Clean code for `from_filter_repr

Author: ValekoZ

docs/commands/vmmap.md

@@ -16,6 +16,8 @@ to determine which section it belongs to, or the permissions of the sections to
     -  filter by address -> parses the next argument as an integer or asks gdb to interpret the value
 2.  `-n` / `--name`:
     -  filter based on section name
+2.  `-p` / `--perms`:
+    -  filter based on section permissions
 3.  If nothing is specified, it prints a warning and guesses the type
 
 ![vmmap-grep](https://github.com/hugsy/gef/assets/11377623/a3dbaa3e-88b0-407f-a0dd-07e65c4a3f73)

gef.py

@@ -668,24 +668,15 @@ def from_info_mem(cls, perm_str: str) -> "Permission":
     @classmethod
     def from_filter_repr(cls, filter_str: str) -> List["Permission"]:
         perms = [cls(0)]
-        if filter_str[0] == "r":
-            for i in range(len(perms)):
-                perms[i] |= Permission.READ
-        elif filter_str[0] == "?":
-            for i in range(len(perms)):
-                perms.append(perms[i] | Permission.READ)
-        if filter_str[1] == "w":
-            for i in range(len(perms)):
-                perms[i] |= Permission.WRITE
-        elif filter_str[1] == "?":
-            for i in range(len(perms)):
-                perms.append(perms[i] | Permission.WRITE)
-        if filter_str[2] == "x":
-            for i in range(len(perms)):
-                perms[i] |= Permission.EXECUTE
-        elif filter_str[2] == "?":
+
+        for k in range(3):
             for i in range(len(perms)):
-                perms.append(perms[i] | Permission.EXECUTE)
+                p = cls(1 << (2-k))
+                if filter_str[k] == "rwx"[k]:
+                    perms[i] |= p
+                elif filter_str[k] == "?":
+                    perms.append(perms[i] | p)
+
         return perms