/usr/lib/x86_64-linux-gnu/perl5/5.22/File/FcntlLock/Inline.pm is in libfile-fcntllock-perl 0.22-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 | # -*- cperl -*-
#
# 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>
# Package for file locking with fcntl(2) in which the binary layout of
# the C flock struct is determined via compiling and running a C program
# each time the package is loaded
package File::FcntlLock::Inline;
use 5.006001;
use strict;
use warnings;
use Fcntl;
use Config;
use File::Temp;
use File::Spec;
use base qw( File::FcntlLock::Core );
our $VERSION = File::FcntlLock::Core->VERSION;
our @EXPORT = @File::FcntlLock::Core::EXPORT;
my ( $packstr, @member_list );
###########################################################
BEGIN {
# Create a C file in the preferred directory for temporary files for
# probing the layout of the C 'flock struct'. Since __DATA__ can't
# be used in a BEGIN block we've got to do with a HEREDOC.
my $c_file = File::Temp->new( TEMPLATE => 'File-FcntlLock-XXXXXX',
SUFFIX => '.c',
DIR => File::Spec->tmpdir( ) );
print $c_file <<EOF;
#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 )
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
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( "%s\\n", packstr );
for ( i = 0; i < NUM_ELEMS( params ); ++i )
printf( "%s\\n", params[ i ].name );
return 0;
}
EOF
close $c_file;
# Try to compile and link the file.
my $exec_file = File::Temp->new( TEMPLATE => 'File=FcntlLock-XXXXXX',
DIR => File::Spec->tmpdir( ) );
close $exec_file;
my $qflag = eval { pack 'q', 1 };
$qflag = $@ ? '-DNO_Q_FORMAT' : '';
die "Failed to run the C compiler '$Config{cc}'\n"
if system "$Config{cc} $Config{ccflags} $qflag -o $exec_file $c_file";
# Run the program and read it's output, it writes out the template string
# we need for packing and unpacking the binary C struct flock required for
# fcntl() and then the members of the structures in the sequence they are
# defined in there.
open my $pipe, '-|', $exec_file
or die "Failed to run a compiled program: $!\n";
chomp( $packstr = <$pipe> );
while ( my $line = <$pipe> ) {
chomp $line;
push @member_list, $line;
}
# Make sure we got all information needed
die "Your Perl version does not support the 'q' format for pack() "
. "and unpack()\n" unless defined $packstr;
die "Failed to obtain all needed data about the C struct flock\n"
unless @member_list == 5;
}
###########################################################
# Function for doing the actual fcntl() call: assembles the binary
# structure that must be passed to fcntl() from the File::FcntlLock
# object we get passed, calls it and then modifies the File::FcntlLock
# with the data from the flock structure
sub lock {
my ( $self, $fh, $action ) = @_;
my $buf = $self->pack_flock( );
my $ret = fcntl( $fh, $action, $buf );
if ( $ret ) {
$self->unpack_flock( $buf );
$self->{ errno } = $self->{ error } = undef;
} else {
$self->get_error( $self->{ errno } = $! + 0 );
}
return $ret;
}
###########################################################
# Method for packing the data from the 'flock_struct' into a
# binary blob to be passed to fcntl().
sub pack_flock {
my $self = shift;
my @args;
push @args, $self->{ $_ } for @member_list;
return pack $packstr, @args;
}
###########################################################
# Method for unpacking the binary blob received from a call of
# fcntl() into the 'flock_struct'.
sub unpack_flock {
my ( $self, $data ) = @_;
my @res = unpack $packstr, $data;
$self->{ $_ } = shift @res for @member_list;
}
=cut
1;
# Local variables:
# tab-width: 4
# indent-tabs-mode: nil
# End:
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