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<?php
/**
* Functionatility for line by line reverse reading of a file. It is done by blockwise
* fetching the file from the end and putting the lines into an array.
*
* @author Thomas Graff<thomas.graff@uninett.no>
*
*/
class sspmod_logpeek_File_reverseRead{
// 8192 is max number of octets limited by fread.
private $blockSize;
private $blockStart;
private $fileHandle;
// fileSize may be changed after initial file size check
private $fileSize;
private $fileMtime;
// Array containing file lines
private $content;
// Leftover before first complete line
private $remainder;
// Count read lines from the end
private $readPointer;
/**
* File is checked and file handle to file is opend. But no data is read
* from the file.
*
* @param string $fileUrl Path and filename to file to be read
* @param int $blockSize File read block size in byte
* @return bool Success
*/
public function __construct($fileUrl, $blockSize = 8192){
if(!is_readable($fileUrl)){
return FALSE;
}
$this->blockSize = $blockSize;
$this->content = array();
$this->remainder = '';
$this->readPointer = 0;
$fileInfo = stat($fileUrl);
$this->fileSize = $this->blockStart = $fileInfo['size'];
$this->fileMtime = $fileInfo['mtime'];
if($this->fileSize > 0){
$this->fileHandle = fopen($fileUrl, 'rb');
return TRUE;
}else{
return FALSE;
}
}
public function __destruct(){
if(is_resource($this->fileHandle)){
fclose($this->fileHandle);
}
}
/**
* Fetch chunk of data from file.
* Each time this function is called, will it fetch a chunk
* of data from the file. It starts from the end of the file
* and work towards the beginning of the file.
*
* @return string buffer with datablock.
* Will return bool FALSE when there is no more data to get.
*/
private function readChunk(){
$splits = $this->blockSize;
$this->blockStart -= $splits;
if($this->blockStart < 0){
$splits += $this->blockStart;
$this->blockStart = 0;
}
// Return false if nothing more to read
if($splits === 0){
return FALSE;
}
fseek($this->fileHandle, $this->blockStart, SEEK_SET);
$buff = fread($this->fileHandle, $splits);
// $buff = stream_get_contents($this->fileHandle, $splits, $this->blockStart);
return $buff;
}
/**
* Get one line of data from the file, starting from the end of the file.
*
* @return string One line of data from the file.
* Bool FALSE when there is no more data to get.
*/
public function getPreviousLine(){
if(count($this->content) === 0 || $this->readPointer < 1){
do {
$buff = $this->readChunk();
if($buff !== FALSE){
$eolPos = strpos($buff, "\n");
}else{
// Empty buffer, no more to read.
if(strlen($this->remainder) > 0){
$buff = $this->remainder;
$this->remainder = '';
// Exit from while-loop
break;
}else{
// Remainder also empty.
return FALSE;
}
}
if($eolPos === FALSE){
// No eol found. Make buffer head of remainder and empty buffer.
$this->remainder = $buff . $this->remainder;
$buff = '';
}elseif($eolPos !== 0){
// eol found.
$buff .= $this->remainder;
$this->remainder = substr($buff, 0, $eolPos);
$buff = substr($buff, $eolPos+1);
}elseif($eolPos === 0){
$buff .= $this->remainder;
$buff = substr($buff, 1);
$this->remainder = '';
}
}while(($buff !== FALSE) && ($eolPos === FALSE));
$this->content = explode("\n", $buff);
$this->readPointer = count($this->content);
}
if(count($this->content) > 0){
return $this->content[--$this->readPointer];
}else{
return FALSE;
}
}
private function cutHead(&$haystack, $needle, $exit){
$pos = 0;
$cnt = 0;
// Holder på inntill antall ønskede linjer eller vi ikke finner flere linjer
while($cnt < $exit && ($pos = strpos($haystack, $needle, $pos)) !==false ){
$pos++;
$cnt++;
}
return $pos == false? false: substr($haystack, $pos, strlen($haystack));
}
// FIXME: This function hawe som error, do not use before auditing and testing
public function getTail($lines = 10){
$this->blockStart = $this->fileSize;
$buff1 = Array();
$lastLines = array();
while($this->blockStart){
$buff = $this->readChunk();
if(!$buff)break;
$lines -= substr_count($buff, "\n");
if($lines <= 0)
{
$buff1[] = $this->cutHead($buff, "\n", abs($lines)+1);
break;
}
$buff1[] = $buff;
}
for($i = count($buff1); $i >= 0; $i--){
$lastLines = array_merge($lastLines, explode("\n", $buff1[$i]));
}
return $lastLines;
// return str_replace("\r", '', implode('', array_reverse($buff1)));
}
private function getLineAtPost($pos){
if($pos < 0 || $pos > $this->fileSize){
return FALSE;
}
$seeker = $pos;
fseek($this->fileHandle, $seeker, SEEK_SET);
while($seeker > 0 && fgetc($this->fileHandle) !== "\n"){
fseek($this->fileHandle, --$seeker, SEEK_SET);
}
return rtrim(fgets($this->fileHandle));
}
public function getFirstLine(){
return $this->getLineAtPost(0);
}
public function getLastLine(){
return $this->getLineAtPost($this->fileSize-2);
}
public function getFileSize(){
return $this->fileSize;
}
public function getFileMtime(){
return $this->fileMtime;
}
}
?>
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