Fortunately this is a bit less relevant today as Windows loses market share in database and server applications, but:
UUIDs have historically massively screwed up endian handling. While this new draft discusses sorting UUIDs as strings of octets (bytes) and the text of RFC4122 is fairly explicit about most significant bytes coming first, the C UUID structure in RFC 4122 appendix A is entirely misguided:
typedef struct {
unsigned32 time_low;
unsigned16 time_mid;
unsigned16 time_hi_and_version;
unsigned8 clock_seq_hi_and_reserved;
unsigned8 clock_seq_low;
byte node[6];
} uuid_t;
Those aren’t bytes — they’re integers of various sizes. (Hint: do
not use integer types in C code for portable data structures. ntohl, etc are a mess. Just use arrays of bytes.)
I don’t know the whole history, but MS somehow took this structure at face value and caused problems like this:
https://github.com/uuid-rs/uuid/issues/277
So, if you want to do anything (e.g. sorting) that depends on the representation of a UUID (or even depends on converting between string and binary representations), be aware that UUIDs coming from Windows may be little-endian. In my book, this is a Windows bug, but opinions may differ here.
UUIDs have historically massively screwed up endian handling. While this new draft discusses sorting UUIDs as strings of octets (bytes) and the text of RFC4122 is fairly explicit about most significant bytes coming first, the C UUID structure in RFC 4122 appendix A is entirely misguided:
Those aren’t bytes — they’re integers of various sizes. (Hint: do not use integer types in C code for portable data structures. ntohl, etc are a mess. Just use arrays of bytes.)I don’t know the whole history, but MS somehow took this structure at face value and caused problems like this:
https://github.com/uuid-rs/uuid/issues/277
So, if you want to do anything (e.g. sorting) that depends on the representation of a UUID (or even depends on converting between string and binary representations), be aware that UUIDs coming from Windows may be little-endian. In my book, this is a Windows bug, but opinions may differ here.