/dev/tty*'))
         if include_links:
-            devices.extend(list_ports_common.list_links(devices))
+            devices.update(list_ports_common.list_links(devices))
         return [list_ports_common.ListPortInfo(d) for d in devices]
 
 else: