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fix: Python Function Block compilation and cleanup #91

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Merged
thiagoralves merged 5 commits into from
Jan 28, 2026
Merged

fix: Python Function Block compilation and cleanup #91

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99b9faa
fix: Add unistd.h include for getpid() in Python POU compilation
thiagoralves Jan 28, 2026
4df63a0
fix: Add cleanup for Python Function Blocks to prevent crash on stop
thiagoralves Jan 28, 2026
83d07c2
refactor: Increase MAX_PYTHON_BLOCKS from 32 to 128
thiagoralves Jan 28, 2026
44fc5ac
debug: Add logging to diagnose python_blocks_cleanup symbol lookup
thiagoralves Jan 28, 2026
3403de3
refactor: Remove debug logging from Python cleanup
thiagoralves Jan 28, 2026
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15 changes: 15 additions & 0 deletions core/src/plc_app/include/iec_python.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@

#include <stddef.h>
#include <sys/types.h>
#include <unistd.h>

#ifdef __cplusplus
extern "C"
Expand Down Expand Up @@ -80,6 +81,20 @@ extern "C"
void python_loader_set_loggers(void (*log_info_func)(const char *, ...),
void (*log_error_func)(const char *, ...));

/**
* @brief Cleanup all Python function blocks
*
* This function must be called before unloading libplc.so to:
* 1. Terminate all Python subprocesses (SIGTERM, then SIGKILL)
* 2. Wait for all runner threads to exit
* 3. Unmap and unlink shared memory regions
* 4. Remove Python script files
*
* Failure to call this before dlclose() will cause a crash because
* the runner threads' code lives in the shared library.
*/
void python_blocks_cleanup(void);

#ifdef __cplusplus
}
#endif
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12 changes: 12 additions & 0 deletions core/src/plc_app/plc_state_manager.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#include "image_tables.h"
#include "journal_buffer.h"
#include "plc_state_manager.h"
#include "plcapp_manager.h"
#include "scan_cycle_manager.h"
#include "utils/log.h"
#include "utils/utils.h"
Expand Down Expand Up @@ -206,6 +207,17 @@ int unload_plc_program(PluginManager *pm)
image_tables_clear_null_pointers();
plugin_mutex_give(&plugin_driver->buffer_mutex);

// Cleanup Python function blocks BEFORE unloading the shared library
// This terminates Python subprocesses and joins runner threads to prevent
// crash when dlclose() unmaps the code while threads are still running
void (*python_cleanup)(void);
*(void **)(&python_cleanup) =
plugin_manager_get_symbol(pm, "python_blocks_cleanup");
Comment on lines +214 to +215

Copilot AI Jan 28, 2026

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The double cast *(void **)(&python_cleanup) is used to suppress compiler warnings about converting between function and object pointers, but this is a POSIX extension not guaranteed by C standard. A more portable pattern would be to use a union to perform the type-punning, though this may be acceptable for this codebase if targeting POSIX systems exclusively.

Suggested change
*(void **)(&python_cleanup) =
plugin_manager_get_symbol(pm, "python_blocks_cleanup");
union
{
void *obj;
void (*func)(void);
} sym;
sym.obj = plugin_manager_get_symbol(pm, "python_blocks_cleanup");
python_cleanup = sym.func;

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if (python_cleanup)
{
python_cleanup();
}

// Destroy the plugin manager
plugin_manager_destroy(pm);
plc_program = NULL;
Expand Down
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