source: trunk/essentials/dev-lang/perl/t/op/sysio.t

#!./perl

print "1..42\n";

chdir('op') || chdir('t/op') || die "sysio.t: cannot look for myself: $!";
@INC = '../../lib';

open(I, 'sysio.t') || die "sysio.t: cannot find myself: $!";

$reopen = ($^O eq 'VMS' ||
           $^O eq 'os2' ||
           $^O eq 'MSWin32' ||
           $^O eq 'NetWare' ||
           $^O eq 'dos' ||
           $^O eq 'mpeix');

$x = 'abc';

# should not be able to do negative lengths
eval { sysread(I, $x, -1) };
print 'not ' unless ($@ =~ /^Negative length /);
print "ok 1\n";

# $x should be intact
print 'not ' unless ($x eq 'abc');
print "ok 2\n";

# should not be able to read before the buffer
eval { sysread(I, $x, 1, -4) };
print 'not ' unless ($x eq 'abc');
print "ok 3\n";

# $x should be intact
print 'not ' unless ($x eq 'abc');
print "ok 4\n";

$a ='0123456789';

# default offset 0
print 'not ' unless(sysread(I, $a, 3) == 3);
print "ok 5\n";

# $a should be as follows
print 'not ' unless ($a eq '#!.');
print "ok 6\n";

# reading past the buffer should zero pad
print 'not ' unless(sysread(I, $a, 2, 5) == 2);
print "ok 7\n";

# the zero pad should be seen now
print 'not ' unless ($a eq "#!.\0\0/p");
print "ok 8\n";

# try changing the last two characters of $a
print 'not ' unless(sysread(I, $a, 3, -2) == 3);
print "ok 9\n";

# the last two characters of $a should have changed (into three)
print 'not ' unless ($a eq "#!.\0\0erl");
print "ok 10\n";