Re: [RFC/PATCH v11 02/13] bisect: rewrite `check_term_format` shell function in C

[Pranit Bauva]

Hey Junio,

On Tue, Aug 2, 2016 at 11:01 PM, Junio C Hamano  wrote:
> Pranit Bauva  writes:
>
>> +/*
>> + * Check whether the string `term` belongs to the set of strings
>> + * included in the variable arguments.
>> + */
>> +static int one_of(const char *term, ...)
>> +{
>> + int res = 0;
>> + va_list matches;
>> + const char *match;
>> +
>> + va_start(matches, term);
>> + while (!res && (match = va_arg(matches, const char *)))
>> + res = !strcmp(term, match);
>> + va_end(matches);
>> +
>> + return res;
>> +}
>
> It might be safer to mark this function with LAST_ARG_MUST_BE_NULL,
> but because this is static to this function, it may not matter too
> much.  Just an observation, not a strong suggestion to change the
> patch.

Yes, I could do that.

>> +static int check_term_format(const char *term, const char *orig_term)
>> +{
>> + int res;
>> + char *new_term = xstrfmt("refs/bisect/%s", term);
>> +
>> + res = check_refname_format(new_term, 0);
>> + free(new_term);
>
> Yup, that looks much more straight-forward than using a one-time-use
> strbuf.

Thanks!

Regards,
Pranit Bauva
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Re: [RFC/PATCH v11 02/13] bisect: rewrite `check_term_format` shell function in C

[Junio C Hamano]

Pranit Bauva  writes:

> +/*
> + * Check whether the string `term` belongs to the set of strings
> + * included in the variable arguments.
> + */
> +static int one_of(const char *term, ...)
> +{
> + int res = 0;
> + va_list matches;
> + const char *match;
> +
> + va_start(matches, term);
> + while (!res && (match = va_arg(matches, const char *)))
> + res = !strcmp(term, match);
> + va_end(matches);
> +
> + return res;
> +}

It might be safer to mark this function with LAST_ARG_MUST_BE_NULL,
but because this is static to this function, it may not matter too
much.  Just an observation, not a strong suggestion to change the
patch.

> +static int check_term_format(const char *term, const char *orig_term)
> +{
> + int res;
> + char *new_term = xstrfmt("refs/bisect/%s", term);
> +
> + res = check_refname_format(new_term, 0);
> + free(new_term);

Yup, that looks much more straight-forward than using a one-time-use
strbuf.
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[RFC/PATCH v11 02/13] bisect: rewrite `check_term_format` shell function in C

[Pranit Bauva]

Reimplement the `check_term_format` shell function in C and add
a `--check-term-format` subcommand to `git bisect--helper` to call it
from git-bisect.sh

Using `--check-term-format` 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/subcommand. For eg. In conversion of
write_terms() of git-bisect.sh, the subcommand will be removed and
instead check_term_format() will be called in its C implementation while
a new subcommand will be introduced for write_terms().

Helped-by: Johannes Schindelein 
Mentored-by: Lars Schneider 
Mentored-by: Christian Couder 
Signed-off-by: Pranit Bauva 
---
 builtin/bisect--helper.c | 59 +++-
 git-bisect.sh| 31 ++---
 2 files changed, 60 insertions(+), 30 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 8111c91..48285d4 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -2,19 +2,72 @@
 #include "cache.h"
 #include "parse-options.h"
 #include "bisect.h"
+#include "refs.h"
 
 static const char * const git_bisect_helper_usage[] = {
N_("git bisect--helper --next-all [--no-checkout]"),
+   N_("git bisect--helper --check-term-format  "),
NULL
 };
 
+/*
+ * Check whether the string `term` belongs to the set of strings
+ * included in the variable arguments.
+ */
+static int one_of(const char *term, ...)
+{
+   int res = 0;
+   va_list matches;
+   const char *match;
+
+   va_start(matches, term);
+   while (!res && (match = va_arg(matches, const char *)))
+   res = !strcmp(term, match);
+   va_end(matches);
+
+   return res;
+}
+
+static int check_term_format(const char *term, const char *orig_term)
+{
+   int res;
+   char *new_term = xstrfmt("refs/bisect/%s", term);
+
+   res = check_refname_format(new_term, 0);
+   free(new_term);
+
+   if (res)
+   return error(_("'%s' is not a valid term"), term);
+
+   if (one_of(term, "help", "start", "skip", "next", "reset",
+   "visualize", "replay", "log", "run", NULL))
+   return error(_("can't use the builtin command '%s' as a term"), 
term);
+
+   /*
+* In theory, nothing prevents swapping completely good and bad,
+* but this situation could be confusing and hasn't been tested
+* enough. Forbid it for now.
+*/
+
+   if ((strcmp(orig_term, "bad") && one_of(term, "bad", "new", NULL)) ||
+(strcmp(orig_term, "good") && one_of(term, "good", "old", 
NULL)))
+   return error(_("can't change the meaning of the term '%s'"), 
term);
+
+   return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
-   enum { NEXT_ALL = 1 } cmdmode = 0;
+   enum {
+   NEXT_ALL = 1,
+   CHECK_TERM_FMT
+   } cmdmode = 0;
int no_checkout = 0;
struct option options[] = {
OPT_CMDMODE(0, "next-all", ,
 N_("perform 'git bisect next'"), NEXT_ALL),
+   OPT_CMDMODE(0, "check-term-format", ,
+N_("check format of the term"), CHECK_TERM_FMT),
OPT_BOOL(0, "no-checkout", _checkout,
 N_("update BISECT_HEAD instead of checking out the 
current commit")),
OPT_END()
@@ -29,6 +82,10 @@ 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:
+   if (argc != 2)
+   die(_("--check-term-format requires two arguments"));
+   return check_term_format(argv[0], argv[1]);
default:
die("BUG: unknown subcommand '%d'", cmdmode);
}
diff --git a/git-bisect.sh b/git-bisect.sh
index 5d1cb00..7d7965d 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -564,38 +564,11 @@ write_terms () {
then
die "$(gettext "please use two different terms")"
fi
-   check_term_format "$TERM_BAD" bad
-   check_term_format "$TERM_GOOD" good
+   git bisect--helper --check-term-format "$TERM_BAD" bad || exit
+   git bisect--helper --check-term-format "$TERM_GOOD" good || exit
printf '%s\n%s\n' "$TERM_BAD" "$TERM_GOOD" >"$GIT_DIR/BISECT_TERMS"
 }
 
-check_term_format () {
-   term=$1
-   git check-ref-format refs/bisect/"$term" ||
-   die "$(eval_gettext "'\$term' is not a valid term")"
-   case "$term" in
-   help|start|terms|skip|next|reset|visualize|replay|log|run)
-   die "$(eval_gettext "can't use the builtin command