Add GzipInputStream

examples/gzip-decompress.php

@@ -0,0 +1,19 @@
+<?php
+
+use Amp\ByteStream\GzipInputStream;
+use Amp\ByteStream\ResourceInputStream;
+use Amp\ByteStream\ResourceOutputStream;
+use Amp\Loop;
+
+require __DIR__ . "/../vendor/autoload.php";
+
+Loop::run(function () {
+    $stdin = new ResourceInputStream(STDIN);
+    $stdout = new ResourceOutputStream(STDOUT);
+
+    $gzin = new GzipInputStream($stdin);
+
+    while (($chunk = yield $gzin->read()) !== null) {
+        yield $stdout->write($chunk);
+    }
+});

lib/GzipInputStream.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace Amp\ByteStream;
+
+use Amp\Promise;
+use function Amp\call;
+
+class GzipInputStream implements InputStream {
+    const STATE_FAILED = -1;
+    const STATE_NORMAL = 0;
+    const STATE_ENDING = 1;
+    const STATE_ENDED = 2;
+
+    private $source;
+    private $resource;
+    private $state = 0;
+
+    public function __construct(InputStream $source) {
+        $this->source = $source;
+        $this->resource = \inflate_init(\ZLIB_ENCODING_GZIP);
+
+        if ($this->resource === false) {
+            throw new StreamException("Failed initializing deflate context");
+        }
+    }
+
+    public function read(): Promise {
+        return call(function () {
+            if ($this->state === self::STATE_ENDED) {
+                throw new ClosedException("The stream has already been closed");
+            }
+
+            if ($this->state === self::STATE_ENDING) {
+                $this->state = self::STATE_ENDED;
+                return null;
+            }
+
+            if ($this->state === self::STATE_FAILED) {
+                throw new StreamException("The stream has previously failed");
+            }
+
+            $data = yield $this->source->read();
+
+            if ($data === null) {
+                $decompressed = \inflate_add($this->resource, "", \ZLIB_FINISH);
+
+                $this->state = self::STATE_ENDING;
+
+                if ($decompressed === false) {
+                    $this->state = self::STATE_FAILED;
+                    throw new StreamException("Failed adding data to deflate context");
+                }
+
+                return $decompressed;
+            }
+
+            $decompressed = \inflate_add($this->resource, $data, \ZLIB_SYNC_FLUSH);
+
+            if ($decompressed === false) {
+                $this->state = self::STATE_FAILED;
+                throw new StreamException("Failed adding data to deflate context");
+            }
+
+            return $decompressed;
+        });
+    }
+
+    public function close() {
+        $this->state = self::STATE_ENDED;
+        $this->source->close();
+    }
+}