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Assume that files which start with a unicode BOM are valid files of that type

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This commit is contained in:
Thomas Goyne 2019-09-28 13:53:26 -07:00
parent e1a8ab1c10
commit 8d17a0e88a
1 changed files with 17 additions and 9 deletions
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26
libaegisub/common/charset.cpp
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@ -29,20 +29,28 @@ namespace agi { namespace charset {
std::string Detect(agi::fs::path const& file) {
agi::read_file_mapping fp(file);
// First check for known magic bytes which identify the file type
if (fp.size() >= 4) {
const char* header = fp.read(0, 4);
if (!strncmp(header, "\xef\xbb\xbf", 3))
return "utf-8";
if (!strncmp(header, "\x00\x00\xfe\xff", 4))
return "utf-32be";
if (!strncmp(header, "\xff\xfe\x00\x00", 4))
return "utf-32le";
if (!strncmp(header, "\xfe\xff", 2))
return "utf-16be";
if (!strncmp(header, "\xff\xfe", 2))
return "utf-16le";
if (!strncmp(header, "\x1a\x45\xdf\xa3", 4))
return "binary"; // Actually EBML/Matroska
}
// If it's over 100 MB it's either binary or big enough that we won't
// be able to do anything useful with it anyway
if (fp.size() > 100 * 1024 * 1024)
return "binary";
// FIXME: Dirty hack for Matroska. These 4 bytes are the magic
// number of EBML which is used by mkv and webm
if (fp.size() >= 4) {
const char* buf = fp.read(0, 4);
if (!strncmp(buf, "\x1a\x45\xdf\xa3", 4))
return "binary";
}
uint64_t binaryish = 0;
#ifdef WITH_UCHARDET