Add emscripten guards to shared_library.c's dlopen path - #591
Open
Tobias-Fischer wants to merge 1 commit into
Open
Add emscripten guards to shared_library.c's dlopen path#591Tobias-Fischer wants to merge 1 commit into
Tobias-Fischer wants to merge 1 commit into
Conversation
Tobias-Fischer
added a commit
to Tobias-Fischer/ros-rolling
that referenced
this pull request
Sep 9, 2026
- Bump the vinca pin to 325d0af, which also sets CMAKE_SHARED_MODULE_CREATE_C/CXX_FLAGS (not just the SHARED-library variants) -- CMake's MODULE library type, used by pybind11_add_module() for every Python C extension (rclpy's own _rclpy_pybind11, and each message package's rosidl_generator_py typesupport accessor), was linking without USE_PTHREADS=1 even though its objects compiled with atomics fine, producing a load-time "mismatch in shared state of memory" next to the rest of a pthreads build. Invisible until something used pybind11_add_module() -- found getting a live rclpy demo running. - Add two Emscripten guards to patch/ros-rolling-rcutils.emscripten.patch (upstreamed as ros2/rcutils#591) so rcl_logging_implementation's dlopen-by-name backend selection works: rcutils_get_platform_library_name() had no emscripten case (always "failed to format library name"), and the post-dlopen path resolution took a dlinfo(RTLD_DI_LINKMAP) branch that Emscripten's JS-backed dlopen doesn't support, treating a successful dlopen() as a failure. - Document a known gap (see pixi.toml comment): rosidl_typesupport_ microxrcedds_cpp's codegen doesn't handle service "_Event" messages, so action_msgs/lifecycle_msgs/rcl_interfaces/rosgraph_msgs/statistics_msgs/ type_description_interfaces/micro_ros_msgs need a second, C-only rebuild pass rather than the global STATIC_ROSIDL_TYPESUPPORT_CPP override this task sets -- a real rclpy talker (not just rclc) verified end-to-end through this same rmw_zenoh_pico pipeline surfaced this. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
5 tasks
Member
|
Looks like AI was used here, but no AI attestation in the PR description, if you could update that please. It also looks like DCO signoff wasn't done here either. |
Two related gaps in rcutils_load_shared_library() / rcutils_get_platform_library_name(),
found while getting rcl_logging_implementation's dlopen-by-name backend
selection working on emscripten-wasm32:
- rcutils_get_platform_library_name() had no emscripten branch, so it always
fell through with written == 0 ("failed to format library name"),
regardless of which RCL_LOGGING_IMPLEMENTATION backend was requested.
wasm32 side modules use the same "lib<name>.so" convention as Linux.
- The post-dlopen path-resolution code took the _GNU_SOURCE branch (which
emscripten's headers define) and called dlinfo(..., RTLD_DI_LINKMAP, ...).
Emscripten's dlopen()/dlinfo() are a JS-backed shim, not glibc's, and
don't support reading back a real struct link_map -- so a successful
dlopen() got treated as a failure once dlinfo() returned -1. The #else
branch (reuse the path dlopen() was given) already covers this platform
correctly.
Verified end-to-end on a ROS 2 rolling + rmw_zenoh_pico + real-pthreads
emscripten-wasm32 build: a wasm32 rclpy talker's logging initialization
(rcl_logging_configure -> rcl_logging_implementation -> this dlopen path)
now succeeds instead of aborting with "failed to load any logging
implementations".
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Tobias Fischer <info@tobiasfischer.info>
Tobias-Fischer
force-pushed
the
fix/emscripten-shared-library-guards
branch
from
September 10, 2026 23:10
595b55a to
2da7412
Compare
Contributor
Author
Thanks for the review! |
ahcorde
approved these changes
Sep 11, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Two related gaps in
rcutils_load_shared_library()/rcutils_get_platform_library_name(), found while gettingrcl_logging_implementation's dlopen-by-name backend selection working onemscripten-wasm32:rcutils_get_platform_library_name()had no emscripten branch, so it always fell through withwritten == 0("failed to format library name"), regardless of whichRCL_LOGGING_IMPLEMENTATIONbackend was requested. wasm32 side modules use the samelib<name>.sonaming convention as Linux, so this reuses that branch.dlopen()path-resolution code took the_GNU_SOURCEbranch (which emscripten's headers define) and calleddlinfo(..., RTLD_DI_LINKMAP, ...). Emscripten'sdlopen()/dlinfo()are a JS-backed shim, not glibc's, and don't support reading back a realstruct link_map— so a successfuldlopen()was getting treated as a failure oncedlinfo()returned -1. The#elsebranch (reuse the pathdlopen()was given) already covers this platform correctly, so this just excludes emscripten from the glibc-specific branch above it.Both are narrow, additive
#if/#elifguard changes — no behavior change on any existing platform.Test plan
Verified end-to-end on a ROS 2 rolling +
rmw_zenoh_pico+ real-pthreadsemscripten-wasm32build (companion work in RoboStack/vinca#154 and RoboStack/ros-rolling#46): a wasm32rclpytalker's logging initialization (rcl_logging_configure→rcl_logging_implementation→ this dlopen path) now succeeds instead of aborting with "failed to load any logging implementations", regardless of which backend (rcl_logging_spdlogorrcl_logging_noop) is selected.Full write-up
All the changes this required, across every repo, are documented together in Tobias-Fischer/ros2-emscripten-zenoh-demo — including a working
rclcandrclpybrowser demo verified end-to-end against a nativezenohdrouter.🤖 Generated with Claude Code