Support for single-ended byte ranges

src/server/request_context.cpp

@@ -26,6 +26,7 @@
 #include <sstream>
 #include <cstdio>
 #include <atomic>
+#include <limits>
 
 namespace kiwix {
 
@@ -64,6 +65,8 @@ fullURL2LocalURL(const std::string& full_url, const std::string& rootLocation)
 
 ByteRange parse_byte_range(std::string range)
 {
+  const int64_t int64_max = std::numeric_limits<int64_t>::max();
+
   ByteRange byteRange;
   const std::string byteUnitSpec("bytes=");
   if ( kiwix::startsWith(range, byteUnitSpec) ) {
@@ -73,7 +76,12 @@ ByteRange parse_byte_range(std::string range)
     std::istringstream iss(range);
     char c;
 
-    iss >> start >> c;
+    iss >> start;
+    if ( start < 0 ) {
+      if ( iss.eof() )
+        byteRange = ByteRange(ByteRange::PARSED, start, int64_max);
+    } else {
+      iss >> c;
       if (iss.good() && c=='-') {
         iss >> end;
         if (iss.fail()) {
@@ -85,6 +93,7 @@ ByteRange parse_byte_range(std::string range)
         }
       }
     }
+  }
   return byteRange;
 }
 

src/server/response.cpp

@@ -46,10 +46,15 @@ ByteRange resolve_byte_range(const kiwix::Entry& entry, ByteRange range)
   if ( range.kind() == ByteRange::NONE )
     return ByteRange(ByteRange::RESOLVED_FULL_CONTENT, 0, entrySize-1);
 
+  const int64_t resolved_first = range.first() < 0
+                               ? std::max(int64_t(0), entrySize + range.first())
+                               : range.first();
+
   const int64_t resolved_last = range.last() < 0
                               ? entrySize - 1
                               : std::min(entrySize-1, range.last());
-  return ByteRange(ByteRange::RESOLVED_PARTIAL_CONTENT, range.first(), resolved_last);
+
+  return ByteRange(ByteRange::RESOLVED_PARTIAL_CONTENT, resolved_first, resolved_last);
 }
 
 } // unnamed namespace

test/server.cpp

@@ -436,4 +436,18 @@ TEST_F(ServerTest, ValidSingleRangeByteRangeRequestsAreHandledProperly)
     EXPECT_EQ(334, p->body.size());
     EXPECT_EQ(full->body.substr(123, 334), p->body);
   }
+
+  {
+    const auto p = zfs1_->GET(url, { {"Range", "bytes=20000-"} } );
+    EXPECT_EQ(206, p->status);
+    EXPECT_EQ(full->body.substr(20000), p->body);
+    EXPECT_EQ("bytes 20000-20076/20077", p->get_header_value("Content-Range"));
+  }
+
+  {
+    const auto p = zfs1_->GET(url, { {"Range", "bytes=-100"} } );
+    EXPECT_EQ(206, p->status);
+    EXPECT_EQ(full->body.substr(19977), p->body);
+    EXPECT_EQ("bytes 19977-20076/20077", p->get_header_value("Content-Range"));
+  }
 }