MDEV-27037 mysqlbinlog emits a warning when reaching EOF before stop-condition

Emit a warning in the event that we finished processing input files
before reaching the boundary indicated by --stop-position.

client/mysqlbinlog.cc

@@ -142,6 +142,7 @@ static char *charset= 0;
 static uint verbose= 0;
 
 static ulonglong start_position, stop_position;
+static const longlong stop_position_default= (longlong)(~(my_off_t)0);
 #define start_position_mot ((my_off_t)start_position)
 #define stop_position_mot  ((my_off_t)stop_position)
 
@@ -1684,8 +1685,8 @@ static struct my_option my_options[] =
    "Stop reading the binlog at position N. Applies to the last binlog "
    "passed on the command line.",
    &stop_position, &stop_position, 0, GET_ULL,
-   REQUIRED_ARG, (longlong)(~(my_off_t)0), BIN_LOG_HEADER_SIZE,
+   REQUIRED_ARG, stop_position_default, BIN_LOG_HEADER_SIZE,
-   (ulonglong)(~(my_off_t)0), 0, 0, 0},
+   (ulonglong)stop_position_default, 0, 0, 0},
   {"table", 'T', "List entries for just this table (affects only row events).",
    &table, &table, 0, GET_STR_ALLOC, REQUIRED_ARG,
    0, 0, 0, 0, 0, 0},
@@ -2937,7 +2938,20 @@ static Exit_status dump_local_log_entries(PRINT_EVENT_INFO *print_event_info,
               llstr(old_off,llbuff));
         goto err;
       }
-      // file->error == 0 means EOF, that's OK, we break in this case
+      // else file->error == 0 means EOF, that's OK, we break in this case
+
+      /*
+        Emit a warning in the event that we finished processing input
+        before reaching the boundary indicated by --stop-position.
+      */
+      if (((longlong)stop_position != stop_position_default) &&
+          stop_position > my_b_tell(file))
+      {
+          retval = OK_STOP;
+          warning("Did not reach stop position %llu before "
+                  "end of input", stop_position);
+      }
+
       goto end;
     }
     if ((retval= process_event(print_event_info, ev, old_off, logname)) !=

mysql-test/suite/binlog/r/binlog_mysqlbinlog_warn_stop_position.result

@@ -0,0 +1,13 @@
+
+# MDEV-27037 mysqlbinlog emits a warning when reaching EOF before stop-condition
+
+Case: Default stop position, WARNING must not appear
+# MYSQL_BINLOG --short-form --start-position=4 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+Case: Stop position before EOF, WARNING must not appear
+# MYSQL_BINLOG --short-form --start-position=4 --stop-position=97 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+Case: Stop position at EOF, WARNING must not appear
+# MYSQL_BINLOG --short-form --start-position=4 --stop-position=98 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+Case: Stop position after EOF, WARNING must appear
+# MYSQL_BINLOG --short-form --start-position=4 --stop-position=99 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+WARNING: Did not reach stop position 99 before end of input
+# End of binlog_mysqlbinlog_warn_stop_position.test

mysql-test/suite/binlog/t/binlog_mysqlbinlog_warn_stop_position.test

@@ -0,0 +1,26 @@
+--echo
+--echo # MDEV-27037 mysqlbinlog emits a warning when reaching EOF before stop-condition
+--echo
+
+--let assert_file= $MYSQLTEST_VARDIR/tmp/warn_pos_test_file.out
+--let data_file= $MYSQLTEST_VARDIR/std_data/master-bin.000001
+
+--echo Case: Default stop position, WARNING must not appear
+--echo # MYSQL_BINLOG --short-form --start-position=4 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+--exec $MYSQL_BINLOG --short-form --start-position=4 $data_file --result-file=$assert_file 2>&1
+
+--echo Case: Stop position before EOF, WARNING must not appear
+--echo # MYSQL_BINLOG --short-form --start-position=4 --stop-position=97 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+--exec $MYSQL_BINLOG --short-form --start-position=4 --stop-position=97 $data_file --result-file=$assert_file 2>&1
+
+--echo Case: Stop position at EOF, WARNING must not appear
+--echo # MYSQL_BINLOG --short-form --start-position=4 --stop-position=98 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+--exec $MYSQL_BINLOG --short-form --start-position=4 --stop-position=98 $data_file --result-file=$assert_file 2>&1
+
+--echo Case: Stop position after EOF, WARNING must appear
+--echo # MYSQL_BINLOG --short-form --start-position=4 --stop-position=99 mysql-test/std_data/master-bin.000001 --result-file=warn_pos_test_file.out 2>&1
+--exec $MYSQL_BINLOG --short-form --start-position=4 --stop-position=99 $data_file --result-file=$assert_file 2>&1
+
+--remove_file $assert_file
+
+--echo # End of binlog_mysqlbinlog_warn_stop_position.test