> it should also offer a new API that simply returns a copy every time
Returning a copy isn't great (memory allocation!), the API should probably be something like:
int getenv(const char *varName, char *buf, size_t bufSize, size_t *varSize);
Where the caller manages the buffer and getenv writes into it (so it can e.g. be stack or statically allocated), the third argument is the size of the caller-managed buffer, then the last variable is an "out parameter" that returns the "true" length of the environment variable. Then afterwards, you can check if `*varSize > bufSize`, and if so, you need to make your buffer larger. The return value is an error code.
Doing it like this, you can easily implement the "return a malloced copy" if you want to, but it also gives you the option to avoid allocation entirely. This is important for e.g. embedded or real-time applications, or anything that just likes to avoid `malloc()/free()`.
Returning a copy isn't great (memory allocation!), the API should probably be something like:
Where the caller manages the buffer and getenv writes into it (so it can e.g. be stack or statically allocated), the third argument is the size of the caller-managed buffer, then the last variable is an "out parameter" that returns the "true" length of the environment variable. Then afterwards, you can check if `*varSize > bufSize`, and if so, you need to make your buffer larger. The return value is an error code.Doing it like this, you can easily implement the "return a malloced copy" if you want to, but it also gives you the option to avoid allocation entirely. This is important for e.g. embedded or real-time applications, or anything that just likes to avoid `malloc()/free()`.