Re: [PATCH] strbuf: add and use strbuf_insertstr()

[Taylor Blau <me@ttaylorr.com>]

Hi René,

On Sat, Feb 08, 2020 at 08:56:43PM +0100, René Scharfe wrote:
> Add a function for inserting a C string into a strbuf.  Use it
> throughout the source to get rid of magic string length constants and
> explicit strlen() calls.
>
> Like strbuf_addstr(), implement it as an inline function to avoid the
> implicit strlen() calls to cause runtime overhead.

This all looks quite reasonable to me. Did you have a specific
motivation in mind when writing this patch, other than to get rid of
having to call strlen on the same argument like:

  strbuf_insert(&buf, pos, x, strlen(x))

? Not that this needs more motivation than that, I'm just curious.

I looked through 'git grep strbuf_insert(', and only noticed one spot
that I could be updated with 'strbuf_insertstr' in mailinfo.c:

diff --git a/mailinfo.c b/mailinfo.c
index c535dec2e9..543962d40c 100644
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -570,7 +570,7 @@ static int check_header(struct mailinfo *mi,
    len = strlen("Content-Type: ");
    strbuf_add(&sb, line->buf + len, line->len - len);
    decode_header(mi, &sb);
-		strbuf_insert(&sb, 0, "Content-Type: ", len);
+		strbuf_insertstr(&sb, 0, "Content-Type: ");
    handle_content_type(mi, &sb);
    ret = 1;
    goto check_header_out;

Otherwise this looks quite good to me.

>
> Signed-off-by: René Scharfe <l.s.r@web.de>
> ---
>  builtin/checkout.c        |  2 +-
>  builtin/notes.c           |  4 ++--
>  builtin/sparse-checkout.c |  2 +-
>  commit.c                  |  2 +-
>  config.c                  |  2 +-
>  http.c                    |  4 ++--
>  mailinfo.c                |  2 +-
>  notes-utils.c             |  2 +-
>  notes.c                   |  4 ++--
>  pretty.c                  |  4 ++--
>  strbuf.h                  | 12 ++++++++++++
>  11 files changed, 26 insertions(+), 14 deletions(-)
>
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index fc2eb1befc..d6773818b8 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -865,7 +865,7 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
>  		strbuf_addf(&msg, "checkout: moving from %s to %s",
>  			old_desc ? old_desc : "(invalid)", new_branch_info->name);
>  	else
> -		strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
> +		strbuf_insertstr(&msg, 0, reflog_msg);
>
>  	if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
>  		/* Nothing to do. */
> diff --git a/builtin/notes.c b/builtin/notes.c
> index 95456f3165..35e468ea2d 100644
> --- a/builtin/notes.c
> +++ b/builtin/notes.c
> @@ -622,7 +622,7 @@ static int append_edit(int argc, const char **argv, const char *prefix)
>
>  		strbuf_grow(&d.buf, size + 1);
>  		if (d.buf.len && prev_buf && size)
> -			strbuf_insert(&d.buf, 0, "\n", 1);
> +			strbuf_insertstr(&d.buf, 0, "\n");
>  		if (prev_buf && size)
>  			strbuf_insert(&d.buf, 0, prev_buf, size);
>  		free(prev_buf);
> @@ -745,7 +745,7 @@ static int merge_commit(struct notes_merge_options *o)
>  	memset(&pretty_ctx, 0, sizeof(pretty_ctx));
>  	format_commit_message(partial, "%s", &msg, &pretty_ctx);
>  	strbuf_trim(&msg);
> -	strbuf_insert(&msg, 0, "notes: ", 7);
> +	strbuf_insertstr(&msg, 0, "notes: ");
>  	update_ref(msg.buf, o->local_ref, &oid,
>  		   is_null_oid(&parent_oid) ? NULL : &parent_oid,
>  		   0, UPDATE_REFS_DIE_ON_ERR);
> diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
> index b3bed891cb..38d0d944b3 100644
> --- a/builtin/sparse-checkout.c
> +++ b/builtin/sparse-checkout.c
> @@ -373,7 +373,7 @@ static void strbuf_to_cone_pattern(struct strbuf *line, struct pattern_list *pl)
>  		return;
>
>  	if (line->buf[0] != '/')
> -		strbuf_insert(line, 0, "/", 1);
> +		strbuf_insertstr(line, 0, "/");
>
>  	insert_recursive_pattern(pl, line);
>  }
> diff --git a/commit.c b/commit.c
> index 3f91d3efc5..a6cfa41a4e 100644
> --- a/commit.c
> +++ b/commit.c
> @@ -993,7 +993,7 @@ static int do_sign_commit(struct strbuf *buf, const char *keyid)
>  			strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
>  			inspos += gpg_sig_header_len;
>  		}
> -		strbuf_insert(buf, inspos++, " ", 1);
> +		strbuf_insertstr(buf, inspos++, " ");
>  		strbuf_insert(buf, inspos, bol, len);
>  		inspos += len;
>  		copypos += len;
> diff --git a/config.c b/config.c
> index d75f88ca0c..b386c0c628 100644
> --- a/config.c
> +++ b/config.c
> @@ -204,7 +204,7 @@ static int prepare_include_condition_pattern(struct strbuf *pat)
>  		strbuf_splice(pat, 0, 1, path.buf, slash - path.buf);
>  		prefix = slash - path.buf + 1 /* slash */;
>  	} else if (!is_absolute_path(pat->buf))
> -		strbuf_insert(pat, 0, "**/", 3);
> +		strbuf_insertstr(pat, 0, "**/");
>
>  	add_trailing_starstar_for_dir(pat);
>
> diff --git a/http.c b/http.c
> index 5f348169c3..00a0e50763 100644
> --- a/http.c
> +++ b/http.c
> @@ -680,8 +680,8 @@ static void curl_dump_header(const char *text, unsigned char *ptr, size_t size,
>  	for (header = headers; *header; header++) {
>  		if (hide_sensitive_header)
>  			redact_sensitive_header(*header);
> -		strbuf_insert((*header), 0, text, strlen(text));
> -		strbuf_insert((*header), strlen(text), ": ", 2);
> +		strbuf_insertstr((*header), 0, text);
> +		strbuf_insertstr((*header), strlen(text), ": ");
>  		strbuf_rtrim((*header));
>  		strbuf_addch((*header), '\n');
>  		trace_strbuf(&trace_curl, (*header));
> diff --git a/mailinfo.c b/mailinfo.c
> index b395adbdf2..c535dec2e9 100644
> --- a/mailinfo.c
> +++ b/mailinfo.c
> @@ -254,7 +254,7 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
>  	mi->delsp = has_attr_value(line->buf, "delsp=", "yes");
>
>  	if (slurp_attr(line->buf, "boundary=", boundary)) {
> -		strbuf_insert(boundary, 0, "--", 2);
> +		strbuf_insertstr(boundary, 0, "--");
>  		if (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) {
>  			error("Too many boundaries to handle");
>  			mi->input_error = -1;
> diff --git a/notes-utils.c b/notes-utils.c
> index a819410698..5f94c513d4 100644
> --- a/notes-utils.c
> +++ b/notes-utils.c
> @@ -52,7 +52,7 @@ void commit_notes(struct repository *r, struct notes_tree *t, const char *msg)
>  	strbuf_complete_line(&buf);
>
>  	create_notes_commit(r, t, NULL, buf.buf, buf.len, &commit_oid);
> -	strbuf_insert(&buf, 0, "notes: ", 7); /* commit message starts at index 7 */
> +	strbuf_insertstr(&buf, 0, "notes: "); /* commit message starts at index 7 */
>  	update_ref(buf.buf, t->update_ref, &commit_oid, NULL, 0,
>  		   UPDATE_REFS_DIE_ON_ERR);
>
> diff --git a/notes.c b/notes.c
> index 0c79964c26..a24af53de6 100644
> --- a/notes.c
> +++ b/notes.c
> @@ -1332,9 +1332,9 @@ void expand_notes_ref(struct strbuf *sb)
>  	if (starts_with(sb->buf, "refs/notes/"))
>  		return; /* we're happy */
>  	else if (starts_with(sb->buf, "notes/"))
> -		strbuf_insert(sb, 0, "refs/", 5);
> +		strbuf_insertstr(sb, 0, "refs/");
>  	else
> -		strbuf_insert(sb, 0, "refs/notes/", 11);
> +		strbuf_insertstr(sb, 0, "refs/notes/");
>  }
>
>  void expand_loose_notes_ref(struct strbuf *sb)
> diff --git a/pretty.c b/pretty.c
> index f5fbbc5ffb..28afc701b6 100644
> --- a/pretty.c
> +++ b/pretty.c
> @@ -1609,9 +1609,9 @@ static size_t format_commit_item(struct strbuf *sb, /* in UTF-8 */
>  			strbuf_setlen(sb, sb->len - 1);
>  	} else if (orig_len != sb->len) {
>  		if (magic == ADD_LF_BEFORE_NON_EMPTY)
> -			strbuf_insert(sb, orig_len, "\n", 1);
> +			strbuf_insertstr(sb, orig_len, "\n");
>  		else if (magic == ADD_SP_BEFORE_NON_EMPTY)
> -			strbuf_insert(sb, orig_len, " ", 1);
> +			strbuf_insertstr(sb, orig_len, " ");
>  	}
>  	return consumed + 1;
>  }
> diff --git a/strbuf.h b/strbuf.h
> index bfa66569a4..aae7ac3a82 100644
> --- a/strbuf.h
> +++ b/strbuf.h
> @@ -244,6 +244,18 @@ void strbuf_addchars(struct strbuf *sb, int c, size_t n);
>   */
>  void strbuf_insert(struct strbuf *sb, size_t pos, const void *, size_t);
>
> +/**
> + * Insert a NUL-terminated string to the given position of the buffer.
> + * The remaining contents will be shifted, not overwritten.  It's an
> + * inline function to allow the compiler to resolve strlen() calls on
> + * constants at compile time.
> + */
> +static inline void strbuf_insertstr(struct strbuf *sb, size_t pos,
> +				    const char *s)
> +{
> +	strbuf_insert(sb, pos, s, strlen(s));
> +}
> +
>  /**
>   * Insert data to the given position of the buffer giving a printf format
>   * string. The contents will be shifted, not overwritten.
> --
> 2.25.0
>

Thanks,
Taylor