Commit 12d8f2bf authored by thek@kpdesk.mysql.com's avatar thek@kpdesk.mysql.com
Browse files

Bug#22828 _my_b_read() ignores return values for my_seek() calls 

- Because my_seek actually is capable of returning an error code we should
  exploit that in the best possible way.
- There might be kernel errors or other errors we can't predict and capturing
  the return value of all system calls gives us better understanding of
  possible errors.
parent 397f0df9

mysys/mf_iocache.c

+90 −12
Original line number Diff line number Diff line
@@ -440,11 +440,24 @@ int _my_b_read(register IO_CACHE *info, byte *Buffer, uint Count) 


  /* pos_in_file always point on where info->buffer was read */

  pos_in_file=info->pos_in_file+(uint) (info->read_end - info->buffer);



  /* 

    Whenever a function which operates on IO_CACHE flushes/writes

    some part of the IO_CACHE to disk it will set the property

    "seek_not_done" to indicate this to other functions operating

    on the IO_CACHE.

  */

  if (info->seek_not_done)

  {					/* File touched, do seek */

    VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)));

  {

    if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)) 

        == MY_FILEPOS_ERROR)

    {

        info->error= -1;

        DBUG_RETURN(1);

    }

    info->seek_not_done=0;

  }



  diff_length=(uint) (pos_in_file & (IO_SIZE-1));

  if (Count >= (uint) (IO_SIZE+(IO_SIZE-diff_length)))

  {					/* Fill first intern buffer */
@@ -633,8 +646,22 @@ int _my_b_read_r(register IO_CACHE *info, byte *Buffer, uint Count) 
    if (lock_io_cache(info, pos_in_file))

    {

      info->share->active=info;

      if (info->seek_not_done)             /* File touched, do seek */

        VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)));

      /*

        Whenever a function which operates on IO_CACHE flushes/writes

        some part of the IO_CACHE to disk it will set the property

        "seek_not_done" to indicate this to other functions operating

        on the IO_CACHE.

      */

      if (info->seek_not_done)

      {

        if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0))

            == MY_FILEPOS_ERROR)

        {

          info->error= -1;

          unlock_io_cache(info);

          DBUG_RETURN(1);

        }

      }

      len=(int)my_read(info->file,info->buffer, length, info->myflags);

      info->read_end=info->buffer + (len == -1 ? 0 : len);

      info->error=(len == (int)length ? 0 : len);
@@ -668,11 +695,16 @@ int _my_b_read_r(register IO_CACHE *info, byte *Buffer, uint Count) 




/*

  Do sequential read from the SEQ_READ_APPEND cache

  we do this in three stages:

  Do sequential read from the SEQ_READ_APPEND cache.

  

  We do this in three stages:

   - first read from info->buffer

   - then if there are still data to read, try the file descriptor

   - afterwards, if there are still data to read, try append buffer



  RETURNS

    0  Success

    1  Failed to read

*/



int _my_b_seq_read(register IO_CACHE *info, byte *Buffer, uint Count)
@@ -700,7 +732,13 @@ int _my_b_seq_read(register IO_CACHE *info, byte *Buffer, uint Count) 
    With read-append cache we must always do a seek before we read,

    because the write could have moved the file pointer astray

  */

  VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)));

  if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0))

      == MY_FILEPOS_ERROR)

  {

   info->error= -1;

   unlock_append_buffer(info);

   return (1);

  }

  info->seek_not_done=0;



  diff_length=(uint) (pos_in_file & (IO_SIZE-1));
@@ -816,6 +854,21 @@ int _my_b_seq_read(register IO_CACHE *info, byte *Buffer, uint Count) 


#ifdef HAVE_AIOWAIT



/*

  Read from the IO_CACHE into a buffer and feed asynchronously

  from disk when needed.



  SYNOPSIS

    _my_b_async_read()

      info                      IO_CACHE pointer

      Buffer                    Buffer to retrieve count bytes from file

      Count                     Number of bytes to read into Buffer



  RETURN VALUE

    -1          An error has occurred; my_errno is set.

     0          Success

     1          An error has occurred; IO_CACHE to error state.

*/

int _my_b_async_read(register IO_CACHE *info, byte *Buffer, uint Count)

{

  uint length,read_length,diff_length,left_length,use_length,org_Count;
@@ -906,7 +959,14 @@ int _my_b_async_read(register IO_CACHE *info, byte *Buffer, uint Count) 
      info->error=(int) (read_length+left_length);

      return 1;

    }

    VOID(my_seek(info->file,next_pos_in_file,MY_SEEK_SET,MYF(0)));

    

    if (my_seek(info->file,next_pos_in_file,MY_SEEK_SET,MYF(0))

        == MY_FILEPOS_ERROR)

    {

      info->error= -1;

      return (1);

    }



    read_length=IO_SIZE*2- (uint) (next_pos_in_file & (IO_SIZE-1));

    if (Count < read_length)

    {					/* Small block, read to cache */
@@ -999,7 +1059,15 @@ int _my_b_get(IO_CACHE *info) 
  return (int) (uchar) buff;

}



	/* Returns != 0 if error on write */

/* 

   Write a byte buffer to IO_CACHE and flush to disk

   if IO_CACHE is full.



   RETURN VALUE

    1 On error on write

    0 On success

   -1 On error; my_errno contains error code.

*/



int _my_b_write(register IO_CACHE *info, const byte *Buffer, uint Count)

{
@@ -1022,8 +1090,18 @@ int _my_b_write(register IO_CACHE *info, const byte *Buffer, uint Count) 
  {					/* Fill first intern buffer */

    length=Count & (uint) ~(IO_SIZE-1);

    if (info->seek_not_done)

    {					/* File touched, do seek */

      VOID(my_seek(info->file,info->pos_in_file,MY_SEEK_SET,MYF(0)));

    {

      /*

        Whenever a function which operates on IO_CACHE flushes/writes

        some part of the IO_CACHE to disk it will set the property

        "seek_not_done" to indicate this to other functions operating

        on the IO_CACHE.

      */

      if (my_seek(info->file,info->pos_in_file,MY_SEEK_SET,MYF(0)))

      {

        info->error= -1;

        return (1);

      }

      info->seek_not_done=0;

    }

    if (my_write(info->file,Buffer,(uint) length,info->myflags | MY_NABP))

mysys/my_chsize.c

+5 −1
Original line number Diff line number Diff line
@@ -88,7 +88,11 @@ int my_chsize(File fd, my_off_t newlength, int filler, myf MyFlags) 
      Fill space between requested length and true length with 'filler'

      We should never come here on any modern machine

    */

    VOID(my_seek(fd, newlength, MY_SEEK_SET, MYF(MY_WME+MY_FAE)));

    if (my_seek(fd, newlength, MY_SEEK_SET, MYF(MY_WME+MY_FAE))

        == MY_FILEPOS_ERROR)

    {

      goto err;

    }

    swap_variables(my_off_t, newlength, oldsize);

  }

#endif

mysys/my_lock.c

+34 −5
Original line number Diff line number Diff line
@@ -35,7 +35,14 @@ 
#include <nks/fsio.h>

#endif



	/* Lock a part of a file */

/* 

  Lock a part of a file 



  RETURN VALUE

    0   Success

    -1  An error has occured and 'my_errno' is set

        to indicate the actual error code.

*/



int my_lock(File fd, int locktype, my_off_t start, my_off_t length,

	    myf MyFlags)
@@ -104,10 +111,22 @@ int my_lock(File fd, int locktype, my_off_t start, my_off_t length, 
#elif defined(HAVE_LOCKING)

  /* Windows */

  {

    my_bool error;

    my_bool error= false;

    pthread_mutex_lock(&my_file_info[fd].mutex);

    if (MyFlags & MY_SEEK_NOT_DONE) 

      VOID(my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)));

    {

      if( my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE))

           == MY_FILEPOS_ERROR )

      {

        /*

          If my_seek fails my_errno will already contain an error code;

          just unlock and return error code.

         */

        DBUG_PRINT("error",("my_errno: %d (%d)",my_errno,errno));

        pthread_mutex_unlock(&my_file_info[fd].mutex);

        DBUG_RETURN(-1);

      }

    }

    error= locking(fd,locktype,(ulong) length) && errno != EINVAL;

    pthread_mutex_unlock(&my_file_info[fd].mutex);

    if (!error)
@@ -145,7 +164,17 @@ int my_lock(File fd, int locktype, my_off_t start, my_off_t length, 
  }

#else

  if (MyFlags & MY_SEEK_NOT_DONE)

    VOID(my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE)));

  {

    if (my_seek(fd,start,MY_SEEK_SET,MYF(MyFlags & ~MY_SEEK_NOT_DONE))

        == MY_FILEPOS_ERROR)

    {

      /*

        If an error has occured in my_seek then we will already

        have an error code in my_errno; Just return error code.

      */

      DBUG_RETURN(-1);

    }

  }

  if (lockf(fd,locktype,length) != -1)

    DBUG_RETURN(0);

#endif /* HAVE_FCNTL */

mysys/my_seek.c

+24 −2
Original line number Diff line number Diff line
@@ -16,8 +16,30 @@ 


#include "mysys_priv.h"



	/* Seek to position in file */

	/*ARGSUSED*/

/* 

  Seek to a position in a file.



  ARGUMENTS

  File fd          The file descriptor

  my_off_t pos     The expected position (absolute or relative)

  int whence       A direction parameter and one of 

                   {SEEK_SET, SEEK_CUR, SEEK_END}

  myf MyFlags      Not used.



  DESCRIPTION

    The my_seek  function  is a wrapper around the system call lseek and

    repositions  the  offset of the file descriptor fd to the argument 

    offset according to the directive whence as follows:

      SEEK_SET    The offset is set to offset bytes.

      SEEK_CUR    The offset is set to its current location plus offset bytes

      SEEK_END    The offset is set to the size of the file plus offset bytes



  RETURN VALUE

    my_off_t newpos    The new position in the file.

    MY_FILEPOS_ERROR   An error was encountered while performing 

                       the seek. my_errno is set to indicate the

                       actual error.

*/



my_off_t my_seek(File fd, my_off_t pos, int whence,

		 myf MyFlags __attribute__((unused)))