Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Often I have a task to read/write data to/from pipes without perl buffered IO (because same pipes used in select()). AFAIK this should be implemented via sysread/syswrite, and sysread/syswrite are documented to sometimes return less data, than available and sometimes return EINTR (let's talk about blocking pipes for now). So every time I end up with the following wrappers:
# args: ($file, $buffer, $length) # returns data in $buffer and number of bytes read, or undef on EOF sub sysreadfull { my ($file, $len) = ($_[0], $_[2]); my $n = 0; while ($len - $n) { my $i = sysread($file, $_[1], $len - $n, $n); if (defined($i)) { if ($i == 0) { return $n; } else { $n += $i; } } elsif ($!{EINTR}) { redo; } else { return $n ? $n : undef; } } return $n; } # args: ($file, $buffer) # returns number of bytes actually written sub syswritefull { my ($file, $len) = ($_[0], length($_[1])); my $n = 0; while ($len - $n) { my $i = syswrite($file, $_[1], $len - $n, $n); if (defined($i)) { $n += $i; } elsif ($!{EINTR}) { redo; } else { return $n ? $n : undef; } } return $n; }
Question is: It's should be very common problem for everyone who deals with IPC or network programming, why nobody wrote CPAN module with such wrappers? Maybe because there is easier way ? Maybe ":raw" handles? I saw similar code only here (but for non-blocking), but seems it has bug

In reply to sysread/syswrite wrappers by vsespb

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others rifling through the Monastery: (4)
As of 2022-12-01 17:28 GMT
Find Nodes?
    Voting Booth?