archiver: add Gzip support

Add methods for Gzip file compression/decompression.

Change-Id: I81d52c09a98b835c32d7a07ab2cb9a22aca19e8e
Reviewed-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

src/archiver.cpp

@@ -223,6 +223,33 @@ compress(const std::string& str)
     return outbuffer;
 }
 
+void
+compressGzip(const std::string& str, const std::string& path)
+{
+    auto fi = gzopen(path.c_str(), "wb");
+    gzwrite(fi, str.data(), str.size());
+    gzclose(fi);
+}
+
+std::vector<uint8_t>
+decompressGzip(const std::string& path)
+{
+    std::vector<uint8_t> out;
+    auto fi = gzopen(path.c_str(),"rb");
+    gzrewind(fi);
+    while (not gzeof(fi)) {
+        std::array<uint8_t, 32768> outbuffer;
+        int len = gzread(fi, outbuffer.data(), outbuffer.size());
+        if (len == -1) {
+            gzclose(fi);
+            throw std::runtime_error("Exception during gzip decompression");
+        }
+        out.insert(out.end(), outbuffer.begin(), outbuffer.begin() +  len);
+    }
+    gzclose(fi);
+    return out;
+}
+
 std::vector<uint8_t>
 decompress(const std::vector<uint8_t>& str)
 {

src/archiver.h

@@ -64,6 +64,16 @@ std::vector<uint8_t> compress(const std::string& str);
  */
 std::vector<uint8_t> decompress(const std::vector<uint8_t>& dat);
 
+/**
+ * Compress string to a Gzip file
+ */
+void compressGzip(const std::string& str, const std::string& path);
+
+/**
+ * Decompress Gzip file to bytes
+ */
+std::vector<uint8_t> decompressGzip(const std::string& path);
+
 }
 
 } // namespace ring