Re: bullet proof SLURP file

Do you have control of the process that writes to the file? If so, assure that it implements file locking, and cause it to also create a checksum that is saved in another file alongside the primary file. After writing, verify the checksum matches what got written.

Then the reader can obtain a lock, read the checksum, read the target file, compare, and derive a strong assurance that the entire file was read.

Otherwise, check file size before the read and after the read. Check the mtime before the read and after. If it changed, that's bad. Use the bytes pragma and get the length of the scalar holding the input. Compare that length to the file size detected before the read. And check for eof after the read.

Dave

Comment on Re: bullet proof SLURP file Download Code

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Re^2: bullet proof SLURP file by karlgoethebier (Abbot) on Jan 10, 2018 at 20:19 UTC
Perhaps with something like this?: `#!/usr/bin/env perl use strict; use warnings; use Path::Tiny; use feature qw(say); use open ':encoding(UTF-8)'; my $file = q(data.txt); path($file)->spew_utf8(q(Lorem ipsum kizuaheli)); my $digest = qq($file\.digest); path($digest)->spew_utf8( path($file)->digest ); # path ($digest)->append_utf8("nose"); if ( path($file)->digest ne path($digest)->slurp_utf8 ) { say q(Something went wrong!); } else { my $fh = path($file)->filehandle( { locked => 1 }, "<" ); say <$fh>; } __END__` [download] Not really tested. Just an idea. Best regards, Karl ŤThe Crux of the Biscuit is the Apostropheť `perl -MCrypt::CBC -E 'say Crypt::CBC->new(-key=>'kgb',-cipher=>"Blowfish")->decrypt_hex($ENV{KARL});'`Help	[reply] [d/l] [select]

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Re^2: bullet proof SLURP file
by karlgoethebier (Abbot) on Jan 10, 2018 at 20:19 UTC

Perhaps with something like this?:

#!/usr/bin/env perl

use strict;
use warnings;
use Path::Tiny;
use feature qw(say);
use open ':encoding(UTF-8)';

my $file = q(data.txt);

path($file)->spew_utf8(q(Lorem ipsum kizuaheli));

my $digest = qq($file\.digest);

path($digest)->spew_utf8( path($file)->digest );

# path ($digest)->append_utf8("nose");

if ( path($file)->digest ne path($digest)->slurp_utf8 ) {
    say q(Something went wrong!);
}
else {
    my $fh = path($file)->filehandle( { locked => 1 }, "<" );
    say <$fh>;
}

__END__
[download]

Not really tested. Just an idea.

Best regards, Karl

ŤThe Crux of the Biscuit is the Apostropheť

perl -MCrypt::CBC -E 'say Crypt::CBC->new(-key=>'kgb',-cipher=>"Blowfish")->decrypt_hex($ENV{KARL});'Help

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