ftruncate - PHP code example

PHP Function Ftruncate

php function ftruncate is an inbuilt php function which is used to truncate(shorten) an open file to the specified length. It accepts two parameters, file and size, and returns True on success and False on failure.

You must first open the file you want to truncate using the fopen() function and set the mode to w. Then, call ftruncate with the file pointer and the new size. Finally, close the file with fclose().

The ftruncate function works by comparing the new size to the old one, and if it is smaller, rewinds (decrements) the file pointer to a position before the start of the data and truncates the remaining data to that offset. The original data is still stored on disk, but it can't be accessed as the file pointer is repositioned after the truncate operation.

RFCs and major pull-requests discussed, voted on, and implemented since our last update

Ilija Tovilo and Larry Garfield proposed a new RFC to allow granular visibility conditions for class property set operations (such as assigning a value) to be restricted to private scope only. This would be similar to the __clone() magic method that allows you to clone a class and change its properties.

The RFC was voted on and approved in the 8.3 release of PHP. See the changelog for more details.

ftruncate example

$this->assertFalse(@stream_set_blocking($handle, 1), 'Unable to set to blocking using a local stream wrapper.');
    $this->assertFalse(@stream_set_timeout($handle, 1), 'Unable to set read time out using a local stream wrapper.');
    $this->assertEquals(-1 /*EOF*/, @stream_set_write_buffer($handle, 512), 'Unable to set write buffer using a local stream wrapper.');

    // This will test stream_cast().     $read = [$handle];
    $write = NULL;
    $except = NULL;
    $this->assertEquals(1, stream_select($read, $write, $except, 0), 'Able to cast a stream via stream_select.');

    // This will test stream_truncate().     $this->assertEquals(1, ftruncate($handle, 0), 'Able to truncate a stream via ftruncate().');
    fclose($handle);
    $this->assertEquals(0, filesize($filename), 'Able to truncate a stream.');

    // Cleanup.     unlink($filename);
  }

  /** * Tests the scheme functions. */
  public function testGetValidStreamScheme() {

$this->dumper->setColors($colors);
        }

        if (!$data instanceof Data) {
            $data = $this->cloner->cloneVar($data);
        }
        $data = $data->withRefHandles(false);
        $this->dumper->dump($data);

        $dump = stream_get_contents($this->outputBuffer, -1, 0);
        rewind($this->outputBuffer);
        ftruncate($this->outputBuffer, 0);

        return rtrim($dump);
    }
}

$this->readPipesForOutput(__FUNCTION__, $blocking);
        }
    }

    /** * Clears the process output. * * @return $this */
    public function clearOutput(): static
    {
        ftruncate($this->stdout, 0);
        fseek($this->stdout, 0);
        $this->incrementalOutputOffset = 0;

        return $this;
    }

    /** * Returns the current error output of the process (STDERR). * * @throws LogicException in case the output has been disabled * @throws LogicException In case the process is not started */

try {
                        // Notify the progress callback so that it can e.g. cancel                         // the request if the stream is inactive for too long                         $info['total_time'] = microtime(true) - $info['start_time'];
                        $onProgress();
                    } catch (\Throwable $e) {
                        // no-op                     }
                }
            } elseif ('' !== $data = stream_get_contents($buffer, -1, 0)) {
                rewind($buffer);
                ftruncate($buffer, 0);

                if (null === $e) {
                    $multi->handlesActivity[$i][] = $data;
                }
            }

            if (null !== $e || !$remaining || feof($h)) {
                // Stream completed                 $info['total_time'] = microtime(true) - $info['start_time'];
                $info['starttransfer_time'] = $info['starttransfer_time'] ?: $info['total_time'];

return $body;
    }

    private static function dechunk(string $body): string
    {
        $h = fopen('php://temp', 'w+');
        stream_filter_append($h, 'dechunk', \STREAM_FILTER_WRITE);
        fwrite($h, $body);
        $body = stream_get_contents($h, -1, 0);
        rewind($h);
        ftruncate($h, 0);

        if (fwrite($h, '-') && '' !== stream_get_contents($h, -1, 0)) {
            throw new TransportException('Request body has broken chunked encoding.');
        }

        return $body;
    }

    /** * @throws InvalidArgumentException When an invalid fingerprint is passed */

    private function save(string $key, string $data, bool $overwrite = true): bool
    {
        $path = $this->getPath($key);

        if (!$overwrite && file_exists($path)) {
            return true;
        }

        if (isset($this->locks[$key])) {
            $fp = $this->locks[$key];
            @ftruncate($fp, 0);
            @fseek($fp, 0);
            $len = @fwrite($fp, $data);
            if (\strlen($data) !== $len) {
                @ftruncate($fp, 0);

                return false;
            }
        } else {
            if (!is_dir(\dirname($path)) && false === @mkdir(\dirname($path), 0777, true) && !is_dir(\dirname($path))) {
                return false;
            }

    protected function _filePutContents($file, $string)
    {
        $result = false;
        $f = @fopen($file, 'ab+');
        if ($f) {
            if ($this->_options['file_locking']) @flock($f, LOCK_EX);
            fseek($f, 0);
            ftruncate($f, 0);
            $tmp = @fwrite($f, $string);
            if (!($tmp === FALSE)) {
                $result = true;
            }
            @fclose($f);
        }
        @chmod($file, $this->_options['cache_file_perm']);
        return $result;
    }

    /** * Transform a file name into cache id and return it * * @param string $fileName File name * @return string Cache id */

usleep(Process::TIMEOUT_PRECISION * 1E6);
            }
        }
        foreach ($this->fileHandles as $type => $fileHandle) {
            $data = stream_get_contents($fileHandle, -1, $this->readBytes[$type]);

            if (isset($data[0])) {
                $this->readBytes[$type] += \strlen($data);
                $read[$type] = $data;
            }
            if ($close) {
                ftruncate($fileHandle, 0);
                fclose($fileHandle);
                flock($this->lockHandles[$type], \LOCK_UN);
                fclose($this->lockHandles[$type]);
                unset($this->fileHandles[$type], $this->lockHandles[$type]);
            }
        }

        return $read;
    }

    public function haveReadSupport(): bool
    {

$insertion,
            array( $end_marker ),
            $post_lines
        )
    );

    // Write to the start of the file, and truncate it to that length.     fseek( $fp, 0 );
    $bytes = fwrite( $fp, $new_file_data );

    if ( $bytes ) {
        ftruncate( $fp, ftell( $fp ) );
    }

    fflush( $fp );
    flock( $fp, LOCK_UN );
    fclose( $fp );

    return (bool) $bytes;
}

/** * Updates the htaccess file with the current rules if it is writable. * * Always writes to the file if it exists and is writable to ensure that we * blank out old rules. * * @since 1.5.0 * * @global WP_Rewrite $wp_rewrite WordPress rewrite component. * * @return bool|null True on write success, false on failure. Null in multisite. */

        if (! is_resource($this->fileHandle)) {
            return false;
        }

        if ($this->fingerprint === md5($data)) {
            return ($this->fileNew) ? true : touch($this->filePath . $id);
        }

        if (! $this->fileNew) {
            ftruncate($this->fileHandle, 0);
            rewind($this->fileHandle);
        }

        if (($length = strlen($data)) > 0) {
            $result = null;

            for ($written = 0; $written < $length; $written += $result) {
                if (($result = fwrite($this->fileHandle, substr($data, $written))) === false) {
                    break;
                }
            }

$info['total_time'] -= $info['starttransfer_time'] ?: $info['total_time'];
                $info['starttransfer_time'] = 0.0;
            }

            rewind($this->debugBuffer);
            $info['debug'] = stream_get_contents($this->debugBuffer);
            $waitFor = curl_getinfo($this->handle, \CURLINFO_PRIVATE);

            if ('H' !== $waitFor[0] && 'C' !== $waitFor[0]) {
                curl_setopt($this->handle, \CURLOPT_VERBOSE, false);
                rewind($this->debugBuffer);
                ftruncate($this->debugBuffer, 0);
                $this->finalInfo = $info;
            }
        }

        return null !== $type ? $info[$type] ?? null : $info;
    }

    public function getContent(bool $throw = true): string
    {
        $performing = $this->multi->performing;
        $this->multi->performing = $performing || '_0' === curl_getinfo($this->handle, \CURLINFO_PRIVATE);

throw new \InvalidArgumentException(sprintf('Invalid dump format: "%s".', $format));
        }
        $dumps = [];

        if (!$this->dataCount) {
            return $this->data = [];
        }

        foreach ($this->data as $dump) {
            $dumper->dump($dump['data']->withMaxDepth($maxDepthLimit)->withMaxItemsPerDepth($maxItemsPerDepth));
            $dump['data'] = stream_get_contents($data, -1, 0);
            ftruncate($data, 0);
            rewind($data);
            $dumps[] = $dump;
        }

        return $dumps;
    }

    public function getName(): string
    {
        return 'dump';
    }

  public function stream_set_option($option, $arg1, $arg2) {
    trigger_error('stream_set_option() not supported for local file based stream wrappers', E_USER_WARNING);
    return FALSE;
  }

  /** * {@inheritdoc} */
  public function stream_truncate($new_size) {
    return ftruncate($this->handle, $new_size);
  }

  /** * {@inheritdoc} */
  public function unlink($uri) {
    $this->uri = $uri;
    return $this->getFileSystem()->unlink($this->getLocalPath());
  }

  /** * {@inheritdoc} */