#22882 [Bgs]: shmop_read should return string length, not shm segment size

[discussion at vodopivec dot com]

 ID:               22882
 User updated by:  discussion at vodopivec dot com
 Reported By:      discussion at vodopivec dot com
 Status:           Bogus
 Bug Type:         Strings related
 Operating System: Linux
 PHP Version:      4.3.1
 New Comment:

You have the point and I agree; But how about having a separate
function for this purpose, like shmop_read_string?

The submitted php script demonstrates this problem, and although not
impossible, it's extremely difficult to deal with this.

After all, it doesn't make sense to write, then read shared memory,
compare values and get false result.


Previous Comments:
------------------------------------------------------------------------

[2003-03-25 14:50:46] [EMAIL PROTECTED]

This would break binary data stored in the shm segment; we will not
apply this patch.

------------------------------------------------------------------------

[2003-03-25 14:42:08] discussion at vodopivec dot com

My opinion is that shmop_read function has wrong behaviour, returning
'count' parameter as the length of the string, instead of real length
of the string, up to the terminating zero.
 
This should be easy to fix, in fact I already did, but 
someone should apply this patch - in shmop_read, 
instead of
 
RETURN_STRINGL(return_string, bytes, 0);
 
you can use 
 
RETURN_STRINGL(return_string, strlen(return_string), 0);
 
Below is the php code that demonstrates this problem.
 
Thanks,
 
Mario.
 
<?php
 
  $buffer = "12345";
 
  // Create 100 byte shared memory block with system id if 0xff3
  $shm_id = shmop_open(0xff3, "c", 0644, 100);
  if(!$shm_id) {
    echo "Couldn't create shared memory segment\n";
  }
 
  // Get shared memory block's size
  $shm_size = shmop_size($shm_id);
  echo "SHM Block Size: ".$shm_size. " has been created.\n";
 
  // Lets write a test string into shared memory
  $shm_bytes_written = shmop_write($shm_id, $buffer, 0);
  if($shm_bytes_written != strlen($buffer)) {
    echo "Couldn't write the entire length of data\n";
  }
 
  // Now lets read the string back
  $my_string = shmop_read($shm_id, 0, $shm_size);
  if(!$my_string) {
    echo "Couldn't read from shared memory block\n";
  }
  echo "The data inside shared memory was: ".$my_string."<br>\n";
 
  if ($my_string != $buffer)
  {
    print "This is where it doesn't make sense"."<br>\n";
    print "buffer len = ".strlen($buffer)."<br>\n";
    print "my string len = ".strlen($my_string)."<br>\n";
  }
 
  //Now lets delete the block and close the shared memory segment
  if(!shmop_delete($shm_id)) {
    echo "Couldn't mark shared memory block for deletion.";
  }
  else
    echo "Deleted shm block";
 
  shmop_close($shm_id);
 
?>
 

------------------------------------------------------------------------


-- 
Edit this bug report at http://bugs.php.net/?id=22882&edit=1