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/*----------------------------------------------------------------*
* This program is free software; you can redistribute it and/or
* modify it under the same terms as Perl itself.
*
* Copyright (C) 2002-2014 Jens Thoms Toerring <jt@toerring.de>
*----------------------------------------------------------------*/
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <limits.h>
#define membersize( type, member ) ( sizeof( ( ( type * ) NULL )->member ) )
#define NUM_ELEMS( p ) ( sizeof p / sizeof *p )
/* Structure for names, sizes and offsets of the flcok struct */
typedef struct {
const char * name;
size_t size;
size_t offset;
} Params;
/*-------------------------------------------------*
* Called from qsort() for sorting an array of Params structures
* in ascending order of their 'offset' members
*-------------------------------------------------*/
static int
comp( const void * a,
const void * b )
{
if ( a == b )
return 0;
return ( ( Params * ) a )->offset < ( ( Params * ) b )->offset ? -1 : 1;
}
/*-------------------------------------------------*
*-------------------------------------------------*/
int
main( void )
{
Params params[ ] = { { "l_type",
CHAR_BIT * membersize( struct flock, l_type ),
CHAR_BIT * offsetof( struct flock, l_type ) },
{ "l_whence",
CHAR_BIT * membersize( struct flock, l_whence ),
CHAR_BIT * offsetof( struct flock, l_whence ) },
{ "l_start",
CHAR_BIT * membersize( struct flock, l_start ),
CHAR_BIT * offsetof( struct flock, l_start ) },
{ "l_len",
CHAR_BIT * membersize( struct flock, l_len ),
CHAR_BIT * offsetof( struct flock, l_len ) },
{ "l_pid",
CHAR_BIT * membersize( struct flock, l_pid ),
CHAR_BIT * offsetof( struct flock, l_pid ) } };
size_t size = CHAR_BIT * sizeof( struct flock );
size_t i;
size_t pos = 0;
char packstr[ 128 ] = "";
/* All sizes and offsets must be divisable by 8 and the sizes of the
members must be either 8-, 16-, 32- or 64-bit values, otherwise
there's no good way to pack them. */
if ( size % 8 )
exit( EXIT_FAILURE );
size /= 8;
for ( i = 0; i < NUM_ELEMS( params ); ++i )
{
if ( params[ i ].size % 8
|| params[ i ].offset % 8
|| ( params[ i ].size != 8
&& params[ i ].size != 16
&& params[ i ].size != 32
&& params[ i ].size != 64 ) )
exit( EXIT_FAILURE );
params[ i ].size /= 8;
params[ i ].offset /= 8;
}
/* Sort the array of structures for the members in ascending order of
the offset */
qsort( params, NUM_ELEMS( params ), sizeof *params, comp );
/* Cobble together the template string to be passed to pack(), taking
care of padding and also extra members we're not interested in. All
the interesting members have signed integer types. */
for ( i = 0; i < NUM_ELEMS( params ); ++i )
{
if ( pos != params[ i ].offset )
sprintf( packstr + strlen( packstr ), "x%lu",
( unsigned long )( params[ i ].offset - pos ) );
pos = params[ i ].offset;
switch ( params[ i ].size )
{
case 1 :
strcat( packstr, "c" );
break;
case 2 :
strcat( packstr, "s" );
break;
case 4 :
strcat( packstr, "l" );
break;
case 8 :
#if defined NO_Q_FORMAT
/* There seem to be some 32-bit systems out there where off_t
is a 64-bit integer but Perl has no 'q' format for its
pack() and unpack() functions. For these systemsthere
doesn't seem to be a good way for setting up the flock
structure properly using pure Perl. */
exit( EXIT_FAILURE );
#endif
strcat( packstr, "q" );
break;
default :
exit( EXIT_FAILURE );
}
pos += params[ i ].size;
}
if ( pos < size )
sprintf( packstr + strlen( packstr ), "x%lu",
(unsigned long ) ( size - pos ) );
printf( "###########################################################\n\n"
"# Method created automatically while running 'perl Makefile.PL'\n"
"# (based on the the C 'struct flock' in <fcntl.h>) for packing\n"
"# the data from the 'flock_struct' into a binary blob to be\n"
"# passed to fcntl().\n\n"
"sub pack_flock {\n"
" my $self = shift;\n"
" return pack( '%s',\n", packstr );
for ( i = 0; i < NUM_ELEMS( params ); ++i )
printf( " $self->{ %s }%s", params[ i ].name,
i == NUM_ELEMS( params ) - 1 ? " " : ",\n" );
printf( ");\n}\n\n\n"
"###########################################################\n\n"
"# Method created automatically while running 'perl Makefile.PL'\n"
"# (based on the the C 'struct flock' in <fcntl.h>) for unpacking\n"
"# the binary blob received from a call of fcntl() into the\n"
"# 'flock_struct'.\n\n"
"sub unpack_flock {\n"
" my ( $self, $data ) = @_;\n"
" ( " );
for ( i = 0; i < NUM_ELEMS( params ); ++i )
printf( "$self->{ %-8s }%s", params[ i ].name,
i == NUM_ELEMS( params ) - 1 ? " " : ",\n " );
printf( ") = unpack( '%s', $data );\n}\n", packstr );
return 0;
}
/*
* Local variables:
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
|
