MDEV-22387: Do not violate __attribute__((nonnull))

This follows up commit
commit 94a520ddbe39ae97de1135d98699cf2674e6b77e and
commit 7c5519c12d46ead947d341cbdcbb6fbbe4d4fe1b.

After these changes, the default test suites on a
cmake -DWITH_UBSAN=ON build no longer fail due to passing
null pointers as parameters that are declared to never be null,
but plenty of other runtime errors remain.

22 files changed, 88 insertions, 47 deletions

diff --git a/client/completion_hash.cc b/client/completion_hash.cc
index 553d0a1f926..30c0dc6260b 100644
--- a/client/completion_hash.cc
+++ b/client/completion_hash.cc
@@ -205,7 +205,8 @@ Bucket *find_longest_match(HashTable *ht, char *str, uint length,
 void completion_hash_clean(HashTable *ht)
 {
   free_root(&ht->mem_root,MYF(0));
-  bzero((char*) ht->arBuckets,ht->nTableSize*sizeof(Bucket *));
+  if (size_t s= ht->nTableSize)
+    bzero((char*) ht->arBuckets, s * sizeof(Bucket *));
 }
 
 
diff --git a/include/my_sys.h b/include/my_sys.h
index 08b06951d0d..ac1730eeaff 100644
--- a/include/my_sys.h
+++ b/include/my_sys.h
@@ -534,8 +534,11 @@ static inline int my_b_write(IO_CACHE *info, const uchar *Buffer, size_t Count)
 {
   if (info->write_pos + Count <= info->write_end)
   {
-    memcpy(info->write_pos, Buffer, Count);
-    info->write_pos+= Count;
+    if (Count)
+    {
+      memcpy(info->write_pos, Buffer, Count);
+      info->write_pos+= Count;
+    }
     return 0;
   }
   return _my_b_write(info, Buffer, Count);
diff --git a/libmariadb b/libmariadb
-Subproject 62427520a5ba20e42fe51f5045062a7a9cadb46
+Subproject e38244220646a7e95c9be22576460aa7a4eb715
diff --git a/mysys/array.c b/mysys/array.c
index 07abc460de7..e8b253a9e99 100644
--- a/mysys/array.c
+++ b/mysys/array.c
@@ -138,8 +138,9 @@ void *alloc_dynamic(DYNAMIC_ARRAY *array)
                                         array->size_of_element,
                                         MYF(array->malloc_flags | MY_WME))))
         DBUG_RETURN(0);
-      memcpy(new_ptr, array->buffer,
-             array->elements * array->size_of_element);
+      if (array->elements)
+        memcpy(new_ptr, array->buffer,
+               array->elements * array->size_of_element);
       array->malloc_flags&= ~MY_INIT_BUFFER_USED;
     }
     else if (!(new_ptr=(char*)
diff --git a/mysys/my_alloc.c b/mysys/my_alloc.c
index 5bfcb455b8a..d67b8be9bb8 100644
--- a/mysys/my_alloc.c
+++ b/mysys/my_alloc.c
@@ -461,7 +461,7 @@ char *strmake_root(MEM_ROOT *root, const char *str, size_t len)
 void *memdup_root(MEM_ROOT *root, const void *str, size_t len)
 {
   char *pos;
-  if ((pos=alloc_root(root,len)))
+  if ((pos=alloc_root(root,len)) && len)
     memcpy(pos,str,len);
   return pos;
 }
diff --git a/plugin/server_audit/server_audit.c b/plugin/server_audit/server_audit.c
index a029b426ea1..a4884f17c75 100644
--- a/plugin/server_audit/server_audit.c
+++ b/plugin/server_audit/server_audit.c
@@ -706,6 +706,8 @@ static char *coll_search(struct user_coll *c, const char *n, size_t len)
 {
   struct user_name un;
   struct user_name *found;
+  if (!c->n_users)
+    return 0;
   un.name_len= len;
   un.name= (char *) n;
   found= (struct user_name*)  bsearch(&un, c->users, c->n_users,
@@ -736,7 +738,8 @@ static int coll_insert(struct user_coll *c, char *n, size_t len)
 
 static void coll_sort(struct user_coll *c)
 {
-  qsort(c->users, c->n_users, sizeof(c->users[0]), cmp_users);
+  if (c->n_users)
+    qsort(c->users, c->n_users, sizeof(c->users[0]), cmp_users);
 }
 
 
@@ -967,7 +970,8 @@ static void get_str_n(char *dest, int *dest_len, size_t dest_size,
   if (src_len >= dest_size)
     src_len= dest_size - 1;
 
-  memcpy(dest, src, src_len);
+  if (src_len)
+    memcpy(dest, src, src_len);
   dest[src_len]= 0;
   *dest_len= (int)src_len;
 }
diff --git a/sql/field.cc b/sql/field.cc
index bdaaecc2026..fbce8b9041d 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -8446,7 +8446,10 @@ int Field_blob::cmp_binary(const uchar *a_ptr, const uchar *b_ptr,
   b_length=get_length(b_ptr);
   if (b_length > max_length)
     b_length=max_length;
-  diff=memcmp(a,b,MY_MIN(a_length,b_length));
+  if (uint32 len= MY_MIN(a_length,b_length))
+    diff= memcmp(a,b,len);
+  else
+    diff= 0;
   return diff ? diff : (int) (a_length - b_length);
 }
 
@@ -8503,7 +8506,8 @@ uint Field_blob::get_key_image(uchar *buff,uint length, imagetype type_arg)
     length=(uint) blob_length;
   }
   int2store(buff,length);
-  memcpy(buff+HA_KEY_BLOB_LENGTH, blob, length);
+  if (length)
+    memcpy(buff+HA_KEY_BLOB_LENGTH, blob, length);
   return HA_KEY_BLOB_LENGTH+length;
 }
 
diff --git a/sql/handler.h b/sql/handler.h
index 0aa56afe1a5..96f2836c921 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -584,8 +584,10 @@ struct xid_t {
   void set(long f, const char *g, long gl, const char *b, long bl)
   {
     formatID= f;
-    memcpy(data, g, gtrid_length= gl);
-    memcpy(data+gl, b, bqual_length= bl);
+    if ((gtrid_length= gl))
+      memcpy(data, g, gl);
+    if ((bqual_length= bl))
+      memcpy(data+gl, b, bl);
   }
   void set(ulonglong xid)
   {
diff --git a/sql/item_func.cc b/sql/item_func.cc
index 4d03e209eab..7b39b7710fb 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -4882,7 +4882,8 @@ update_hash(user_var_entry *entry, bool set_null, void *ptr, uint length,
       length--;					// Fix length change above
       entry->value[length]= 0;			// Store end \0
     }
-    memmove(entry->value, ptr, length);
+    if (length)
+      memmove(entry->value, ptr, length);
     if (type == DECIMAL_RESULT)
       ((my_decimal*)entry->value)->fix_buffer_pointer();
     entry->length= length;
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index e50822e71f2..9490c71c19e 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2015, Oracle and/or its affiliates.
-   Copyright (c) 2008, 2015, MariaDB
+   Copyright (c) 2008, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -464,7 +464,8 @@ Item_sum::Item_sum(THD *thd, Item_sum *item):
     if (!(orig_args= (Item**) thd->alloc(sizeof(Item*)*arg_count)))
       return;
   }
-  memcpy(orig_args, item->orig_args, sizeof(Item*)*arg_count);
+  if (arg_count)
+    memcpy(orig_args, item->orig_args, sizeof(Item*)*arg_count);
   init_aggregator();
   with_distinct= item->with_distinct;
   if (item->aggr)
@@ -1136,7 +1137,8 @@ Item_sum_num::fix_fields(THD *thd, Item **ref)
       check_sum_func(thd, ref))
     return TRUE;
 
-  memcpy (orig_args, args, sizeof (Item *) * arg_count);
+  if (arg_count)
+    memcpy (orig_args, args, sizeof (Item *) * arg_count);
   fixed= 1;
   return FALSE;
 }
@@ -3312,7 +3314,8 @@ Item_func_group_concat(THD *thd, Name_resolution_context *context_arg,
 
   /* orig_args is only used for print() */
   orig_args= (Item**) (order + arg_count_order);
-  memcpy(orig_args, args, sizeof(Item*) * arg_count);
+  if (arg_count)
+    memcpy(orig_args, args, sizeof(Item*) * arg_count);
 }
 
 
diff --git a/sql/mf_iocache_encr.cc b/sql/mf_iocache_encr.cc
index 29d7074aeb1..434ae08fde0 100644
--- a/sql/mf_iocache_encr.cc
+++ b/sql/mf_iocache_encr.cc
@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2015, MariaDB
+   Copyright (c) 2015, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -85,7 +85,6 @@ static int my_b_encr_read(IO_CACHE *info, uchar *Buffer, size_t Count)
 
   do
   {
-    size_t copied;
     uint elength, wlength, length;
     uchar iv[MY_AES_BLOCK_SIZE]= {0};
 
@@ -116,11 +115,13 @@ static int my_b_encr_read(IO_CACHE *info, uchar *Buffer, size_t Count)
 
     DBUG_ASSERT(length <= info->buffer_length);
 
-    copied= MY_MIN(Count, (size_t)(length - pos_offset));
-
-    memcpy(Buffer, info->buffer + pos_offset, copied);
-    Count-= copied;
-    Buffer+= copied;
+    size_t copied= MY_MIN(Count, (size_t)(length - pos_offset));
+    if (copied)
+    {
+      memcpy(Buffer, info->buffer + pos_offset, copied);
+      Count-= copied;
+      Buffer+= copied;
+    }
 
     info->read_pos= info->buffer + pos_offset + copied;
     info->read_end= info->buffer + length;
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 0a8c136e556..488424d5da5 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -4548,7 +4548,8 @@ extern "C" size_t thd_query_safe(MYSQL_THD thd, char *buf, size_t buflen)
   if (!mysql_mutex_trylock(&thd->LOCK_thd_data))
   {
     len= MY_MIN(buflen - 1, thd->query_length());
-    memcpy(buf, thd->query(), len);
+    if (len)
+      memcpy(buf, thd->query(), len);
     mysql_mutex_unlock(&thd->LOCK_thd_data);
   }
   buf[len]= '\0';
diff --git a/sql/sql_join_cache.cc b/sql/sql_join_cache.cc
index 77017812074..1dfc9385a0d 100644
--- a/sql/sql_join_cache.cc
+++ b/sql/sql_join_cache.cc
@@ -1395,7 +1395,8 @@ uint JOIN_CACHE::write_record_data(uchar * link, bool *is_full)
 	blob_field->get_image(cp, copy->length, 
 			      blob_field->charset());
         DBUG_ASSERT(cp + copy->length + copy->blob_length <= buff + buff_size);
-	memcpy(cp+copy->length, copy->str, copy->blob_length);               
+        if (copy->blob_length)
+          memcpy(cp+copy->length, copy->str, copy->blob_length);
 	cp+= copy->length+copy->blob_length;
       }
       break;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 3b090093060..d1076a54f1b 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -26064,10 +26064,10 @@ JOIN::reoptimize(Item *added_where, table_map join_tables,
   if (save_to)
   {
     DBUG_ASSERT(!keyuse.elements);
-    memcpy(keyuse.buffer,
-           save_to->keyuse.buffer,
-           (size_t) save_to->keyuse.elements * keyuse.size_of_element);
     keyuse.elements= save_to->keyuse.elements;
+    if (size_t e= keyuse.elements)
+      memcpy(keyuse.buffer,
+             save_to->keyuse.buffer, e * keyuse.size_of_element);
   }
 
   /* Add the new access methods to the keyuse array. */
diff --git a/sql/sql_string.cc b/sql/sql_string.cc
index b79ca82698b..4e0c7aea84b 100644
--- a/sql/sql_string.cc
+++ b/sql/sql_string.cc
@@ -1,5 +1,5 @@
 /* Copyright (c) 2000, 2013, Oracle and/or its affiliates.
-   Copyright (c) 2016, MariaDB
+   Copyright (c) 2016, 2020, MariaDB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -175,8 +175,8 @@ bool String::copy(const String &str)
 {
   if (alloc(str.str_length))
     return TRUE;
-  str_length=str.str_length;
-  bmove(Ptr,str.Ptr,str_length);		// May be overlapping
+  if ((str_length=str.str_length))
+    bmove(Ptr,str.Ptr,str_length);		// May be overlapping
   Ptr[str_length]=0;
   str_charset=str.str_charset;
   return FALSE;
@@ -539,8 +539,11 @@ bool String::append_ulonglong(ulonglong val)
 
 bool String::append(const char *s,uint32 arg_length, CHARSET_INFO *cs)
 {
+  if (!arg_length)
+    return false;
+
   uint32 offset;
-  
+
   if (needs_conversion(arg_length, cs, str_charset, &offset))
   {
     uint32 add_length;
diff --git a/sql/table.h b/sql/table.h
index 14ab0027a79..9a864f7ce9f 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -2924,7 +2924,8 @@ inline void mark_as_null_row(TABLE *table)
 {
   table->null_row=1;
   table->status|=STATUS_NULL_ROW;
-  bfill(table->null_flags,table->s->null_bytes,255);
+  if (table->s->null_bytes)
+    bfill(table->null_flags,table->s->null_bytes,255);
 }
 
 bool is_simple_order(ORDER *order);
diff --git a/sql/unireg.cc b/sql/unireg.cc
index 083960523c1..92949931f77 100644
--- a/sql/unireg.cc
+++ b/sql/unireg.cc
@@ -921,8 +921,11 @@ static bool pack_fields(uchar **buff_arg, List<Create_field> &create_fields,
     it.rewind();
     while ((field=it++))
     {
-      memcpy(buff, field->comment.str, field->comment.length);
-      buff+= field->comment.length;
+      if (size_t l= field->comment.length)
+      {
+        memcpy(buff, field->comment.str, l);
+        buff+= l;
+      }
     }
   }
   *buff_arg= buff;
diff --git a/sql/unireg.h b/sql/unireg.h
index 6ce638928e8..efc3d6958f5 100644
--- a/sql/unireg.h
+++ b/sql/unireg.h
@@ -78,7 +78,8 @@
 #define cmp_record(A,B) memcmp((A)->record[0],(A)->B,(size_t) (A)->s->reclength)
 #define empty_record(A) { \
                           restore_record((A),s->default_values); \
-                          bfill((A)->null_flags,(A)->s->null_bytes,255);\
+                          if ((A)->s->null_bytes) \
+                            bfill((A)->null_flags,(A)->s->null_bytes,255); \
                         }
 
 	/* Defines for use with openfrm, openprt and openfrd */
diff --git a/storage/myisam/mi_key.c b/storage/myisam/mi_key.c
index 9247fae9e3c..1298232b5fa 100644
--- a/storage/myisam/mi_key.c
+++ b/storage/myisam/mi_key.c
@@ -144,8 +144,11 @@ uint _mi_make_key(register MI_INFO *info, uint keynr, uchar *key,
       set_if_smaller(length,tmp_length);
       FIX_LENGTH(cs, pos, length, char_length);
       store_key_length_inc(key,char_length);
-      memcpy((uchar*) key,(uchar*) pos,(size_t) char_length);
-      key+= char_length;
+      if (char_length)
+      {
+        memcpy(key, pos, char_length);
+        key+= char_length;
+      }
       continue;
     }
     else if (keyseg->flag & HA_SWAP_KEY)
diff --git a/storage/perfschema/pfs_setup_object.cc b/storage/perfschema/pfs_setup_object.cc
index f33030e927f..8da9fccc65f 100644
--- a/storage/perfschema/pfs_setup_object.cc
+++ b/storage/perfschema/pfs_setup_object.cc
@@ -144,12 +144,18 @@ static void set_setup_object_key(PFS_setup_object_key *key,
   char *ptr= &key->m_hash_key[0];
   ptr[0]= (char) object_type;
   ptr++;
-  memcpy(ptr, schema, schema_length);
-  ptr+= schema_length;
+  if (schema_length)
+  {
+    memcpy(ptr, schema, schema_length);
+    ptr+= schema_length;
+  }
   ptr[0]= 0;
   ptr++;
-  memcpy(ptr, object, object_length);
-  ptr+= object_length;
+  if (object_length)
+  {
+    memcpy(ptr, object, object_length);
+    ptr+= object_length;
+  }
   ptr[0]= 0;
   ptr++;
   key->m_key_length= (uint)(ptr - &key->m_hash_key[0]);
diff --git a/strings/ctype-bin.c b/strings/ctype-bin.c
index e4bd6d2b5c2..c052e427322 100644
--- a/strings/ctype-bin.c
+++ b/strings/ctype-bin.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2002-2007 MySQL AB & tommy@valley.ne.jp
    Copyright (c) 2002, 2014, Oracle and/or its affiliates.
-   Copyright (c) 2009, 2014, SkySQL Ab.
+   Copyright (c) 2009, 2020, MariaDB Corporation.
    
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ -399,7 +399,7 @@ my_strnxfrm_8bit_bin(CHARSET_INFO *cs,
 {
   set_if_smaller(srclen, dstlen);
   set_if_smaller(srclen, nweights);
-  if (dst != src)
+  if (srclen && dst != src)
     memcpy(dst, src, srclen);
   return my_strxfrm_pad_desc_and_reverse(cs, dst, dst + srclen, dst + dstlen,
                                          (uint)(nweights - srclen), flags, 0);
diff --git a/strings/ctype-tis620.c b/strings/ctype-tis620.c
index bfd8b0db1d5..66bd1604803 100644
--- a/strings/ctype-tis620.c
+++ b/strings/ctype-tis620.c
@@ -553,9 +553,11 @@ int my_strnncollsp_tis620(CHARSET_INFO * cs __attribute__((unused)),
     alloced= a= (uchar*) my_malloc(a_length+b_length+2, MYF(MY_FAE));
   
   b= a + a_length+1;
-  memcpy((char*) a, (char*) a0, a_length);
+  if (a_length)
+    memcpy((char*) a, (char*) a0, a_length);
   a[a_length]= 0;	/* if length(a0)> len1, need to put 'end of string' */
-  memcpy((char *)b, (char *)b0, b_length);
+  if (b_length)
+    memcpy((char *)b, (char *)b0, b_length);
   b[b_length]= 0;	/* put end of string */
   a_length= thai2sortable(a, a_length);
   b_length= thai2sortable(b, b_length);