I have a file that is sorted using natsort()...(In ascending order)
But actually i want to sort it in descending order..
I mean the last line of document must be first line and vice versa
Pls let me know is there any function or snippet to achive this..
I'm not that good at php, Appreciate all responses irrespective of quality...Thank You
use natsort() and than use function array_reverse().
Also refer link
PHP Grab last 15 lines in txt file
it might help you.
array_reverse will give the contents in descending order
$reverse = array_reverse($array, true);
Whilst not the most efficient approach for a large text file, you could use file, array_reverse and file_put_contents to achieve this as follows...
<?php
// Fetch each line from the file into an array
$fileLines = file('/path/to/text/file.txt');
// Swap the order of the array
$invertedLines = array_reverse($fileLines);
// Write the data back to disk
file_put_contents('/path/to/write/new/file/to.txt', $invertedLines);
?>
...to achieve what you're after.
For longer files:
<?php
function rfopen($path, $mode)
{
$fp = fopen($path, $mode);
fseek($fp, -1, SEEK_END);
if (fgetc($fp) !== PHP_EOL) fseek($fp, 1, SEEK_END);
return $fp;
}
function rfgets($fp, $strip = false)
{
$s = '';
while (true) {
if (fseek($fp, -2, SEEK_CUR) === -1) {
if (!empty($s)) break;
return false;
}
if (($c = fgetc($fp)) === PHP_EOL) break;
$s = $c . $s;
}
if (!$strip) $s .= PHP_EOL;
return $s;
}
$file = '/path/to/your/file.txt';
$src = rfopen($file, 'rb');
$tgt = fopen("$file.rev", 'w');
while ($line = rfgets($src)) {
fwrite($tgt, $line);
}
fclose($src);
fclose($tgt);
// rename("$file.rev", $file);
Replace '/path/to/your/file.txt' with the path to your file.
Uncomment the last line to overwrite your file.
Related
I would like to extract the first x lines of an html page
I know that I can extract the amount of characters with something like this:
file_get_contents('http://xx.xxx.158.239/fin.html' , NULL, NULL, 0, 125);
but what about lines ? like to extract the text from line 1 to line 4? is that possible ?
You can read the file using dedicated method calls instead of the one-for-all file_get_contents():
$fp = fopen('my/file/name', 'r');
for ($i = 0; $i < 4; $i++) {
if (feof($fp)) {
echo 'EOF reached';
break;
}
echo fgets($fp);
}
fclose($fp);
Here's a little code snippet that you might find useful:
$file = 'http://xx.xxx.158.239/fin.html'; // remote or local file
$lines = 3; // how many lines do you want?
if (file_exists($file)) {
$contents = #file_get_contents($file); // suppress errors, esp. for remote files
$head = implode("\n", array_slice(explode("\n", $contents), 0, $lines));
} else {
$head = 'File does not exist';
}
echo $head;
You can use file on a File- or URL-Handle created by fopen to load the content into an array and read only the relevant lines.
To get the content line by line in a loop, you can use fgets.
I'm not sure how to word this so I'll type it out and then edit and answer any questions that come up..
Currently on my local network device (PHP4 based) I'm using this to tail a live system log file: http://commavee.com/2007/04/13/ajax-logfile-tailer-viewer/
This works well and every 1 second it loads an external page (logfile.php) that does a tail -n 100 logfile.log The script doesn't do any buffering so the results it displayes onscreen are the last 100 lines from the log file.
The logfile.php contains :
<? // logtail.php $cmd = "tail -10 /path/to/your/logs/some.log"; exec("$cmd 2>&1", $output);
foreach($output as $outputline) {
echo ("$outputline\n");
}
?>
This part is working well.
I have adapted the logfile.php page to write the $outputline to a new text file, simply using fwrite($fp,$outputline."\n");
Whilst this works I am having issues with duplication in the new file that is created.
Obviously each time tail -n 100 is run produces results, the next time it runs it could produce some of the same lines, as this repeats I can end up with multiple lines of duplication in the new text file.
I can't directly compare the line I'm about to write to previous lines as there could be identical matches.
Is there any way I can compare this current block of 100 lines with the previous block and then only write the lines that are not matching.. Again possible issue that block A & B will contain identical lines that are needed...
Is it possible to update logfile.php to note the position it last tooked at in my logfile and then only read the next 100 lines from there and write those to the new file ?
The log file could be upto 500MB so I don't want to read it all in each time..
Any advice or suggestions welcome..
Thanks
UPDATE # 16:30
I've sort of got this working using :
$file = "/logs/syst.log";
$handle = fopen($file, "r");
if(isset($_SESSION['ftell'])) {
clearstatcache();
fseek($handle, $_SESSION['ftell']);
while ($buffer = fgets($handle)) {
echo $buffer."<br/>";
#ob_flush(); #flush();
}
fclose($handle);
#$_SESSION['ftell'] = ftell($handle);
} else {
fseek($handle, -1024, SEEK_END);
fclose($handle);
#$_SESSION['ftell'] = ftell($handle);
}
This seems to work, but it loads the entire file first and then just the updates.
How would I get it start with the last 50 lines and then just the updates ?
Thanks :)
UPDATE 04/06/2013
Whilst this works it's very slow with large files.
I've tried this code and it seems faster, but it doesn't just read from where it left off.
function last_lines($path, $line_count, $block_size = 512){
$lines = array();
// we will always have a fragment of a non-complete line
// keep this in here till we have our next entire line.
$leftover = "";
$fh = fopen($path, 'r');
// go to the end of the file
fseek($fh, 0, SEEK_END);
do{
// need to know whether we can actually go back
// $block_size bytes
$can_read = $block_size;
if(ftell($fh) < $block_size){
$can_read = ftell($fh);
}
// go back as many bytes as we can
// read them to $data and then move the file pointer
// back to where we were.
fseek($fh, -$can_read, SEEK_CUR);
$data = fread($fh, $can_read);
$data .= $leftover;
fseek($fh, -$can_read, SEEK_CUR);
// split lines by \n. Then reverse them,
// now the last line is most likely not a complete
// line which is why we do not directly add it, but
// append it to the data read the next time.
$split_data = array_reverse(explode("\n", $data));
$new_lines = array_slice($split_data, 0, -1);
$lines = array_merge($lines, $new_lines);
$leftover = $split_data[count($split_data) - 1];
}
while(count($lines) < $line_count && ftell($fh) != 0);
if(ftell($fh) == 0){
$lines[] = $leftover;
}
fclose($fh);
// Usually, we will read too many lines, correct that here.
return array_slice($lines, 0, $line_count);
}
Any way this can be amend so it will read from the last known position.. ?
Thanks
Introduction
You can tail a file by tracking the last position;
Example
$file = __DIR__ . "/a.log";
$tail = new TailLog($file);
$data = $tail->tail(100) ;
// Save $data to new file
TailLog is a simple class i wrote for this task here is a simple example to show its actually tailing the file
Simple Test
$file = __DIR__ . "/a.log";
$tail = new TailLog($file);
// Some Random Data
$data = array_chunk(range("a", "z"), 3);
// Write Log
file_put_contents($file, implode("\n", array_shift($data)));
// First Tail (2) Run
print_r($tail->tail(2));
// Run Tail (2) Again
print_r($tail->tail(2));
// Write Another data to Log
file_put_contents($file, "\n" . implode("\n", array_shift($data)), FILE_APPEND);
// Call Tail Again after writing Data
print_r($tail->tail(2));
// See the full content
print_r(file_get_contents($file));
Output
// First Tail (2) Run
Array
(
[0] => c
[1] => b
)
// Run Tail (2) Again
Array
(
)
// Call Tail Again after writing Data
Array
(
[0] => f
[1] => e
)
// See the full content
a
b
c
d
e
f
Real Time Tailing
while(true) {
$data = $tail->tail(100);
// write data to another file
sleep(5);
}
Note: Tailing 100 lines does not mean it would always return 100 lines. It would return new lines added 100 is just the maximum number of lines to return. This might not be efficient where you have heavy logging of more than 100 line per sec is there is any
Tail Class
class TailLog {
private $file;
private $data;
private $timeout = 5;
private $lock;
function __construct($file) {
$this->file = $file;
$this->lock = new TailLock($file);
}
public function tail($lines) {
$pos = - 2;
$t = $lines;
$fp = fopen($this->file, "r");
$break = false;
$line = "";
$text = array();
while($t > 0) {
$c = "";
// Seach for End of line
while($c != "\n" && $c != PHP_EOL) {
if (fseek($fp, $pos, SEEK_END) == - 1) {
$break = true;
break;
}
if (ftell($fp) < $this->lock->getPosition()) {
break;
}
$c = fgetc($fp);
$pos --;
}
if (ftell($fp) < $this->lock->getPosition()) {
break;
}
$t --;
$break && rewind($fp);
$text[$lines - $t - 1] = fgets($fp);
if ($break) {
break;
}
}
// Move to end
fseek($fp, 0, SEEK_END);
// Save Position
$this->lock->save(ftell($fp));
// Close File
fclose($fp);
return array_map("trim", $text);
}
}
Tail Lock
class TailLock {
private $file;
private $lock;
private $data;
function __construct($file) {
$this->file = $file;
$this->lock = $file . ".tail";
touch($this->lock);
if (! is_file($this->lock))
throw new Exception("can't Create Lock File");
$this->data = json_decode(file_get_contents($this->lock));
// Check if file is valida json
// Check if Data in the original files as not be delete
// You expect data to increate not decrease
if (! $this->data || $this->data->size > filesize($this->file)) {
$this->reset($file);
}
}
function getPosition() {
return $this->data->position;
}
function reset() {
$this->data = new stdClass();
$this->data->size = filesize($this->file);
$this->data->modification = filemtime($this->file);
$this->data->position = 0;
$this->update();
}
function save($pos) {
$this->data = new stdClass();
$this->data->size = filesize($this->file);
$this->data->modification = filemtime($this->file);
$this->data->position = $pos;
$this->update();
}
function update() {
return file_put_contents($this->lock, json_encode($this->data, 128));
}
}
Not really clear on how you want to use the output but would something like this work ....
$dat = file_get_contents("tracker.dat");
$fp = fopen("/logs/syst.log", "r");
fseek($fp, $dat, SEEK_SET);
ob_start();
// alternatively you can do a while fgets if you want to interpret the file or do something
fpassthru($fp);
$pos = ftell($fp);
fclose($fp);
echo nl2br(ob_get_clean());
file_put_contents("tracker.dat", ftell($fp));
tracker.dat is just a text file that contains where the read position position was from the previous run. I'm just seeking to that position and piping the rest to the output buffer.
Use tail -c <number of bytes, instead of number of lines, and then check the file size. The rough idea is:
$old_file_size = 0;
$max_bytes = 512;
function last_lines($path) {
$new_file_size = filesize($path);
$pending_bytes = $new_file_size - $old_file_size;
if ($pending_bytes > $max_bytes) $pending_bytes = $max_bytes;
exec("tail -c " + $pending_bytes + " /path/to/your_log", $output);
$old_file_size = $new_file_size;
return $output;
}
The advantage is that you can do away with all the special processing stuff, and get good performance. The disadvantage is that you have to manually split the output into lines, and probably you could end up with unfinished lines. But this isn't a big deal, you can easily work around by omitting the last line alone from the output (and appropriately subtracting the last line number of bytes from old_file_size).
I've searched for an answer for quite a while, and haven't found anything that works correctly.
I have log files, some reaching 100MB in size, around 140,000 lines of text.
With PHP, I am trying to get the last 500 lines of the file.
How would I get the 500 lines? With most functions, the file is read into memory, and that isn't a plausible case for this matter. I would preferably stay away from executing system commands.
If you are on a 'nix machine, you should be able to use shell escaping and the tool 'tail'.
It's been a while, but something like this:
$lastLines = `tail -n 500`;
notice the use of tick marks, which executes the string in BASH or similar and returns the results.
I wrote this function which seems to work quite nicely to me. It returns an array of lines just like file. If you want it to return a string like file_get_contents, then just change the return statement to return implode('', array_reverse($lines));:
function file_get_tail($filename, $num_lines = 10){
$file = fopen($filename, "r");
fseek($file, -1, SEEK_END);
for ($line = 0, $lines = array(); $line < $num_lines && false !== ($char = fgetc($file));) {
if($char === "\n"){
if(isset($lines[$line])){
$lines[$line][] = $char;
$lines[$line] = implode('', array_reverse($lines[$line]));
$line++;
}
}else
$lines[$line][] = $char;
fseek($file, -2, SEEK_CUR);
}
fclose($file);
if($line < $num_lines)
$lines[$line] = implode('', array_reverse($lines[$line]));
return array_reverse($lines);
}
Example:
file_get_tail('filename.txt', 500);
If you want to do it in PHP:
<?php
/**
Read last N lines from file.
#param $filename string path to file. must support seeking
#param $n int number of lines to get.
#return array up to $n lines of text
*/
function tail($filename, $n)
{
$buffer_size = 1024;
$fp = fopen($filename, 'r');
if (!$fp) return array();
fseek($fp, 0, SEEK_END);
$pos = ftell($fp);
$input = '';
$line_count = 0;
while ($line_count < $n + 1)
{
// read the previous block of input
$read_size = $pos >= $buffer_size ? $buffer_size : $pos;
fseek($fp, $pos - $read_size, SEEK_SET);
// prepend the current block, and count the new lines
$input = fread($fp, $read_size).$input;
$line_count = substr_count(ltrim($input), "\n");
// if $pos is == 0 we are at start of file
$pos -= $read_size;
if (!$pos) break;
}
fclose($fp);
// return the last 50 lines found
return array_slice(explode("\n", rtrim($input)), -$n);
}
var_dump(tail('/var/log/syslog', 50));
This is largely untested, but should be enough for you to get a fully working solution.
The buffer size is 1024, but can be changed to be bigger or larger. (You could even dynamically set it based on $n * estimate of line length.) This should be better than seeking character by character, although it does mean we need to do substr_count() to look for new lines.
Can I read a file in PHP from my end, for example if I want to read last 10-20 lines?
And, as I read, if the size of the file is more than 10mbs I start getting errors.
How can I prevent this error?
For reading a normal file, we use the code :
if ($handle) {
while (($buffer = fgets($handle, 4096)) !== false) {
$i1++;
$content[$i1]=$buffer;
}
if (!feof($handle)) {
echo "Error: unexpected fgets() fail\n";
}
fclose($handle);
}
My file might go over 10mbs, but I just need to read the last few lines. How do I do it?
Thanks
You can use fopen and fseek to navigate in file backwards from end. For example
$fp = #fopen($file, "r");
$pos = -2;
while (fgetc($fp) != "\n") {
fseek($fp, $pos, SEEK_END);
$pos = $pos - 1;
}
$lastline = fgets($fp);
It's not pure PHP, but the common solution is to use the tac command which is the revert of cat and loads the file in reverse. Use exec() or passthru() to run it on the server and then read the results. Example usage:
<?php
$myfile = 'myfile.txt';
$command = "tac $myfile > /tmp/myfilereversed.txt";
exec($command);
$currentRow = 0;
$numRows = 20; // stops after this number of rows
$handle = fopen("/tmp/myfilereversed.txt", "r");
while (!feof($handle) && $currentRow <= $numRows) {
$currentRow++;
$buffer = fgets($handle, 4096);
echo $buffer."<br>";
}
fclose($handle);
?>
It depends how you interpret "can".
If you wonder whether you can do this directly (with PHP function) without reading the all the preceding lines, then the answer is: No, you cannot.
A line ending is an interpretation of the data and you can only know where they are, if you actually read the data.
If it is a really big file, I'd not do that though.
It would be better if you were to scan the file starting from the end, and gradually read blocks from the end to the file.
Update
Here's a PHP-only way to read the last n lines of a file without reading through all of it:
function last_lines($path, $line_count, $block_size = 512){
$lines = array();
// we will always have a fragment of a non-complete line
// keep this in here till we have our next entire line.
$leftover = "";
$fh = fopen($path, 'r');
// go to the end of the file
fseek($fh, 0, SEEK_END);
do{
// need to know whether we can actually go back
// $block_size bytes
$can_read = $block_size;
if(ftell($fh) < $block_size){
$can_read = ftell($fh);
}
// go back as many bytes as we can
// read them to $data and then move the file pointer
// back to where we were.
fseek($fh, -$can_read, SEEK_CUR);
$data = fread($fh, $can_read);
$data .= $leftover;
fseek($fh, -$can_read, SEEK_CUR);
// split lines by \n. Then reverse them,
// now the last line is most likely not a complete
// line which is why we do not directly add it, but
// append it to the data read the next time.
$split_data = array_reverse(explode("\n", $data));
$new_lines = array_slice($split_data, 0, -1);
$lines = array_merge($lines, $new_lines);
$leftover = $split_data[count($split_data) - 1];
}
while(count($lines) < $line_count && ftell($fh) != 0);
if(ftell($fh) == 0){
$lines[] = $leftover;
}
fclose($fh);
// Usually, we will read too many lines, correct that here.
return array_slice($lines, 0, $line_count);
}
Following snippet worked for me.
$file = popen("tac $filename",'r');
while ($line = fgets($file)) {
echo $line;
}
Reference: http://laughingmeme.org/2008/02/28/reading-a-file-backwards-in-php/
If your code is not working and reporting an error you should include the error in your posts!
The reason you are getting an error is because you are trying to store the entire contents of the file in PHP's memory space.
The most effiicent way to solve the problem would be as Greenisha suggests and seek to the end of the file then go back a bit. But Greenisha's mecanism for going back a bit is not very efficient.
Consider instead the method for getting the last few lines from a stream (i.e. where you can't seek):
while (($buffer = fgets($handle, 4096)) !== false) {
$i1++;
$content[$i1]=$buffer;
unset($content[$i1-$lines_to_keep]);
}
So if you know that your max line length is 4096, then you would:
if (4096*lines_to_keep<filesize($input_file)) {
fseek($fp, -4096*$lines_to_keep, SEEK_END);
}
Then apply the loop I described previously.
Since C has some more efficient methods for dealing with byte streams, the fastest solution (on a POSIX/Unix/Linux/BSD) system would be simply:
$last_lines=system("last -" . $lines_to_keep . " filename");
For Linux you can do
$linesToRead = 10;
exec("tail -n{$linesToRead} {$myFileName}" , $content);
You will get an array of lines in $content variable
Pure PHP solution
$f = fopen($myFileName, 'r');
$maxLineLength = 1000; // Real maximum length of your records
$linesToRead = 10;
fseek($f, -$maxLineLength*$linesToRead, SEEK_END); // Moves cursor back from the end of file
$res = array();
while (($buffer = fgets($f, $maxLineLength)) !== false) {
$res[] = $buffer;
}
$content = array_slice($res, -$linesToRead);
If you know about how long the lines are, you can avoid a lot of the black magic and just grab a chunk of the end of the file.
I needed the last 15 lines from a very large log file, and altogether they were about 3000 characters. So I just grab the last 8000 bytes to be safe, then read the file as normal and take what I need from the end.
$fh = fopen($file, "r");
fseek($fh, -8192, SEEK_END);
$lines = array();
while($lines[] = fgets($fh)) {}
This is possibly even more efficient than the highest rated answer, which reads the file character by character, compares each character, and splits based on newline characters.
Here is another solution. It doesn't have line length control in fgets(), you can add it.
/* Read file from end line by line */
$fp = fopen( dirname(__FILE__) . '\\some_file.txt', 'r');
$lines_read = 0;
$lines_to_read = 1000;
fseek($fp, 0, SEEK_END); //goto EOF
$eol_size = 2; // for windows is 2, rest is 1
$eol_char = "\r\n"; // mac=\r, unix=\n
while ($lines_read < $lines_to_read) {
if (ftell($fp)==0) break; //break on BOF (beginning...)
do {
fseek($fp, -1, SEEK_CUR); //seek 1 by 1 char from EOF
$eol = fgetc($fp) . fgetc($fp); //search for EOL (remove 1 fgetc if needed)
fseek($fp, -$eol_size, SEEK_CUR); //go back for EOL
} while ($eol != $eol_char && ftell($fp)>0 ); //check EOL and BOF
$position = ftell($fp); //save current position
if ($position != 0) fseek($fp, $eol_size, SEEK_CUR); //move for EOL
echo fgets($fp); //read LINE or do whatever is needed
fseek($fp, $position, SEEK_SET); //set current position
$lines_read++;
}
fclose($fp);
Well while searching for the same thing, I can across the following and thought it might be useful to others as well so sharing it here:
/* Read file from end line by line */
function tail_custom($filepath, $lines = 1, $adaptive = true) {
// Open file
$f = #fopen($filepath, "rb");
if ($f === false) return false;
// Sets buffer size, according to the number of lines to retrieve.
// This gives a performance boost when reading a few lines from the file.
if (!$adaptive) $buffer = 4096;
else $buffer = ($lines < 2 ? 64 : ($lines < 10 ? 512 : 4096));
// Jump to last character
fseek($f, -1, SEEK_END);
// Read it and adjust line number if necessary
// (Otherwise the result would be wrong if file doesn't end with a blank line)
if (fread($f, 1) != "\n") $lines -= 1;
// Start reading
$output = '';
$chunk = '';
// While we would like more
while (ftell($f) > 0 && $lines >= 0) {
// Figure out how far back we should jump
$seek = min(ftell($f), $buffer);
// Do the jump (backwards, relative to where we are)
fseek($f, -$seek, SEEK_CUR);
// Read a chunk and prepend it to our output
$output = ($chunk = fread($f, $seek)) . $output;
// Jump back to where we started reading
fseek($f, -mb_strlen($chunk, '8bit'), SEEK_CUR);
// Decrease our line counter
$lines -= substr_count($chunk, "\n");
}
// While we have too many lines
// (Because of buffer size we might have read too many)
while ($lines++ < 0) {
// Find first newline and remove all text before that
$output = substr($output, strpos($output, "\n") + 1);
}
// Close file and return
fclose($f);
return trim($output);
}
As Einstein said every thing should be made as simple as possible but no simpler. At this point you are in need of a data structure, a LIFO data structure or simply put a stack.
A more complete example of the "tail" suggestion above is provided here. This seems to be a simple and efficient method -- thank-you. Very large files should not be an issue and a temporary file is not required.
$out = array();
$ret = null;
// capture the last 30 files of the log file into a buffer
exec('tail -30 ' . $weatherLog, $buf, $ret);
if ( $ret == 0 ) {
// process the captured lines one at a time
foreach ($buf as $line) {
$n = sscanf($line, "%s temperature %f", $dt, $t);
if ( $n > 0 ) $temperature = $t;
$n = sscanf($line, "%s humidity %f", $dt, $h);
if ( $n > 0 ) $humidity = $h;
}
printf("<tr><th>Temperature</th><td>%0.1f</td></tr>\n",
$temperature);
printf("<tr><th>Humidity</th><td>%0.1f</td></tr>\n", $humidity);
}
else { # something bad happened }
In the above example, the code reads 30 lines of text output and displays the last temperature and humidity readings in the file (that's why the printf's are outside of the loop, in case you were wondering). The file is filled by an ESP32 which adds to the file every few minutes even when the sensor reports only nan. So thirty lines gets plenty of readings so it should never fail. Each reading includes the date and time so in the final version the output will include the time the reading was taken.
This is what I have so far:
<?php
$file = "18201010338AM16390621000846.png";
$test = file_get_contents($file, FILE_BINARY);
echo str_replace("\n","<br>",$test);
?>
The output is sorta what I want, but I really only need lines 3-7 (inclusively). This is what the output looks like now: http://silentnoobs.com/pbss/collector/test.php. I am trying to get the data from "PunkBuster Screenshot (±) AAO Bridge Crossing" to "Resulting: w=394 X h=196 sample=2". I think it'd be fairly straight forward to read through the file, and store each line in an array, line[0] would need to be "PunkBuster Screenshot (±) AAO Bridge Crossing", and so on. All those lines are subject to change, so I can't just search for something finite.
I've tried for a few days now, and it doesn't help much that I'm poor at php.
The PNG file format defines that a PNG document is split up into multiple chunks of data. You must therefore navigate your way to the chunk you desire.
The data you want to extract seem to be defined in a tEXt chunk. I've written the following class to allow you to extract chunks from PNG files.
class PNG_Reader
{
private $_chunks;
private $_fp;
function __construct($file) {
if (!file_exists($file)) {
throw new Exception('File does not exist');
}
$this->_chunks = array ();
// Open the file
$this->_fp = fopen($file, 'r');
if (!$this->_fp)
throw new Exception('Unable to open file');
// Read the magic bytes and verify
$header = fread($this->_fp, 8);
if ($header != "\x89PNG\x0d\x0a\x1a\x0a")
throw new Exception('Is not a valid PNG image');
// Loop through the chunks. Byte 0-3 is length, Byte 4-7 is type
$chunkHeader = fread($this->_fp, 8);
while ($chunkHeader) {
// Extract length and type from binary data
$chunk = #unpack('Nsize/a4type', $chunkHeader);
// Store position into internal array
if ($this->_chunks[$chunk['type']] === null)
$this->_chunks[$chunk['type']] = array ();
$this->_chunks[$chunk['type']][] = array (
'offset' => ftell($this->_fp),
'size' => $chunk['size']
);
// Skip to next chunk (over body and CRC)
fseek($this->_fp, $chunk['size'] + 4, SEEK_CUR);
// Read next chunk header
$chunkHeader = fread($this->_fp, 8);
}
}
function __destruct() { fclose($this->_fp); }
// Returns all chunks of said type
public function get_chunks($type) {
if ($this->_chunks[$type] === null)
return null;
$chunks = array ();
foreach ($this->_chunks[$type] as $chunk) {
if ($chunk['size'] > 0) {
fseek($this->_fp, $chunk['offset'], SEEK_SET);
$chunks[] = fread($this->_fp, $chunk['size']);
} else {
$chunks[] = '';
}
}
return $chunks;
}
}
You may use it as such to extract your desired tEXt chunk as such:
$file = '18201010338AM16390621000846.png';
$png = new PNG_Reader($file);
$rawTextData = $png->get_chunks('tEXt');
$metadata = array();
foreach($rawTextData as $data) {
$sections = explode("\0", $data);
if($sections > 1) {
$key = array_shift($sections);
$metadata[$key] = implode("\0", $sections);
} else {
$metadata[] = $data;
}
}
<?php
$fp = fopen('18201010338AM16390621000846.png', 'rb');
$sig = fread($fp, 8);
if ($sig != "\x89PNG\x0d\x0a\x1a\x0a")
{
print "Not a PNG image";
fclose($fp);
die();
}
while (!feof($fp))
{
$data = unpack('Nlength/a4type', fread($fp, 8));
if ($data['type'] == 'IEND') break;
if ($data['type'] == 'tEXt')
{
list($key, $val) = explode("\0", fread($fp, $data['length']));
echo "<h1>$key</h1>";
echo nl2br($val);
fseek($fp, 4, SEEK_CUR);
}
else
{
fseek($fp, $data['length'] + 4, SEEK_CUR);
}
}
fclose($fp);
?>
It assumes a basically well formed PNG file.
I found this problem a few days ago, so I made a library to extract the metadata (Exif, XMP and GPS) of a PNG in PHP, 100% native, I hope it helps. :) PNGMetadata
How about:
http://www.php.net/manual/en/function.getimagesize.php