Extract the install prefix from the shared library.

src/mca/prteinstalldirs/runtime/Makefile.am

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+#
+# Copyright (c) 2025      NVIDIA Corporation.  All rights reserved.
+# $COPYRIGHT$
+#
+# Additional copyrights may follow
+#
+# $HEADER$
+#
+
+noinst_LTLIBRARIES = libprtemca_prteinstalldirs_runtime.la
+
+libprtemca_prteinstalldirs_runtime_la_SOURCES = \
+	prte_installdirs_runtime.c
+

src/mca/prteinstalldirs/runtime/configure.m4

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+# -*- shell-script -*-
+#
+# Copyright (c) 2025      NVIDIA Corporation.  All rights reserved.
+# $COPYRIGHT$
+#
+# Additional copyrights may follow
+#
+# $HEADER$
+#
+AC_DEFUN([MCA_prte_prteinstalldirs_runtime_PRIORITY], [5])
+
+AC_DEFUN([MCA_prte_prteinstalldirs_runtime_COMPILE_MODE], [
+    AC_MSG_CHECKING([for MCA component $2:$3 compile mode])
+    $4="static"
+    AC_MSG_RESULT([$$4])
+])
+
+# MCA_prteinstalldirs_config_CONFIG(action-if-can-compile,
+#                        [action-if-cant-compile])
+# ------------------------------------------------
+AC_DEFUN([MCA_prte_prteinstalldirs_runtime_CONFIG], [
+    # Check if we are building a shared library or not. Disable if static
+    AC_MSG_CHECKING([if shared libraries are enabled])
+    AS_IF([test "$enable_shared" != "yes"],
+          [prteinstalldirs_runtime_happy="no"],
+          [prteinstalldirs_runtime_happy="yes"])
+    AC_MSG_RESULT([$prteinstalldirs_runtime_happy])
+
+    # Check if dladdr is available
+    AS_IF([test "$prteinstalldirs_runtime_happy" = "yes"],
+          [AC_CHECK_HEADERS([dlfcn.h],
+                            [],
+                            [prteinstalldirs_runtime_happy="no"])])
+    AS_IF([test "$prteinstalldirs_runtime_happy" = "yes"],
+          [AC_CHECK_LIB([dl], [dladdr],
+                        [],
+                        [prteinstalldirs_runtime_happy="no"])
+          ])
+    #
+    AS_IF([test "$prteinstalldirs_runtime_happy" = "yes"],
+          [AC_CONFIG_FILES([src/mca/prteinstalldirs/runtime/Makefile])
+           $1], [$2])
+])
+

src/mca/prteinstalldirs/runtime/prte_installdirs_runtime.c

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+/*
+ * Copyright (c) 2025      NVIDIA Corporation.  All rights reserved.
+ * $COPYRIGHT$
+ *
+ * Additional copyrights may follow
+ *
+ * $HEADER$
+ */
+
+#include "prte_config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "constants.h"
+#include "src/mca/prteinstalldirs/prteinstalldirs.h"
+#include <dlfcn.h>
+#include "src/util/pmix_basename.h"
+
+static int prteinstalldirs_runtime_open(void);
+
+prte_prteinstalldirs_base_component_t prte_mca_prteinstalldirs_runtime_component = {
+    /* First, the mca_component_t struct containing meta information
+       about the component itself */
+    .component = {
+        PRTE_INSTALLDIRS_BASE_VERSION_2_0_0,
+
+         /* Component name and version */
+         .pmix_mca_component_name = "runtime",
+         PMIX_MCA_BASE_MAKE_VERSION(component,
+                                   PRTE_MAJOR_VERSION,
+                                   PRTE_MINOR_VERSION,
+                                   PRTE_RELEASE_VERSION),
+         /* Component open and close functions */
+         .pmix_mca_open_component = prteinstalldirs_runtime_open
+    },
+
+    /* Next the prte_install_dirs_t install_dirs_data information */
+    {
+        NULL,
+    },
+};
+
+static int prteinstalldirs_runtime_open(void)
+{
+    Dl_info info;
+    void* prte_fct;
+
+    /* Casting from void* to fct pointer according to POSIX.1-2001 and POSIX.1-2008 */
+    *(void **)&prte_fct = dlsym(RTLD_DEFAULT, "pmix_init_util");
+
+    if( 0 == dladdr(prte_fct, &info) ) {
+        /* Can't find the symbol */
+        return PRTE_ERROR;
+    }
+
+    char* dname = pmix_dirname(info.dli_fname);
+    char* prefix = pmix_dirname(dname);
+    free(dname);
+
+    prte_mca_prteinstalldirs_runtime_component.install_dirs_data.prefix = prefix;
+
+    return PRTE_SUCCESS;
+}