magic: implement buffer processing support

1 files changed, 16 insertions, 2 deletions

diff --git a/cabinet/main.cpp b/cabinet/main.cpp
index ff35d34..3602142 100644
--- a/cabinet/main.cpp
+++ b/cabinet/main.cpp
@@ -1,8 +1,13 @@
 #include <cabinet/magic.hpp>
 
 #include <fcntl.h>
+#include <unistd.h>
 
+#include <array>
+#include <cerrno>
+#include <cstddef>
 #include <cstdlib>
+#include <cstring>
 #include <iostream>
 #include <print>
 
@@ -23,12 +28,21 @@ auto main(int argc, char ** argv) -> int
     return EXIT_FAILURE;
   }
 
-  auto fd = open(argv[1], O_RDONLY);
-  auto mime_type = magic->process(fd);
+  auto fd = ::open(argv[1], O_RDONLY);
+  if (fd < 0)
+  {
+    std::println(std::cerr, "Failed to determine file type: {}", ::strerror(errno));
+    return EXIT_FAILURE;
+  }
+
+  std::array<std::byte, 512> buffer{};
+  ::read(fd, buffer.data(), buffer.size());
+  auto mime_type = magic->process(buffer);
   if (!mime_type)
   {
     std::println(std::cerr, "Failed to determine file type: {}", mime_type.error().message());
     return EXIT_FAILURE;
   }
+
   std::println("{}: {}", argv[1], mime_type.value());
 }