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

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~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.
This commit is contained in:
Alexey Kopytov 2009-03-18 11:18:24 +03:00
commit 73a7d99331
5 changed files with 86 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

46
client/readline.cc
View file

@ -24,7 +24,7 @@ static bool init_line_buffer(LINE_BUFFER *buffer,File file,ulong size,
ulong max_size);
static bool init_line_buffer_from_string(LINE_BUFFER *buffer,my_string str);
static uint fill_buffer(LINE_BUFFER *buffer);
static char *intern_read_line(LINE_BUFFER *buffer,ulong *out_length);
static char *intern_read_line(LINE_BUFFER *buffer, ulong *out_length, bool *truncated);
LINE_BUFFER *batch_readline_init(ulong max_size,FILE *file)
@ -42,12 +42,13 @@ LINE_BUFFER *batch_readline_init(ulong max_size,FILE *file)
}
char *batch_readline(LINE_BUFFER *line_buff)
char *batch_readline(LINE_BUFFER *line_buff, bool *truncated)
{
char *pos;
ulong out_length;
DBUG_ASSERT(truncated != NULL);
if (!(pos=intern_read_line(line_buff,&out_length)))
if (!(pos=intern_read_line(line_buff,&out_length, truncated)))
return 0;
if (out_length && pos[out_length-1] == '\n')
if (--out_length && pos[out_length-1] == '\r') /* Remove '\n' */
@ -149,6 +150,14 @@ static uint fill_buffer(LINE_BUFFER *buffer)
read_count=(buffer->bufread - bufbytes)/IO_SIZE;
if ((read_count*=IO_SIZE))
break;
if (buffer->bufread * 2 > buffer->max_size)
{
/*
So we must grow the buffer but we cannot due to the max_size limit.
Return 0 w/o setting buffer->eof to signal this condition.
*/
return 0;
}
buffer->bufread *= 2;
if (!(buffer->buffer = (char*) my_realloc(buffer->buffer,
buffer->bufread+1,
@ -172,11 +181,15 @@ static uint fill_buffer(LINE_BUFFER *buffer)
DBUG_PRINT("fill_buff", ("Got %d bytes", read_count));
/* Kludge to pretend every nonempty file ends with a newline. */
if (!read_count && bufbytes && buffer->end[-1] != '\n')
if (!read_count)
{
buffer->eof = read_count = 1;
*buffer->end = '\n';
buffer->eof = 1;
/* Kludge to pretend every nonempty file ends with a newline. */
if (bufbytes && buffer->end[-1] != '\n')
{
read_count = 1;
*buffer->end = '\n';
}
}
buffer->end_of_line=(buffer->start_of_line=buffer->buffer)+bufbytes;
buffer->end+=read_count;
@ -186,7 +199,7 @@ static uint fill_buffer(LINE_BUFFER *buffer)
char *intern_read_line(LINE_BUFFER *buffer,ulong *out_length)
char *intern_read_line(LINE_BUFFER *buffer, ulong *out_length, bool *truncated)
{
char *pos;
uint length;
@ -200,14 +213,23 @@ char *intern_read_line(LINE_BUFFER *buffer,ulong *out_length)
pos++;
if (pos == buffer->end)
{
if ((uint) (pos - buffer->start_of_line) < buffer->max_size)
/*
fill_buffer() can return 0 either on EOF in which case we abort
or when the internal buffer has hit the size limit. In the latter case
return what we have read so far and signal string truncation.
*/
if (!(length=fill_buffer(buffer)) || length == (uint) -1)
{
if (!(length=fill_buffer(buffer)) || length == (uint) -1)
DBUG_RETURN(0);
continue;
if (buffer->eof)
DBUG_RETURN(0);
}
else
continue;
pos--; /* break line here */
*truncated= 1;
}
else
*truncated= 0;
buffer->end_of_line=pos+1;
*out_length=(ulong) (pos + 1 - buffer->eof - buffer->start_of_line);
DBUG_RETURN(buffer->start_of_line);