[PATCH] vi: allow delimiter in ':s' to be escaped

[Denys Vlasenko]

Applied 4 vi patches. Thank you.
Let me know if something does not work.

On Sat, Jul 10, 2021 at 12:00 PM Ron Yorston <rmy at pobox.com> wrote:
>
> When regular expressions are allowed in search commands it becomes
> possible to escape the delimiter in search/replace commands.  For
> example, this command will replace '/abc' with '/abc/':
>
>    :s/\/abc/\/abc\//g
>
> The code to split the command into 'find' and 'replace' strings
> should allow for this possibility.
>
> VI_REGEX_SEARCH isn't enabled by default.  When it is:
>
> function                                             old     new   delta
> strchr_backslash                                       -      38     +38
> colon                                               4378    4373      -5
> ------------------------------------------------------------------------------
> (add/remove: 1/0 grow/shrink: 0/1 up/down: 38/-5)              Total: 33 bytes
>
> Signed-off-by: Ron Yorston <rmy at pobox.com>
> ---
>  editors/vi.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/editors/vi.c b/editors/vi.c
> index f830368c2..ce5740e49 100644
> --- a/editors/vi.c
> +++ b/editors/vi.c
> @@ -2680,6 +2680,19 @@ static char *expand_args(char *args)
>  #if ENABLE_FEATURE_VI_REGEX_SEARCH
>  # define MAX_SUBPATTERN 10     // subpatterns \0 .. \9
>
> +// Like strchr() but skipping backslash-escaped characters
> +static char *strchr_backslash(const char *s, int c)
> +{
> +       for (; *s; ++s) {
> +               if (*s == c) {
> +                       return (char *)s;
> +               } else if (*s == '\\' && *++s == '\0') {
> +                       break;
> +               }
> +       }
> +       return NULL;
> +}
> +
>  // If the return value is not NULL the caller should free R
>  static char *regex_search(char *q, regex_t *preg, const char *Rorig,
>                                 size_t *len_F, size_t *len_R, char **R)
> @@ -2728,6 +2741,8 @@ static char *regex_search(char *q, regex_t *preg, const char *Rorig,
>
>         return found;
>  }
> +#else /* !ENABLE_FEATURE_VI_REGEX_SEARCH */
> +# define strchr_backslash(s, c) strchr(s, c)
>  #endif /* ENABLE_FEATURE_VI_REGEX_SEARCH */
>
>  // buf must be no longer than MAX_INPUT_LEN!
> @@ -3151,12 +3166,12 @@ static void colon(char *buf)
>                 // replace the cmd line delimiters "/" with NULs
>                 c = buf[1];     // what is the delimiter
>                 F = buf + 2;    // start of "find"
> -               R = strchr(F, c);       // middle delimiter
> +               R = strchr_backslash(F, c);     // middle delimiter
>                 if (!R)
>                         goto colon_s_fail;
>                 len_F = R - F;
>                 *R++ = '\0';    // terminate "find"
> -               flags = strchr(R, c);
> +               flags = strchr_backslash(R, c);
>                 if (flags) {
>                         *flags++ = '\0';        // terminate "replace"
>                         gflag = *flags;
> --
> 2.31.1
>
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