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LibCore: Implement basic mime type guessing based on binary patterns

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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!
This commit is contained in:
Valtteri Koskivuori 2021-05-03 21:48:21 +03:00 • committed by Linus Groh
parent 1069979ddf
commit cf5f3a9874
2 changed files with 33 additions and 0 deletions
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31
Userland/Libraries/LibCore/MimeData.cpp
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@ -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 {};
}
}