Fix for bug#41486: extra character appears in BLOB for every

~40Mb after mysqldump/import 
        
When the input string exceeds the maximum allowed size for the 
internal buffer, batch_readline() returns a truncated string. 
Since there was no way for a caller to determine whether the 
string was truncated or not, the command line client assumed 
batch_readline() to always return the whole input string and 
appended a newline character. This resulted in garbled data 
when importing dumps containing strings longer than the 
maximum input buffer size. 
  
Fixed by adding a flag to the batch_readline() interface to 
signal a truncated string to the caller. 
  
Other minor problems fixed during patch implementation: 
 
- The maximum allowed buffer size for batch_readline() was set 
up depending on the client's max_allowed_packet value. It does 
not actully make any sense, as those variables are not 
related. The input buffer size limit is now always set to 1 
MB. 
  
- fill_buffer() did not always set the EOF flag. 
 
- The input buffer could actually grow twice as the specified 
limit due to insufficient checks in intern_read_line(). 

client/my_readline.h:
  Changed the interface of batch_readline().
client/mysql.cc:
  Honor the truncated flag returned by batch_readline() and do  
  not append the newline character if it was set. Since we can't 
  change the interfaces for readline()/fgets() used in the  
  interactive mode, always assume the returned string was not  
  truncated. In addition, always set the batch_readline()  
  internal buffer to 1 MB, independently from the client's  
  max_allowed_packet.
client/readline.cc:
  Added the 'truncated' argument do batch_readline() to signal 
  truncated string to a caller. 
  Fixed fill_buffer() to set the EOF flag correctly. 
  Fixed checks in intern_read_line() to not allow the internal  
  buffer grow past the specified limit.
mysql-test/r/mysql.result:
  Added a test case for bug #41486.
mysql-test/t/mysql.test:
  Added a test case for bug #41486.

client/mysql.cc

@@ -112,6 +112,8 @@ extern "C" {
 #define PROMPT_CHAR '\\'
 #define DEFAULT_DELIMITER ";"
 
+#define MAX_BATCH_BUFFER_SIZE (1024L * 1024L)
+
 typedef struct st_status
 {
   int exit_status;
@@ -1035,7 +1037,7 @@ static void fix_history(String *final_command);
 
 static COMMANDS *find_command(char *name,char cmd_name);
 static bool add_line(String &buffer,char *line,char *in_string,
-                     bool *ml_comment);
+                     bool *ml_comment, bool truncated);
 static void remove_cntrl(String &buffer);
 static void print_table_data(MYSQL_RES *result);
 static void print_table_data_html(MYSQL_RES *result);
@@ -1117,7 +1119,7 @@ int main(int argc,char *argv[])
     exit(1);
   }
   if (status.batch && !status.line_buff &&
-      !(status.line_buff=batch_readline_init(opt_max_allowed_packet+512,stdin)))
+      !(status.line_buff= batch_readline_init(MAX_BATCH_BUFFER_SIZE, stdin)))
   {
     free_defaults(defaults_argv);
     my_end(0);
@@ -1766,13 +1768,14 @@ static int read_and_execute(bool interactive)
   ulong line_number=0;
   bool ml_comment= 0;  
   COMMANDS *com;
+  bool truncated= 0;
   status.exit_status=1;
   
   for (;;)
   {
     if (!interactive)
     {
-      line=batch_readline(status.line_buff);
+      line=batch_readline(status.line_buff, &truncated);
       /*
         Skip UTF8 Byte Order Marker (BOM) 0xEFBBBF.
         Editors like "notepad" put this marker in
@@ -1891,7 +1894,7 @@ static int read_and_execute(bool interactive)
 #endif
       continue;
     }
-    if (add_line(glob_buffer,line,&in_string,&ml_comment))
+    if (add_line(glob_buffer,line,&in_string,&ml_comment, truncated))
       break;
   }
   /* if in batch mode, send last query even if it doesn't end with \g or go */
@@ -1977,7 +1980,7 @@ static COMMANDS *find_command(char *name,char cmd_char)
 
 
 static bool add_line(String &buffer,char *line,char *in_string,
-                     bool *ml_comment)
+                     bool *ml_comment, bool truncated)
 {
   uchar inchar;
   char buff[80], *pos, *out;
@@ -2224,9 +2227,10 @@ static bool add_line(String &buffer,char *line,char *in_string,
   {
     uint length=(uint) (out-line);
 
-    if (length < 9 || 
-        my_strnncoll (charset_info, 
-                      (uchar *)line, 9, (const uchar *) "delimiter", 9))
+    if (!truncated &&
+        (length < 9 || 
+         my_strnncoll (charset_info, 
+                       (uchar *)line, 9, (const uchar *) "delimiter", 9)))
     {
       /* 
         Don't add a new line in case there's a DELIMITER command to be 
@@ -3886,7 +3890,7 @@ static int com_source(String *buffer, char *line)
     return put_info(buff, INFO_ERROR, 0);
   }
 
-  if (!(line_buff=batch_readline_init(opt_max_allowed_packet+512,sql_file)))
+  if (!(line_buff= batch_readline_init(MAX_BATCH_BUFFER_SIZE, sql_file)))
   {
     my_fclose(sql_file,MYF(0));
     return put_info("Can't initialize batch_readline", INFO_ERROR, 0);