Re: [PATCH v3 1/9] show, log: provide a --remerge-diff capability

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Thu, Dec 30 2021, Elijah Newren via GitGitGadget wrote:

> From: Elijah Newren <newren@gmail.com>
> +	struct tmp_objdir *remerge_objdir = NULL;
> +
> +	if (rev->remerge_diff) {
> +		remerge_objdir = tmp_objdir_create("remerge-diff");
> +		if (!remerge_objdir)
> +			die_errno(_("unable to create temporary object directory"));
> +		tmp_objdir_replace_primary_odb(remerge_objdir, 1);
> +	}

Re the errno feedback on v1
https://lore.kernel.org/git/211221.864k71r6kz.gmgdl@evledraar.gmail.com/
the API might lose the "errno" due to e.g. the remove_dir_recurse()
codepath. This seems like it would take care of that:

diff --git a/builtin/log.c b/builtin/log.c
index 944d9c0d9b5..d4b8b1aa4b6 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -424,9 +424,9 @@ static int cmd_log_walk(struct rev_info *rev)
 	int saved_dcctc = 0;
 
 	if (rev->remerge_diff) {
-		rev->remerge_objdir = tmp_objdir_create("remerge-diff");
+		rev->remerge_objdir = tmp_objdir_create_gently("remerge-diff", 0);
 		if (!rev->remerge_objdir)
-			die_errno(_("unable to create temporary object directory"));
+			exit(128);
 		tmp_objdir_replace_primary_odb(rev->remerge_objdir, 1);
 	}
 
diff --git a/tmp-objdir.c b/tmp-objdir.c
index adf6033549e..3c656120003 100644
--- a/tmp-objdir.c
+++ b/tmp-objdir.c
@@ -121,19 +121,21 @@ static void env_replace(struct strvec *env, const char *key, const char *val)
 	strvec_pushf(env, "%s=%s", key, val);
 }
 
-static int setup_tmp_objdir(const char *root)
+static int setup_tmp_objdir(const char *root, int quiet)
 {
 	char *path;
 	int ret = 0;
 
 	path = xstrfmt("%s/pack", root);
 	ret = mkdir(path, 0777);
+	if (!quiet && ret < 0)
+		die_errno(_("unable to create temporary object directory '%s'"), path);
 	free(path);
 
 	return ret;
 }
 
-struct tmp_objdir *tmp_objdir_create(const char *prefix)
+struct tmp_objdir *tmp_objdir_create_gently(const char *prefix, int quiet)
 {
 	static int installed_handlers;
 	struct tmp_objdir *t;
@@ -161,6 +163,8 @@ struct tmp_objdir *tmp_objdir_create(const char *prefix)
 	strbuf_grow(&t->path, 1024);
 
 	if (!mkdtemp(t->path.buf)) {
+		if (!quiet)
+			error_errno(_("unable to create temporary directory '%s'"), t->path.buf);
 		/* free, not destroy, as we never touched the filesystem */
 		tmp_objdir_free(t);
 		return NULL;
@@ -173,7 +177,7 @@ struct tmp_objdir *tmp_objdir_create(const char *prefix)
 		installed_handlers++;
 	}
 
-	if (setup_tmp_objdir(t->path.buf)) {
+	if (setup_tmp_objdir(t->path.buf, quiet)) {
 		tmp_objdir_destroy(t);
 		return NULL;
 	}
diff --git a/tmp-objdir.h b/tmp-objdir.h
index 76efc7edee5..5072fb860d9 100644
--- a/tmp-objdir.h
+++ b/tmp-objdir.h
@@ -24,8 +24,15 @@ struct tmp_objdir;
 /*
  * Create a new temporary object directory with the specified prefix;
  * returns NULL on failure.
+ *
+ * The tmp_objdir_create() is an a wrapper for
+ * tmp_objdir_create_gently(..., 1).
  */
-struct tmp_objdir *tmp_objdir_create(const char *prefix);
+struct tmp_objdir *tmp_objdir_create_gently(const char *prefix, int quiet);
+static inline struct tmp_objdir *tmp_objdir_create(const char *prefix)
+{
+	return tmp_objdir_create_gently(prefix, 1);
+}
 
 /*
  * Return a list of environment strings, suitable for use with