Fix warnings on Linux

- Missing imports that weren't necessary on Mac OS X.
- Signed comparision issues.
- Content-length was wrong type -- should really be off_t.

src/S3File.cc

@@ -363,7 +363,7 @@ OverlapCopy(off_t req_off, size_t req_size, char *req_buf, off_t cache_off,
 	}
 
 	if (cache_off <= req_off) {
-		auto cache_end = cache_off + cache_size;
+		auto cache_end = cache_off + static_cast<off_t>(cache_size);
 		if (cache_end > req_off) {
 			auto cache_buf_off = static_cast<size_t>(req_off - cache_off);
 			auto cache_copy_bytes =
@@ -426,19 +426,20 @@ bool S3File::S3Cache::CouldUseAligned(off_t req, off_t cache) {
 	if (req < 0 || cache < 0) {
 		return false;
 	}
-	return (req >= cache) && (req < cache + S3File::m_cache_entry_size);
+	return (req >= cache) &&
+		   (req < cache + static_cast<off_t>(S3File::m_cache_entry_size));
 }
 
 bool S3File::S3Cache::CouldUse(off_t req_off, size_t req_size,
 							   off_t cache_off) {
 	if (req_off < 0 || cache_off < 0) {
 		return false;
 	}
-	auto cache_end = cache_off + m_cache_entry_size;
+	auto cache_end = cache_off + static_cast<off_t>(m_cache_entry_size);
 	if (req_off >= cache_off) {
 		return req_off < cache_end;
 	} else {
-		return req_off + req_size > cache_off;
+		return req_off + static_cast<off_t>(req_size) > cache_off;
 	}
 }
 
@@ -790,8 +791,9 @@ ssize_t S3File::S3Cache::Read(S3File &file, char *buffer, off_t offset,
 					}
 				} else {
 					// Select one cache entry to fetch data.
-					auto needed_off =
-						req1_off / m_cache_entry_size * m_cache_entry_size;
+					auto needed_off = req1_off /
+									  static_cast<off_t>(m_cache_entry_size) *
+									  static_cast<off_t>(m_cache_entry_size);
 					if (needed_off > m_a.m_off) {
 						m_b.m_off = needed_off;
 						download_b = true;

src/S3File.hh

@@ -26,6 +26,7 @@
 #include <XrdSec/XrdSecEntityAttr.hh>
 #include <XrdVersion.hh>
 
+#include <atomic>
 #include <condition_variable>
 #include <memory>
 #include <mutex>
@@ -120,7 +121,7 @@ class S3File : public XrdOssDF {
 	std::string m_object;
 	S3AccessInfo m_ai;
 
-	size_t content_length;
+	off_t content_length;
 	time_t last_modified;
 
 	static const size_t m_s3_part_size =