Allow to disable caching (#2484)

* Allow to disable caching

By setting `context.cache_dir = None`. Generate default cache dir again by setting `context.cache_dir = True`.

* Disable cache in `asm` caching test

* Update CHANGELOG

* Fix asm cache test

Author: peace-maker

CHANGELOG.md

@@ -83,6 +83,7 @@ The table below shows which release corresponds to each branch, and what date th
 - [#2483][2483] Only print `checksec` output of `ELF.libc` when it was printed for the `ELF` already
 - [#2482][2482] Throw error when using `sni` and setting `server_hostname` manually in `remote`
 - [#2478][2478] libcdb-cli: add `--offline-only`, refactor unstrip and add fetch parser for download libc-database
+- [#2484][2484] Allow to disable caching
 
 [2471]: https://github.com/Gallopsled/pwntools/pull/2471
 [2358]: https://github.com/Gallopsled/pwntools/pull/2358
@@ -94,6 +95,7 @@ The table below shows which release corresponds to each branch, and what date th
 [2483]: https://github.com/Gallopsled/pwntools/pull/2483
 [2482]: https://github.com/Gallopsled/pwntools/pull/2482
 [2478]: https://github.com/Gallopsled/pwntools/pull/2478
+[2484]: https://github.com/Gallopsled/pwntools/pull/2484
 
 ## 4.14.0 (`beta`)
 

pwnlib/asm.py

@@ -765,9 +765,11 @@ def asm(shellcode, vma = 0, extract = True, shared = False):
         The output is cached:
 
         >>> start = time.time()
-        >>> asm("lea rax, [rip+0]", arch = 'amd64')
+        >>> asm("lea rax, [rip+0]", arch = 'amd64', cache_dir = None) # force uncached time
         b'H\x8d\x05\x00\x00\x00\x00'
         >>> uncached_time = time.time() - start
+        >>> asm("lea rax, [rip+0]", arch = 'amd64') # cache it
+        b'H\x8d\x05\x00\x00\x00\x00'
         >>> start = time.time()
         >>> asm("lea rax, [rip+0]", arch = 'amd64')
         b'H\x8d\x05\x00\x00\x00\x00'

pwnlib/context/__init__.py

@@ -1377,9 +1377,9 @@ def buffer_size(self, size):
     def cache_dir_base(self, new_base):
         """Base directory to use for caching content.
 
-        Changing this to a different value will clear the `cache_dir` path
+        Changing this to a different value will clear the :attr:`cache_dir` path
         stored in TLS since a new path will need to be generated to respect the
-        new `cache_dir_base` value.
+        new :attr:`cache_dir_base` value.
         """
 
         if new_base != self.cache_dir_base:
@@ -1394,19 +1394,28 @@ def cache_dir(self):
 
         Note:
             May be either a path string, or :const:`None`.
+            Set to :const:`None` to disable caching.
+            Set to :const:`True` to generate the default cache directory path
+            based on :attr:`cache_dir_base` again.
 
         Example:
 
             >>> cache_dir = context.cache_dir
             >>> cache_dir is not None
             True
             >>> os.chmod(cache_dir, 0o000)
-            >>> del context._tls['cache_dir']
+            >>> context.cache_dir = True
             >>> context.cache_dir is None
             True
             >>> os.chmod(cache_dir, 0o755)
             >>> cache_dir == context.cache_dir
             True
+            >>> context.cache_dir = None
+            >>> context.cache_dir is None
+            True
+            >>> context.cache_dir = True
+            >>> context.cache_dir is not None
+            True
         """
         try:
             # If the TLS already has a cache directory path, we return it
@@ -1451,7 +1460,9 @@ def cache_dir(self):
 
     @cache_dir.setter
     def cache_dir(self, v):
-        if os.access(v, os.W_OK):
+        if v is True:
+            del self._tls["cache_dir"]
+        elif v is None or os.access(v, os.W_OK):
             # Stash this in TLS for later reuse
             self._tls["cache_dir"] = v