Re: [PATCH v8 3/3] bisect--helper: `write_terms` shell function in C

> Reimplement the `write_terms` shell function in C and add a `write-terms`
> subcommand to `git bisect--helper` to call it from git-bisect.sh . Also
> remove the subcommand `--check-term-format` as it can now be called from
> inside the function write_terms() C implementation.
>
> Also `|| exit` is added when calling write-terms subcommand from
> git-bisect.sh so as to exit whenever there is an error.
>
> Using `--write-terms` subcommand is a temporary measure to port shell
> function to C so as to use the existing test suite. As more functions
> are ported, this subcommand will be retired and will be called by some
> other method.
>
> Mentored-by: Lars Schneider <larsxschneider@gmail.com>
> Mentored-by: Christian Couder <chriscool@tuxfamily.org>
> Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
> ---
>  builtin/bisect--helper.c | 36 +++++++++++++++++++++++++++++-------
>  git-bisect.sh            | 22 +++++++---------------
>  2 files changed, 36 insertions(+), 22 deletions(-)
>
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 3c748d1..91027b0 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -4,9 +4,11 @@
>  #include "bisect.h"
>  #include "refs.h"
>
> +static GIT_PATH_FUNC(git_path_bisect_write_terms, "BISECT_TERMS")
> +
>  static const char * const git_bisect_helper_usage[] = {
>         N_("git bisect--helper --next-all [--no-checkout]"),
> -       N_("git bisect--helper --check-term-format <term> <orig_term>"),
> +       N_("git bisect--helper --write-terms <bad_term> <good_term>"),
>         NULL
>  };
>
> @@ -56,18 +58,38 @@ static int check_term_format(const char *term, const char *orig_term)
>         return 0;
>  }
>
> +static int write_terms(const char *bad, const char *good)
> +{
> +       FILE *fp;
> +       int res;
> +
> +       if (!strcmp(bad, good))
> +               return error(_("please use two different terms"));
> +
> +       if (check_term_format(bad, "bad") || check_term_format(good, "good"))
> +               return -1;
> +
> +       fp = fopen(git_path_bisect_write_terms(), "w");
> +       if (!fp)
> +               return error_errno(_("could not open the file BISECT_TERMS"));
> +
> +       res = fprintf(fp, "%s\n%s\n", bad, good);
> +       fclose(fp);
> +       return (res < 0) ? -1 : 0;
> +}
> +
>  int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>  {
>         enum {
>                 NEXT_ALL = 1,
> -               CHECK_TERM_FMT
> +               WRITE_TERMS
>         } cmdmode = 0;
>         int no_checkout = 0;
>         struct option options[] = {
>                 OPT_CMDMODE(0, "next-all", &cmdmode,
>                          N_("perform 'git bisect next'"), NEXT_ALL),
> -               OPT_CMDMODE(0, "check-term-format", &cmdmode,
> -                        N_("check format of the term"), CHECK_TERM_FMT),
> +               OPT_CMDMODE(0, "write-terms", &cmdmode,
> +                        N_("write the terms to .git/BISECT_TERMS"), WRITE_TERMS),
>                 OPT_BOOL(0, "no-checkout", &no_checkout,
>                          N_("update BISECT_HEAD instead of checking out the current commit")),
>                 OPT_END()
> @@ -82,10 +104,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>         switch (cmdmode) {
>         case NEXT_ALL:
>                 return bisect_next_all(prefix, no_checkout);
> -       case CHECK_TERM_FMT:
> +       case WRITE_TERMS:
>                 if (argc != 2)
> -                       die(_("--check-term-format requires two arguments"));
> -               return check_term_format(argv[0], argv[1]);
> +                       die(_("--write-terms requires two arguments"));
> +               return write_terms(argv[0], argv[1]);
>         default:
>                 die("BUG: unknown subcommand '%d'", cmdmode);
>         }
> diff --git a/git-bisect.sh b/git-bisect.sh
> index 7d7965d..cd39bd0 100755
> --- a/git-bisect.sh
> +++ b/git-bisect.sh
> @@ -210,7 +210,7 @@ bisect_start() {
>         eval "$eval true" &&
>         if test $must_write_terms -eq 1
>         then
> -               write_terms "$TERM_BAD" "$TERM_GOOD"
> +               git bisect--helper --write-terms "$TERM_BAD" "$TERM_GOOD" || exit