First I'd like to get the test suite to run all the way through, then to pass.

cc @freakboy3742

Update 2025/01/30

Emscripten 4.0.2 has fixes for all of the file system bugs I've looked into. There are still problems with nonblocking I/O which I haven't looked into.

Emscripten PRs:

• Make seek work on /dev/null emscripten-core/emscripten#22886
  Make readlink system call not resolve the link emscripten-core/emscripten#23000
  Trying to create a directory in a file should return ENOTDIR not EPERM emscripten-core/emscripten#23025
  Refactor lookupPath to avoid recursion. NFC emscripten-core/emscripten#23017
  Fix path resolution for symlinks emscripten-core/emscripten#23072
  Make readdir on /proc/self/fd work emscripten-core/emscripten#23073
  Add nodefs readdir handling for directories that contain exotic entries emscripten-core/emscripten#22925
  Make fstat work on file descriptor with no name emscripten-core/emscripten#23058
  When opening broken symlink with O_CREAT, create file at target emscripten-core/emscripten#23002
  JS file system: distinguish between atime, mtime, and ctime emscripten-core/emscripten#22998
  Fix renaming a file on top of an existing file in memfs and nodefs emscripten-core/emscripten#23074
  Handle trailing % in strftime emscripten-core/emscripten#23045
  Add wcsftime from musl. NFC emscripten-core/emscripten#23061
  Return EISDIR when trying to create a path ending in / with open emscripten-core/emscripten#23135
  Fix mkdir("a/b/..") should return EEXIST emscripten-core/emscripten#23136
  Make open O_CREATE mode 0 work emscripten-core/emscripten#23137
  Ensure the ino we give to readdir matches the ino we give to stat emscripten-core/emscripten#23139
  Correctly handle calls setting timestamp to 0 emscripten-core/emscripten#23310
  Raise ENOSYS if AT_SYMLINK_NOFOLLOW is used with chmod or chown in nodefs emscripten-core/emscripten#23307
  [FS] Allow pipes to be stat'ed emscripten-core/emscripten#23306
  [FS] lookupPath should throw an error on an empty string emscripten-core/emscripten#23366
  [FS] Make fstat work on file descriptors with no name in node rawfs emscripten-core/emscripten#23364
  [FS] Make fstatfs actually work emscripten-core/emscripten#23381
  [FS] Make fstat work on file descriptors with no name in memfs emscripten-core/emscripten#23470
  [FS] Make fstat work on file descriptors with no name in nodefs emscripten-core/emscripten#23480
  JS FS: Don't return ELOOP on a path with a large number of ..'s emscripten-core/emscripten#24591
  Looking up ip for localhost should return 127.0.0.1 emscripten-core/emscripten#24593

Linked PRs

• gh-127146: Emscripten: Skip segfaults in test suite #127151
• gh-127146: Mark test_bz2 tests with requires_subprocess #127562
• gh-127146: Resolve some minor problems in Emscripten tests #127565
• gh-127146: Some expected failures in Emscripten time tests #127843
• gh-127146: Emscripten clean up test suite #127984
• gh-127146: Emscripten Include compiler version in _PYTHON_HOST_PLATFORM #127992
• gh-127146: Fix test_sysconfidata_json in Emscripten #128545
• gh-127146: skip Emscripten tests with pending fixes #128549
• gh-127146: Fix test_sysconfigdata_json for Emscripten #128556
• gh-127146: Strip dash from Emscripten compiler version #128557
• gh-127146: Update test skips for Emscripten 4.0.1 #129375
• gh-127146: Skip test_readinto_non_blocking on Emscripten #129421
• gh-127146: Don't compare userbase in test_sysconfig_json #129422
• gh-127146: Update test skips for Emscripten 4.0.2 #129474
• gh-127146: Fix Emscripten build with --pydebug #131672
• gh-127146: Fix Emscripten test suite when run with -uall #132092
• gh-127146: xfail more Emscripten stack overflows #134358
• [3.14] gh-127146: xfail more Emscripten stack overflows (GH-134358) #134382
• gh-127146: Allow ignored keys to be missing in test_sysconfig #135622
• gh-127146: Emscripten: Fix pathlib glob_dotdot test #135624
• gh-127146: Emscripten: Fix test failure due to missing os.link #135626
• gh-127146: Emscripten: Skip test_url2pathname_resolve_host #135634
• gh-127146: Enable large files on Emscripten #135635
• [3.14] gh-127146: Allow ignored keys to be missing in test_sysconfig (GH-135622) #135650
• [3.14] gh-127146: Emscripten: Skip test_url2pathname_resolve_host (GH-135634) #135651
• [3.14] gh-127146: Emscripten: Fix test failure due to missing os.link (GH-135626) #135652
• [3.14] gh-127146: Emscripten: Fix pathlib glob_dotdot test (GH-135624) #135653
• [3.14] gh-127146: Enable large files on Emscripten (GH-135635) #135655
• gh-127146: Add skip_emscripten_stack_overflow in a few places #135722
• [3.14] gh-127146: Add skip_emscripten_stack_overflow in a few places (GH-135722) #135733
• gh-127146: Skip test_os.test_mode for Emscripten #135764
• [3.14] gh-127146: Skip test_os.test_mode for Emscripten (GH-135764) #135784
• gh-127146: Skip test_netrc.test_security on Emscripten #136227
• gh-127146: Report uid in Emscripten + node as native uid #136509
• gh-127146: Skip test_open_undecodable_uri on Emscripten #136510
• gh-127146: Emscripten: Fix test_open_undecodable_uri by setting -sTEXTDECODER=2 #136624
• [3.14] gh-127146: Emscripten: Fix test_open_undecodable_uri by setting -sTEXTDECODER=2 (GH-136624) #136631
• [3.14] gh-127146: Report uid in Emscripten + node as native uid (GH-136509) #136699
• gh-127146: Emscripten: Make os.umask() actually work #136706
• gh-127146: Emscripten: Don't need to avoid unpaired surrogate anymore #136707
• gh-127146: Emscripten: more regular stack overflow skips #136708
• [3.14] gh-127146: Emscripten: Make os.umask() actually work (GH-136706) #136711
• [3.14] gh-127146: Emscripten: more regular stack overflow skips (GH-136708) #136712
• [3.14] gh-127146: Emscripten: Don't need to avoid unpaired surrogate anymore (GH-136707) #136717
• gh-127146: Emscripten: Set umask to zero in test_apropos_empty_doc #136740
• [3.14] gh-127146: Emscripten: Set umask to zero in python.sh (GH-136740) #136745
• gh-127146: Emscripten: Add test_sample_profiler skips where needed #137815