Add overflow-safe allocation wrappers to pmem module

pclsync/pmem.c

@@ -1,4 +1,6 @@
 #include <sys/mman.h>
+#include <stdlib.h>
+#include <stdint.h>
 
 #include "pcompiler.h"
 #include "psql.h"
@@ -60,3 +62,10 @@ int pmem_munlock(void *ptr, size_t size) {
 void pmem_reset(void *ptr, size_t size) {
   madvise(ptr, size, MADV_DONTNEED);
 }
+
+void *pmem_calloc_safe(size_t nmemb, size_t size) {
+  if (nmemb != 0 && size > SIZE_MAX / nmemb) {
+    return NULL;
+  }
+  return calloc(nmemb, size);
+}

pclsync/pmem.h

@@ -2,6 +2,7 @@
 #define __PMEM_H
 
 #include <stddef.h>
+#include <stdint.h>
 
 void *pmem_mmap(size_t size);
 void *pmem_mmap_safe(size_t size);
@@ -9,5 +10,6 @@ int pmem_munmap(void *ptr, size_t size);
 int pmem_mlock(void *ptr, size_t size);
 int pmem_munlock(void *ptr, size_t size);
 void pmem_reset(void *ptr, size_t size);
+void *pmem_calloc_safe(size_t nmemb, size_t size);
 
 #endif