FHU: Add helpers for symlink checking

FEXHeaderUtils/FEXHeaderUtils/SymlinkChecks.h

@@ -0,0 +1,28 @@
+#pragma once
+#include <fcntl.h>
+#include <string>
+#include <sys/stat.h>
+#include <span>
+#include <unistd.h>
+
+namespace FHU::Symlinks {
+// Checks to see if a filepath is a symlink.
+inline bool IsSymlink(const std::string &Filename) {
+  struct stat Buffer{};
+  int Result = lstat(Filename.c_str(), &Buffer);
+  return Result == 0 && S_ISLNK(Buffer.st_mode);
+}
+
+// Resolves a symlink path.
+// Doesn't handle recursive symlinks.
+// Doesn't append null terminator character.
+// Returns a string_view of the resolved path, or an empty view on error.
+inline std::string_view ResolveSymlink(const std::string &Filename, std::span<char> ResultBuffer) {
+  ssize_t Result = readlink(Filename.c_str(), ResultBuffer.data(), ResultBuffer.size());
+  if (Result == -1) {
+    return {};
+  }
+
+  return std::string_view(ResultBuffer.data(), Result);
+}
+}