[Outreachy] [PATCH v3 00/13] Finish converting git bisect to C part 1

[Outreachy] [PATCH v3 00/13] Finish converting git bisect to C part 1

[Miriam Rubio]

These patches correspond to a first part of patch series 
of Outreachy project "Finish converting `git bisect` from shell to C" 
started by Pranit Bauva and Tanushree Tumane
(https://public-inbox.org/git/pull.117.git.gitgitgadget@gmail.com) and
continued by me.

This first part is formed of preparatory/clean-up patches and all 
`bisect.c` libification work. 

I would like to thank Johannes Schindelin and Junio Hamano for reviewing
the patch series.

These patch series emails were generated from:
https://gitlab.com/mirucam/git/commits/git-bisect-work-part1-v3

--- Changes since v2 Finish converting git bisect to C part 1 patch series ---

General changes
---------------

* Rebase on master branch: de93cc14ab (The third batch for 2.26, 2020-02-05).
* Amend commit messages.
* Add an enum to represent bisecting error codes.

Specific changes
----------------

[5/13] bisect--helper: introduce new `decide_next()` function

* Change const char* types to char* and fix `free()` calls.

--

[6/13] bisect: add enum to represent bisect returning codes

* New patch that adds an enum to represent bisecting error codes.

--

[7/13] bisect--helper: return error codes from `cmd_bisect__helper()`

* New patch split from `libify `check_good_are_ancestors_of_bad` and its 
dependents`.
* Change code in return for readability.

--

[8/13] bisect: libify `exit_if_skipped_commits` to `error_if_skipped*` 
and its dependents

* Remove comments.

--

[9/13] bisect: libify `bisect_checkout`

* Fix declaration block.
* Change code in return for readability.
* Add comments.

--

[11/13] bisect: libify `check_good_are_ancestors_of_bad` and its 
dependents

* Fix brace location.

--

Miriam Rubio (3):
  bisect--helper: convert `vocab_*` char pointers to char arrays
  bisect: use the standard 'if (!var)' way to check for 0
  bisect: add enum to represent bisect returning codes

Pranit Bauva (8):
  run-command: make `exists_in_PATH()` non-static
  bisect--helper: return error codes from `cmd_bisect__helper()`
  bisect: libify `exit_if_skipped_commits` to `error_if_skipped*` and
    its dependents
  bisect: libify `bisect_checkout`
  bisect: libify `check_merge_bases` and its dependents
  bisect: libify `check_good_are_ancestors_of_bad` and its dependents
  bisect: libify `handle_bad_merge_base` and its dependents
  bisect: libify `bisect_next_all`

Tanushree Tumane (2):
  bisect--helper: change `retval` to `res`
  bisect--helper: introduce new `decide_next()` function

 bisect.c                 | 135 +++++++++++++++++++++++++++------------
 bisect.h                 |  29 ++++++++-
 builtin/bisect--helper.c | 123 +++++++++++++++++++----------------
 run-command.c            |   2 +-
 run-command.h            |  11 ++++
 5 files changed, 201 insertions(+), 99 deletions(-)

-- 
2.25.0

[PATCH v3 01/13] bisect--helper: convert `vocab_*` char pointers to char arrays

[Miriam Rubio]

Instead of using a pointer that points at a constant string,
just give name directly to the constant string; this way, we
do not have to allocate a pointer variable in addition to
the string we want to use.

Let's convert `vocab_bad` and `vocab_good` char pointers to char arrays.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 builtin/bisect--helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 1718df7f09..36c09b7238 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -52,8 +52,8 @@ static void set_terms(struct bisect_terms *terms, const char *bad,
 	terms->term_bad = xstrdup(bad);
 }
 
-static const char *vocab_bad = "bad|new";
-static const char *vocab_good = "good|old";
+static const char vocab_bad[] = "bad|new";
+static const char vocab_good[] = "good|old";
 
 /*
  * Check whether the string `term` belongs to the set of strings
-- 
2.25.0

[PATCH v3 02/13] bisect--helper: change `retval` to `res`

[Miriam Rubio]

From: Tanushree Tumane <tanushreetumane@gmail.com>

Let's rename variable retval to res, so that variable names
in bisect--helper.c are more consistent.

After this change, there are 110 occurrences of res in the file
and zero of retval, while there were 26 instances of retval before.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 builtin/bisect--helper.c | 52 ++++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 36c09b7238..21de5c096c 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -206,31 +206,31 @@ static int bisect_write(const char *state, const char *rev,
 	struct object_id oid;
 	struct commit *commit;
 	FILE *fp = NULL;
-	int retval = 0;
+	int res = 0;
 
 	if (!strcmp(state, terms->term_bad)) {
 		strbuf_addf(&tag, "refs/bisect/%s", state);
 	} else if (one_of(state, terms->term_good, "skip", NULL)) {
 		strbuf_addf(&tag, "refs/bisect/%s-%s", state, rev);
 	} else {
-		retval = error(_("Bad bisect_write argument: %s"), state);
+		res = error(_("Bad bisect_write argument: %s"), state);
 		goto finish;
 	}
 
 	if (get_oid(rev, &oid)) {
-		retval = error(_("couldn't get the oid of the rev '%s'"), rev);
+		res = error(_("couldn't get the oid of the rev '%s'"), rev);
 		goto finish;
 	}
 
 	if (update_ref(NULL, tag.buf, &oid, NULL, 0,
 		       UPDATE_REFS_MSG_ON_ERR)) {
-		retval = -1;
+		res = -1;
 		goto finish;
 	}
 
 	fp = fopen(git_path_bisect_log(), "a");
 	if (!fp) {
-		retval = error_errno(_("couldn't open the file '%s'"), git_path_bisect_log());
+		res = error_errno(_("couldn't open the file '%s'"), git_path_bisect_log());
 		goto finish;
 	}
 
@@ -244,7 +244,7 @@ static int bisect_write(const char *state, const char *rev,
 	if (fp)
 		fclose(fp);
 	strbuf_release(&tag);
-	return retval;
+	return res;
 }
 
 static int check_and_set_terms(struct bisect_terms *terms, const char *cmd)
@@ -294,7 +294,7 @@ static const char need_bisect_start_warning[] =
 static int bisect_next_check(const struct bisect_terms *terms,
 			     const char *current_term)
 {
-	int missing_good = 1, missing_bad = 1, retval = 0;
+	int missing_good = 1, missing_bad = 1, res = 0;
 	const char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
 	const char *good_glob = xstrfmt("%s-*", terms->term_good);
 
@@ -308,7 +308,7 @@ static int bisect_next_check(const struct bisect_terms *terms,
 		goto finish;
 
 	if (!current_term) {
-		retval = -1;
+		res = -1;
 		goto finish;
 	}
 
@@ -329,21 +329,21 @@ static int bisect_next_check(const struct bisect_terms *terms,
 		 */
 		yesno = git_prompt(_("Are you sure [Y/n]? "), PROMPT_ECHO);
 		if (starts_with(yesno, "N") || starts_with(yesno, "n"))
-			retval = -1;
+			res = -1;
 		goto finish;
 	}
 	if (!is_empty_or_missing_file(git_path_bisect_start())) {
-		retval = error(_(need_bad_and_good_revision_warning),
+		res = error(_(need_bad_and_good_revision_warning),
 			       vocab_bad, vocab_good, vocab_bad, vocab_good);
 	} else {
-		retval = error(_(need_bisect_start_warning),
+		res = error(_(need_bisect_start_warning),
 			       vocab_good, vocab_bad, vocab_good, vocab_bad);
 	}
 
 finish:
 	free((void *) good_glob);
 	free((void *) bad_ref);
-	return retval;
+	return res;
 }
 
 static int get_terms(struct bisect_terms *terms)
@@ -397,7 +397,7 @@ static int bisect_terms(struct bisect_terms *terms, const char *option)
 
 static int bisect_append_log_quoted(const char **argv)
 {
-	int retval = 0;
+	int res = 0;
 	FILE *fp = fopen(git_path_bisect_log(), "a");
 	struct strbuf orig_args = STRBUF_INIT;
 
@@ -405,25 +405,25 @@ static int bisect_append_log_quoted(const char **argv)
 		return -1;
 
 	if (fprintf(fp, "git bisect start") < 1) {
-		retval = -1;
+		res = -1;
 		goto finish;
 	}
 
 	sq_quote_argv(&orig_args, argv);
 	if (fprintf(fp, "%s\n", orig_args.buf) < 1)
-		retval = -1;
+		res = -1;
 
 finish:
 	fclose(fp);
 	strbuf_release(&orig_args);
-	return retval;
+	return res;
 }
 
 static int bisect_start(struct bisect_terms *terms, int no_checkout,
 			const char **argv, int argc)
 {
 	int i, has_double_dash = 0, must_write_terms = 0, bad_seen = 0;
-	int flags, pathspec_pos, retval = 0;
+	int flags, pathspec_pos, res = 0;
 	struct string_list revs = STRING_LIST_INIT_DUP;
 	struct string_list states = STRING_LIST_INIT_DUP;
 	struct strbuf start_head = STRBUF_INIT;
@@ -524,7 +524,7 @@ static int bisect_start(struct bisect_terms *terms, int no_checkout,
 			argv_array_pushl(&argv, "checkout", start_head.buf,
 					 "--", NULL);
 			if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
-				retval = error(_("checking out '%s' failed."
+				res = error(_("checking out '%s' failed."
 						 " Try 'git bisect start "
 						 "<valid-branch>'."),
 					       start_head.buf);
@@ -572,12 +572,12 @@ static int bisect_start(struct bisect_terms *terms, int no_checkout,
 
 	if (no_checkout) {
 		if (get_oid(start_head.buf, &oid) < 0) {
-			retval = error(_("invalid ref: '%s'"), start_head.buf);
+			res = error(_("invalid ref: '%s'"), start_head.buf);
 			goto finish;
 		}
 		if (update_ref(NULL, "BISECT_HEAD", &oid, NULL, 0,
 			       UPDATE_REFS_MSG_ON_ERR)) {
-			retval = -1;
+			res = -1;
 			goto finish;
 		}
 	}
@@ -589,26 +589,26 @@ static int bisect_start(struct bisect_terms *terms, int no_checkout,
 	for (i = 0; i < states.nr; i++)
 		if (bisect_write(states.items[i].string,
 				 revs.items[i].string, terms, 1)) {
-			retval = -1;
+			res = -1;
 			goto finish;
 		}
 
 	if (must_write_terms && write_terms(terms->term_bad,
 					    terms->term_good)) {
-		retval = -1;
+		res = -1;
 		goto finish;
 	}
 
-	retval = bisect_append_log_quoted(argv);
-	if (retval)
-		retval = -1;
+	res = bisect_append_log_quoted(argv);
+	if (res)
+		res = -1;
 
 finish:
 	string_list_clear(&revs, 0);
 	string_list_clear(&states, 0);
 	strbuf_release(&start_head);
 	strbuf_release(&bisect_names);
-	return retval;
+	return res;
 }
 
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
-- 
2.25.0

[PATCH v3 03/13] bisect: use the standard 'if (!var)' way to check for 0

[Miriam Rubio]

Instead of using 'var == 0' in an if condition, let's use '!var' and
make 'bisect.c' more consistent with the rest of the code.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/bisect.c b/bisect.c
index e81c91d02c..83cb5b3a98 100644
--- a/bisect.c
+++ b/bisect.c
@@ -572,7 +572,7 @@ static int sqrti(int val)
 {
 	float d, x = val;
 
-	if (val == 0)
+	if (!val)
 		return 0;
 
 	do {
@@ -869,7 +869,7 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
 		goto done;
 
 	/* Bisecting with no good rev is ok. */
-	if (good_revs.nr == 0)
+	if (!good_revs.nr)
 		goto done;
 
 	/* Check if all good revs are ancestor of the bad rev. */
-- 
2.25.0

[PATCH v3 04/13] run-command: make `exists_in_PATH()` non-static

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Removes the `static` keyword from `exists_in_PATH()` function
and declares the function in `run-command.h` file.
The function will be used in bisect_visualize() in a later
commit.

`exists_in_PATH()` and `locate_in_PATH()` functions don't
depend on file-local variables.

Mentored by: Christian Couder <chriscool@tuxfamily.org>
Mentored by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 run-command.c |  2 +-
 run-command.h | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/run-command.c b/run-command.c
index f5e1149f9b..4df975178d 100644
--- a/run-command.c
+++ b/run-command.c
@@ -210,7 +210,7 @@ static char *locate_in_PATH(const char *file)
 	return NULL;
 }
 
-static int exists_in_PATH(const char *file)
+int exists_in_PATH(const char *file)
 {
 	char *r = locate_in_PATH(file);
 	int found = r != NULL;
diff --git a/run-command.h b/run-command.h
index 592d9dc035..7c8e206d97 100644
--- a/run-command.h
+++ b/run-command.h
@@ -172,6 +172,17 @@ void child_process_clear(struct child_process *);
 
 int is_executable(const char *name);
 
+/**
+ * Returns if a $PATH given by parameter is found or not (it is NULL). This
+ * function uses locate_in_PATH() function that emulates the path search that
+ * execvp would perform. Memory used to store the resultant path is freed by
+ * the function.
+ *
+ * The caller should ensure that $PATH contains no directory
+ * separators.
+ */
+int exists_in_PATH(const char *);
+
 /**
  * Start a sub-process. Takes a pointer to a `struct child_process`
  * that specifies the details and returns pipe FDs (if requested).
-- 
2.25.0

Re: [PATCH v3 04/13] run-command: make `exists_in_PATH()` non-static

[René Scharfe]

Am 08.02.20 um 10:06 schrieb Miriam Rubio:
> From: Pranit Bauva <pranit.bauva@gmail.com>
>
> Removes the `static` keyword from `exists_in_PATH()` function
> and declares the function in `run-command.h` file.
> The function will be used in bisect_visualize() in a later
> commit.

I couldn't find the mentioned later commit in this series.  Do you
actually still need to export exists_in_PATH()?

And if yes: locate_in_PATH() splits PATH by colon.  That means it
doesn't work on Windows, where the paths are separated by semicolons.
exists_in_PATH() wraps it, so it shares that limitation.  Wouldn't that
cause issues for your use?

René

Re: [PATCH v3 04/13] run-command: make `exists_in_PATH()` non-static

[Miriam R.]

Hi,

El sáb., 8 feb. 2020 a las 11:55, René Scharfe (<l.s.r@web.de>) escribió:
>
> Am 08.02.20 um 10:06 schrieb Miriam Rubio:
> > From: Pranit Bauva <pranit.bauva@gmail.com>
> >
> > Removes the `static` keyword from `exists_in_PATH()` function
> > and declares the function in `run-command.h` file.
> > The function will be used in bisect_visualize() in a later
> > commit.
>
> I couldn't find the mentioned later commit in this series.  Do you
> actually still need to export exists_in_PATH()?

This series is part of a bigger patch series
(https://public-inbox.org/git/20200120143800.900-1-mirucam@gmail.com/)
that has been split as a suggestion of a reviewer in order to be
easily reviewed.
This first part is formed of preparatory/clean-up patches and all
`bisect.c` libification work. The actual patch is one of the
preparatory patches and the function will be used in the upcoming
patch series.

>
> And if yes: locate_in_PATH() splits PATH by colon.  That means it
> doesn't work on Windows, where the paths are separated by semicolons.
> exists_in_PATH() wraps it, so it shares that limitation.  Wouldn't that
> cause issues for your use?

Thank you, for point that out.  I will check this.
Best,
Miriam
>
> René

Re: [PATCH v3 04/13] run-command: make `exists_in_PATH()` non-static

[Miriam R.]

Hi René,

El lun., 10 feb. 2020 a las 16:43, René Scharfe (<l.s.r@web.de>) escribió:
>
> Hello Miriam,
>
> did you remove the Git mailing list from cc: intentionally?
No, no.
Maybe I clicked reply, instead reply all. Sorry.
It is included in CC now.

>
> Am 10.02.20 um 12:16 schrieb Miriam R.:
> > El dom., 9 feb. 2020 a las 10:59, Miriam R. (<mirucam@gmail.com>) escribió:
> >> El sáb., 8 feb. 2020 a las 11:55, René Scharfe (<l.s.r@web.de>) escribió:
> >>> And if yes: locate_in_PATH() splits PATH by colon.  That means it
> >>> doesn't work on Windows, where the paths are separated by semicolons.
> >>> exists_in_PATH() wraps it, so it shares that limitation.  Wouldn't that
> >>> cause issues for your use?
> >>
> >> Thank you, for point that out.  I will check this.
> >
> > This function is used only to test if gitk exists. But as gitk does not work
> > on Windows, then I think it is all ok because the evaluation is going to
> > return false and nothing has to be changed.
>
> Now I'm confused, because I do use gitk on Windows.  The third
> screenshot on https://gitforwindows.org/ shows it as well, so you don't
> have to just take my word on it.

Ohh, as I'm not a Windows user, and after some google searches it
seems to me it doesn't. It is clear that I was not asking the correct
things, hehe. Thank you for the clarification.

>
> > Also, as this patch is not really needed for this part1, I will move
> > it to the upcoming patch series.
>
> That makes sense.
>
> I guess it's to used in the C equivalent of the Shell function
> bisect_visualize(), which resolves gitk using type, calls it if it's
> found and falls back to git log if it isn't.
Exactly.

>Why not try to exec gitk
> and fall back to git log if that fails?
>
It seems a good solution for me :)

Thank you for reviewing.
Best,
Miriam.

> René

Re: [PATCH v3 04/13] run-command: make `exists_in_PATH()` non-static

[Taylor Blau]

On Sat, Feb 08, 2020 at 10:06:55AM +0100, Miriam Rubio wrote:
> From: Pranit Bauva <pranit.bauva@gmail.com>
>
> Removes the `static` keyword from `exists_in_PATH()` function
> and declares the function in `run-command.h` file.
> The function will be used in bisect_visualize() in a later
> commit.

There may be some odd line-wrapping going on here.

> `exists_in_PATH()` and `locate_in_PATH()` functions don't
> depend on file-local variables.
>
> Mentored by: Christian Couder <chriscool@tuxfamily.org>
> Mentored by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
> Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
> Signed-off-by: Miriam Rubio <mirucam@gmail.com>
> ---
>  run-command.c |  2 +-
>  run-command.h | 11 +++++++++++
>  2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/run-command.c b/run-command.c
> index f5e1149f9b..4df975178d 100644
> --- a/run-command.c
> +++ b/run-command.c
> @@ -210,7 +210,7 @@ static char *locate_in_PATH(const char *file)
>  	return NULL;
>  }
>
> -static int exists_in_PATH(const char *file)
> +int exists_in_PATH(const char *file)
>  {
>  	char *r = locate_in_PATH(file);
>  	int found = r != NULL;
> diff --git a/run-command.h b/run-command.h
> index 592d9dc035..7c8e206d97 100644
> --- a/run-command.h
> +++ b/run-command.h
> @@ -172,6 +172,17 @@ void child_process_clear(struct child_process *);
>
>  int is_executable(const char *name);
>
> +/**
> + * Returns if a $PATH given by parameter is found or not (it is NULL). This
> + * function uses locate_in_PATH() function that emulates the path search that
> + * execvp would perform. Memory used to store the resultant path is freed by
> + * the function.
> + *
> + * The caller should ensure that $PATH contains no directory
> + * separators.

This line-wrapping caught my eye: it looks like 'separators' would fit
on the line before, or at least that this paragraph and the one above it
are wrapped at two different widths.

I'm not sure that it really matters, since it looks like the wrapping in
this file isn't entirely consistent, but I figured that I'd point it out
nonetheless.

> + */
> +int exists_in_PATH(const char *);

Have you considered naming this argument? It's somewhat clear from the
documentation, but I don't see a reason not to name it (especially since
other declarations in this file *do* name their parameters). What about:

  int exists_in_PATH(const char *file);

To match its definition in 'run-command.c'? (Admittedly, if I had
written this I'd probably call it 'entry', but they should at least be
consistent).

> +
>  /**
>   * Start a sub-process. Takes a pointer to a `struct child_process`
>   * that specifies the details and returns pipe FDs (if requested).
> --
> 2.25.0
>

Thanks,
Taylor

[PATCH v3 05/13] bisect--helper: introduce new `decide_next()` function

[Miriam Rubio]

From: Tanushree Tumane <tanushreetumane@gmail.com>

Let's refactor code from bisect_next_check() into a new
decide_next() helper function.

This removes some goto statements and makes the code simpler,
clearer and easier to understand.

While at it `bad_ref` and `good_glob` are not const any more
to void casting them inside `free()`.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 builtin/bisect--helper.c | 66 +++++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 32 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 21de5c096c..e21d3d1a4c 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -291,26 +291,14 @@ static const char need_bisect_start_warning[] =
 	   "You then need to give me at least one %s and %s revision.\n"
 	   "You can use \"git bisect %s\" and \"git bisect %s\" for that.");
 
-static int bisect_next_check(const struct bisect_terms *terms,
-			     const char *current_term)
+static int decide_next(const struct bisect_terms *terms,
+		       const char *current_term, int missing_good,
+		       int missing_bad)
 {
-	int missing_good = 1, missing_bad = 1, res = 0;
-	const char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
-	const char *good_glob = xstrfmt("%s-*", terms->term_good);
-
-	if (ref_exists(bad_ref))
-		missing_bad = 0;
-
-	for_each_glob_ref_in(mark_good, good_glob, "refs/bisect/",
-			     (void *) &missing_good);
-
 	if (!missing_good && !missing_bad)
-		goto finish;
-
-	if (!current_term) {
-		res = -1;
-		goto finish;
-	}
+		return 0;
+	if (!current_term)
+		return -1;
 
 	if (missing_good && !missing_bad &&
 	    !strcmp(current_term, terms->term_good)) {
@@ -321,7 +309,7 @@ static int bisect_next_check(const struct bisect_terms *terms,
 		 */
 		warning(_("bisecting only with a %s commit"), terms->term_bad);
 		if (!isatty(0))
-			goto finish;
+			return 0;
 		/*
 		 * TRANSLATORS: Make sure to include [Y] and [n] in your
 		 * translation. The program will only accept English input
@@ -329,21 +317,35 @@ static int bisect_next_check(const struct bisect_terms *terms,
 		 */
 		yesno = git_prompt(_("Are you sure [Y/n]? "), PROMPT_ECHO);
 		if (starts_with(yesno, "N") || starts_with(yesno, "n"))
-			res = -1;
-		goto finish;
-	}
-	if (!is_empty_or_missing_file(git_path_bisect_start())) {
-		res = error(_(need_bad_and_good_revision_warning),
-			       vocab_bad, vocab_good, vocab_bad, vocab_good);
-	} else {
-		res = error(_(need_bisect_start_warning),
-			       vocab_good, vocab_bad, vocab_good, vocab_bad);
+			return -1;
+		return 0;
 	}
 
-finish:
-	free((void *) good_glob);
-	free((void *) bad_ref);
-	return res;
+	if (!is_empty_or_missing_file(git_path_bisect_start()))
+		return error(_(need_bad_and_good_revision_warning),
+			     vocab_bad, vocab_good, vocab_bad, vocab_good);
+	else
+		return error(_(need_bisect_start_warning),
+			     vocab_good, vocab_bad, vocab_good, vocab_bad);
+}
+
+static int bisect_next_check(const struct bisect_terms *terms,
+			     const char *current_term)
+{
+	int missing_good = 1, missing_bad = 1;
+	char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
+	char *good_glob = xstrfmt("%s-*", terms->term_good);
+
+	if (ref_exists(bad_ref))
+		missing_bad = 0;
+
+	for_each_glob_ref_in(mark_good, good_glob, "refs/bisect/",
+			     (void *) &missing_good);
+
+	free(good_glob);
+	free(bad_ref);
+
+	return decide_next(terms, current_term, missing_good, missing_bad);
 }
 
 static int get_terms(struct bisect_terms *terms)
-- 
2.25.0

[PATCH v3 06/13] bisect: add enum to represent bisect returning codes

[Miriam Rubio]

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Create an enum called `bisect_error` with the bisecting return codes
to use in `bisect.c` libification process.

Change bisect_next_all() to make it return this enum.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c |  2 +-
 bisect.h | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/bisect.c b/bisect.c
index 83cb5b3a98..e4573c7ba1 100644
--- a/bisect.c
+++ b/bisect.c
@@ -945,7 +945,7 @@ void read_bisect_terms(const char **read_bad, const char **read_good)
  * If no_checkout is non-zero, the bisection process does not
  * checkout the trial commit but instead simply updates BISECT_HEAD.
  */
-int bisect_next_all(struct repository *r, const char *prefix, int no_checkout)
+enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int no_checkout)
 {
 	struct rev_info revs;
 	struct commit_list *tried;
diff --git a/bisect.h b/bisect.h
index 4e69a11ea8..c921ead02c 100644
--- a/bisect.h
+++ b/bisect.h
@@ -31,7 +31,19 @@ struct rev_list_info {
 	const char *header_prefix;
 };
 
-int bisect_next_all(struct repository *r,
+/*
+ * enum bisect_error represents the following return codes:
+ * BISECT_OK: success code. Internally, it means that next
+ * commit has been found (and possibly checked out) and it
+ * should be tested.
+ * BISECT_FAILED error code: default error code.
+ */
+enum bisect_error {
+	BISECT_OK = 0,
+	BISECT_FAILED = -1
+};
+
+enum bisect_error bisect_next_all(struct repository *r,
 		    const char *prefix,
 		    int no_checkout);
 
-- 
2.25.0

[PATCH v3 07/13] bisect--helper: return error codes from `cmd_bisect__helper()`

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary
to convert bisect.c exit() calls to return statements so
that errors can be reported. Let's prepare for that by making
it possible to return different error codes than just 0 or 1.

Different error codes might enable a bisecting script calling the
bisect command that uses this function to do different things
depending on the exit status of the bisect command.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 builtin/bisect--helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index e21d3d1a4c..e6bd4d6645 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -713,5 +713,5 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		return error("BUG: unknown subcommand '%d'", cmdmode);
 	}
 	free_terms(&terms);
-	return !!res;
+	return abs(res);
 }
-- 
2.25.0

[PATCH v3 08/13] bisect: libify `exit_if_skipped_commits` to `error_if_skipped*` and its dependents

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

Update all callers to handle the error returns.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 17 +++++++++++------
 bisect.h |  5 ++++-
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/bisect.c b/bisect.c
index e4573c7ba1..85bda3500b 100644
--- a/bisect.c
+++ b/bisect.c
@@ -661,11 +661,11 @@ static void bisect_common(struct rev_info *revs)
 		mark_edges_uninteresting(revs, NULL, 0);
 }
 
-static void exit_if_skipped_commits(struct commit_list *tried,
+static enum bisect_error error_if_skipped_commits(struct commit_list *tried,
 				    const struct object_id *bad)
 {
 	if (!tried)
-		return;
+		return BISECT_OK;
 
 	printf("There are only 'skip'ped commits left to test.\n"
 	       "The first %s commit could be any of:\n", term_bad);
@@ -676,7 +676,8 @@ static void exit_if_skipped_commits(struct commit_list *tried,
 	if (bad)
 		printf("%s\n", oid_to_hex(bad));
 	printf(_("We cannot bisect more!\n"));
-	exit(2);
+
+	return BISECT_ONLY_SKIPPED_LEFT;
 }
 
 static int is_expected_rev(const struct object_id *oid)
@@ -950,6 +951,7 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 	struct rev_info revs;
 	struct commit_list *tried;
 	int reaches = 0, all = 0, nr, steps;
+	enum bisect_error res = BISECT_OK;
 	struct object_id *bisect_rev;
 	char *steps_msg;
 
@@ -972,8 +974,9 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 		 * We should exit here only if the "bad"
 		 * commit is also a "skip" commit.
 		 */
-		exit_if_skipped_commits(tried, NULL);
-
+		res = error_if_skipped_commits(tried, NULL);
+		if (res < 0)
+			exit(-res);
 		printf(_("%s was both %s and %s\n"),
 		       oid_to_hex(current_bad_oid),
 		       term_good,
@@ -990,7 +993,9 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 	bisect_rev = &revs.commits->item->object.oid;
 
 	if (oideq(bisect_rev, current_bad_oid)) {
-		exit_if_skipped_commits(tried, current_bad_oid);
+		res = error_if_skipped_commits(tried, current_bad_oid);
+		if (res)
+			exit(-res);
 		printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
 			term_bad);
 		show_diff_tree(r, prefix, revs.commits->item);
diff --git a/bisect.h b/bisect.h
index c921ead02c..19d90e4870 100644
--- a/bisect.h
+++ b/bisect.h
@@ -37,10 +37,13 @@ struct rev_list_info {
  * commit has been found (and possibly checked out) and it
  * should be tested.
  * BISECT_FAILED error code: default error code.
+ * BISECT_ONLY_SKIPPED_LEFT error code: only skipped
+ * commits left to be tested.
  */
 enum bisect_error {
 	BISECT_OK = 0,
-	BISECT_FAILED = -1
+	BISECT_FAILED = -1,
+	BISECT_ONLY_SKIPPED_LEFT = -2
 };
 
 enum bisect_error bisect_next_all(struct repository *r,
-- 
2.25.0

[PATCH v3 09/13] bisect: libify `bisect_checkout`

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

Turn `exit()` to `return` calls in `bisect_checkout()`.
Changes related to return values have no bad side effects on the
code that calls `bisect_checkout()`.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/bisect.c b/bisect.c
index 85bda3500b..f6582ddfed 100644
--- a/bisect.c
+++ b/bisect.c
@@ -704,9 +704,10 @@ static int is_expected_rev(const struct object_id *oid)
 	return res;
 }
 
-static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
+static enum bisect_error bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
 {
 	char bisect_rev_hex[GIT_MAX_HEXSZ + 1];
+	enum bisect_error res = BISECT_OK;
 
 	memcpy(bisect_rev_hex, oid_to_hex(bisect_rev), the_hash_algo->hexsz + 1);
 	update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
@@ -716,14 +717,24 @@ static int bisect_checkout(const struct object_id *bisect_rev, int no_checkout)
 		update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0,
 			   UPDATE_REFS_DIE_ON_ERR);
 	} else {
-		int res;
 		res = run_command_v_opt(argv_checkout, RUN_GIT_CMD);
 		if (res)
-			exit(res);
+			/*
+			 * Errors in `run_command()` itself, signaled by res < 0,
+			 * and errors in the child process, signaled by res > 0
+			 * can both be treated as regular BISECT_FAILURE (-1).
+			 */
+			return -abs(res);
 	}
 
 	argv_show_branch[1] = bisect_rev_hex;
-	return run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
+	res = run_command_v_opt(argv_show_branch, RUN_GIT_CMD);
+	/*
+	 * Errors in `run_command()` itself, signaled by res < 0,
+	 * and errors in the child process, signaled by res > 0
+	 * can both be treated as regular BISECT_FAILURE (-1).
+	 */
+	return -abs(res);
 }
 
 static struct commit *get_commit_reference(struct repository *r,
-- 
2.25.0

[PATCH v3 10/13] bisect: libify `check_merge_bases` and its dependents

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

In `check_merge_bases()` there is an early success special case,
so we have introduced special error code
BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) which indicates early
success. This BISECT_INTERNAL_SUCCESS_MERGE_BASE is converted back
to BISECT_OK (0) in `check_good_are_ancestors_of_bad()`.

Update all callers to handle the error returns.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 22 ++++++++++++++++++----
 bisect.h |  7 ++++++-
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/bisect.c b/bisect.c
index f6582ddfed..382e0b471f 100644
--- a/bisect.c
+++ b/bisect.c
@@ -811,13 +811,18 @@ static void handle_skipped_merge_base(const struct object_id *mb)
  * "check_merge_bases" checks that merge bases are not "bad" (or "new").
  *
  * - If one is "bad" (or "new"), it means the user assumed something wrong
- * and we must exit with a non 0 error code.
+ * and we must return error with a non 0 error code.
  * - If one is "good" (or "old"), that's good, we have nothing to do.
  * - If one is "skipped", we can't know but we should warn.
  * - If we don't know, we should check it out and ask the user to test.
+ * - If a merge base must be tested, on success return
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) a special condition
+ * for early success, this will be converted back to 0 in
+ * check_good_are_ancestors_of_bad().
  */
-static void check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
+static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
 {
+	enum bisect_error res = BISECT_OK;
 	struct commit_list *result;
 
 	result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1);
@@ -832,11 +837,16 @@ static void check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
 			handle_skipped_merge_base(mb);
 		} else {
 			printf(_("Bisecting: a merge base must be tested\n"));
-			exit(bisect_checkout(mb, no_checkout));
+			res = bisect_checkout(mb, no_checkout);
+			if (!res)
+				/* indicate early success */
+				res = BISECT_INTERNAL_SUCCESS_MERGE_BASE;
+			break;
 		}
 	}
 
 	free_commit_list(result);
+	return res;
 }
 
 static int check_ancestors(struct repository *r, int rev_nr,
@@ -871,6 +881,7 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
 	char *filename = git_pathdup("BISECT_ANCESTORS_OK");
 	struct stat st;
 	int fd, rev_nr;
+	enum bisect_error res = BISECT_OK;
 	struct commit **rev;
 
 	if (!current_bad_oid)
@@ -885,10 +896,13 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
 		goto done;
 
 	/* Check if all good revs are ancestor of the bad rev. */
+
 	rev = get_bad_and_good_commits(r, &rev_nr);
 	if (check_ancestors(r, rev_nr, rev, prefix))
-		check_merge_bases(rev_nr, rev, no_checkout);
+		res = check_merge_bases(rev_nr, rev, no_checkout);
 	free(rev);
+	if (res)
+		exit(res == BISECT_INTERNAL_SUCCESS_MERGE_BASE ? BISECT_OK : -res);
 
 	/* Create file BISECT_ANCESTORS_OK. */
 	fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
diff --git a/bisect.h b/bisect.h
index 19d90e4870..f68ae85376 100644
--- a/bisect.h
+++ b/bisect.h
@@ -39,11 +39,16 @@ struct rev_list_info {
  * BISECT_FAILED error code: default error code.
  * BISECT_ONLY_SKIPPED_LEFT error code: only skipped
  * commits left to be tested.
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE early success
+ * code: found merge base that should be tested.
+ * Early success code BISECT_INTERNAL_SUCCESS_MERGE_BASE
+ * should be only an internal code.
  */
 enum bisect_error {
 	BISECT_OK = 0,
 	BISECT_FAILED = -1,
-	BISECT_ONLY_SKIPPED_LEFT = -2
+	BISECT_ONLY_SKIPPED_LEFT = -2,
+	BISECT_INTERNAL_SUCCESS_MERGE_BASE = -11
 };
 
 enum bisect_error bisect_next_all(struct repository *r,
-- 
2.25.0

[PATCH v3 11/13] bisect: libify `check_good_are_ancestors_of_bad` and its dependents

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

Code that turns BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11)
 to BISECT_OK (0) from `check_good_are_ancestors_of_bad()` has been moved to
`cmd_bisect__helper()`.

Update all callers to handle the error returns.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c                 | 41 ++++++++++++++++++++++++++--------------
 builtin/bisect--helper.c | 11 ++++++++++-
 2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/bisect.c b/bisect.c
index 382e0b471f..f5ce3a4b70 100644
--- a/bisect.c
+++ b/bisect.c
@@ -872,20 +872,23 @@ static int check_ancestors(struct repository *r, int rev_nr,
  *
  * If that's not the case, we need to check the merge bases.
  * If a merge base must be tested by the user, its source code will be
- * checked out to be tested by the user and we will exit.
+ * checked out to be tested by the user and we will return.
  */
-static void check_good_are_ancestors_of_bad(struct repository *r,
+
+static enum bisect_error check_good_are_ancestors_of_bad(struct repository *r,
 					    const char *prefix,
 					    int no_checkout)
 {
-	char *filename = git_pathdup("BISECT_ANCESTORS_OK");
+	char *filename;
 	struct stat st;
 	int fd, rev_nr;
 	enum bisect_error res = BISECT_OK;
 	struct commit **rev;
 
 	if (!current_bad_oid)
-		die(_("a %s revision is needed"), term_bad);
+		return error(_("a %s revision is needed"), term_bad);
+
+	filename = git_pathdup("BISECT_ANCESTORS_OK");
 
 	/* Check if file BISECT_ANCESTORS_OK exists. */
 	if (!stat(filename, &st) && S_ISREG(st.st_mode))
@@ -901,18 +904,26 @@ static void check_good_are_ancestors_of_bad(struct repository *r,
 	if (check_ancestors(r, rev_nr, rev, prefix))
 		res = check_merge_bases(rev_nr, rev, no_checkout);
 	free(rev);
-	if (res)
-		exit(res == BISECT_INTERNAL_SUCCESS_MERGE_BASE ? BISECT_OK : -res);
 
-	/* Create file BISECT_ANCESTORS_OK. */
-	fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
-	if (fd < 0)
-		warning_errno(_("could not create file '%s'"),
-			      filename);
-	else
-		close(fd);
+	if (!res) {
+		/* Create file BISECT_ANCESTORS_OK. */
+		fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
+		if (fd < 0)
+			/*
+			 * BISECT_ANCESTORS_OK file is not absolutely necessary,
+			 * the bisection process will continue at the next
+			 * bisection step.
+			 * So, just signal with a warning that something
+			 * might be wrong.
+			 */
+			warning_errno(_("could not create file '%s'"),
+				filename);
+		else
+			close(fd);
+	}
  done:
 	free(filename);
+	return res;
 }
 
 /*
@@ -984,7 +995,9 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 	if (read_bisect_refs())
 		die(_("reading bisect refs failed"));
 
-	check_good_are_ancestors_of_bad(r, prefix, no_checkout);
+	res = check_good_are_ancestors_of_bad(r, prefix, no_checkout);
+	if (res)
+		return res;
 
 	bisect_rev_setup(r, &revs, prefix, "%s", "^%s", 1);
 	revs.limited = 1;
diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index e6bd4d6645..c1c40b516d 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -666,7 +666,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 
 	switch (cmdmode) {
 	case NEXT_ALL:
-		return bisect_next_all(the_repository, prefix, no_checkout);
+		res = bisect_next_all(the_repository, prefix, no_checkout);
+		break;
 	case WRITE_TERMS:
 		if (argc != 2)
 			return error(_("--write-terms requires two arguments"));
@@ -713,5 +714,13 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		return error("BUG: unknown subcommand '%d'", cmdmode);
 	}
 	free_terms(&terms);
+
+	/*
+	 * Handle early success
+	 * From check_merge_bases > check_good_are_ancestors_of_bad > bisect_next_all
+	 */
+	if (res == BISECT_INTERNAL_SUCCESS_MERGE_BASE)
+		res = BISECT_OK;
+
 	return abs(res);
 }
-- 
2.25.0

[PATCH v3 12/13] bisect: libify `handle_bad_merge_base` and its dependents

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

Update all callers to handle the error returns.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 9 +++++----
 bisect.h | 1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/bisect.c b/bisect.c
index f5ce3a4b70..837332a428 100644
--- a/bisect.c
+++ b/bisect.c
@@ -761,7 +761,7 @@ static struct commit **get_bad_and_good_commits(struct repository *r,
 	return rev;
 }
 
-static void handle_bad_merge_base(void)
+static enum bisect_error handle_bad_merge_base(void)
 {
 	if (is_expected_rev(current_bad_oid)) {
 		char *bad_hex = oid_to_hex(current_bad_oid);
@@ -782,14 +782,14 @@ static void handle_bad_merge_base(void)
 				"between %s and [%s].\n"),
 				bad_hex, term_bad, term_good, bad_hex, good_hex);
 		}
-		exit(3);
+		return BISECT_MERGE_BASE_CHECK;
 	}
 
 	fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
 		"git bisect cannot work properly in this case.\n"
 		"Maybe you mistook %s and %s revs?\n"),
 		term_good, term_bad, term_good, term_bad);
-	exit(1);
+	return BISECT_FAILED;
 }
 
 static void handle_skipped_merge_base(const struct object_id *mb)
@@ -830,7 +830,8 @@ static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int
 	for (; result; result = result->next) {
 		const struct object_id *mb = &result->item->object.oid;
 		if (oideq(mb, current_bad_oid)) {
-			handle_bad_merge_base();
+			res = handle_bad_merge_base();
+			break;
 		} else if (0 <= oid_array_lookup(&good_revs, mb)) {
 			continue;
 		} else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
diff --git a/bisect.h b/bisect.h
index f68ae85376..0d9758179f 100644
--- a/bisect.h
+++ b/bisect.h
@@ -48,6 +48,7 @@ enum bisect_error {
 	BISECT_OK = 0,
 	BISECT_FAILED = -1,
 	BISECT_ONLY_SKIPPED_LEFT = -2,
+	BISECT_MERGE_BASE_CHECK = -3,
 	BISECT_INTERNAL_SUCCESS_MERGE_BASE = -11
 };
 
-- 
2.25.0

[PATCH v3 13/13] bisect: libify `bisect_next_all`

[Miriam Rubio]

From: Pranit Bauva <pranit.bauva@gmail.com>

Since we want to get rid of git-bisect.sh, it would be necessary to
convert those exit() calls to return statements so that errors can be
reported.

Emulate try catch in C by converting `exit(<positive-value>)` to
`return <negative-value>`. Follow POSIX conventions to return
<negative-value> to indicate error.

All the functions calling `bisect_next_all()` are already able to
handle return values from it.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
---
 bisect.c | 29 +++++++++++++++++++----------
 bisect.h | 10 ++++++++--
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/bisect.c b/bisect.c
index 837332a428..9154f810f7 100644
--- a/bisect.c
+++ b/bisect.c
@@ -976,10 +976,10 @@ void read_bisect_terms(const char **read_bad, const char **read_good)
 }
 
 /*
- * We use the convention that exiting with an exit code 10 means that
+ * We use the convention that return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10) means
  * the bisection process finished successfully.
- * In this case the calling shell script should exit 0.
- *
+ * In this case the calling function or command should not turn a
+ * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND return code into an error or a non zero exit code.
  * If no_checkout is non-zero, the bisection process does not
  * checkout the trial commit but instead simply updates BISECT_HEAD.
  */
@@ -1010,23 +1010,25 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 
 	if (!revs.commits) {
 		/*
-		 * We should exit here only if the "bad"
+		 * We should return error here only if the "bad"
 		 * commit is also a "skip" commit.
 		 */
 		res = error_if_skipped_commits(tried, NULL);
 		if (res < 0)
-			exit(-res);
+			return res;
 		printf(_("%s was both %s and %s\n"),
 		       oid_to_hex(current_bad_oid),
 		       term_good,
 		       term_bad);
-		exit(1);
+
+		return BISECT_FAILED;
 	}
 
 	if (!all) {
 		fprintf(stderr, _("No testable commit found.\n"
 			"Maybe you started with bad path parameters?\n"));
-		exit(4);
+
+		return BISECT_NO_TESTABLE_COMMIT;
 	}
 
 	bisect_rev = &revs.commits->item->object.oid;
@@ -1034,12 +1036,19 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix, int
 	if (oideq(bisect_rev, current_bad_oid)) {
 		res = error_if_skipped_commits(tried, current_bad_oid);
 		if (res)
-			exit(-res);
+			return res;
 		printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
 			term_bad);
+
 		show_diff_tree(r, prefix, revs.commits->item);
-		/* This means the bisection process succeeded. */
-		exit(10);
+		/*
+		 * This means the bisection process succeeded.
+		 * Using BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10)
+		 * so that the call chain can simply check
+		 * for negative return values for early returns up
+		 * until the cmd_bisect__helper() caller.
+		 */
+		return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
 	}
 
 	nr = all - reaches - 1;
diff --git a/bisect.h b/bisect.h
index 0d9758179f..8bad8d8391 100644
--- a/bisect.h
+++ b/bisect.h
@@ -39,16 +39,22 @@ struct rev_list_info {
  * BISECT_FAILED error code: default error code.
  * BISECT_ONLY_SKIPPED_LEFT error code: only skipped
  * commits left to be tested.
+ * BISECT_MERGE_BASE_CHECK error code: merge base check failed.
+ * BISECT_NO_TESTABLE_COMMIT error code: no testable commit found.
+ * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND early success code:
+ * first term_bad commit found.
  * BISECT_INTERNAL_SUCCESS_MERGE_BASE early success
  * code: found merge base that should be tested.
- * Early success code BISECT_INTERNAL_SUCCESS_MERGE_BASE
- * should be only an internal code.
+ * Early success codes BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND and
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE should be only internal codes.
  */
 enum bisect_error {
 	BISECT_OK = 0,
 	BISECT_FAILED = -1,
 	BISECT_ONLY_SKIPPED_LEFT = -2,
 	BISECT_MERGE_BASE_CHECK = -3,
+	BISECT_NO_TESTABLE_COMMIT = -4,
+	BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND = -10,
 	BISECT_INTERNAL_SUCCESS_MERGE_BASE = -11
 };
 
-- 
2.25.0