From 4c6cd1a9322ed3cf089f849751d74884b530f476 Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Thu, 23 Oct 2025 14:18:04 -0500
Subject: [PATCH 01/10] Fix overflow on long link names

---
 CMakeLists.txt      |   3 -
 src/H5LS.c          |   8 ++
 src/H5LS.h          |   4 +-
 src/H5VLcache_ext.c | 180 ++++++++++++++++++++++++++++++--------------
 src/cache_utils.c   |  51 +++++++++++++
 src/cache_utils.h   |   4 +
 6 files changed, 189 insertions(+), 61 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9d2e9ad..1be3af6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,9 +8,6 @@ include(CTest)
 enable_testing()
 
 find_package(MPI REQUIRED)
-find_package(ASYNC REQUIRED)
-find_package(HDF5 REQUIRED COMPONENTS C)
-
 include_directories(${MPI_INCLUDE_PATH})
 include_directories(${HDF5_INCLUDE_DIRS})
 include_directories(${ASYNC_INCLUDE_DIRS})
diff --git a/src/H5LS.c b/src/H5LS.c
index bc0cf41..215cfac 100644
--- a/src/H5LS.c
+++ b/src/H5LS.c
@@ -481,6 +481,10 @@ herr_t H5LSremove_cache(cache_storage_t *LS, cache_t *cache) {
       LOG_DEBUG(-1, "Cache storage space left: %lu bytes\n", LS->mspace_left);
 #endif
 
+      if (cache->path != NULL) {
+        free(cache->path);
+        cache->path = NULL;
+      }
       free(cache);
       cache = NULL;
     }
@@ -511,6 +515,10 @@ herr_t H5LSremove_cache_all(cache_storage_t *LS) {
   while (head != NULL) {
     if (LS->io_node) {
       ret_value = LS->mmap_cls->removeCacheFolder(head->cache->path);
+      if (head->cache->path != NULL) {
+        free(head->cache->path);
+        head->cache->path = NULL;
+      }
       free(head->cache);
       head->cache = NULL;
       head = head->next;
diff --git a/src/H5LS.h b/src/H5LS.h
index ab359e6..f9b8103 100644
--- a/src/H5LS.h
+++ b/src/H5LS.h
@@ -50,7 +50,7 @@ typedef struct cache_t {
   hsize_t mspace_per_rank_total; // total space per process
   hsize_t mspace_per_rank_left;  // space left per process
   hid_t fd;                      // the associate file
-  char path[255];                // path
+  char *path;                    // dynamically allocated path
   AccessHistory access_history;
 } cache_t;
 
@@ -116,7 +116,7 @@ typedef struct _IO_THREAD {
 typedef struct _MMAP {
   // for write
   int fd;          // file handle for write
-  char fname[255]; // full path of the memory mapped file
+  char *fname;     // dynamically allocated full path of the memory mapped file
   void *obj;       // this will be used for cache data on global storage layer
   void *buf;       // pointer that map the file to the memory
   void *tmp_buf;   // temporally buffer, used for parallel read: copy the read
diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 18695d4..d0089a2 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -3186,6 +3186,7 @@ static herr_t H5VL_cache_ext_dataset_close(void *dset, hid_t dxpl_id,
   H5VL_cache_ext_t *o = (H5VL_cache_ext_t *)dset;
   herr_t ret_value;
   H5VL_cache_ext_t *p = o;
+
   while (p->parent != NULL)
     p = p->parent;
 
@@ -5386,7 +5387,9 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DWMM->io->fusion_data_size = 0.0;
       file->H5DWMM->io->num_fusion_requests = 0;
       file->H5DWMM->cache = (cache_t *)malloc(sizeof(cache_t));
+      file->H5DWMM->cache->path = NULL;
       file->H5DWMM->mmap = (MMAP *)malloc(sizeof(MMAP));
+      file->H5DWMM->mmap->fname = NULL;
     } else {
 #ifndef NDEBUG
       LOG_WARN(-1, "file_cache_create: cache data already exist. "
@@ -5415,6 +5418,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
     file->H5DWMM->io->num_request = 0;
 
     file->H5DWMM->cache = (cache_t *)malloc(sizeof(cache_t));
+    file->H5DWMM->cache->path = NULL;
     file->H5DWMM->cache->mspace_total =
         file->H5LS->write_buffer_size * file->H5DWMM->mpi->ppn;
     if (file->H5LS->mspace_total < file->H5DWMM->cache->mspace_total) {
@@ -5423,12 +5427,14 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
                     "        Will turn off Cache effect."
                     "        Try to decrease HDF5_CACHE_WRITE_BUFFER_SIZE.");
       file->write_cache = false;
+      free(file->H5DWMM->cache);
       return FAIL;
     } else if (H5LSclaim_space(file->H5LS, file->H5DWMM->cache->mspace_total,
                                HARD, file->H5LS->replacement_policy) == FAIL) {
       LOG_ERROR(-1, "Unable to claim space, turning off write "
                     "cache");
       file->write_cache = false;
+      free(file->H5DWMM->cache);
       return FAIL;
     }
 
@@ -5441,19 +5447,26 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
     file->H5DWMM->cache->duration = PERMANENT;
 
     if (file->H5LS->path != NULL) {
-      strcpy(file->H5DWMM->cache->path, file->H5LS->path);
-      strcat(file->H5DWMM->cache->path, "/");
-      strcat(file->H5DWMM->cache->path, basename((char *)name));
-      strcat(file->H5DWMM->cache->path, "-cache/");
-      // mkdir(file->H5DWMM->cache->path, 0755); // setup the folder with the
-      // name of the file, and put everything under it.
-
-      strcpy(file->H5DWMM->mmap->fname, file->H5DWMM->cache->path);
-      strcat(file->H5DWMM->mmap->fname, "mmap-");
+      // Build cache path: <storage_path>/<filename>-cache/
       char rnd[255];
       sprintf(rnd, "%d", file->H5DWMM->mpi->rank);
-      strcat(file->H5DWMM->mmap->fname, rnd);
-      strcat(file->H5DWMM->mmap->fname, ".dat");
+
+      file->H5DWMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "-cache", NULL);
+      if (file->H5DWMM->cache->path == NULL) {
+        LOG_ERROR(-1, "Failed to allocate cache path");
+        free(file->H5DWMM->cache);
+        return FAIL;
+      }
+
+      // Build mmap fname: <cache_path>/mmap-<rank>.dat
+      file->H5DWMM->mmap->fname = cache_utils_build_path(file->H5DWMM->cache->path, "mmap-", rnd, ".dat", NULL);
+      if (file->H5DWMM->mmap->fname == NULL) {
+        LOG_ERROR(-1, "Failed to allocate mmap fname");
+        free(file->H5DWMM->cache->path);
+        file->H5DWMM->cache->path = NULL;
+        free(file->H5DWMM->cache);
+        return FAIL;
+      }
 #ifndef NDEBUG
       LOG_DEBUG(-1, "**Using node local storage to cache the file");
       LOG_DEBUG(-1, "**path: %s", file->H5DWMM->cache->path);
@@ -5486,7 +5499,9 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DRMM->mpi = (MPI_INFO *)malloc(sizeof(MPI_INFO));
       file->H5DRMM->io = (IO_THREAD *)malloc(sizeof(IO_THREAD));
       file->H5DRMM->cache = (cache_t *)malloc(sizeof(cache_t));
+      file->H5DRMM->cache->path = NULL;
       file->H5DRMM->mmap = (MMAP *)malloc(sizeof(MMAP));
+      file->H5DRMM->mmap->fname = NULL;
     } else {
 #ifndef NDEBUG
       LOG_WARN(-1, "file cache create: cache data already exist. "
@@ -5510,10 +5525,18 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
     /* setting up cache within a folder */
 
     if (file->H5LS->path != NULL) {
-      strcpy(file->H5DRMM->cache->path, file->H5LS->path);
-      strcat(file->H5DRMM->cache->path, "/");
-      strcat(file->H5DRMM->cache->path, basename((char *)name));
-      strcat(file->H5DRMM->cache->path, "/");
+      // Build cache path: <storage_path>/<filename>/
+      file->H5DRMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "/", NULL);
+      if (file->H5DRMM->cache->path == NULL) {
+        LOG_ERROR(-1, "Failed to allocate file read cache path");
+        free(file->H5DRMM->mmap);
+        free(file->H5DRMM->cache);
+        free(file->H5DRMM->io);
+        free(file->H5DRMM->mpi);
+        free(file->H5DRMM);
+        file->H5DRMM = NULL;
+        return FAIL;
+      }
 #ifndef NDEBUG
 
       LOG_DEBUG(-1, "file cache created: %s", file->H5DRMM->cache->path);
@@ -5647,6 +5670,7 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
                         dset->H5DRMM->dset.size * dset->H5DRMM->mpi->ppn, HARD,
                         dset->H5LS->replacement_policy) == SUCCEED) {
       dset->H5DRMM->cache = (cache_t *)malloc(sizeof(cache_t));
+      dset->H5DRMM->cache->path = NULL;
 
       // set cache size
 
@@ -5659,31 +5683,27 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
       dset->H5DRMM->cache->mspace_left = dset->H5DRMM->cache->mspace_total;
 
       if (dset->H5LS->path != NULL) {
-        strcpy(dset->H5DRMM->cache->path, p->H5DRMM->cache->path); // create
-        strncat(dset->H5DRMM->cache->path, "/",
-                sizeof(dset->H5DRMM->cache->path) -
-                    strlen(dset->H5DRMM->cache->path) - 1);
-        strncat(dset->H5DRMM->cache->path, name,
-                sizeof(dset->H5DRMM->cache->path) -
-                    strlen(dset->H5DRMM->cache->path) - 1);
-        strncat(dset->H5DRMM->cache->path, "/",
-                sizeof(dset->H5DRMM->cache->path) -
-                    strlen(dset->H5DRMM->cache->path) - 1);
-        strncpy(dset->H5DRMM->mmap->fname, dset->H5DRMM->cache->path,
-                sizeof(dset->H5DRMM->mmap->fname) - 1);
-        dset->H5DRMM->mmap->fname[sizeof(dset->H5DRMM->mmap->fname) - 1] =
-            '\0'; // Ensure null-termination
-        strncat(dset->H5DRMM->mmap->fname, "/dset-mmap-",
-                sizeof(dset->H5DRMM->mmap->fname) -
-                    strlen(dset->H5DRMM->mmap->fname) - 1);
+        // Build cache path: <parent_cache_path>/<dataset_name>/
+        dset->H5DRMM->cache->path = cache_utils_build_path(p->H5DRMM->cache->path, name, "/", NULL);
+        if (dset->H5DRMM->cache->path == NULL) {
+          LOG_ERROR(-1, "Failed to allocate dataset read cache path");
+          free(dset->H5DRMM->cache);
+          dset->H5DRMM->cache = NULL;
+          return FAIL;
+        }
+
+        // Build mmap fname: <cache_path>/dset-mmap-<rank>.dat
         char cc[255];
         int2char(dset->H5DRMM->mpi->rank, cc);
-        strncat(dset->H5DRMM->mmap->fname, cc,
-                sizeof(dset->H5DRMM->mmap->fname) -
-                    strlen(dset->H5DRMM->mmap->fname) - 1);
-        strncat(dset->H5DRMM->mmap->fname, ".dat",
-                sizeof(dset->H5DRMM->mmap->fname) -
-                    strlen(dset->H5DRMM->mmap->fname) - 1);
+        dset->H5DRMM->mmap->fname = cache_utils_build_path(dset->H5DRMM->cache->path, "dset-mmap-", cc, ".dat", NULL);
+        if (dset->H5DRMM->mmap->fname == NULL) {
+          LOG_ERROR(-1, "Failed to allocate dataset read mmap fname");
+          free(dset->H5DRMM->cache->path);
+          dset->H5DRMM->cache->path = NULL;
+          free(dset->H5DRMM->cache);
+          dset->H5DRMM->cache = NULL;
+          return FAIL;
+        }
 #ifndef NDEBUG
 
         LOG_DEBUG(-1, "Dataset read cache created: %s",
@@ -5756,19 +5776,20 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
   if (group->read_cache) {
     group->H5DRMM = (io_handler_t *)malloc(sizeof(io_handler_t));
     group->H5DRMM->cache = (cache_t *)malloc(sizeof(cache_t));
+    group->H5DRMM->cache->path = NULL;
     group->H5DRMM->mpi = (MPI_INFO *)malloc(sizeof(MPI_INFO));
     memcpy(group->H5DRMM->mpi, o->H5DRMM->mpi, sizeof(MPI_INFO));
     if (group->H5LS->path != NULL) {
-      strcpy(group->H5DRMM->cache->path, o->H5DRMM->cache->path); // create
-      size_t remaining_size = sizeof(group->H5DRMM->cache->path) -
-                              strlen(group->H5DRMM->cache->path) - 1;
-      strncat(group->H5DRMM->cache->path, "/", remaining_size);
-      remaining_size = sizeof(group->H5DRMM->cache->path) -
-                       strlen(group->H5DRMM->cache->path) - 1;
-      strncat(group->H5DRMM->cache->path, name, remaining_size);
-      remaining_size = sizeof(group->H5DRMM->cache->path) -
-                       strlen(group->H5DRMM->cache->path) - 1;
-      strncat(group->H5DRMM->cache->path, "/", remaining_size);
+      // Build cache path: <parent_cache_path>/<group_name>/
+      group->H5DRMM->cache->path = cache_utils_build_path(o->H5DRMM->cache->path, name, "/", NULL);
+      if (group->H5DRMM->cache->path == NULL) {
+        LOG_ERROR(-1, "Failed to allocate group read cache path");
+        free(group->H5DRMM->mpi);
+        free(group->H5DRMM->cache);
+        free(group->H5DRMM);
+        group->H5DRMM = NULL;
+        return FAIL;
+      }
 #ifndef NDEBUG
       LOG_DEBUG(-1, "group cache created: %s", group->H5DRMM->cache->path);
 #endif
@@ -5793,6 +5814,8 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
 static herr_t remove_group_cache_on_local_storage(void *obj, void **req) {
   H5VL_cache_ext_t *group = (H5VL_cache_ext_t *)obj;
   if (group->read_cache) {
+    free(group->H5DRMM->cache->path);
+          group->H5DRMM->cache->path = NULL;
     free(group->H5DRMM->cache);
     free(group->H5DRMM->mpi);
     free(group->H5DRMM);
@@ -6083,9 +6106,11 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
       file->H5DWMM->mpi = (MPI_INFO *)malloc(sizeof(MPI_INFO));
       file->H5DWMM->io = (IO_THREAD *)malloc(sizeof(IO_THREAD));
       file->H5DWMM->mmap = (MMAP *)malloc(sizeof(MMAP));
+      file->H5DWMM->mmap->fname = NULL;
       file->H5DWMM->io->fusion_data_size = 0.0;
       file->H5DWMM->io->num_fusion_requests = 0;
       file->H5DWMM->cache = (cache_t *)malloc(sizeof(cache_t));
+      file->H5DWMM->cache->path = NULL;
     } else {
       LOG_ERROR(-1, "file_cache_create: cache data already exist. "
                     "Remove first!");
@@ -6101,15 +6126,36 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
     file->H5LS->io_node = (file->H5DWMM->mpi->rank == 0); // set up I/O node
     file->H5DWMM->io->num_request = 0;
     if (file->H5LS->path != NULL) {
-      strcpy(file->H5DWMM->cache->path, file->H5LS->path);
-      strcat(file->H5DWMM->cache->path, "/");
-      strcat(file->H5DWMM->cache->path, basename((char *)name));
-      strcat(file->H5DWMM->cache->path, "-global-cache/");
+      // Build cache path: <storage_path>/<filename>-global-cache/
+      file->H5DWMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "-global-cache/", NULL);
+      if (file->H5DWMM->cache->path == NULL) {
+        LOG_ERROR(-1, "Failed to allocate file GLOBAL cache path");
+        free(file->H5DWMM->mmap);
+        free(file->H5DWMM->cache);
+        free(file->H5DWMM->io);
+        free(file->H5DWMM->mpi);
+        free(file->H5DWMM);
+        file->H5DWMM = NULL;
+        return FAIL;
+      }
       mkdir(file->H5DWMM->cache->path,
             0755); // setup the folder with the name of the file, and put
                    // everything under it.
-      strcpy(file->H5DWMM->mmap->fname, file->H5DWMM->cache->path);
-      strcat(file->H5DWMM->mmap->fname, basename((char *)name));
+
+      // Build mmap fname: <cache_path>/<filename>
+      file->H5DWMM->mmap->fname = cache_utils_build_path(file->H5DWMM->cache->path, basename((char *)name), NULL);
+      if (file->H5DWMM->mmap->fname == NULL) {
+        LOG_ERROR(-1, "Failed to allocate file GLOBAL mmap fname");
+        free(file->H5DWMM->cache->path);
+          file->H5DWMM->cache->path = NULL;
+        free(file->H5DWMM->mmap);
+        free(file->H5DWMM->cache);
+        free(file->H5DWMM->io);
+        free(file->H5DWMM->mpi);
+        free(file->H5DWMM);
+        file->H5DWMM = NULL;
+        return FAIL;
+      }
 #ifndef NDEBUG
 
       LOG_INFO(-1, "Using global storage as a cache");
@@ -6256,6 +6302,7 @@ static herr_t create_dataset_cache_on_global_storage(void *obj, void *dset_args,
                         dset->H5DWMM->dset.size * dset->H5DWMM->mpi->nproc,
                         HARD, dset->H5LS->replacement_policy) == SUCCEED) {
       dset->H5DWMM->cache = (cache_t *)malloc(sizeof(cache_t));
+      dset->H5DWMM->cache->path = NULL;
 
       dset->H5DWMM->cache->mspace_per_rank_total = dset->H5DWMM->dset.size;
       dset->H5DWMM->cache->mspace_per_rank_left =
@@ -6266,8 +6313,25 @@ static herr_t create_dataset_cache_on_global_storage(void *obj, void *dset_args,
       dset->H5DWMM->cache->mspace_left = dset->H5DWMM->cache->mspace_total;
 
       if (dset->H5LS->path != NULL) {
-        strcpy(dset->H5DWMM->cache->path, o->H5DWMM->cache->path); // create
-        strcpy(dset->H5DWMM->mmap->fname, args->name);
+        // Copy parent cache path
+        dset->H5DWMM->cache->path = strdup(o->H5DWMM->cache->path);
+        if (dset->H5DWMM->cache->path == NULL) {
+          LOG_ERROR(-1, "Failed to allocate dataset GLOBAL cache path");
+          free(dset->H5DWMM->cache);
+          dset->H5DWMM->cache = NULL;
+          return FAIL;
+        }
+
+        // Copy dataset name to mmap fname
+        dset->H5DWMM->mmap->fname = strdup(args->name);
+        if (dset->H5DWMM->mmap->fname == NULL) {
+          LOG_ERROR(-1, "Failed to allocate dataset GLOBAL mmap fname");
+          free(dset->H5DWMM->cache->path);
+          dset->H5DWMM->cache->path = NULL;
+          free(dset->H5DWMM->cache);
+          dset->H5DWMM->cache = NULL;
+          return FAIL;
+        }
 #ifndef NDEBUG
 
         LOG_DEBUG(-1, "Dataset cache created: %s", dset->H5DWMM->mmap->fname);
@@ -6482,7 +6546,11 @@ static herr_t remove_dataset_cache_on_global_storage(void *dset, void **req) {
     H5VL_cache_ext_dataset_wait(dset);
   if (o->write_cache || o->read_cache) {
     H5Dclose_async(o->hd_glob, H5ES_NONE);
+    free(o->H5DWMM->cache->path);
+          o->H5DWMM->cache->path = NULL;
     free(o->H5DWMM->cache);
+    free(o->H5DWMM->mmap->fname);
+          o->H5DWMM->mmap->fname = NULL;
     free(o->H5DWMM->mmap);
     free(o->H5DWMM);
     o->H5DWMM = NULL;
diff --git a/src/cache_utils.c b/src/cache_utils.c
index da5286e..4a908cd 100644
--- a/src/cache_utils.c
+++ b/src/cache_utils.c
@@ -12,6 +12,7 @@
 #include "stdlib.h"
 #include "string.h"
 #include "unistd.h"
+#include <stdarg.h>
 #include <stdio.h>
 // POSIX I/O
 #include "cache_utils.h"
@@ -164,3 +165,53 @@ herr_t rmdirRecursive(const char *path) {
   ret = rmdir(path);
   return ret;
 }
+
+/*-------------------------------------------------------------------------
+ * Function:    cache_utils_build_path
+ *
+ * Purpose:     Build a path from multiple components (varargs, NULL-terminated)
+ *
+ * Return:      Pointer to newly allocated path string, or NULL on failure
+ *
+ * Example:     cache_utils_build_path("/tmp", "file.h5", "group", NULL)
+ *              Returns: "/tmp/file.h5/group"
+ *
+ *-------------------------------------------------------------------------
+ */
+char *cache_utils_build_path(const char *base, ...) {
+  if (base == NULL)
+    return NULL;
+
+  va_list args;
+  const char *component;
+  size_t total_len = strlen(base);
+  int num_components = 0;
+
+  // First pass: calculate total length
+  va_start(args, base);
+  while ((component = va_arg(args, const char *)) != NULL) {
+    total_len += strlen(component);
+    num_components++;
+  }
+  va_end(args);
+
+  // Allocate buffer (base + components + separators + null terminator)
+  char *result = (char *)malloc(total_len + num_components + 1);
+  if (result == NULL)
+    return NULL;
+
+  // Second pass: build the path
+  strcpy(result, base);
+
+  va_start(args, base);
+  while ((component = va_arg(args, const char *)) != NULL) {
+    // Add separator if needed (avoid double slashes)
+    size_t current_len = strlen(result);
+    if (current_len > 0 && result[current_len - 1] != '/' && component[0] != '/')
+      strcat(result, "/");
+    strcat(result, component);
+  }
+  va_end(args);
+
+  return result;
+}
diff --git a/src/cache_utils.h b/src/cache_utils.h
index 2208917..762c1cf 100644
--- a/src/cache_utils.h
+++ b/src/cache_utils.h
@@ -45,6 +45,10 @@ void parallel_dist(size_t dim, int nproc, int rank, size_t *ldim,
 void int2char(int a, char str[255]);
 void mkdirRecursive(const char *path, mode_t mode);
 herr_t rmdirRecursive(const char *path);
+
+// Helper functions for dynamic string allocation
+char *cache_utils_build_path(const char *base, ...); // NULL-terminated varargs
+
 #ifdef __cplusplus
 }
 #endif

From f1a7ab9b93ff00581ca9f147539a37112fef5a8a Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Fri, 24 Oct 2025 10:45:41 -0500
Subject: [PATCH 02/10] Reference count cache objects

---
 CMakeLists.txt      |  3 ++
 src/H5VLcache_ext.c | 85 +++++++++++++++++++++++++++++++++++----------
 src/H5VLcache_ext.h | 10 ++++--
 src/cache_utils.c   | 51 ---------------------------
 src/cache_utils.h   |  4 ---
 5 files changed, 77 insertions(+), 76 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1be3af6..9d2e9ad 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,9 @@ include(CTest)
 enable_testing()
 
 find_package(MPI REQUIRED)
+find_package(ASYNC REQUIRED)
+find_package(HDF5 REQUIRED COMPONENTS C)
+
 include_directories(${MPI_INCLUDE_PATH})
 include_directories(${HDF5_INCLUDE_DIRS})
 include_directories(${ASYNC_INCLUDE_DIRS})
diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index d0089a2..37acc3b 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -875,6 +875,7 @@ static H5VL_cache_ext_t *H5VL_cache_ext_new_obj(void *under_obj,
   new_obj = (H5VL_cache_ext_t *)calloc(1, sizeof(H5VL_cache_ext_t));
   new_obj->under_object = under_obj;
   new_obj->under_vol_id = under_vol_id;
+  new_obj->ref_count = 1;
   H5Iinc_ref(new_obj->under_vol_id);
 
   return new_obj;
@@ -897,17 +898,34 @@ static H5VL_cache_ext_t *H5VL_cache_ext_new_obj(void *under_obj,
  *-------------------------------------------------------------------------
  */
 static herr_t H5VL_cache_ext_free_obj(H5VL_cache_ext_t *obj) {
-  hid_t err_id;
+  hid_t err_id = H5I_INVALID_HID;
 
   err_id = H5Eget_current_stack();
 
-  H5Idec_ref(obj->under_vol_id);
+  assert(obj->ref_count > 0);
+  obj->ref_count--;
 
-  H5Eset_current_stack(err_id);
+  if (obj->ref_count == 0) {
+    if (H5Idec_ref(obj->under_vol_id) < 0) {
+      LOG_ERROR(-1, "H5Idec_ref failed on underlying VOL ID");
+      goto error;
+    }
+    /* Close this object's reference to its parent object (if any) */
+    if (obj->parent)
+      if (H5VL_cache_ext_free_obj(obj->parent) < 0) {
+        LOG_ERROR(-1, "can't free parent object");
+        goto error;
+      }
 
-  free(obj);
+    free(obj);
+  }
 
+  H5Eset_current_stack(err_id);
   return 0;
+
+error:
+  H5Eset_current_stack(err_id);
+  return -1;
 } /* end H5VL_cache_extfree_obj() */
 
 /*-------------------------------------------------------------------------
@@ -1990,7 +2008,8 @@ static void *H5VL_cache_ext_dataset_create(void *obj,
   if (under) {
     dset = H5VL_cache_ext_new_obj(under, o->under_vol_id);
     /* inherit cache information from loc */
-    dset->parent = obj;
+    dset->parent = o;
+    o->ref_count++;
     // inherit variables from parent object
     dset->H5DWMM = o->H5DWMM;
     dset->write_cache = o->write_cache;
@@ -2179,7 +2198,8 @@ static void *H5VL_cache_ext_dataset_open(void *obj,
   if (under) {
     dset = H5VL_cache_ext_new_obj(under, o->under_vol_id);
     /* Inherit Cache information from obj */
-    dset->parent = obj;
+    dset->parent = o;
+    o->ref_count++;
     dset->H5DWMM = o->H5DWMM;
     dset->write_cache = o->write_cache;
     dset->read_cache = o->read_cache;
@@ -3545,6 +3565,11 @@ static herr_t set_file_cache(void *obj, void *file_args, void **req) {
 
   file->write_cache = false;
   file->read_cache = false;
+  if (file->parent != NULL) {
+    assert(file->parent->ref_count > 0);
+    H5VL_cache_ext_free_obj(file->parent);
+  }
+
   file->parent = NULL;
 
   file->H5DRMM = NULL;
@@ -4163,7 +4188,8 @@ static void *H5VL_cache_ext_group_create(void *obj,
     /* passing the cache information on from file to group */
     group->write_cache = o->write_cache;
     group->read_cache = o->read_cache;
-    group->parent = obj;
+    group->parent = o;
+    o->ref_count++;
     group->H5LS = o->H5LS;
     group->async_pause = o->async_pause;
     if (group->write_cache || group->read_cache) {
@@ -4221,7 +4247,8 @@ static void *H5VL_cache_ext_group_open(void *obj,
     group->H5DWMM = o->H5DWMM;
     group->read_cache = o->read_cache;
     group->H5DRMM = o->H5DRMM;
-    group->parent = obj;
+    group->parent = o;
+    o->ref_count++;
     group->H5LS = o->H5LS;
     group->async_pause = o->async_pause;
     if (group->write_cache || group->read_cache) {
@@ -4707,7 +4734,8 @@ static void *H5VL_cache_ext_object_open(void *obj,
       new_obj->write_cache = o->write_cache;
       new_obj->H5DWMM = o->H5DWMM;
       new_obj->H5DRMM = o->H5DRMM;
-      new_obj->parent = obj;
+      new_obj->parent = o;
+      o->ref_count++;
       new_obj->H5LS = o->H5LS;
       new_obj->async_close = o->async_close;
 #ifndef NDEBUG
@@ -4739,7 +4767,8 @@ static void *H5VL_cache_ext_object_open(void *obj,
       new_obj->async_close = p->async_close;
       new_obj->H5DRMM = o->H5DRMM;
       new_obj->H5DWMM = o->H5DWMM;
-      new_obj->parent = obj;
+      new_obj->parent = o;
+      o->ref_count++;
       new_obj->H5LS = o->H5LS;
       new_obj->es_id = H5EScreate();
       int called = 0;
@@ -5450,16 +5479,20 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       // Build cache path: <storage_path>/<filename>-cache/
       char rnd[255];
       sprintf(rnd, "%d", file->H5DWMM->mpi->rank);
+      char *base = basename((char *)name);
 
-      file->H5DWMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "-cache", NULL);
+      size_t path_len = strlen(file->H5LS->path) + strlen(base) + strlen("-cache") + 2;
+      file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate cache path");
         free(file->H5DWMM->cache);
         return FAIL;
       }
+      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache", file->H5LS->path, base);
 
       // Build mmap fname: <cache_path>/mmap-<rank>.dat
-      file->H5DWMM->mmap->fname = cache_utils_build_path(file->H5DWMM->cache->path, "mmap-", rnd, ".dat", NULL);
+      size_t fname_len = strlen(file->H5DWMM->cache->path) + strlen("mmap-") + strlen(rnd) + strlen(".dat") + 2;
+      file->H5DWMM->mmap->fname = (char *)malloc(fname_len);
       if (file->H5DWMM->mmap->fname == NULL) {
         LOG_ERROR(-1, "Failed to allocate mmap fname");
         free(file->H5DWMM->cache->path);
@@ -5467,6 +5500,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         free(file->H5DWMM->cache);
         return FAIL;
       }
+      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s/mmap-%s.dat", file->H5DWMM->cache->path, rnd);
 #ifndef NDEBUG
       LOG_DEBUG(-1, "**Using node local storage to cache the file");
       LOG_DEBUG(-1, "**path: %s", file->H5DWMM->cache->path);
@@ -5526,7 +5560,9 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
 
     if (file->H5LS->path != NULL) {
       // Build cache path: <storage_path>/<filename>/
-      file->H5DRMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "/", NULL);
+      char *base = basename((char *)name);
+      size_t path_len = strlen(file->H5LS->path) + strlen(base) + 2;
+      file->H5DRMM->cache->path = (char *)malloc(path_len);
       if (file->H5DRMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate file read cache path");
         free(file->H5DRMM->mmap);
@@ -5537,6 +5573,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         file->H5DRMM = NULL;
         return FAIL;
       }
+      snprintf(file->H5DRMM->cache->path, path_len, "%s/%s", file->H5LS->path, base);
 #ifndef NDEBUG
 
       LOG_DEBUG(-1, "file cache created: %s", file->H5DRMM->cache->path);
@@ -5628,6 +5665,7 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
                                         H5P_DATASET_XFER_DEFAULT, NULL);
 
       o->read_cache = true;
+      // TODO - May create persistent ref that needs ref counting?
       o->H5LS->cache_io_cls->create_cache((void *)o, &file_args, req);
     }
     int np;
@@ -5684,18 +5722,21 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
 
       if (dset->H5LS->path != NULL) {
         // Build cache path: <parent_cache_path>/<dataset_name>/
-        dset->H5DRMM->cache->path = cache_utils_build_path(p->H5DRMM->cache->path, name, "/", NULL);
+        size_t path_len = strlen(p->H5DRMM->cache->path) + strlen(name) + 2;
+        dset->H5DRMM->cache->path = (char *)malloc(path_len);
         if (dset->H5DRMM->cache->path == NULL) {
           LOG_ERROR(-1, "Failed to allocate dataset read cache path");
           free(dset->H5DRMM->cache);
           dset->H5DRMM->cache = NULL;
           return FAIL;
         }
+        snprintf(dset->H5DRMM->cache->path, path_len, "%s/%s", p->H5DRMM->cache->path, name);
 
         // Build mmap fname: <cache_path>/dset-mmap-<rank>.dat
         char cc[255];
         int2char(dset->H5DRMM->mpi->rank, cc);
-        dset->H5DRMM->mmap->fname = cache_utils_build_path(dset->H5DRMM->cache->path, "dset-mmap-", cc, ".dat", NULL);
+        size_t fname_len = strlen(dset->H5DRMM->cache->path) + strlen("dset-mmap-") + strlen(cc) + strlen(".dat") + 2;
+        dset->H5DRMM->mmap->fname = (char *)malloc(fname_len);
         if (dset->H5DRMM->mmap->fname == NULL) {
           LOG_ERROR(-1, "Failed to allocate dataset read mmap fname");
           free(dset->H5DRMM->cache->path);
@@ -5704,6 +5745,7 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
           dset->H5DRMM->cache = NULL;
           return FAIL;
         }
+        snprintf(dset->H5DRMM->mmap->fname, fname_len, "%s/dset-mmap-%s.dat", dset->H5DRMM->cache->path, cc);
 #ifndef NDEBUG
 
         LOG_DEBUG(-1, "Dataset read cache created: %s",
@@ -5781,7 +5823,8 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
     memcpy(group->H5DRMM->mpi, o->H5DRMM->mpi, sizeof(MPI_INFO));
     if (group->H5LS->path != NULL) {
       // Build cache path: <parent_cache_path>/<group_name>/
-      group->H5DRMM->cache->path = cache_utils_build_path(o->H5DRMM->cache->path, name, "/", NULL);
+      size_t path_len = strlen(o->H5DRMM->cache->path) + strlen(name) + 2;
+      group->H5DRMM->cache->path = (char *)malloc(path_len);
       if (group->H5DRMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate group read cache path");
         free(group->H5DRMM->mpi);
@@ -5790,6 +5833,7 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
         group->H5DRMM = NULL;
         return FAIL;
       }
+      snprintf(group->H5DRMM->cache->path, path_len, "%s/%s", o->H5DRMM->cache->path, name);
 #ifndef NDEBUG
       LOG_DEBUG(-1, "group cache created: %s", group->H5DRMM->cache->path);
 #endif
@@ -6127,7 +6171,9 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
     file->H5DWMM->io->num_request = 0;
     if (file->H5LS->path != NULL) {
       // Build cache path: <storage_path>/<filename>-global-cache/
-      file->H5DWMM->cache->path = cache_utils_build_path(file->H5LS->path, basename((char *)name), "-global-cache/", NULL);
+      char *base = basename((char *)name);
+      size_t path_len = strlen(file->H5LS->path) + strlen(base) + strlen("-global-cache/") + 2;
+      file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate file GLOBAL cache path");
         free(file->H5DWMM->mmap);
@@ -6138,12 +6184,14 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
         file->H5DWMM = NULL;
         return FAIL;
       }
+      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-global-cache/", file->H5LS->path, base);
       mkdir(file->H5DWMM->cache->path,
             0755); // setup the folder with the name of the file, and put
                    // everything under it.
 
       // Build mmap fname: <cache_path>/<filename>
-      file->H5DWMM->mmap->fname = cache_utils_build_path(file->H5DWMM->cache->path, basename((char *)name), NULL);
+      size_t fname_len = strlen(file->H5DWMM->cache->path) + strlen(base) + 1;
+      file->H5DWMM->mmap->fname = (char *)malloc(fname_len);
       if (file->H5DWMM->mmap->fname == NULL) {
         LOG_ERROR(-1, "Failed to allocate file GLOBAL mmap fname");
         free(file->H5DWMM->cache->path);
@@ -6156,6 +6204,7 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
         file->H5DWMM = NULL;
         return FAIL;
       }
+      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s%s", file->H5DWMM->cache->path, base);
 #ifndef NDEBUG
 
       LOG_INFO(-1, "Using global storage as a cache");
diff --git a/src/H5VLcache_ext.h b/src/H5VLcache_ext.h
index cd1bb61..fafd0ea 100644
--- a/src/H5VLcache_ext.h
+++ b/src/H5VLcache_ext.h
@@ -36,8 +36,11 @@ typedef struct H5VL_cache_ext_info_t {
   char fconfig[255]; /* file name for config, this is specific to caching VOL */
 } H5VL_cache_ext_info_t;
 
+/* Forward declaration for self-referential struct */
+typedef struct H5VL_cache_ext_t H5VL_cache_ext_t;
+
 /* The Cache VOL info object */
-typedef struct H5VL_cache_ext_t {
+struct H5VL_cache_ext_t {
   hid_t under_vol_id; /* ID for underlying VOL connector */
   void *under_object; /* Info object for underlying VOL connector */
   // the following are specific to caching vol.
@@ -55,10 +58,11 @@ typedef struct H5VL_cache_ext_t {
   object_close_task_t *async_close_task_list, *async_close_task_current,
       *async_close_task_head;
   hid_t es_id;  // event set id associated to all
-  void *parent; // parent object, file->group->dataset
+  H5VL_cache_ext_t *parent; // parent object, file->group->dataset
   cache_storage_t *H5LS;
   H5I_type_t obj_type;
-} H5VL_cache_ext_t;
+  size_t ref_count;
+};
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/src/cache_utils.c b/src/cache_utils.c
index 4a908cd..da5286e 100644
--- a/src/cache_utils.c
+++ b/src/cache_utils.c
@@ -12,7 +12,6 @@
 #include "stdlib.h"
 #include "string.h"
 #include "unistd.h"
-#include <stdarg.h>
 #include <stdio.h>
 // POSIX I/O
 #include "cache_utils.h"
@@ -165,53 +164,3 @@ herr_t rmdirRecursive(const char *path) {
   ret = rmdir(path);
   return ret;
 }
-
-/*-------------------------------------------------------------------------
- * Function:    cache_utils_build_path
- *
- * Purpose:     Build a path from multiple components (varargs, NULL-terminated)
- *
- * Return:      Pointer to newly allocated path string, or NULL on failure
- *
- * Example:     cache_utils_build_path("/tmp", "file.h5", "group", NULL)
- *              Returns: "/tmp/file.h5/group"
- *
- *-------------------------------------------------------------------------
- */
-char *cache_utils_build_path(const char *base, ...) {
-  if (base == NULL)
-    return NULL;
-
-  va_list args;
-  const char *component;
-  size_t total_len = strlen(base);
-  int num_components = 0;
-
-  // First pass: calculate total length
-  va_start(args, base);
-  while ((component = va_arg(args, const char *)) != NULL) {
-    total_len += strlen(component);
-    num_components++;
-  }
-  va_end(args);
-
-  // Allocate buffer (base + components + separators + null terminator)
-  char *result = (char *)malloc(total_len + num_components + 1);
-  if (result == NULL)
-    return NULL;
-
-  // Second pass: build the path
-  strcpy(result, base);
-
-  va_start(args, base);
-  while ((component = va_arg(args, const char *)) != NULL) {
-    // Add separator if needed (avoid double slashes)
-    size_t current_len = strlen(result);
-    if (current_len > 0 && result[current_len - 1] != '/' && component[0] != '/')
-      strcat(result, "/");
-    strcat(result, component);
-  }
-  va_end(args);
-
-  return result;
-}
diff --git a/src/cache_utils.h b/src/cache_utils.h
index 762c1cf..2208917 100644
--- a/src/cache_utils.h
+++ b/src/cache_utils.h
@@ -45,10 +45,6 @@ void parallel_dist(size_t dim, int nproc, int rank, size_t *ldim,
 void int2char(int a, char str[255]);
 void mkdirRecursive(const char *path, mode_t mode);
 herr_t rmdirRecursive(const char *path);
-
-// Helper functions for dynamic string allocation
-char *cache_utils_build_path(const char *base, ...); // NULL-terminated varargs
-
 #ifdef __cplusplus
 }
 #endif

From 9ffc2254d9c35ebed7e9938097c0a1cff51b0edb Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Fri, 24 Oct 2025 11:16:01 -0500
Subject: [PATCH 03/10] Clang-format

---
 src/H5LS.h          | 16 ++++++++--------
 src/H5VLcache_ext.c | 45 +++++++++++++++++++++++++++++----------------
 src/H5VLcache_ext.h |  2 +-
 3 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/src/H5LS.h b/src/H5LS.h
index f9b8103..1d7cb32 100644
--- a/src/H5LS.h
+++ b/src/H5LS.h
@@ -115,14 +115,14 @@ typedef struct _IO_THREAD {
 // Memory mapped files
 typedef struct _MMAP {
   // for write
-  int fd;          // file handle for write
-  char *fname;     // dynamically allocated full path of the memory mapped file
-  void *obj;       // this will be used for cache data on global storage layer
-  void *buf;       // pointer that map the file to the memory
-  void *tmp_buf;   // temporally buffer, used for parallel read: copy the read
-                   // buffer, return the H5Dread_to_cache function, the back
-                   // ground thread write the data to the SSD.
-  hsize_t offset;  // the offset of the memory map
+  int fd;         // file handle for write
+  char *fname;    // dynamically allocated full path of the memory mapped file
+  void *obj;      // this will be used for cache data on global storage layer
+  void *buf;      // pointer that map the file to the memory
+  void *tmp_buf;  // temporally buffer, used for parallel read: copy the read
+                  // buffer, return the H5Dread_to_cache function, the back
+                  // ground thread write the data to the SSD.
+  hsize_t offset; // the offset of the memory map
 } MMAP;
 
 // Dataset
diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 37acc3b..7154d29 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -5481,17 +5481,20 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       sprintf(rnd, "%d", file->H5DWMM->mpi->rank);
       char *base = basename((char *)name);
 
-      size_t path_len = strlen(file->H5LS->path) + strlen(base) + strlen("-cache") + 2;
+      size_t path_len =
+          strlen(file->H5LS->path) + strlen(base) + strlen("-cache") + 2;
       file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate cache path");
         free(file->H5DWMM->cache);
         return FAIL;
       }
-      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache", file->H5LS->path, base);
+      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache",
+               file->H5LS->path, base);
 
       // Build mmap fname: <cache_path>/mmap-<rank>.dat
-      size_t fname_len = strlen(file->H5DWMM->cache->path) + strlen("mmap-") + strlen(rnd) + strlen(".dat") + 2;
+      size_t fname_len = strlen(file->H5DWMM->cache->path) + strlen("mmap-") +
+                         strlen(rnd) + strlen(".dat") + 2;
       file->H5DWMM->mmap->fname = (char *)malloc(fname_len);
       if (file->H5DWMM->mmap->fname == NULL) {
         LOG_ERROR(-1, "Failed to allocate mmap fname");
@@ -5500,7 +5503,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         free(file->H5DWMM->cache);
         return FAIL;
       }
-      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s/mmap-%s.dat", file->H5DWMM->cache->path, rnd);
+      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s/mmap-%s.dat",
+               file->H5DWMM->cache->path, rnd);
 #ifndef NDEBUG
       LOG_DEBUG(-1, "**Using node local storage to cache the file");
       LOG_DEBUG(-1, "**path: %s", file->H5DWMM->cache->path);
@@ -5573,7 +5577,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         file->H5DRMM = NULL;
         return FAIL;
       }
-      snprintf(file->H5DRMM->cache->path, path_len, "%s/%s", file->H5LS->path, base);
+      snprintf(file->H5DRMM->cache->path, path_len, "%s/%s", file->H5LS->path,
+               base);
 #ifndef NDEBUG
 
       LOG_DEBUG(-1, "file cache created: %s", file->H5DRMM->cache->path);
@@ -5730,12 +5735,15 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
           dset->H5DRMM->cache = NULL;
           return FAIL;
         }
-        snprintf(dset->H5DRMM->cache->path, path_len, "%s/%s", p->H5DRMM->cache->path, name);
+        snprintf(dset->H5DRMM->cache->path, path_len, "%s/%s",
+                 p->H5DRMM->cache->path, name);
 
         // Build mmap fname: <cache_path>/dset-mmap-<rank>.dat
         char cc[255];
         int2char(dset->H5DRMM->mpi->rank, cc);
-        size_t fname_len = strlen(dset->H5DRMM->cache->path) + strlen("dset-mmap-") + strlen(cc) + strlen(".dat") + 2;
+        size_t fname_len = strlen(dset->H5DRMM->cache->path) +
+                           strlen("dset-mmap-") + strlen(cc) + strlen(".dat") +
+                           2;
         dset->H5DRMM->mmap->fname = (char *)malloc(fname_len);
         if (dset->H5DRMM->mmap->fname == NULL) {
           LOG_ERROR(-1, "Failed to allocate dataset read mmap fname");
@@ -5745,7 +5753,8 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
           dset->H5DRMM->cache = NULL;
           return FAIL;
         }
-        snprintf(dset->H5DRMM->mmap->fname, fname_len, "%s/dset-mmap-%s.dat", dset->H5DRMM->cache->path, cc);
+        snprintf(dset->H5DRMM->mmap->fname, fname_len, "%s/dset-mmap-%s.dat",
+                 dset->H5DRMM->cache->path, cc);
 #ifndef NDEBUG
 
         LOG_DEBUG(-1, "Dataset read cache created: %s",
@@ -5833,7 +5842,8 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
         group->H5DRMM = NULL;
         return FAIL;
       }
-      snprintf(group->H5DRMM->cache->path, path_len, "%s/%s", o->H5DRMM->cache->path, name);
+      snprintf(group->H5DRMM->cache->path, path_len, "%s/%s",
+               o->H5DRMM->cache->path, name);
 #ifndef NDEBUG
       LOG_DEBUG(-1, "group cache created: %s", group->H5DRMM->cache->path);
 #endif
@@ -5859,7 +5869,7 @@ static herr_t remove_group_cache_on_local_storage(void *obj, void **req) {
   H5VL_cache_ext_t *group = (H5VL_cache_ext_t *)obj;
   if (group->read_cache) {
     free(group->H5DRMM->cache->path);
-          group->H5DRMM->cache->path = NULL;
+    group->H5DRMM->cache->path = NULL;
     free(group->H5DRMM->cache);
     free(group->H5DRMM->mpi);
     free(group->H5DRMM);
@@ -6172,7 +6182,8 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
     if (file->H5LS->path != NULL) {
       // Build cache path: <storage_path>/<filename>-global-cache/
       char *base = basename((char *)name);
-      size_t path_len = strlen(file->H5LS->path) + strlen(base) + strlen("-global-cache/") + 2;
+      size_t path_len = strlen(file->H5LS->path) + strlen(base) +
+                        strlen("-global-cache/") + 2;
       file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate file GLOBAL cache path");
@@ -6184,7 +6195,8 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
         file->H5DWMM = NULL;
         return FAIL;
       }
-      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-global-cache/", file->H5LS->path, base);
+      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-global-cache/",
+               file->H5LS->path, base);
       mkdir(file->H5DWMM->cache->path,
             0755); // setup the folder with the name of the file, and put
                    // everything under it.
@@ -6195,7 +6207,7 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
       if (file->H5DWMM->mmap->fname == NULL) {
         LOG_ERROR(-1, "Failed to allocate file GLOBAL mmap fname");
         free(file->H5DWMM->cache->path);
-          file->H5DWMM->cache->path = NULL;
+        file->H5DWMM->cache->path = NULL;
         free(file->H5DWMM->mmap);
         free(file->H5DWMM->cache);
         free(file->H5DWMM->io);
@@ -6204,7 +6216,8 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
         file->H5DWMM = NULL;
         return FAIL;
       }
-      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s%s", file->H5DWMM->cache->path, base);
+      snprintf(file->H5DWMM->mmap->fname, fname_len, "%s%s",
+               file->H5DWMM->cache->path, base);
 #ifndef NDEBUG
 
       LOG_INFO(-1, "Using global storage as a cache");
@@ -6596,10 +6609,10 @@ static herr_t remove_dataset_cache_on_global_storage(void *dset, void **req) {
   if (o->write_cache || o->read_cache) {
     H5Dclose_async(o->hd_glob, H5ES_NONE);
     free(o->H5DWMM->cache->path);
-          o->H5DWMM->cache->path = NULL;
+    o->H5DWMM->cache->path = NULL;
     free(o->H5DWMM->cache);
     free(o->H5DWMM->mmap->fname);
-          o->H5DWMM->mmap->fname = NULL;
+    o->H5DWMM->mmap->fname = NULL;
     free(o->H5DWMM->mmap);
     free(o->H5DWMM);
     o->H5DWMM = NULL;
diff --git a/src/H5VLcache_ext.h b/src/H5VLcache_ext.h
index fafd0ea..e4abffe 100644
--- a/src/H5VLcache_ext.h
+++ b/src/H5VLcache_ext.h
@@ -57,7 +57,7 @@ struct H5VL_cache_ext_t {
   hid_t hd_glob;
   object_close_task_t *async_close_task_list, *async_close_task_current,
       *async_close_task_head;
-  hid_t es_id;  // event set id associated to all
+  hid_t es_id;              // event set id associated to all
   H5VL_cache_ext_t *parent; // parent object, file->group->dataset
   cache_storage_t *H5LS;
   H5I_type_t obj_type;

From ce9b9b316bbffd2e92f3e801c81add71e021ac94 Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Fri, 24 Oct 2025 14:31:02 -0500
Subject: [PATCH 04/10] Fix bad arg memory access

---
 src/H5VLcache_ext.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 7154d29..b8b7b25 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -3761,12 +3761,12 @@ static void *H5VL_cache_ext_file_open(const char *name, unsigned flags,
     file->async_pause = false;
     set_file_cache((void *)file, (void *)args, req);
   }
-  free(args);
   /* Close underlying FAPL */
   H5Pclose(under_fapl_id);
   H5Pclose(args->fapl_id);
   H5Pclose(args->fcpl_id);
   H5Pclose(args->dxpl_id);
+  free(args);
   H5VL_cache_ext_info_free(info);
   return (void *)file;
 } /* end H5VL_cache_ext_file_open() */
@@ -5670,7 +5670,6 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
                                         H5P_DATASET_XFER_DEFAULT, NULL);
 
       o->read_cache = true;
-      // TODO - May create persistent ref that needs ref counting?
       o->H5LS->cache_io_cls->create_cache((void *)o, &file_args, req);
     }
     int np;

From 4864c74ab0f02bc70b1cec7339dbd260c067df7b Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Mon, 3 Nov 2025 11:58:49 -0600
Subject: [PATCH 05/10] Address comments

---
 src/H5VLcache_ext.c | 42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index b8b7b25..8eeff81 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -902,7 +902,11 @@ static herr_t H5VL_cache_ext_free_obj(H5VL_cache_ext_t *obj) {
 
   err_id = H5Eget_current_stack();
 
-  assert(obj->ref_count > 0);
+  if (obj->ref_count == 0) {
+    LOG_ERROR(-1, "Attempting to decrement ref_count that is already 0");
+    return FAIL;
+  }
+
   obj->ref_count--;
 
   if (obj->ref_count == 0) {
@@ -3508,12 +3512,6 @@ static herr_t H5VL_cache_ext_datatype_close(void *dt, hid_t dxpl_id,
   return ret_value;
 } /* end H5VL_cache_ext_datatype_close() */
 
-char *get_fname(const char *path) {
-  char tmp[255];
-  strcpy(tmp, path);
-  return basename(tmp);
-}
-
 static ssize_t file_get_name(void *file, hid_t driver_id, size_t buf_size,
                              char *buf, hid_t dxpl_id, void **req) {
   H5VL_file_get_args_t vol_cb_args;
@@ -3566,7 +3564,10 @@ static herr_t set_file_cache(void *obj, void *file_args, void **req) {
   file->write_cache = false;
   file->read_cache = false;
   if (file->parent != NULL) {
-    assert(file->parent->ref_count > 0);
+    if (file->parent->ref_count == 0) {
+      LOG_ERROR(-1, "Parent ref count is zero!");
+      return FAIL;
+    }
     H5VL_cache_ext_free_obj(file->parent);
   }
 
@@ -5415,8 +5416,6 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DWMM->io = (IO_THREAD *)malloc(sizeof(IO_THREAD));
       file->H5DWMM->io->fusion_data_size = 0.0;
       file->H5DWMM->io->num_fusion_requests = 0;
-      file->H5DWMM->cache = (cache_t *)malloc(sizeof(cache_t));
-      file->H5DWMM->cache->path = NULL;
       file->H5DWMM->mmap = (MMAP *)malloc(sizeof(MMAP));
       file->H5DWMM->mmap->fname = NULL;
     } else {
@@ -5457,6 +5456,10 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
                     "        Try to decrease HDF5_CACHE_WRITE_BUFFER_SIZE.");
       file->write_cache = false;
       free(file->H5DWMM->cache);
+      free(file->H5DWMM->mpi);
+      free(file->H5DWMM->io);
+      free(file->H5DWMM);
+      file->H5DWMM = NULL;
       return FAIL;
     } else if (H5LSclaim_space(file->H5LS, file->H5DWMM->cache->mspace_total,
                                HARD, file->H5LS->replacement_policy) == FAIL) {
@@ -5464,6 +5467,10 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
                     "cache");
       file->write_cache = false;
       free(file->H5DWMM->cache);
+      free(file->H5DWMM->mpi);
+      free(file->H5DWMM->io);
+      free(file->H5DWMM);
+      file->H5DWMM = NULL;
       return FAIL;
     }
 
@@ -5479,7 +5486,10 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       // Build cache path: <storage_path>/<filename>-cache/
       char rnd[255];
       sprintf(rnd, "%d", file->H5DWMM->mpi->rank);
-      char *base = basename((char *)name);
+      char name_buf[4096];
+      strncpy(name_buf, name, sizeof(name_buf) - 1);
+      name_buf[sizeof(name_buf) - 1] = '\0';
+      char *base = basename(name_buf);
 
       size_t path_len =
           strlen(file->H5LS->path) + strlen(base) + strlen("-cache") + 2;
@@ -5564,7 +5574,10 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
 
     if (file->H5LS->path != NULL) {
       // Build cache path: <storage_path>/<filename>/
-      char *base = basename((char *)name);
+      char name_buf[4096];
+      strncpy(name_buf, name, sizeof(name_buf) - 1);
+      name_buf[sizeof(name_buf) - 1] = '\0';
+      char *base = basename(name_buf);
       size_t path_len = strlen(file->H5LS->path) + strlen(base) + 2;
       file->H5DRMM->cache->path = (char *)malloc(path_len);
       if (file->H5DRMM->cache->path == NULL) {
@@ -6180,7 +6193,10 @@ static herr_t create_file_cache_on_global_storage(void *obj, void *file_args,
     file->H5DWMM->io->num_request = 0;
     if (file->H5LS->path != NULL) {
       // Build cache path: <storage_path>/<filename>-global-cache/
-      char *base = basename((char *)name);
+      char name_buf[4096];
+      strncpy(name_buf, name, sizeof(name_buf) - 1);
+      name_buf[sizeof(name_buf) - 1] = '\0';
+      char *base = basename(name_buf);
       size_t path_len = strlen(file->H5LS->path) + strlen(base) +
                         strlen("-global-cache/") + 2;
       file->H5DWMM->cache->path = (char *)malloc(path_len);

From caf929ccf6e4d4aacd7e1ac60ed2c44aa9a6f0ae Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Mon, 10 Nov 2025 11:49:05 -0600
Subject: [PATCH 06/10] Correct early return

---
 src/H5VLcache_ext.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 8eeff81..89e7c1e 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -904,7 +904,7 @@ static herr_t H5VL_cache_ext_free_obj(H5VL_cache_ext_t *obj) {
 
   if (obj->ref_count == 0) {
     LOG_ERROR(-1, "Attempting to decrement ref_count that is already 0");
-    return FAIL;
+    goto error;
   }
 
   obj->ref_count--;

From a560b8a5853c14945540122757a535d3ef1cb50c Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Mon, 10 Nov 2025 11:49:52 -0600
Subject: [PATCH 07/10] Remove redundant check

---
 src/H5VLcache_ext.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 89e7c1e..f73cb6b 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -3563,13 +3563,8 @@ static herr_t set_file_cache(void *obj, void *file_args, void **req) {
 
   file->write_cache = false;
   file->read_cache = false;
-  if (file->parent != NULL) {
-    if (file->parent->ref_count == 0) {
-      LOG_ERROR(-1, "Parent ref count is zero!");
-      return FAIL;
-    }
+  if (file->parent != NULL)
     H5VL_cache_ext_free_obj(file->parent);
-  }
 
   file->parent = NULL;
 

From 1cb0d94f35ce39979f19131c95543abf14e0821a Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Mon, 10 Nov 2025 12:15:47 -0600
Subject: [PATCH 08/10] Consolidate cleanup

---
 src/H5VLcache_ext.c | 55 ++++++++++++++++++++++++---------------------
 1 file changed, 30 insertions(+), 25 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index f73cb6b..971330e 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -5399,6 +5399,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
   file_args_t *args = (file_args_t *)file_args;
   const char *name = args->name;
   H5VL_cache_ext_t *file = (H5VL_cache_ext_t *)obj;
+  bool write_fail = false;
+  bool read_fail = false;
 
   H5VL_cache_ext_info_t *info;
   /* Get copy of our VOL info from FAPL */
@@ -5450,23 +5452,15 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
                     "        Will turn off Cache effect."
                     "        Try to decrease HDF5_CACHE_WRITE_BUFFER_SIZE.");
       file->write_cache = false;
-      free(file->H5DWMM->cache);
-      free(file->H5DWMM->mpi);
-      free(file->H5DWMM->io);
-      free(file->H5DWMM);
-      file->H5DWMM = NULL;
-      return FAIL;
+      write_fail = true;
+      goto error;
     } else if (H5LSclaim_space(file->H5LS, file->H5DWMM->cache->mspace_total,
                                HARD, file->H5LS->replacement_policy) == FAIL) {
       LOG_ERROR(-1, "Unable to claim space, turning off write "
                     "cache");
       file->write_cache = false;
-      free(file->H5DWMM->cache);
-      free(file->H5DWMM->mpi);
-      free(file->H5DWMM->io);
-      free(file->H5DWMM);
-      file->H5DWMM = NULL;
-      return FAIL;
+      write_fail = true;
+      goto error;
     }
 
     file->H5DWMM->cache->mspace_left = file->H5DWMM->cache->mspace_total;
@@ -5491,8 +5485,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate cache path");
-        free(file->H5DWMM->cache);
-        return FAIL;
+        write_fail = true;
+        goto error;
       }
       snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache",
                file->H5LS->path, base);
@@ -5503,10 +5497,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DWMM->mmap->fname = (char *)malloc(fname_len);
       if (file->H5DWMM->mmap->fname == NULL) {
         LOG_ERROR(-1, "Failed to allocate mmap fname");
-        free(file->H5DWMM->cache->path);
-        file->H5DWMM->cache->path = NULL;
-        free(file->H5DWMM->cache);
-        return FAIL;
+        write_fail = true;
+        goto error;
       }
       snprintf(file->H5DWMM->mmap->fname, fname_len, "%s/mmap-%s.dat",
                file->H5DWMM->cache->path, rnd);
@@ -5577,13 +5569,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       file->H5DRMM->cache->path = (char *)malloc(path_len);
       if (file->H5DRMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate file read cache path");
-        free(file->H5DRMM->mmap);
-        free(file->H5DRMM->cache);
-        free(file->H5DRMM->io);
-        free(file->H5DRMM->mpi);
-        free(file->H5DRMM);
-        file->H5DRMM = NULL;
-        return FAIL;
+        read_fail = true;
+        goto error;
       }
       snprintf(file->H5DRMM->cache->path, path_len, "%s/%s", file->H5LS->path,
                base);
@@ -5596,6 +5583,24 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
     // mkdir(file->H5DRMM->cache->path, 0755);
   }
   return SUCCEED;
+
+error:
+  if (write_fail) {
+    free(file->H5DWMM->cache);
+    free(file->H5DWMM->mpi);
+    free(file->H5DWMM->io);
+    free(file->H5DWMM);
+    file->H5DWMM = NULL;
+  }
+  if (read_fail) {
+    free(file->H5DRMM->mmap);
+    free(file->H5DRMM->cache);
+    free(file->H5DRMM->io);
+    free(file->H5DRMM->mpi);
+    free(file->H5DRMM);
+    file->H5DRMM = NULL;
+  }
+  return FAIL;
 }
 
 static herr_t remove_file_cache_on_local_storage(void *file, void **req) {

From 0a0ad899df7b98f73cb392359e6baff7a74a21ee Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Mon, 10 Nov 2025 14:13:38 -0600
Subject: [PATCH 09/10] Re-add trailing slashes to paths

---
 src/H5VLcache_ext.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index 971330e..ea2f76f 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -5488,7 +5488,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         write_fail = true;
         goto error;
       }
-      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache",
+      snprintf(file->H5DWMM->cache->path, path_len, "%s/%s-cache/",
                file->H5LS->path, base);
 
       // Build mmap fname: <cache_path>/mmap-<rank>.dat
@@ -5572,7 +5572,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
         read_fail = true;
         goto error;
       }
-      snprintf(file->H5DRMM->cache->path, path_len, "%s/%s", file->H5LS->path,
+      snprintf(file->H5DRMM->cache->path, path_len, "%s/%s/", file->H5LS->path,
                base);
 #ifndef NDEBUG
 
@@ -5747,7 +5747,7 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
           dset->H5DRMM->cache = NULL;
           return FAIL;
         }
-        snprintf(dset->H5DRMM->cache->path, path_len, "%s/%s",
+        snprintf(dset->H5DRMM->cache->path, path_len, "%s/%s/",
                  p->H5DRMM->cache->path, name);
 
         // Build mmap fname: <cache_path>/dset-mmap-<rank>.dat
@@ -5854,7 +5854,7 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
         group->H5DRMM = NULL;
         return FAIL;
       }
-      snprintf(group->H5DRMM->cache->path, path_len, "%s/%s",
+      snprintf(group->H5DRMM->cache->path, path_len, "%s/%s/",
                o->H5DRMM->cache->path, name);
 #ifndef NDEBUG
       LOG_DEBUG(-1, "group cache created: %s", group->H5DRMM->cache->path);

From 93dfb3a85361644728fb626042f6d35253ade03a Mon Sep 17 00:00:00 2001
From: Matthew Larson <matthewjlar@gmail.com>
Date: Tue, 11 Nov 2025 11:22:39 -0600
Subject: [PATCH 10/10] Update path buffer sizes to hold slashes

---
 src/H5VLcache_ext.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/H5VLcache_ext.c b/src/H5VLcache_ext.c
index ea2f76f..6b34701 100644
--- a/src/H5VLcache_ext.c
+++ b/src/H5VLcache_ext.c
@@ -5481,7 +5481,7 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       char *base = basename(name_buf);
 
       size_t path_len =
-          strlen(file->H5LS->path) + strlen(base) + strlen("-cache") + 2;
+          strlen(file->H5LS->path) + strlen(base) + strlen("-cache/") + 2;
       file->H5DWMM->cache->path = (char *)malloc(path_len);
       if (file->H5DWMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate cache path");
@@ -5565,7 +5565,8 @@ static herr_t create_file_cache_on_local_storage(void *obj, void *file_args,
       strncpy(name_buf, name, sizeof(name_buf) - 1);
       name_buf[sizeof(name_buf) - 1] = '\0';
       char *base = basename(name_buf);
-      size_t path_len = strlen(file->H5LS->path) + strlen(base) + 2;
+      size_t path_len = strlen(file->H5LS->path) + strlen(base) +
+                        3; // 3 for two slashes and null
       file->H5DRMM->cache->path = (char *)malloc(path_len);
       if (file->H5DRMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate file read cache path");
@@ -5739,7 +5740,8 @@ static herr_t create_dataset_cache_on_local_storage(void *obj, void *dset_args,
 
       if (dset->H5LS->path != NULL) {
         // Build cache path: <parent_cache_path>/<dataset_name>/
-        size_t path_len = strlen(p->H5DRMM->cache->path) + strlen(name) + 2;
+        size_t path_len = strlen(p->H5DRMM->cache->path) + strlen(name) +
+                          3; // 3 for two slashes and null
         dset->H5DRMM->cache->path = (char *)malloc(path_len);
         if (dset->H5DRMM->cache->path == NULL) {
           LOG_ERROR(-1, "Failed to allocate dataset read cache path");
@@ -5844,7 +5846,8 @@ static herr_t create_group_cache_on_local_storage(void *obj, void *group_args,
     memcpy(group->H5DRMM->mpi, o->H5DRMM->mpi, sizeof(MPI_INFO));
     if (group->H5LS->path != NULL) {
       // Build cache path: <parent_cache_path>/<group_name>/
-      size_t path_len = strlen(o->H5DRMM->cache->path) + strlen(name) + 2;
+      size_t path_len = strlen(o->H5DRMM->cache->path) + strlen(name) +
+                        3; // 3 for two slashes and null
       group->H5DRMM->cache->path = (char *)malloc(path_len);
       if (group->H5DRMM->cache->path == NULL) {
         LOG_ERROR(-1, "Failed to allocate group read cache path");