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Full Discussion: write() issue during a low level hdd access
Top Forums Programming write() issue during a low level hdd access Post 302397279 by sponnusa on Sunday 21st of February 2010 05:42:10 PM
Old 02-21-2010
Here is the code which I am using.

Code:
int writesector(const uint64_t offset, const int fd, const uint8_t *mybuff, const uint16_t len)
{
	if(!fd)
  {
    return 4;
  }
  errno = 0;
  if(lseek64(fd, offset, SEEK_SET) != -1)
  {
    if (errno!=0)
    {
      return 1;
    }
    
    errno = 0;
    
    if( (write(fd, mybuff, len)) != len)
    {
      return 1;
    }
    
    if (errno!=0)
    {
      return 1;
    }
    
    if(fsync(fd)!=0)
    {
      return 1;
    }
    //sync();
  }
  else
  {
    return 2;
  }

  return 0;
}

The buffer I am using is aligned. PATTERN_LEN len is currently set to 8192 bytes. (i.e., 16 sectors).

The code is:
Code:
      diskdata = memalign(512,PATTERN_LEN);

    	if(diskdata == NULL)
    	{
    		printf("FATAL ERROR: Unable to allocate memory for write buffer!\n");
    		exit (0);
    	}

      memset(diskdata,0,PATTERN_LEN);

The file is opened using:

Code:
handle = open64(devicename, O_WRONLY | O_DIRECT | O_SYNC);

I don't know what causes the write call to pass always! Smilie

And yes, I am using the
Code:
#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE

flags in the code for compilation of O_DIRECT and *64() functions.
Thank you.
 

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LEARN ABOUT MOJAVE

locale::codes::langfam

Locale::Codes::LangFam(3pm)				 Perl Programmers Reference Guide			       Locale::Codes::LangFam(3pm)

NAME

       Locale::Codes::LangFam - standard codes for language extension identification

SYNOPSIS

	  use Locale::Codes::LangFam;

	  $lext = code2langfam('apa');		       # $lext gets 'Apache languages'
	  $code = langfam2code('Apache languages');    # $code gets 'apa'

	  @codes   = all_langfam_codes();
	  @names   = all_langfam_names();

DESCRIPTION

       The "Locale::Codes::LangFam" module provides access to standard codes used for identifying language families, such as those as defined in
       ISO 639-5.

       Most of the routines take an optional additional argument which specifies the code set to use. If not specified, the default ISO 639-5
       language family codes will be used.

SUPPORTED CODE SETS

       There are several different code sets you can use for identifying language families. A code set may be specified using either a name, or a
       constant that is automatically exported by this module.

       For example, the two are equivalent:

	  $lext = code2langfam('apa','alpha');
	  $lext = code2langfam('apa',LOCALE_LANGFAM_ALPHA);

       The codesets currently supported are:

       alpha
	   This is the set of three-letter (lowercase) codes from ISO 639-5 such as 'apa' for Apache languages.

	   This is the default code set.

ROUTINES

       code2langfam ( CODE [,CODESET] )
       langfam2code ( NAME [,CODESET] )
       langfam_code2code ( CODE ,CODESET ,CODESET2 )
       all_langfam_codes ( [CODESET] )
       all_langfam_names ( [CODESET] )
       Locale::Codes::LangFam::rename_langfam  ( CODE ,NEW_NAME [,CODESET] )
       Locale::Codes::LangFam::add_langfam  ( CODE ,NAME [,CODESET] )
       Locale::Codes::LangFam::delete_langfam  ( CODE [,CODESET] )
       Locale::Codes::LangFam::add_langfam_alias  ( NAME ,NEW_NAME )
       Locale::Codes::LangFam::delete_langfam_alias  ( NAME )
       Locale::Codes::LangFam::rename_langfam_code  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangFam::add_langfam_code_alias  ( CODE ,NEW_CODE [,CODESET] )
       Locale::Codes::LangFam::delete_langfam_code_alias  ( CODE [,CODESET] )
	   These routines are all documented in the Locale::Codes::API man page.

SEE ALSO

       Locale::Codes
	   The Locale-Codes distribution.

       Locale::Codes::API
	   The list of functions supported by this module.

       http://www.loc.gov/standards/iso639-5/id.php
	   ISO 639-5 .

AUTHOR

       See Locale::Codes for full author history.

       Currently maintained by Sullivan Beck (sbeck@cpan.org).

COPYRIGHT

	  Copyright (c) 2011-2013 Sullivan Beck

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.18.2							    2013-11-04					       Locale::Codes::LangFam(3pm)
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