Recipe 19.13 Program: Web Server Directory Listing
The web-ls.php
program shown in Example 19-4 provides a view of the
files inside your web server's document root,
formatted like the output of the Unix command
ls. Filenames are linked so that you can
download each file, and directory names are linked so that you can
browse in each directory, as shown in Figure 19-1.
Most lines in Example 19-4 are devoted to building an
easy-to-read representation of the file's
permissions, but the guts of the program are in the
while loop at the end. The $d->read(
)
method gets the name of each file in
the directory. Then, lstat( ) retrieves
information about that file, and printf(
) prints
out the formatted information about that file.
The mode_string( )
functions and the constants it uses
turn the octal representation of a file's mode
(e.g., 35316) into an easier-to-read string (e.g.,
-rwsrw-r--).
Example 19-4. web-ls.php /* Bit masks for determining file permissions and type. The names and values
* listed below are POSIX-compliant, individual systems may have their own
* extensions.
*/
define('S_IFMT',0170000); // mask for all types
define('S_IFSOCK',0140000); // type: socket
define('S_IFLNK',0120000); // type: symbolic link
define('S_IFREG',0100000); // type: regular file
define('S_IFBLK',0060000); // type: block device
define('S_IFDIR',0040000); // type: directory
define('S_IFCHR',0020000); // type: character device
define('S_IFIFO',0010000); // type: fifo
define('S_ISUID',0004000); // set-uid bit
define('S_ISGID',0002000); // set-gid bit
define('S_ISVTX',0001000); // sticky bit
define('S_IRWXU',00700); // mask for owner permissions
define('S_IRUSR',00400); // owner: read permission
define('S_IWUSR',00200); // owner: write permission
define('S_IXUSR',00100); // owner: execute permission
define('S_IRWXG',00070); // mask for group permissions
define('S_IRGRP',00040); // group: read permission
define('S_IWGRP',00020); // group: write permission
define('S_IXGRP',00010); // group: execute permission
define('S_IRWXO',00007); // mask for others permissions
define('S_IROTH',00004); // others: read permission
define('S_IWOTH',00002); // others: write permission
define('S_IXOTH',00001); // others: execute permission
/* mode_string() is a helper function that takes an octal mode and returns
* a ten character string representing the file type and permissions that
* correspond to the octal mode. This is a PHP version of the mode_string()
* function in the GNU fileutils package.
*/
function mode_string($mode) {
$s = array();
// set type letter
if (($mode & S_IFMT) == S_IFBLK) {
$s[0] = 'b';
} elseif (($mode & S_IFMT) == S_IFCHR) {
$s[0] = 'c';
} elseif (($mode & S_IFMT) == S_IFDIR) {
$s[0] = 'd';
} elseif (($mode & S_IFMT) == S_IFREG) {
$s[0] = '-';
} elseif (($mode & S_IFMT) == S_IFIFO) {
$s[0] = 'p';
} elseif (($mode & S_IFMT) == S_IFLNK) {
$s[0] = 'l';
} elseif (($mode & S_IFMT) == S_IFSOCK) {
$s[0] = 's';
}
// set user permissions
$s[1] = $mode & S_IRUSR ? 'r' : '-';
$s[2] = $mode & S_IWUSR ? 'w' : '-';
$s[3] = $mode & S_IXUSR ? 'x' : '-';
// set group permissions
$s[4] = $mode & S_IRGRP ? 'r' : '-';
$s[5] = $mode & S_IWGRP ? 'w' : '-';
$s[6] = $mode & S_IXGRP ? 'x' : '-';
// set other permissions
$s[7] = $mode & S_IROTH ? 'r' : '-';
$s[8] = $mode & S_IWOTH ? 'w' : '-';
$s[9] = $mode & S_IXOTH ? 'x' : '-';
// adjust execute letters for set-uid, set-gid, and sticky
if ($mode & S_ISUID) {
if ($s[3] != 'x') {
// set-uid but not executable by owner
$s[3] = 'S';
} else {
$s[3] = 's';
}
}
if ($mode & S_ISGID) {
if ($s[6] != 'x') {
// set-gid but not executable by group
$s[6] = 'S';
} else {
$s[6] = 's';
}
}
if ($mode & S_ISVTX) {
if ($s[9] != 'x') {
// sticky but not executable by others
$s[9] = 'T';
} else {
$s[9] = 't';
}
}
// return formatted string
return join('',$s);
}
// Start at the document root if not specified
if (isset($_REQUEST['dir'])) {
$dir = $_REQUEST['dir'];
} else {
$dir = '';
}
// locate $dir in the filesystem
$real_dir = realpath($_SERVER['DOCUMENT_ROOT'].$dir);
// make sure $real_dir is inside document root
if (! preg_match('/^'.preg_quote($_SERVER['DOCUMENT_ROOT'],'/').'/',
$real_dir)) {
die("$dir is not inside the document root");
}
// canonicalize $dir by removing the document root from its beginning
$dir = substr_replace($real_dir,'',0,strlen($_SERVER['DOCUMENT_ROOT']));
// are we opening a directory?
if (! is_dir($real_dir)) {
die("$real_dir is not a directory");
}
// open the specified directory
$d = dir($real_dir) or die("can't open $real_dir: $php_errormsg");
print '<table>';
// read each entry in the directory
while (false !== ($f = $d->read())) {
// get information about this file
$s = lstat($d->path.'/'.$f);
// translate uid into user name
$user_info = posix_getpwuid($s['uid']);
// translate gid into group name
$group_info = posix_getgrgid($s['gid']);
// format the date for readability
$date = strftime('%b %e %H:%M',$s['mtime']);
// translate the octal mode into a readable string
$mode = mode_string($s['mode']);
$mode_type = substr($mode,0,1);
if (($mode_type == 'c') || ($mode_type == 'b')) {
/* if it's a block or character device, print out the major and
* minor device type instead of the file size */
$major = ($s['rdev'] >> 8) & 0xff;
$minor = $s['rdev'] & 0xff;
$size = sprintf('%3u, %3u',$major,$minor);
} else {
$size = $s['size'];
}
// format the <a href=""> around the filename
// no link for the current directory
if ('.' == $f) {
$href = $f;
} else {
// don't include the ".." in the parent directory link
if ('..' == $f) {
$href = urlencode(dirname($dir));
} else {
$href = urlencode($dir) . '/' . urlencode($f);
}
/* everything but "/" should be urlencoded */
$href = str_replace('%2F','/',$href);
// browse other directories with web-ls
if (is_dir(realpath($d->path . '/' . $f))) {
$href = sprintf('<a href="%s?dir=%s">%s</a>',
$_SERVER['PHP_SELF'],$href,$f);
} else {
// link to files to download them
$href= sprintf('<a href="%s">%s</a>',$href,$f);
}
// if it's a link, show the link target, too
if ('l' == $mode_type) {
$href .= ' -> ' . readlink($d->path.'/'.$f);
}
}
// print out the appropriate info for this file
printf('<tr><td>%s</td><td>%3u</td><td align="right">%s</td>
<td align="right">%s</td><td align="right">%s</td>
<td align="right">%s</td><td>%s</td></tr>',
$mode, // formatted mode string
$s['nlink'], // number of links to this file
$user_info['name'], // owner's user name
$group_info['name'], // group name
$size, // file size (or device numbers)
$date, // last modified date and time
$href); // link to browse or download
}
print '</table>';
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