Re: [GSoC Patch v7 1/3] path: extract append_formatted_path() and use in rev-parse

> -static void print_path(const char *path, const char *prefix, enum format_type format, enum default_type def)
>  {
> -	char *cwd = NULL;
> -	/*
> -	 * We don't ever produce a relative path if prefix is NULL, so set the
> -	 * prefix to the current directory so that we can produce a relative
> -	 * path whenever possible.  If we're using RELATIVE_IF_SHARED mode, then
> -	 * we want an absolute path unless the two share a common prefix, so don't
> -	 * set it in that case, since doing so causes a relative path to always
> -	 * be produced if possible.
> -	 */
> -	if (!prefix && (format != FORMAT_DEFAULT || def != DEFAULT_RELATIVE_IF_SHARED))
> -		prefix = cwd = xgetcwd();
> -	if (format == FORMAT_DEFAULT && def == DEFAULT_UNMODIFIED) {
> -		puts(path);
> -	} else if (format == FORMAT_RELATIVE ||
> -		  (format == FORMAT_DEFAULT && def == DEFAULT_RELATIVE)) {
> -		/*
> -		 * In order for relative_path to work as expected, we need to
> -		 * make sure that both paths are absolute paths.  If we don't,
> -		 * we can end up with an unexpected absolute path that the user
> -		 * didn't want.
> -		 */
> -		struct strbuf buf = STRBUF_INIT, realbuf = STRBUF_INIT, prefixbuf = STRBUF_INIT;
> -		if (!is_absolute_path(path)) {
> -			strbuf_realpath_forgiving(&realbuf, path,  1);
> -			path = realbuf.buf;
> -		}
> -		if (!is_absolute_path(prefix)) {
> -			strbuf_realpath_forgiving(&prefixbuf, prefix, 1);
> -			prefix = prefixbuf.buf;
>  		}
> -		puts(relative_path(path, prefix, &buf));
> -		strbuf_release(&buf);
> -		strbuf_release(&realbuf);
> -		strbuf_release(&prefixbuf);
> -	} else if (format == FORMAT_DEFAULT && def == DEFAULT_RELATIVE_IF_SHARED) {
> -		struct strbuf buf = STRBUF_INIT;
> -		puts(relative_path(path, prefix, &buf));
> -		strbuf_release(&buf);
> -	} else {
> -		struct strbuf buf = STRBUF_INIT;
> -		strbuf_realpath_forgiving(&buf, path, 1);
> -		puts(buf.buf);
> -		strbuf_release(&buf);
>  	}
> -	free(cwd);
>  }

> +static void print_path(const char *path, const char *prefix,
> +		       enum format_type format, enum default_type def)
>  {
> +	struct strbuf sb = STRBUF_INIT;
> +	enum path_format fmt;
> +
> +	if (format == FORMAT_RELATIVE) {
> +		fmt = PATH_FORMAT_RELATIVE;
> +	} else if (format == FORMAT_CANONICAL) {
> +		fmt = PATH_FORMAT_CANONICAL;
> +	} else /* FORMAT_DEFAULT */ {
> +		switch (def) {
> +		case DEFAULT_RELATIVE:
> +			fmt = PATH_FORMAT_RELATIVE;
> +			break;
> +		case DEFAULT_RELATIVE_IF_SHARED:
> +			fmt = PATH_FORMAT_RELATIVE_IF_SHARED;
> +			break;
> +		case DEFAULT_CANONICAL:
> +			fmt = PATH_FORMAT_CANONICAL;
> +			break;
> +		case DEFAULT_UNMODIFIED:
> +		default:
> +			fmt = PATH_FORMAT_UNMODIFIED;
> +			break;
>  		}
>  	}
> +
> +	append_formatted_path(&sb, path, prefix, fmt);
> +	puts(sb.buf);
> +
> +	strbuf_release(&sb);
>  }

> diff --git a/path.c b/path.c
> index d7e17bf174..6d8e892ada 100644
> --- a/path.c
> +++ b/path.c
> @@ -1579,6 +1579,75 @@ char *xdg_cache_home(const char *filename)
>  	return NULL;
>  }
>  
> +void append_formatted_path(struct strbuf *dest, const char *path,
> +			   const char *prefix, enum path_format format)
> +{
> +	switch (format) {
> +	case PATH_FORMAT_UNMODIFIED:
> +		strbuf_addstr(dest, path);
> +		break;

> +	case PATH_FORMAT_RELATIVE: {
> +		struct strbuf relative_buf = STRBUF_INIT;
> +		struct strbuf real_path = STRBUF_INIT;
> +		struct strbuf real_prefix = STRBUF_INIT;
> +		char *cwd = NULL;
> +
> +		/*
> +		 * We don't ever produce a relative path if prefix is NULL,
> +		 * so set the prefix to the current directory so that we can
> +		 * produce a relative path whenever possible.
> +		 */
> +		if (!prefix)
> +			prefix = cwd = xgetcwd();

> +		if (!is_absolute_path(path)) {
> +			strbuf_realpath_forgiving(&real_path, path, 1);
> +			path = real_path.buf;
> +		}
> +		if (!is_absolute_path(prefix)) {
> +			strbuf_realpath_forgiving(&real_prefix, prefix, 1);
> +			prefix = real_prefix.buf;
> +		}

> +		strbuf_addstr(dest, relative_path(path, prefix, &relative_buf));
> +
> +		strbuf_release(&relative_buf);
> +		strbuf_release(&real_path);
> +		strbuf_release(&real_prefix);
> +		free(cwd);
> +		break;
> +	}

> +	case PATH_FORMAT_RELATIVE_IF_SHARED: {
> +		struct strbuf relative_buf = STRBUF_INIT;
> +
> +		/*
> +		 * If we're using RELATIVE_IF_SHARED mode, then we want an
> +		 * absolute path unless the two share a common prefix, so don't
> +		 * default the prefix to the current working directory. Doing so
> +		 * would cause a relative path to always be produced if possible.
> +		 */
> +		strbuf_addstr(dest, relative_path(path, prefix, &relative_buf));
> +		strbuf_release(&relative_buf);
> +		break;
> +	}

> +
> +	case PATH_FORMAT_CANONICAL: {
> +		struct strbuf canonical_buf = STRBUF_INIT;
> +
> +		strbuf_realpath_forgiving(&canonical_buf, path, 1);
> +		strbuf_addbuf(dest, &canonical_buf);
> +
> +		strbuf_release(&canonical_buf);
> +		break;
> +	}
> +
> +	default:
> +		BUG("unknown path_format value %d", format);
> +	}
> +}

> +/**
> + * The formatting strategy to apply when writing a path into a buffer.
> + */
> +enum path_format {
> +	/* Output the path exactly as-is without any modifications. */
> +	PATH_FORMAT_UNMODIFIED,
> +
> +	/* Output a path relative to the provided directory prefix. */
> +	PATH_FORMAT_RELATIVE,
> +
> +	/* Output a relative path only if the path shares a root with the prefix. */
> +	PATH_FORMAT_RELATIVE_IF_SHARED,
> +
> +	/* Output a fully resolved, absolute canonical path. */
> +	PATH_FORMAT_CANONICAL
> +};
> +
> +/**
> + * Format a path according to the specified formatting strategy and append
> + * the result to the given strbuf.
> + *
> + * `dest`   : The string buffer to append the formatted path to.
> + * `path`   : The path string that needs to be formatted.
> + * `prefix` : The directory prefix to calculate relative offsets against.
> + * Pass NULL to default to the current working directory where applicable.
> + * `format` : The formatting behavior rule to execute.
> + */
> +void append_formatted_path(struct strbuf *dest, const char *path,
> +			   const char *prefix, enum path_format format);
> +