Issue 47208: Support libffi implementations that cannot support invocations with 1024 arguments

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src="@@file/gh-icon.png" /> <p> <span>This issue has been migrated to GitHub:</span> https://github.com/python/cpython/issues/91364 </p> </a> </div> <fieldset><legend>classification</legend> <table class="form"> <tr> <th class="required"><a href="http://docs.python.org/devguide/triaging.html#title" target="_blank">Title</a>:</th> <td colspan="3"> <span>Support libffi implementations that cannot support invocations with 1024 arguments</span> <input type="hidden" name="title" value="Support libffi implementations that cannot support invocations with 1024 arguments"> </td> </tr> <tr> <th class="required"><a href="http://docs.python.org/devguide/triaging.html#type" target="_blank">Type</a>:</th> <td>behavior</td> <th><a href="http://docs.python.org/devguide/triaging.html#stage" target="_blank">Stage</a>:</th> <td>patch review</td> </tr> <tr> <th><a href="http://docs.python.org/devguide/triaging.html#components" target="_blank">Components</a>:</th> <td>ctypes, Tests</td> <th><a href="http://docs.python.org/devguide/triaging.html#versions" target="_blank">Versions</a>:</th> <td>Python 3.11</td> </tr> </table> </fieldset> <fieldset><legend>process</legend> <table class="form"> <tr> <th><a href="http://docs.python.org/devguide/triaging.html#status" target="_blank">Status</a>:</th> <td>open</td> <th><a href="http://docs.python.org/devguide/triaging.html#resolution" target="_blank">Resolution</a>:</th> <td></td> </tr> <tr> <th> <a href="http://docs.python.org/devguide/triaging.html#dependencies" target="_blank">Dependencies</a>: </th> <td> </td> <th><a href="http://docs.python.org/devguide/triaging.html#superseder" target="_blank">Superseder</a>:</th> <td> </td> </tr> <tr> <th> <a href="http://docs.python.org/devguide/triaging.html#assigned-to" target="_blank">Assigned To</a>: </th> <td> </td> <th> <a href="http://docs.python.org/devguide/triaging.html#nosy-list" target="_blank">Nosy List</a>: </th> <td> amaury.forgeotdarc, belopolsky, christian.heimes, hoodchatham, meador.inge </td> </tr> <tr> <th> <a href="http://docs.python.org/devguide/triaging.html#priority" target="_blank">Priority</a>: </th> <td>normal</td> <th> <a href="http://docs.python.org/devguide/triaging.html#keywords" target="_blank">Keywords</a>: </th> <td>patch</td> </tr> </table> </fieldset> </form> <p>Created on <strong>2022-04-04 00:27</strong> by <strong>hoodchatham</strong>, last changed <strong>2022-04-11 14:59</strong> by <strong>admin</strong>.</p> <table class="files"> <tr><th class="header" colspan="4">Pull Requests</th></tr> <tr> <th>URL</th> <th>Status</th> <th>Linked</th> <th>Edit</th> </tr> <tr> <td><a href="https://github.com/python/cpython/pull/32297" title="bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT (GH-32297)">PR 32297</a></td> <td>merged</td> <td> <span>christian.heimes</span>, <span>2022-04-04 06:59</span> </td> <td> </td> </tr> </table> <table class="messages"> <tr><th colspan="4" class="header">Messages (4)</th></tr> <tr> <th> <a href="#msg416646" id="msg416646">msg416646</a> - <a href="msg416646">(view)</a></th> <th>Author: Hood Chatham (hoodchatham) <span title="Contributor form received">*</span></th> <th>Date: 2022-04-04 00:27</th> </tr> <tr> <td colspan="4" class="content"> <pre>ctypes defines `CTYPES_MAX_ARGCOUNT` to be 1024: <a href="https://github.com/python/cpython/blob/6db2db91b96aaa1270c200ec931a2250fe2799c7/Modules/_ctypes/ctypes.h#L21">https://github.com/python/cpython/blob/6db2db91b96aaa1270c200ec931a2250fe2799c7/Modules/_ctypes/ctypes.h#L21</a> If a function call is attempted with more than 1024 arguments, it will fail. The libffi emscripten port github.com/hoodmane/libffi-emscripten can only support function calls with at most 122 arguments due to limitations in Emscripten / Wasm: <a href="https://github.com/emscripten-core/emscripten/pull/16653">https://github.com/emscripten-core/emscripten/pull/16653</a> I propose to allow the libffi port to define FFI_MAX_CLOSURE_ARGS and if this is defined then use this number instead for `CTYPES_MAX_ARGCOUNT`. <a href="https://github.com/libffi/libffi/issues/703">https://github.com/libffi/libffi/issues/703</a> The test `test_callback_too_many_args` should also be updated to respect the value of `CTYPES_MAX_ARGCOUNT` rather than hardcoding 1024 into the test.</pre> </td> </tr> <tr> <th> <a href="#msg416677" id="msg416677">msg416677</a> - <a href="msg416677">(view)</a></th> <th>Author: Christian Heimes (christian.heimes) <span title="Contributor form received">*</span> <img src="@@file/committer.png" title="Python committer" alt="(Python committer)" /></th> <th>Date: 2022-04-04 17:13</th> </tr> <tr> <td colspan="4" class="content"> <pre> New changeset <a href="https://hg.python.org/lookup/d1b1c885d8f276a0b1ff2e327270916396a8b842">d1b1c885d8f276a0b1ff2e327270916396a8b842</a> by Christian Heimes in branch 'main': <a class="open" title="[open] Support libffi implementations that cannot support invocations with 1024 arguments" href="issue47208">bpo-47208</a>: Allow vendors to override CTYPES_MAX_ARGCOUNT (<a href="https://github.com/python/cpython/pull/32297" class="closed" title="GitHub PR 32297: [merged] bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT (GH-32297)">GH-32297</a>) <a href="https://github.com/python/cpython/commit/d1b1c885d8f276a0b1ff2e327270916396a8b842">https://github.com/python/cpython/commit/d1b1c885d8f276a0b1ff2e327270916396a8b842</a> </pre> </td> </tr> <tr> <th> <a href="#msg416678" id="msg416678">msg416678</a> - <a href="msg416678">(view)</a></th> <th>Author: Christian Heimes (christian.heimes) <span title="Contributor form received">*</span> <img src="@@file/committer.png" title="Python committer" alt="(Python committer)" /></th> <th>Date: 2022-04-04 17:15</th> </tr> <tr> <td colspan="4" class="content"> <pre><a href="https://github.com/python/cpython/pull/32297" class="closed" title="GitHub PR 32297: [merged] bpo-47208: Allow vendors to override CTYPES_MAX_ARGCOUNT (GH-32297)">GH-32297</a> adds #ifndef CTYPES_MAX_ARGCOUNT and exposes the constant in the _ctypes extension module, so the test case can use the constant. It allows you to override CTYPES_MAX_ARGCOUNT until libffi upstream agrees on FFI_MAX_CLOSURE_ARGS.</pre> </td> </tr> <tr> <th> <a href="#msg416692" id="msg416692">msg416692</a> - <a href="msg416692">(view)</a></th> <th>Author: Hood Chatham (hoodchatham) <span title="Contributor form received">*</span></th> <th>Date: 2022-04-04 19:07</th> </tr> <tr> <td colspan="4" class="content"> <pre>Ideally the library should be able to define a different macro, e.g., CTYPES_CUSTOM_MAX_ARGCOUNT. This way the libffi port can define CTYPES_CUSTOM_MAX_ARGCOUNT and it will be compatible with older Python versions without causing Warning: "CTYPES_MAX_ARGCOUNT redefined`.</pre> </td> </tr> </table> <table class="history table table-condensed table-striped"><tr><th colspan="4" class="header"> History </th></tr><tr> <th>Date</th> <th>User</th> <th>Action</th> <th>Args</th> </tr> <tr><td>2022-04-11 14:59:58</td><td>admin</td><td>set</td><td>github: 91364</td></tr> <tr><td>2022-04-04 19:07:48</td><td>hoodchatham</td><td>set</td><td>messages: + <a rel="nofollow" href="msg416692">msg416692</a></td></tr> <tr><td>2022-04-04 17:15:36</td><td>christian.heimes</td><td>set</td><td>type: behavior<br />components: + Tests<br />versions: + Python 3.11</td></tr> <tr><td>2022-04-04 17:15:19</td><td>christian.heimes</td><td>set</td><td>messages: + <a rel="nofollow" href="msg416678">msg416678</a></td></tr> <tr><td>2022-04-04 17:13:50</td><td>christian.heimes</td><td>set</td><td>messages: + <a rel="nofollow" href="msg416677">msg416677</a></td></tr> <tr><td>2022-04-04 06:59:50</td><td>christian.heimes</td><td>set</td><td>keywords: + <a rel="nofollow" href="keyword2">patch</a><br />stage: patch review<br />pull_requests: + <a rel="nofollow" href="pull_request30356">pull_request30356</a></td></tr> <tr><td>2022-04-04 00:28:20</td><td>hoodchatham</td><td>set</td><td>nosy: + <a rel="nofollow" href="user1076">amaury.forgeotdarc</a>, <a rel="nofollow" href="user1427">belopolsky</a>, <a rel="nofollow" href="user3108">christian.heimes</a>, <a rel="nofollow" href="user11255">meador.inge</a><br /></td></tr> <tr><td>2022-04-04 00:27:44</td><td>hoodchatham</td><td>create</td><td></td></tr> </table> </div> </div>  <div id="footer"> <div id="credits"> Supported by <a href="https://python.org/psf-landing/" title="The Python Software Foundation">The Python Software Foundation</a>, <br> Powered by <a href="http://roundup.sourceforge.net" title="Powered by the Roundup Issue Tracker">Roundup</a> </div>  Copyright © 1990-2022, <a href="http://python.org/psf">Python Software Foundation</a><br /> <a href="http://python.org/about/legal">Legal Statements</a> </div>  </div>  </div>  </body> </html>

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Issue 47208: Support libffi implementations that cannot support invocations with 1024 arguments - Python tracker