Add an option to disable GZIP.

webcc/gzip.cc

@@ -0,0 +1,130 @@
+#include "webcc/gzip.h"
+
+#include <cassert>
+#include <utility>  // std::move
+
+#include "zlib.h"
+
+#include "webcc/logger.h"
+
+namespace webcc {
+namespace gzip {
+
+bool Compress(const std::string& input, std::string* output) {
+  output->clear();
+
+  if (input.empty()) {
+    return true;
+  }
+
+  z_stream stream;
+  stream.next_in = (Bytef*)input.data();
+  stream.avail_in = (uInt)input.size();
+  stream.zalloc = Z_NULL;
+  stream.zfree = Z_NULL;
+  stream.opaque = Z_NULL;
+
+  int ret = deflateInit2(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+                         MAX_WBITS + 16, 8, Z_DEFAULT_STRATEGY);
+  if (ret != Z_OK) {
+    return false;
+  }
+
+  std::string buf;
+  buf.resize(input.size() / 2);  // TODO
+
+  // Run deflate() on input until output buffer is not full.
+  do {
+    stream.avail_out = (uInt)buf.size();
+    stream.next_out = (Bytef*)buf.data();
+
+    int err = deflate(&stream, Z_FINISH);
+
+    if (err != Z_OK && err != Z_STREAM_END) {
+      deflateEnd(&stream);
+      if (stream.msg != nullptr) {
+        LOG_ERRO("zlib deflate error: %s", stream.msg);
+      }
+      return false;
+    }
+
+    std::size_t size = buf.size() - stream.avail_out;
+    output->insert(output->end(), buf.data(), buf.data() + size);
+
+  } while (stream.avail_out == 0);
+
+  if (deflateEnd(&stream) != Z_OK) {
+    return false;
+  }
+
+  return true;
+}
+
+// Modified from:
+//   http://windrealm.org/tutorials/decompress-gzip-stream.php
+bool Decompress(const std::string& input, std::string* output) {
+  output->clear();
+
+  if (input.empty()) {
+    return true;
+  }
+
+  // Initialize the output buffer with the same size as the input.
+  std::string buf;
+  buf.resize(input.size());
+
+  z_stream stream;
+  stream.next_in = (Bytef*)input.data();
+  stream.avail_in = (uInt)input.size();
+  stream.total_out = 0;
+  stream.zalloc = Z_NULL;
+  stream.zfree = Z_NULL;
+
+  // About the windowBits paramter:
+  //   (https://stackoverflow.com/a/1838702)
+  //   (http://www.zlib.net/manual.html)
+  // windowBits can also be greater than 15 for optional gzip decoding. Add 32
+  // to windowBits to enable zlib and gzip decoding with automatic header
+  // detection, or add 16 to decode only the gzip format (the zlib format will
+  // return a Z_DATA_ERROR).
+  if (inflateInit2(&stream, MAX_WBITS + 32) != Z_OK) {
+    return false;
+  }
+
+  while (true) {
+    // Enlarge the output buffer if it's too small.
+    if (stream.total_out >= buf.size()) {
+      buf.resize(buf.size() + input.size() / 2);
+    }
+
+    stream.next_out = (Bytef*)(buf.data() + stream.total_out);
+    stream.avail_out = (uInt)buf.size() - stream.total_out;
+
+    // Inflate another chunk.
+    int err = inflate(&stream, Z_SYNC_FLUSH);
+
+    if (err == Z_STREAM_END) {
+      break;
+    }
+    if (err != Z_OK) {
+      inflateEnd(&stream);
+      if (stream.msg != nullptr) {
+        LOG_ERRO("zlib inflate error: %s", stream.msg);
+      }
+      return false;
+    }
+  }
+
+  if (inflateEnd(&stream) != Z_OK) {
+    return false;
+  }
+
+  // Remove the unused part then move to the output
+  buf.erase(stream.total_out);
+  *output = std::move(buf);
+
+  return true;
+}
+
+}  // namespace gzip
+}  // namespace webcc