Fix for bug #23810: Server crashes on various "show status ..." commands

We access some variable values using casts like *(long *) buff
that may cause crashes on some platforms (e.g. solaris 64) if buff is
not properly aligned.
Fix: align the buffer used.


include/my_global.h:
  Fix for bug #23810: Server crashes on various "show status ..." commands
    - MY_DIV_UP(A, B) macro introduced, which devides A then rounds up by B.
    - MY_ALIGNED_BYTE_ARRAY(N, S, T) macro introduced, which declares an S-byte long
      (aligned) N array of type T.
sql/sql_show.cc:
  Fix for bug #23810: Server crashes on various "show status ..." commands
    - align the buffer used.

include/my_global.h

@@ -911,6 +911,9 @@ typedef unsigned long long my_size_t;
 #define ADD_TO_PTR(ptr,size,type) (type) ((byte*) (ptr)+size)
 #define PTR_BYTE_DIFF(A,B) (my_ptrdiff_t) ((byte*) (A) - (byte*) (B))
 
+#define MY_DIV_UP(A, B) (((A) + (B) - 1) / (B))
+#define MY_ALIGNED_BYTE_ARRAY(N, S, T) T N[MY_DIV_UP(S, sizeof(T))]
+
 /*
   Custom version of standard offsetof() macro which can be used to get
   offsets of members in class for non-POD types (according to the current

sql/sql_show.cc

@@ -2035,7 +2035,9 @@ static bool show_status_array(THD *thd, const char *wild,
                               const char *prefix, TABLE *table,
                               bool ucase_names)
 {
-  char buff[SHOW_VAR_FUNC_BUFF_SIZE], *prefix_end;
+  MY_ALIGNED_BYTE_ARRAY(buff_data, SHOW_VAR_FUNC_BUFF_SIZE, long);
+  char * const buff= (char *) &buff_data;
+  char *prefix_end;
   /* the variable name should not be longer than 64 characters */
   char name_buffer[64];
   int len;