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com dot gmail at algofoogle
19 years ago
Re note posted by "salisbm at hotmail dot com":

S_IFDIR is not a single-bit flag. It is a constant that relies on the "S_IFMT" bitmask. This bitmask should be applied to the "mode" parameter before comparing with any of the other "S_IF..." constants, as indicated by stat.h:

#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)

That is, this approach is incorrect:

<?php
define
('S_IFDIR',040000);
if (
$mode & S_IFDIR)
{
/*
incorrect!
format could be S_IFDIR, but also
S_IFBLK, S_IFSOCK, or S_IFWHT.
*/
}
?>

...and should instead be:

<?php
define
('S_IFMT',0170000);
define('S_IFDIR',040000);
if (
S_IFDIR == ($mode & S_IFMT)) { /* ... */ }
?>

As pointed out by "svend at svendtofte dot com", however, there is also the "is_dir" function for this purpose, along with "is_file" and "is_link" to cover the most common format types...

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