Allow servers to be run from directories other than build. Read/write files relative to binary instead of cwd (#834)

Allows the server to be run from a non-build directory.  Also only read or write files relative to the build directory, regardless of where the server is run from

dCommon/BinaryPathFinder.cpp

@@ -0,0 +1,71 @@
+#include <filesystem>
+#include <string>
+#include "BinaryPathFinder.h"
+#include "dPlatforms.h"
+
+#if defined(DARKFLAME_PLATFORM_WIN32)
+#include <Windows.h>
+#elif defined(DARKFLAME_PLATFORM_MACOS) || defined(DARKFLAME_PLATFORM_IOS)
+#include <mach-o/dyld.h>
+#elif defined(DARKFLAME_PLATFORM_FREEBSD)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <stdlib.h>
+#endif
+
+std::filesystem::path BinaryPathFinder::binaryDir;
+
+std::filesystem::path BinaryPathFinder::GetBinaryDir() {
+	if (!binaryDir.empty()) {
+		return binaryDir;
+	}
+
+	std::string pathStr;
+
+	// Derived from boost::dll::program_location, licensed under the Boost Software License: http://www.boost.org/LICENSE_1_0.txt
+#if defined(DARKFLAME_PLATFORM_WIN32)
+	char path[MAX_PATH];
+	GetModuleFileName(NULL, path, MAX_PATH);
+	pathStr = std::string(path);
+#elif defined(DARKFLAME_PLATFORM_MACOS) || defined(DARKFLAME_PLATFORM_IOS)
+	char path[1024];
+	uint32_t size = sizeof(path);
+	if (_NSGetExecutablePath(path, &size) == 0) {
+		pathStr = std::string(path);
+	} else {
+		// The filepath size is greater than our initial buffer size, so try again with the size
+		// that _NSGetExecutablePath told us it actually is
+		char *p = new char[size];
+		if (_NSGetExecutablePath(p, &size) != 0) {
+			throw std::runtime_error("Failed to get binary path from _NSGetExecutablePath");
+		}
+
+		pathStr = std::string(p);
+		delete[] p;
+	}
+#elif defined(DARKFLAME_PLATFORM_FREEBSD)
+	int mib[4];
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_PROC;
+	mib[2] = KERN_PROC_PATHNAME;
+	mib[3] = -1;
+	char buf[10240];
+	size_t cb = sizeof(buf);
+	sysctl(mib, 4, buf, &cb, NULL, 0);
+	pathStr = std::string(buf);
+#else // DARKFLAME_PLATFORM_LINUX || DARKFLAME_PLATFORM_UNIX || DARKFLAME_PLATFORM_ANDROID
+	pathStr = std::filesystem::read_symlink("/proc/self/exe");
+#endif
+
+	// Some methods like _NSGetExecutablePath could return a symlink
+	// Either way, we need to get the parent path because we want the directory, not the binary itself
+	// We also ensure that it is an absolute path so that it is valid if we need to construct a path
+	// to exucute on unix systems (eg sudo BinaryPathFinder::GetBinaryDir() / WorldServer)
+	if (std::filesystem::is_symlink(pathStr)) {
+		binaryDir = std::filesystem::absolute(std::filesystem::read_symlink(pathStr).parent_path());
+	} else {
+		binaryDir = std::filesystem::absolute(std::filesystem::path(pathStr).parent_path());
+	}
+
+	return binaryDir;
+}