Plugins Support for C/C++ #2353

AmmarAbouZor · 2025-06-23T18:58:53Z

This PR closes #2326

It provides:

Templates for parser plugin in C and C++

It provides to starter templates to develop plugins in both C and C++ with directory structure and Makefile which will:

Generates the bindings from WIT files
Compiles the source code to the intermediate WASM module
Convert the WASM module into the final WASM component file
Download wasi reactor if not provided by developers

The template provides starter implementation for parsers demonstrating the function provided by Chipmunk host and the functions needed from the plugins

Documentation for Plugin Development with C/C++

It provides detailed documentation for plugin development with C/C++ including:

Needed tools and SDKs for development
Details about plugins templates
Step by step guide to developing plugins manually, providing description for all commands used in the Makefiles with examples

Refactoring

Plugins examples and templates are now grouped with the their programming language since we are supporting C and C++ besides rust now

plugins/templates/c-cpp/parser_cpp/Makefile

plugins/templates/c-cpp/parser_c/src/my_parser.c

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

docs/plugins/cpp.md

itsmesamster

Apart from the changes suggested, I think this looks good to me. Obviously, this is from my POV after having worked on this for a short time. Would be good to know how it fares for someone looking at it for the first time.

AmmarAbouZor · 2025-06-25T12:13:56Z

Thanks much @itsmesamster for the review. I've resolved the provided issue and added extra readme files for the templates with clearer guide for plugins development in C/C++

itsmesamster

Looks good to me now.

ermankomurcu · 2025-08-13T12:40:50Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+  global_log_level = general_configs->log_level;
+  if (global_log_level >= CHIPMUNK_SHARED_LOGGING_LEVEL_INFO) {
+    parse_string_t log_msg;
+    parse_string_dup(&log_msg, "Initi message called");


typo: "Initi"

ermankomurcu · 2025-08-13T12:41:14Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+  }
+
+  // *** Demonstrate printing to stdout ***
+  std::cout << "Inint function called with log level: "


typo: "Inint"

ermankomurcu · 2025-08-13T12:42:09Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+      break;
+    }
+  }
+


err is not used.

exports_chipmunk_parser_parser_list_config_item_free needs to be called to free the input parameter: plugin_configs

Thanks a lot for the hint of freeing the items. I've added that in multiple items in both C and C++ templates!

err is not used.

I think err here is the output in case this function fails. It will be None by default, and we need to change it only on errors.

err is commented out and a useful note is added to the function docs

ermankomurcu · 2025-08-13T12:43:03Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+
+  // *** Return length of provided bytes ***
+  ret->len = 1;
+  auto &item = ret->ptr[0];


It needs a new memory allocation for the pointer ret->ptr[0]

I think the binding will allocate enough memory for one item by default, therefore there is no need to reallocate memory if case we have one item only. I've allocated memory in scenarios where we need to provide more than one item

ermankomurcu · 2025-08-13T12:46:23Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+
+  std::string log_line =
+      "The length of provided bytes: " + std::to_string(data->len);
+  parse_string_set(&item.value.val.val.message.val.line, log_line.c_str());


I think we need to use dynamically allocated string so we do not need to provide custom *_post_return function:
https://github.com/bytecodealliance/wit-bindgen/blob/main/crates/c/README.md#:~:text=Importantly%2C%20the%20generated,by%20the%20linker.

Great catch, Thanks! It's weird that this function didn't error when we run the plugin.

I've fixed that by using parse_string_dup() instead which will duplicate the string.

ermankomurcu · 2025-08-13T12:47:05Z

plugins/templates/c-cpp/parser_cpp/src/my_parser.cpp

+
+  return true;
+
+#endif


err is not used?

data needs to be freed with : parse_list_u8_free

Resolved freeing the data is resolved. That would have been a huge memory leak without this catch!

err is not used?

As mentioned above, I think error should be used when we want to report an error only.

AmmarAbouZor · 2025-08-18T13:54:57Z

@ermankomurcu Thanks a lot for the valuable review!

I've included some important fixes and added a section in the documentation about memory ownership with a link to the README on wit-bidngen repo.
I've missed this important doc somehow, which led me to have multiple memory related errors.

Changes are all included, and it would be great to give a final review 🙏

* Provide documentation about developing plugins in C/C++ * Template for developing parser plugin in C/C++ * Makefile for plugin template.

* Demonstrate basic logging functionality.

* Add plugins configuration sections to plugin template to show sending configs schemas and log their values in init function. * Add Render options to plugins, providing two modes for messages with single line or multiple columns.

C and C++ differ a lot in the build steps and each of them must have each own template.

* Change the directory structure of the plugins template for C language making the template more professional * Improve Makefile to adjust to the rules + Remove downloading reactor to it's own script file.

* Change the directory structure of the plugins template for C++ language making the template more professional * Improve Makefile to adjust to the rules + Remove downloading reactor to it's own script file.

* Group plugins templates & examples by their programming language since we are supporting rust and C/C++ * Update links in documentation accordingly

* Provide detailed documentation about plugins development with C/C++ providing the needed tools, explaining the templates and a step by step guide for development. * Document source code of plugins templates * README files for the new directory structure

* Provide separated instructions for templates * Separated README file for each template * Remove generated source files since they could confuse developers. * Extend documentation in source code * Include that C++ template will use C bindings and will not generate an abstraction layer on the top of them. * Rename documentation file

* Free memory from input items to function since the plugin owns their memory. * Always allocate memory on the input avoiding relaying on the allocated memory from the runtime because it's not guaranteed. * Explicitly point out that err pointer isn't used. * Extend documentation with memory ownership model. * Duplicate memory when cpp string is used with c_str() method. * Introduce pointers to avoid long nested structures in C template. * Extend documentation inside templates. * Fix typos. * Rearrange include statements.

marcmo

LGTM

AmmarAbouZor requested review from itsmesamster and marcmo June 23, 2025 18:58

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itsmesamster reviewed Jun 25, 2025

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AmmarAbouZor force-pushed the plug-cpp branch from 5be17f5 to 33ec560 Compare June 25, 2025 12:12

itsmesamster reviewed Jun 26, 2025

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AmmarAbouZor requested a review from DmitryAstafyev June 26, 2025 09:39

AmmarAbouZor force-pushed the plug-cpp branch 3 times, most recently from 415da34 to 466e60f Compare July 7, 2025 07:56

AmmarAbouZor force-pushed the plug-cpp branch from 466e60f to ef3c7fb Compare August 8, 2025 06:45

ermankomurcu reviewed Aug 13, 2025

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AmmarAbouZor requested a review from ermankomurcu August 18, 2025 13:51

AmmarAbouZor force-pushed the plug-cpp branch 3 times, most recently from ac0c977 to 3208332 Compare August 20, 2025 14:12

AmmarAbouZor force-pushed the plug-cpp branch from 3208332 to ac1cea5 Compare August 27, 2025 09:04

AmmarAbouZor added 7 commits October 6, 2025 11:24

Plugins CPP: Documentation & Template

7bc9094

* Provide documentation about developing plugins in C/C++ * Template for developing parser plugin in C/C++ * Makefile for plugin template.

Plugins CPP: Improving template.

95899a2

* Demonstrate basic logging functionality.

Plugins C/C++: Separated template for each language

ec7e4a3

C and C++ differ a lot in the build steps and each of them must have each own template.

Plugins C Template: Change structure & Improve Make

d55f237

* Change the directory structure of the plugins template for C language making the template more professional * Improve Makefile to adjust to the rules + Remove downloading reactor to it's own script file.

Plugins C++ Template: Change structure & Improve Make

5ae3a3d

* Change the directory structure of the plugins template for C++ language making the template more professional * Improve Makefile to adjust to the rules + Remove downloading reactor to it's own script file.

Plugins: Rearrange plugins templates & Examples

adf95bd

* Group plugins templates & examples by their programming language since we are supporting rust and C/C++ * Update links in documentation accordingly

AmmarAbouZor added 3 commits October 6, 2025 11:27

AmmarAbouZor force-pushed the plug-cpp branch from ac1cea5 to 8210332 Compare October 6, 2025 09:46

ermankomurcu approved these changes Oct 16, 2025

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marcmo approved these changes Oct 20, 2025

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marcmo merged commit b2553f3 into esrlabs:master Oct 20, 2025
2 checks passed

AmmarAbouZor deleted the plug-cpp branch October 20, 2025 08:41

Plugins Support for C/C++ #2353

Plugins Support for C/C++ #2353

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AmmarAbouZor commented Jun 23, 2025

Templates for parser plugin in C and C++

Documentation for Plugin Development with C/C++

Refactoring

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AmmarAbouZor commented Aug 18, 2025

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