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>

1 files changed, 17 insertions, 15 deletions

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;