From 0d609c9e0208d2ea90dfa55681c8977ad92cba4f Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 4 Aug 2017 23:30:22 +0100
Subject: Improve FileHandle's compatibility with a raw descriptor

---
 libadhocutil/fileUtils.cpp               | 10 ++++++++++
 libadhocutil/fileUtils.h                 | 15 +++++++++++++++
 libadhocutil/unittests/testFileUtils.cpp | 18 ++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/libadhocutil/fileUtils.cpp b/libadhocutil/fileUtils.cpp
index d114d30..23fce0e 100644
--- a/libadhocutil/fileUtils.cpp
+++ b/libadhocutil/fileUtils.cpp
@@ -12,6 +12,11 @@ namespace AdHoc {
 			return *pp;
 		}
 
+		FileHandle::FileHandle(int d) :
+			fh(d)
+		{
+		}
+
 		FileHandle::FileHandle(const boost::filesystem::path & path, int flags) :
 			fh(open(path.c_str(), flags))
 		{
@@ -33,6 +38,11 @@ namespace AdHoc {
 			close(fh);
 		}
 
+		FileHandle::operator int() const
+		{
+			return fh;
+		}
+
 		FileHandleStat::FileHandleStat(const boost::filesystem::path & path) :
 			FileHandle(path)
 		{
diff --git a/libadhocutil/fileUtils.h b/libadhocutil/fileUtils.h
index 6ab20d3..4df8c97 100644
--- a/libadhocutil/fileUtils.h
+++ b/libadhocutil/fileUtils.h
@@ -21,6 +21,12 @@ namespace AdHoc {
 		 */
 		class DLL_PUBLIC FileHandle {
 			public:
+				/**
+				 * Construct from an existing file descriptor.
+				 * @param fd An open file descriptor.
+				 */
+				FileHandle(int fd);
+
 				/**
 				 * Open a new file handle.
 				 * @param path Path of file to open.
@@ -38,6 +44,15 @@ namespace AdHoc {
 
 				virtual ~FileHandle();
 
+				FileHandle(const FileHandle &) = delete;
+				void operator=(const FileHandle &) = delete;
+
+				/**
+				 * Implicit conversion back to raw Unix file descriptor.
+				 * @return The container file descriptor.
+				 */
+				operator int() const;
+
 				/// The file handle.
 				const int fh;
 		};
diff --git a/libadhocutil/unittests/testFileUtils.cpp b/libadhocutil/unittests/testFileUtils.cpp
index 2a5ab60..0e1cb79 100644
--- a/libadhocutil/unittests/testFileUtils.cpp
+++ b/libadhocutil/unittests/testFileUtils.cpp
@@ -5,6 +5,14 @@
 #include <definedDirs.h>
 #include <sys.h>
 
+BOOST_AUTO_TEST_CASE( raw )
+{
+	int f = open("/proc/self/exe", O_RDONLY);
+	BOOST_REQUIRE(f != -1);
+	AdHoc::FileUtils::FileHandle fh(f);
+	BOOST_REQUIRE_EQUAL(f, fh);
+}
+
 BOOST_AUTO_TEST_CASE( memmap )
 {
 	AdHoc::FileUtils::MemMap f(rootDir / "testFileUtils.cpp");
@@ -13,6 +21,16 @@ BOOST_AUTO_TEST_CASE( memmap )
 	BOOST_REQUIRE_EQUAL(0, memcmp(f.data, "#define BOOST_TEST_MODULE FileUtils", 35));
 }
 
+BOOST_AUTO_TEST_CASE( openmode )
+{
+	boost::filesystem::remove(binDir / "test.file");
+	BOOST_REQUIRE_THROW({
+		AdHoc::FileUtils::FileHandle fh(binDir / "test.file", O_RDONLY, S_IRWXU);
+	}, AdHoc::SystemExceptionOn);
+	AdHoc::FileUtils::FileHandle fh(binDir / "test.file", O_CREAT, S_IRWXU);
+	boost::filesystem::remove(binDir / "test.file");
+}
+
 BOOST_AUTO_TEST_CASE( openfail )
 {
 	BOOST_REQUIRE_THROW({
-- 
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