Made online change work on ur20

2026-10-07 21:54:01 -06:00
parent 739347c4da
commit bc27b9bb27
10 changed files with 219 additions and 2 deletions
@@ -1,3 +1,7 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include "atmb_boot_link.h"
 #include "../src/atom_bridge.h"
 /*****************************************************************************
 *	Copyright:		Copyright CODESYS Development GmbH
@@ -38,6 +42,9 @@ DLL_DECL int CDECL ComponentEntry(INIT_STRUCT *pInitStruct)
 	s_pfCMCallHook = pInitStruct->pfCMCallHook;
 	s_pfCMRegisterClass = pInitStruct->pfCMRegisterClass;
 	s_pfCMCreateInstance = pInitStruct->pfCMCreateInstance;
+
+	/* Best effort only: never make component startup depend on this. */
+	atmb_ensure_boot_link();
 	return ERR_OK;
 }

@@ -0,0 +1,109 @@
+#ifndef ATMB_BOOT_LINK_H
+#define ATMB_BOOT_LINK_H
+
+/* Linux-only boot-project pathname workaround. Include in CmpFrame.c only,
+ * with _GNU_SOURCE defined before all system headers.
+ * No PLC memory, communication state, worker thread or cyclic work is involved.
+ */
+#include <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <syslog.h>
+#include <unistd.h>
+#include <stdint.h>
+
+static void atmb_ensure_boot_link(void)
+{
+    /* ComponentEntry is called at module initialization, not on each scan.
+     * Guard against repeated entry; failure is deliberately not retried.
+     */
+    static int attempted;
+    const char *name = "libCmpAtomModbus.so";
+    const char *problem = NULL;
+    Dl_info info;
+    struct stat source, existing;
+    char *module_path = NULL;
+    int directory = -1;
+    int error = 0;
+    int saved_errno = errno;
+
+    if (attempted)
+        return;
+    attempted = 1;
+
+    /* The component function address identifies this loaded ELF object. Using
+     * code rather than a local data symbol also works with runtimes that do not
+     * expose local data addresses through dladdr().
+     */
+    if (!dladdr((void *)(uintptr_t)&atmb_ensure_boot_link, &info) || !info.dli_fname) {
+        problem = "cannot locate loaded module";
+        goto finish;
+    }
+    module_path = realpath(info.dli_fname, NULL);
+    if (!module_path) {
+        error = errno;
+        problem = "cannot resolve loaded module pathname";
+        goto finish;
+    }
+    if (stat(module_path, &source) != 0) {
+        error = errno;
+        problem = "cannot inspect loaded module file";
+        goto finish;
+    }
+    if (!S_ISREG(source.st_mode)) {
+        problem = "loaded module pathname is not a regular file";
+        goto finish;
+    }
+
+    /* Boot creation was observed looking up the bare filename relative to
+     * runtime cwd. Anchor this directory with an FD; never change cwd.
+     */
+    directory = open(".", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
+    if (directory < 0) {
+        error = errno;
+        problem = "cannot open runtime working directory";
+        goto finish;
+    }
+    if (fstatat(directory, name, &existing, AT_SYMLINK_NOFOLLOW) == 0) {
+        struct stat resolved;
+        if (fstatat(directory, name, &resolved, 0) == 0 &&
+            resolved.st_dev == source.st_dev &&
+            resolved.st_ino == source.st_ino)
+            goto finish; /* Correct link, hard link, or the source itself. */
+        problem = "existing file or link left untouched; check boot-project path";
+        goto finish;
+    }
+    if (errno != ENOENT) {
+        error = errno;
+        problem = "cannot inspect boot-project pathname";
+        goto finish;
+    }
+
+    /* symlinkat fails on EEXIST: even a concurrent creator cannot be replaced.
+     * Keep this link on shutdown; boot-project creation may still need it.
+     */
+    if (symlinkat(module_path, directory, name) != 0) {
+        error = errno;
+        problem = "cannot create boot-project link";
+        goto finish;
+    }
+    syslog(LOG_INFO, "CmpAtomModbus: created boot link %s -> %s in runtime cwd",
+           name, module_path);
+
+finish:
+    if (problem) {
+        if (error)
+            syslog(LOG_WARNING, "CmpAtomModbus: %s: %s (errno=%d); Modbus startup continues",
+                   problem, strerror(error), error);
+        else
+            syslog(LOG_WARNING, "CmpAtomModbus: %s; Modbus startup continues", problem);
+    }
+    if (directory >= 0)
+        close(directory);
+    free(module_path);
+    errno = saved_errno;
+}
+#endif
@@ -1,8 +1,8 @@
 # Generated from supplied ExtensionSDK; build with target Linux toolchain.
 SDKDIR ?= ../../ExtensionSDK
 MAJORVER=0
-MINORVER=4
-CMPVERSION=0x00050000
+MINORVER=5
+CMPVERSION=0x00050001
 # Local development ID; check no other component uses this ID.
 CMPID=0x2001
 DOS2UNIX=dos2unix
@@ -10,4 +10,9 @@ M4=m4
 CC ?= gcc
 # The SDK otherwise includes CmpFrame in its component identity wildcard.
 override CSRC := CmpAtomModbus.c
+# dladdr locates this module; -ldl also supports glibc older than 2.34.
+LDLIBS += -ldl
 include $(SDKDIR)/makefile
+
+# Recompile the startup hook when the link helper changes.
+$(OUTDIR)/CmpFrame.o: atmb_boot_link.h