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by jandrese 812 days ago
For me the "real" solution looks something like this:

    ssize_t strxcpy(char* restrict dst, const char* restrict src, ssize_t len)
Strxcpy copies the string from src to dst. The len parameter is the number of bytes available in the dst buffer. The dst buffer is always terminated with a null byte, so the maximum length of string that can be copied into it is len - 1. strxcpy returns the number of characters copied on success, but can return the following negative values:

    E_INVALID_PARAMETER: Ether dst or src are NULL or len < 1, no data was copied
    W_TRUNCATED: len - 1 bytes were copied but more characters were available in src.
strxcat would work similarly. I have not decided if the return value should include the terminating null or not.
1 comments

How is this useful though? I mean yes, it is useful in avoiding the buffer overruns. But that's not the only consideration, you also want code that handles data correctly. This just truncates at buffer size so data is lost.

So, if you want the code to work correctly, you need to either check the return code and reallocate dst and call the copy again. But if you're going to do that might as well check src len and allocate dst correctly before calling it so it never fails. But if you're already doing that, you can call strcpy just fine and never have a problem.

Sometimes truncation is fine or at least can be managed. Yes, strdup() is a better choice in a lot of situations, but depending on how your data is structured it may not be the correct option. I would say my version is useful in any situation where you were previously using strncpy/cat or strlcpy/cat.