Re: [PATCH v2 4/8] http: extract type/subtype portion of content-type

> When we get a content-type from curl, we get the whole
> header line, including any parameters, and without any
> normalization (like downcasing or whitespace) applied.
> If we later try to match it with strcmp() or even
> strcasecmp(), we may get false negatives.
>
> This could cause two visible behaviors:
>
>  1. We might fail to recognize a smart-http server by its
>     content-type.
>
>  2. We might fail to relay text/plain error messages to
>     users (especially if they contain a charset parameter).
>
> This patch teaches the http code to extract and normalize
> just the type/subtype portion of the string. This is
> technically passing out less information to the callers, who
> can no longer see the parameters. But none of the current
> callers cares, and a future patch will add back an
> easier-to-use method for accessing those parameters.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> http.c                     | 32 +++++++++++++++++++++++++++++---
> remote-curl.c              |  2 +-
> t/lib-httpd/error.sh       |  8 +++++++-
> t/t5550-http-fetch-dumb.sh |  5 +++++
> 4 files changed, 42 insertions(+), 5 deletions(-)
>
> diff --git a/http.c b/http.c
> index 94e1afd..4edf5b9 100644
> --- a/http.c
> +++ b/http.c
> @@ -906,6 +906,29 @@ static CURLcode curlinfo_strbuf(CURL *curl,  
> CURLINFO info, struct strbuf *buf)
> 	return ret;
> }
>
> +/*
> + * Extract a normalized version of the content type, with any
> + * spaces suppressed, all letters lowercased, and no trailing ";"
> + * or parameters.
> + *
> + * Example:
> + *   "TEXT/PLAIN; charset=utf-8" -> "text/plain"
> + */
> +static void extract_content_type(struct strbuf *raw, struct strbuf  
> *type)
> +{
> +	const char *p;
> +
> +	strbuf_reset(type);
> +	strbuf_grow(type, raw->len);
> +	for (p = raw->buf; *p; p++) {
> +		if (isspace(*p))
> +			continue;
> +		if (*p == ';')
> +			break;
> +		strbuf_addch(type, tolower(*p));
> +	}
> +}
> +