feat(initial): added portable mfem build system

tools/ceed_jit_source_root_relocatable.c

@@ -0,0 +1,51 @@
+// Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and
+// other CEED contributors. All Rights Reserved.
+// SPDX-License-Identifier: BSD-2-Clause
+
+// Relocatable replacement for libCEED's installed JIT source-root object.
+// Upstream normally compiles the installation prefix into libceed. Native
+// source bundles here are shared libraries, so derive ../include from the
+// loaded library instead. Emscripten has no runtime compiler/JIT filesystem.
+
+#if defined(__EMSCRIPTEN__)
+
+const char *CeedJitSourceRootDefault = "";
+
+#else
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <dlfcn.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+static char ceed_jit_source_root[PATH_MAX];
+const char *CeedJitSourceRootDefault = ceed_jit_source_root;
+
+__attribute__((constructor)) static void CeedSetRelocatableJitSourceRoot(void) {
+  Dl_info info;
+  char library_path[PATH_MAX];
+
+  if (!dladdr((void *)&CeedJitSourceRootDefault, &info) || !info.dli_fname) {
+    return;
+  }
+  if (snprintf(library_path, sizeof library_path, "%s", info.dli_fname) < 0) {
+    return;
+  }
+  char *separator = strrchr(library_path, '/');
+  if (!separator) {
+    return;
+  }
+  *separator = '\0';
+  (void)snprintf(ceed_jit_source_root, sizeof ceed_jit_source_root,
+                 "%s/../include/", library_path);
+}
+
+#endif