流封装与文件系统

$h = fopen('php://memory', 'r+');   // 内存流
fwrite($h, 'hello world');
rewind($h);                          // 指针回到开头
echo fread($h, 5);                   // "hello"
echo ftell($h);                      // 5
fclose($h);

// 一个例子串起三件事：网络下载 → gzip 解压 → base64 解码
$raw = file_get_contents('https://example.com/data.txt.gz');
$text = gzdecode($raw);
$json = base64_decode($text);

file_get_contents('php://input');   // 原始请求体（POST 原始数据）
fopen('php://stdout', 'w');         // 标准输出（CLI）
$tmp = fopen('php://temp', 'r+');   // 内存/临时文件混合（超过阈值自动落盘）
$mem = fopen('php://memory', 'r+'); // 纯内存

$ctx = stream_context_create([
    'http' => [
        'method'  => 'POST',
        'header'  => "Content-Type: application/json\r\n",
        'content' => json_encode(['q' => 'php']),
        'timeout' => 5,               // 秒
        'ignore_errors' => true,      // 4xx/5xx 也返回 body
    ],
]);

$resp = file_get_contents('https://api.example.com/search', false, $ctx);

<?php
final class MemoryWrapper
{
    public $context;
    private string $buffer = '';
    private int $pos = 0;

    public function stream_open(string $path, string $mode, int $options, ?string &$opened): bool
    {
        return true;
    }

    public function stream_read(int $count): string
    {
        $chunk = substr($this->buffer, $this->pos, $count);
        $this->pos += strlen($chunk);
        return $chunk;
    }

    public function stream_write(string $data): int
    {
        $this->buffer = substr($this->buffer, 0, $this->pos) . $data
                      . substr($this->buffer, $this->pos + strlen($data));
        $this->pos += strlen($data);
        return strlen($data);
    }

    public function stream_tell(): int { return $this->pos; }
    public function stream_seek(int $offset, int $whence): bool { /* ... */ return true; }
    public function stream_eof(): bool { return $this->pos >= strlen($this->buffer); }
    public function stream_stat(): array { return []; }
}

stream_wrapper_register('mem', MemoryWrapper::class);
file_put_contents('mem://test', 'hello');
echo file_get_contents('mem://test');   // "hello"

// 读时自动解压
$h = fopen('compress.zlib://file.gz', 'r');
// 等价于附加 zlib.inflate 过滤器

// 写时自动压缩
$out = fopen('out.gz', 'w');
stream_filter_append($out, 'zlib.deflate', STREAM_FILTER_WRITE);
fwrite($out, str_repeat('data', 1000));
fclose($out);

final class UpperFilter extends php_user_filter
{
    public function filter($in, $out, &$consumed, bool $closing): int
    {
        while ($bucket = stream_bucket_make_writeable($in)) {
            $bucket->data = strtoupper($bucket->data);
            $consumed += $bucket->datalen;
            stream_bucket_append($out, $bucket);
        }
        return PSFS_PASS_ON;
    }
}

stream_filter_register('app.upper', UpperFilter::class);
$h = fopen('php://temp', 'r+');
stream_filter_append($h, 'app.upper', STREAM_FILTER_WRITE);
fwrite($h, 'hello');
rewind($h);
echo stream_get_contents($h);   // "HELLO"

// 坏：1GB 文件一次性进内存
$data = file_get_contents('huge.log');    // 可能 OOM

// 好：分块读
$h = fopen('huge.log', 'rb');
try {
    while (!feof($h)) {
        $chunk = fread($h, 8192);          // 每次 8KB
        process($chunk);
    }
} finally {
    fclose($h);
}

function lines(string $file): Generator
{
    $h = fopen($file, 'rb');
    try {
        while (($line = fgets($h)) !== false) {
            yield $line;
        }
    } finally {
        fclose($h);   // 即使提前 break 也会关闭
    }
}

// 下载：不占 PHP 内存
header('Content-Type: application/octet-stream');
header('Content-Length: ' . filesize($path));
readfile($path);   // 内核层面搬运

$h = fopen('big.bin', 'rb');
fseek($h, 1024 * 1024, SEEK_SET);   // 跳到第 1MB
$block = fread($h, 512);

$h = fopen('counter.txt', 'c+');
if (flock($h, LOCK_EX)) {           // 排他锁，阻塞直到拿到
    $n = (int) stream_get_contents($h);
    rewind($h);
    ftruncate($h, 0);
    fwrite($h, (string) ($n + 1));
    fflush($h);
    flock($h, LOCK_UN);             // 释放
}
fclose($h);

function atomicWrite(string $path, string $content): void
{
    $tmp = $path . '.' . bin2hex(random_bytes(6)) . '.tmp';
    file_put_contents($tmp, $content, LOCK_EX);
    rename($tmp, $path);   // 同一文件系统内 rename 是原子操作
}

$it = new RecursiveIteratorIterator(
    new RecursiveDirectoryIterator('/app/src', FilesystemIterator::SKIP_DOTS),
    RecursiveIteratorIterator::LEAVES_ONLY
);
foreach ($it as $file) {
    if ($file->getExtension() !== 'php') continue;
    echo $file->getPathname(), PHP_EOL;
}

$base = '/app/storage/';
$name = basename($_GET['file']);            // 去掉 ../ 等
$path = realpath($base . $name);
if ($path === false || !str_starts_with($path, realpath($base))) {
    throw new \RuntimeException('非法路径');
}

allow_url_fopen = On     ; 允许 file_get_contents 读 URL（通常需要）
allow_url_include = Off  ; 生产必须关闭，否则 include 可执行远程代码