Be a bit safer with signed arithmetic, thus quieting some signed-overflow warnings from GCC (#1706)

* Avoid a signed overflow: check the range of `entry_ptr->age` before
increasing it instead of increasing it and then checking the range.
This quiets a GCC warning.

* Avoid the potential for signed overflow by rewriting expressions
`MAX(0, fwidth - n)` as `MAX(n, fwidth) - n` for various `n`.
This change quiets some GCC warnings.

* Change some local variables that cannot take sensible negative values
from signed to unsigned.  This quiets GCC warnings about potential
signed overflow.

* In a handful of instances, check the range of a signed integer before
increasing/decreasing it, just in case the increase/decrease overflows.
This quiets a handful of GCC signed-overflow warnings.

* Committing clang-format changes

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

3 files changed, 25 insertions, 22 deletions

diff --git a/src/H5Bdbg.c b/src/H5Bdbg.c
index 23d0a8f..de07442 100644
--- a/src/H5Bdbg.c
+++ b/src/H5Bdbg.c
@@ -110,20 +110,20 @@ H5B_debug(H5F_t *f, haddr_t addr, FILE *stream, int indent, int fwidth, const H5
      */
     for (u = 0; u < bt->nchildren; u++) {
         HDfprintf(stream, "%*sChild %d...\n", indent, "", u);
-        HDfprintf(stream, "%*s%-*s %" PRIuHADDR "\n", indent + 3, "", MAX(0, fwidth - 3),
+        HDfprintf(stream, "%*s%-*s %" PRIuHADDR "\n", indent + 3, "", MAX(3, fwidth) - 3,
                   "Address:", bt->child[u]);
 
         /* If there is a key debugging routine, use it to display the left & right keys */
         if (type->debug_key) {
             /* Decode the 'left' key & print it */
-            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3), "Left Key:");
+            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(3, fwidth) - 3, "Left Key:");
             HDassert(H5B_NKEY(bt, shared, u));
-            (void)(type->debug_key)(stream, indent + 6, MAX(0, fwidth - 6), H5B_NKEY(bt, shared, u), udata);
+            (void)(type->debug_key)(stream, indent + 6, MAX(6, fwidth) - 6, H5B_NKEY(bt, shared, u), udata);
 
             /* Decode the 'right' key & print it */
-            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3), "Right Key:");
+            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(3, fwidth) - 3, "Right Key:");
             HDassert(H5B_NKEY(bt, shared, u + 1));
-            (void)(type->debug_key)(stream, indent + 6, MAX(0, fwidth - 6), H5B_NKEY(bt, shared, u + 1),
+            (void)(type->debug_key)(stream, indent + 6, MAX(6, fwidth) - 6, H5B_NKEY(bt, shared, u + 1),
                                     udata);
         } /* end if */
     }     /* end for */
diff --git a/src/H5C.c b/src/H5C.c
index 77f3069..067acfa 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -4667,10 +4667,11 @@ H5C__autoadjust__ageout__cycle_epoch_marker(H5C_t *cache_ptr)
     cache_ptr->epoch_marker_ringbuf_first =
         (cache_ptr->epoch_marker_ringbuf_first + 1) % (H5C__MAX_EPOCH_MARKERS + 1);
 
+    if (cache_ptr->epoch_marker_ringbuf_size <= 0)
+        HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer underflow")
+
     cache_ptr->epoch_marker_ringbuf_size -= 1;
 
-    if (cache_ptr->epoch_marker_ringbuf_size < 0)
-        HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer underflow")
     if ((cache_ptr->epoch_marker_active)[i] != TRUE)
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "unused marker in LRU?!?")
 
@@ -4690,11 +4691,11 @@ H5C__autoadjust__ageout__cycle_epoch_marker(H5C_t *cache_ptr)
 
     (cache_ptr->epoch_marker_ringbuf)[cache_ptr->epoch_marker_ringbuf_last] = i;
 
-    cache_ptr->epoch_marker_ringbuf_size += 1;
-
-    if (cache_ptr->epoch_marker_ringbuf_size > H5C__MAX_EPOCH_MARKERS)
+    if (cache_ptr->epoch_marker_ringbuf_size >= H5C__MAX_EPOCH_MARKERS)
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer overflow")
 
+    cache_ptr->epoch_marker_ringbuf_size += 1;
+
     H5C__DLL_PREPEND((&((cache_ptr->epoch_markers)[i])), (cache_ptr)->LRU_head_ptr, (cache_ptr)->LRU_tail_ptr,
                      (cache_ptr)->LRU_list_len, (cache_ptr)->LRU_list_size, (FAIL))
 done:
@@ -4965,13 +4966,13 @@ H5C__autoadjust__ageout__insert_new_marker(H5C_t *cache_ptr)
 
     (cache_ptr->epoch_marker_ringbuf)[cache_ptr->epoch_marker_ringbuf_last] = i;
 
-    cache_ptr->epoch_marker_ringbuf_size += 1;
-
-    if (cache_ptr->epoch_marker_ringbuf_size > H5C__MAX_EPOCH_MARKERS) {
+    if (cache_ptr->epoch_marker_ringbuf_size >= H5C__MAX_EPOCH_MARKERS) {
 
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer overflow")
     }
 
+    cache_ptr->epoch_marker_ringbuf_size += 1;
+
     H5C__DLL_PREPEND((&((cache_ptr->epoch_markers)[i])), (cache_ptr)->LRU_head_ptr, (cache_ptr)->LRU_tail_ptr,
                      (cache_ptr)->LRU_list_len, (cache_ptr)->LRU_list_size, (FAIL))
 
@@ -5019,11 +5020,11 @@ H5C__autoadjust__ageout__remove_all_markers(H5C_t *cache_ptr)
         cache_ptr->epoch_marker_ringbuf_first =
             (cache_ptr->epoch_marker_ringbuf_first + 1) % (H5C__MAX_EPOCH_MARKERS + 1);
 
-        cache_ptr->epoch_marker_ringbuf_size -= 1;
-
-        if (cache_ptr->epoch_marker_ringbuf_size < 0)
+        if (cache_ptr->epoch_marker_ringbuf_size <= 0)
             HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer underflow")
 
+        cache_ptr->epoch_marker_ringbuf_size -= 1;
+
         if ((cache_ptr->epoch_marker_active)[i] != TRUE)
             HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "unused marker in LRU?!?")
 
@@ -5092,10 +5093,11 @@ H5C__autoadjust__ageout__remove_excess_markers(H5C_t *cache_ptr)
         cache_ptr->epoch_marker_ringbuf_first =
             (cache_ptr->epoch_marker_ringbuf_first + 1) % (H5C__MAX_EPOCH_MARKERS + 1);
 
+        if (cache_ptr->epoch_marker_ringbuf_size <= 0)
+            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer underflow")
+
         cache_ptr->epoch_marker_ringbuf_size -= 1;
 
-        if (cache_ptr->epoch_marker_ringbuf_size < 0)
-            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "ring buffer underflow")
         if ((cache_ptr->epoch_marker_active)[i] != TRUE)
             HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "unused marker in LRU?!?")
 
@@ -5523,8 +5525,8 @@ H5C__flush_invalidate_ring(H5F_t *f, H5C_ring_t ring, unsigned flags)
     hbool_t            restart_slist_scan;
     uint32_t           protected_entries = 0;
     int32_t            i;
-    int32_t            cur_ring_pel_len;
-    int32_t            old_ring_pel_len;
+    uint32_t           cur_ring_pel_len;
+    uint32_t           old_ring_pel_len;
     unsigned           cooked_flags;
     unsigned           evict_flags;
     H5SL_node_t *      node_ptr       = NULL;
diff --git a/src/H5Cimage.c b/src/H5Cimage.c
index ddf5f94..899d6d7 100644
--- a/src/H5Cimage.c
+++ b/src/H5Cimage.c
@@ -2690,10 +2690,11 @@ H5C__prep_for_file_close__setup_image_entries_array(H5C_t *cache_ptr)
              */
             if (entry_ptr->type->id == H5AC_PREFETCHED_ENTRY_ID) {
                 image_entries[u].type_id = entry_ptr->prefetch_type_id;
-                image_entries[u].age     = entry_ptr->age + 1;
 
-                if (image_entries[u].age > H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX)
+                if (entry_ptr->age >= H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX)
                     image_entries[u].age = H5AC__CACHE_IMAGE__ENTRY_AGEOUT__MAX;
+                else
+                    image_entries[u].age = entry_ptr->age + 1;
             } /* end if */
             else {
                 image_entries[u].type_id = entry_ptr->type->id;