LibCore: Implement basic mime type guessing based on binary patterns

This attempts to guess the mime-type from a given set of bytes from the start of a file. It only supports a few well-defined patterns for now, but it's a start!
abyesilyurt · May 7, 2021 · cf5f3a9 · cf5f3a9
1 parent 1069979
commit cf5f3a9
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diff --git a/Userland/Libraries/LibCore/MimeData.cpp b/Userland/Libraries/LibCore/MimeData.cpp
@@ -79,4 +79,35 @@ String guess_mime_type_based_on_filename(const StringView& path)
  return "text/plain";
 }
 
+#define ENUMERATE_HEADER_CONTENTS \
+ __ENUMERATE_MIME_TYPE_HEADER(bmp, "image/bmp", 2, 'B', 'M') \
+ __ENUMERATE_MIME_TYPE_HEADER(bzip2, "application/x-bzip2", 3, 'B', 'Z', 'h') \
+ __ENUMERATE_MIME_TYPE_HEADER(elf, "extra/elf", 4, 0x7F, 'E', 'L', 'F') \
+ __ENUMERATE_MIME_TYPE_HEADER(gif_87, "image/gif", 6, 'G', 'I', 'F', '8', '7', 'a') \
+ __ENUMERATE_MIME_TYPE_HEADER(gif_89, "image/gif", 6, 'G', 'I', 'F', '8', '9', 'a') \
+ __ENUMERATE_MIME_TYPE_HEADER(gzip, "extra/gzip", 2, 0x1F, 0x8B) \
+ __ENUMERATE_MIME_TYPE_HEADER(jpeg, "image/jpeg", 4, 0xFF, 0xD8, 0xFF, 0xDB) \
+ __ENUMERATE_MIME_TYPE_HEADER(jpeg_huh, "image/jpeg", 4, 0xFF, 0xD8, 0xFF, 0xEE) \
+ __ENUMERATE_MIME_TYPE_HEADER(jpeg_jfif, "image/jpeg", 12, 0xFF, 0xD8, 0xFF, 0xE0, 0x00, 0x10, 'J', 'F', 'I', 'F', 0x00, 0x01) \
+ __ENUMERATE_MIME_TYPE_HEADER(pbm, "image/x-portable-bitmap", 3, 0x50, 0x31, 0x0A) \
+ __ENUMERATE_MIME_TYPE_HEADER(pgm, "image/x-portable-graymap", 3, 0x50, 0x32, 0x0A) \
+ __ENUMERATE_MIME_TYPE_HEADER(png, "image/png", 8, 0x89, 'P', 'N', 'G', 0x0D, 0x0A, 0x1A, 0x0A) \
+ __ENUMERATE_MIME_TYPE_HEADER(ppm, "image/x-portable-pixmap", 3, 0x50, 0x33, 0x0A) \
+ __ENUMERATE_MIME_TYPE_HEADER(shell, "text/x-shellscript", 10, '#', '!', '/', 'b', 'i', 'n', '/', 's', 'h', '\n')
+
+#define __ENUMERATE_MIME_TYPE_HEADER(var_name, mime_type, pattern_size, ...) \
+ static const u8 var_name##_arr[pattern_size] = { __VA_ARGS__ }; \
+ static constexpr ReadonlyBytes var_name = ReadonlyBytes { var_name##_arr, pattern_size };
+ENUMERATE_HEADER_CONTENTS
+#undef __ENUMERATE_MIME_TYPE_HEADER
+
+Optional<String> guess_mime_type_based_on_sniffed_bytes(const ReadonlyBytes& bytes)
+{
+#define __ENUMERATE_MIME_TYPE_HEADER(var_name, mime_type, pattern_size, ...) \
+ if (bytes.starts_with(var_name)) \
+ return mime_type;
+ ENUMERATE_HEADER_CONTENTS;
+#undef __ENUMERATE_MIME_TYPE_HEADER
+ return {};
+}
 }
diff --git a/Userland/Libraries/LibCore/MimeData.h b/Userland/Libraries/LibCore/MimeData.h
@@ -49,4 +49,6 @@ class MimeData : public Object {
 
 String guess_mime_type_based_on_filename(const StringView&);
 
+Optional<String> guess_mime_type_based_on_sniffed_bytes(const ReadonlyBytes&);
+
 }