Maria: a stronger checksum in the control file, to test integrity.

4 bytes, using my_checksum() (the old checksum was one byte and just
a sum of the bytes - that was before I saw we have my_checksum :)


storage/maria/ma_control_file.c:
  stronger checksum (4 bytes instead of 1, and using CRC instead of
  simple byte sum).
storage/maria/unittest/ma_control_file-t.c:
  Checksum is now 4 bytes (total length of control file is now 23),
  so LSN and LAST_LOGNO move.

storage/maria/ma_control_file.c

@@ -33,7 +33,7 @@
 #define CONTROL_FILE_MAGIC_STRING_OFFSET 0
 #define CONTROL_FILE_MAGIC_STRING_SIZE (sizeof(CONTROL_FILE_MAGIC_STRING)-1)
 #define CONTROL_FILE_CHECKSUM_OFFSET (CONTROL_FILE_MAGIC_STRING_OFFSET + CONTROL_FILE_MAGIC_STRING_SIZE)
-#define CONTROL_FILE_CHECKSUM_SIZE 1
+#define CONTROL_FILE_CHECKSUM_SIZE 4
 #define CONTROL_FILE_LSN_OFFSET (CONTROL_FILE_CHECKSUM_OFFSET + CONTROL_FILE_CHECKSUM_SIZE)
 #define CONTROL_FILE_LSN_SIZE LSN_STORE_SIZE
 #define CONTROL_FILE_FILENO_OFFSET (CONTROL_FILE_LSN_OFFSET + CONTROL_FILE_LSN_SIZE)
@@ -57,16 +57,6 @@ uint32 last_logno;
 */
 static int control_file_fd= -1;
 
-static char simple_checksum(char *buffer, uint size)
-{
-  /* TODO: improve this sum if we want */
-  char s= 0;
-  uint i;
-  for (i= 0; i<size; i++)
-    s+= buffer[i];
-  return s;
-}
-
 /*
   Initialize control file subsystem
 
@@ -80,7 +70,7 @@ static char simple_checksum(char *buffer, uint size)
 
   The format of the control file is:
   4 bytes: magic string
-  1 byte: checksum of the following bytes
+  4 bytes: checksum of the following bytes
   4 bytes: number of log where last checkpoint is
   4 bytes: offset in log where last checkpoint is
   4 bytes: number of last log
@@ -190,9 +180,9 @@ CONTROL_FILE_ERROR ma_control_file_create_or_open()
     error= CONTROL_FILE_BAD_MAGIC_STRING;
     goto err;
   }
-  if (simple_checksum(buffer + CONTROL_FILE_LSN_OFFSET,
-                      CONTROL_FILE_SIZE - CONTROL_FILE_LSN_OFFSET) !=
-      buffer[CONTROL_FILE_CHECKSUM_OFFSET])
+  if (my_checksum(0, buffer + CONTROL_FILE_LSN_OFFSET,
+                  CONTROL_FILE_SIZE - CONTROL_FILE_LSN_OFFSET) !=
+      uint4korr(buffer + CONTROL_FILE_CHECKSUM_OFFSET))
   {
     /* TODO: store message "checksum mismatch" somewhere */
     error= CONTROL_FILE_BAD_CHECKSUM;
@@ -268,9 +258,12 @@ int ma_control_file_write_and_force(const LSN checkpoint_lsn, uint32 logno,
   else
     int4store(buffer + CONTROL_FILE_FILENO_OFFSET, last_logno);
 
-  buffer[CONTROL_FILE_CHECKSUM_OFFSET]=
-    simple_checksum(buffer + CONTROL_FILE_LSN_OFFSET,
-                    CONTROL_FILE_SIZE - CONTROL_FILE_LSN_OFFSET);
+  {
+    uint32 sum= (uint32)
+      my_checksum(0, buffer + CONTROL_FILE_LSN_OFFSET,
+                  CONTROL_FILE_SIZE - CONTROL_FILE_LSN_OFFSET);
+    int4store(buffer + CONTROL_FILE_CHECKSUM_OFFSET, sum);
+  }
 
   if (my_pwrite(control_file_fd, buffer, sizeof(buffer),
                 0, MYF(MY_FNABP |  MY_WME)) ||

storage/maria/unittest/ma_control_file-t.c

@@ -268,14 +268,14 @@ static int test_binary_content()
   RET_ERR_UNLESS((fd= my_open(file_name,
                           O_BINARY | O_RDWR,
                           MYF(MY_WME))) >= 0);
-  RET_ERR_UNLESS(my_read(fd, buffer, 20, MYF(MY_FNABP |  MY_WME)) == 0);
+  RET_ERR_UNLESS(my_read(fd, buffer, 23, MYF(MY_FNABP |  MY_WME)) == 0);
   RET_ERR_UNLESS(my_close(fd, MYF(MY_WME)) == 0);
   RET_ERR_UNLESS(create_or_open_file() == CONTROL_FILE_OK);
-  i= uint3korr(buffer+9);
+  i= uint3korr(buffer+12);
   RET_ERR_UNLESS(i == LSN_FILE_NO(last_checkpoint_lsn));
-  i= uint4korr(buffer+12);
+  i= uint4korr(buffer+15);
   RET_ERR_UNLESS(i == LSN_OFFSET(last_checkpoint_lsn));
-  i= uint4korr(buffer+16);
+  i= uint4korr(buffer+19);
   RET_ERR_UNLESS(i == last_logno);
   RET_ERR_UNLESS(close_file() == 0);
   return 0;