Re: [PATCH v6] receive-pack.c: consolidate find header logic

> From: John Cai <johncai86@gmail.com>
>
> There are two functions that have very similar logic of finding a header
> value. find_commit_header, and find_header. We can conslidate the logic
> by introducing a new function find_header_mem, which is equivalent to
> find_commit_header except it takes a len parameter that determines how
> many bytes will be read. find_commit_header and find_header can then both
> call find_header_mem.
>
> This reduces duplicate logic, as the logic for finding header values
> can now all live in one place.
>
> Signed-off-by: John Cai <johncai86@gmail.com>
> ---
>     Consolidate find_header logic into one function
> +const char *find_header_mem(const char *msg, size_t len,
> +			const char *key, size_t *out_len)
>  {
>  	int key_len = strlen(key);
>  	const char *line = msg;
>  
> -	while (line) {
> +	/*
> +	 * NEEDSWORK: It's possible for strchrnul() to scan beyond the range
> +	 * given by len. However, current callers are safe because they compute
> +	 * len by scanning a NUL-terminated block of memory starting at msg.
> +	 * Nonetheless, it would be better to ensure the function does not look
> +	 * at msg beyond the len provided by the caller.
> +	 */
> +	while (line && line < msg + len) {
>  		const char *eol = strchrnul(line, '\n');