Re: [PATCH] diff: avoid stack-buffer-read-overrun for very long name

Junio C Hamano wrote:

Jim Meyering [off-list ref] writes:

quoted

What do you think about replacing those two append-if-needed two-liners:

    if (buffer2.len && buffer2.buf[buffer2.len - 1] != '/')
            strbuf_addch(&buffer2, '/');

by something that readably encapsulates the idiom:

    strbuf_append_if_absent (&buffer2, '/');

(though the name isn't particularly apt, because you might
take "absent" to mean "not anywhere in the string," so maybe
  strbuf_append_if_not_already_at_end (ugly) or
  strbuf_append_uniq
)

I am not good at names, but strbuf_terminate_with(&buffer2, '/')
perhaps?

Maybe, but it still doesn't evoke the conditional nature
of don't-append-if-already-there the operation.  i.e., one
might wonder how it's different from "strbuf_append".

How about one of these?

  strbuf_ensure_suffix  // but might make you think suffix==more than 1 byte
  strbuf_ensure_last_byte    // maybe?
  strbuf_ensure_last_byte_is // rather long, but apt

quoted

There are several other uses that would benefit from such a transformation:
To find the easy ones, I ran this:

  git grep -B1 "strbuf_addch.*'"|grep -A1 '!='

I've manually marked/separated the ones that don't apply.

Note how only 2 of the 6 candidates ensure that length is positive
before using ".len - 1":

Yikes, that is embarrasing ;-)

Knowing you/git, each is because the buffer is known to be non-empty.