git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / mirror / code / Atom feed
From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <derrickstolee@github.com>,
	"Jeff King" <peff@peff.net>, "Elijah Newren" <newren@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [PATCH v3 1/4] cocci: add and apply a rule to find "unused" strbufs
Date: Fri,  1 Jul 2022 12:30:56 +0200	[thread overview]
Message-ID: <patch-v3-1.4-49e9ccb5819-20220701T102506Z-avarab@gmail.com> (raw)
In-Reply-To: <cover-v3-0.4-00000000000-20220701T102506Z-avarab@gmail.com>

Add a coccinelle rule to remove "struct strbuf" initialization
followed by calling "strbuf_release()" function.

See extensive commentary in the new "unused.cocci" for how it works,
and what it's intended to find and replace.

The inclusion of "contrib/scalar/scalar.c" is because "spatch" was
manually run on it (we don't usually run spatch on contrib).

The use of "with strict" here will be explained and amended in the
following commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/fetch.c                 |  3 +-
 builtin/merge.c                 |  2 --
 contrib/coccinelle/unused.cocci | 61 +++++++++++++++++++++++++++++++++
 contrib/scalar/scalar.c         |  3 +-
 diff.c                          |  2 --
 5 files changed, 63 insertions(+), 8 deletions(-)
 create mode 100644 contrib/coccinelle/unused.cocci

diff --git a/builtin/fetch.c b/builtin/fetch.c
index ac29c2b1ae3..8a3ae71fed0 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1113,7 +1113,7 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 			      struct fetch_head *fetch_head, struct worktree **worktrees)
 {
 	int url_len, i, rc = 0;
-	struct strbuf note = STRBUF_INIT, err = STRBUF_INIT;
+	struct strbuf note = STRBUF_INIT;
 	const char *what, *kind;
 	struct ref *rm;
 	char *url;
@@ -1281,7 +1281,6 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 
  abort:
 	strbuf_release(&note);
-	strbuf_release(&err);
 	free(url);
 	return rc;
 }
diff --git a/builtin/merge.c b/builtin/merge.c
index d9784d4891c..bbd70b17bc6 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -502,7 +502,6 @@ static void merge_name(const char *remote, struct strbuf *msg)
 {
 	struct commit *remote_head;
 	struct object_id branch_head;
-	struct strbuf buf = STRBUF_INIT;
 	struct strbuf bname = STRBUF_INIT;
 	struct merge_remote_desc *desc;
 	const char *ptr;
@@ -590,7 +589,6 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		oid_to_hex(&remote_head->object.oid), remote);
 cleanup:
 	free(found_ref);
-	strbuf_release(&buf);
 	strbuf_release(&bname);
 }
 
diff --git a/contrib/coccinelle/unused.cocci b/contrib/coccinelle/unused.cocci
new file mode 100644
index 00000000000..bc26d39b313
--- /dev/null
+++ b/contrib/coccinelle/unused.cocci
@@ -0,0 +1,61 @@
+// This rule finds sequences of "unused" declerations and uses of
+// "struct strbuf".
+//
+// I.e. this finds cases where we only declare the variable, and then
+// release it, e.g.:
+//
+//	struct strbuf buf = STRBUF_INIT;
+//      [.. no other use of "buf" in the function ..]
+//	strbuf_release(&buf)
+//
+// Or:
+//
+//	struct strbuf buf;
+//	[.. no other use of "buf" in the function ..]
+//	strbuf_init(&buf, 0);
+//	[.. no other use of "buf" in the function ..]
+//	strbuf_release(&buf)
+//
+// To do do this we find (continued below)...
+@@
+type T;
+identifier I;
+// STRBUF_INIT
+constant INIT_MACRO =~ "^STRBUF_INIT$";
+// strbuf_init(&I, ...) etc.
+identifier INIT_CALL1 =~ "^strbuf_init$";
+// strbuf_release()
+identifier REL1 =~ "^strbuf_release$";
+@@
+
+// .. A declaration like "struct strbuf buf;"...
+(
+- T I;
+// ... or "struct strbuf buf = { 0 };" ...
+|
+- T I = { 0 };
+// ... or "struct STRBUF buf = STRBUF_INIT;" ...
+|
+- T I = INIT_MACRO;
+)
+
+// ... Optionally followed by lines that make no use of "buf", "&buf"
+// etc., but which ...
+<... when != \( I \| &I \)
+     when strict
+// .. (only) make use of "buf" or "&buf" to call something like
+// "strbuf_init(&buf, ...)" ...
+- \( INIT_CALL1 \)( \( I \| &I \), ...);
+...>
+
+// ... and then no mention of "buf" or "&buf" until we get to a
+// strbuf_release(&buf) at the end ...
+- \( REL1 \)( \( &I \| I \) );
+// ... and no use *after* either, e.g. we don't want to delete
+// init/strbuf_release() patterns, where "&buf" could be used
+// afterwards.
+  ... when != \( I \| &I \)
+      when strict
+// This rule also isn't capable of finding cases where &buf is used,
+// but only to e.g. pass that variable to a static function which
+// doesn't use it. The analysis is only function-local.
diff --git a/contrib/scalar/scalar.c b/contrib/scalar/scalar.c
index 28176914e57..97e71fe19cd 100644
--- a/contrib/scalar/scalar.c
+++ b/contrib/scalar/scalar.c
@@ -687,7 +687,7 @@ static int cmd_diagnose(int argc, const char **argv)
 	int stdout_fd = -1, archiver_fd = -1;
 	time_t now = time(NULL);
 	struct tm tm;
-	struct strbuf path = STRBUF_INIT, buf = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT;
 	int res = 0;
 
 	argc = parse_options(argc, argv, NULL, options,
@@ -779,7 +779,6 @@ static int cmd_diagnose(int argc, const char **argv)
 	free(argv_copy);
 	strvec_clear(&archiver_args);
 	strbuf_release(&zip_path);
-	strbuf_release(&path);
 	strbuf_release(&buf);
 
 	return res;
diff --git a/diff.c b/diff.c
index e71cf758861..d4290615aaa 100644
--- a/diff.c
+++ b/diff.c
@@ -1289,7 +1289,6 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 {
 	static const char *nneof = " No newline at end of file\n";
 	const char *context, *reset, *set, *set_sign, *meta, *fraginfo;
-	struct strbuf sb = STRBUF_INIT;
 
 	enum diff_symbol s = eds->s;
 	const char *line = eds->line;
@@ -1521,7 +1520,6 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 	default:
 		BUG("unknown diff symbol");
 	}
-	strbuf_release(&sb);
 }
 
 static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
-- 
@@ -1289,7 +1289,6 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 {
 	static const char *nneof = " No newline at end of file\n";
 	const char *context, *reset, *set, *set_sign, *meta, *fraginfo;
-	struct strbuf sb = STRBUF_INIT;
 
 	enum diff_symbol s = eds->s;
 	const char *line = eds->line;
@@ -1521,7 +1520,6 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 	default:
 		BUG("unknown diff symbol");
 	}
-	strbuf_release(&sb);
 }
 
 static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
-- 
2.37.0.900.g4d0de1cceb2


  reply	other threads:[~2022-07-01 10:36 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20 11:57 [PATCH] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-21 22:44 ` [PATCH v2 0/2] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-06-21 22:44   ` [PATCH v2 1/2] cocci: add and apply a rule to find "unused" variables Ævar Arnfjörð Bjarmason
2022-06-22 16:02     ` Junio C Hamano
2022-06-21 22:44   ` [PATCH v2 2/2] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 10:30   ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Ævar Arnfjörð Bjarmason
2022-07-01 10:30     ` Ævar Arnfjörð Bjarmason [this message]
2022-07-01 18:04       ` [PATCH v3 1/4] cocci: add and apply a rule to find "unused" strbufs Jeff King
2022-07-01 19:55       ` Eric Sunshine
2022-07-01 10:30     ` [PATCH v3 2/4] cocci: catch unused "strbuf" using an xmalloc() pattern Ævar Arnfjörð Bjarmason
2022-07-01 10:30     ` [PATCH v3 3/4] cocci: remove "when strict" from unused.cocci Ævar Arnfjörð Bjarmason
2022-07-01 21:33       ` Eric Sunshine
2022-07-01 10:30     ` [PATCH v3 4/4] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-01 18:09     ` [PATCH v3 0/4] add and apply a rule to find "unused" init+free Jeff King
2022-07-05 13:46     ` [PATCH v4 0/6] " Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 1/6] Makefile: remove mandatory "spatch" arguments from SPATCH_FLAGS Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 2/6] Makefile & .gitignore: ignore & clean "git.res", not "*.res" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 3/6] cocci: add a "coccicheck-test" target and test *.cocci rules Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 4/6] cocci: have "coccicheck{,-pending}" depend on "coccicheck-test" Ævar Arnfjörð Bjarmason
2022-07-05 13:46       ` [PATCH v4 5/6] cocci: add and apply a rule to find "unused" strbufs Ævar Arnfjörð Bjarmason
2022-07-05 13:47       ` [PATCH v4 6/6] cocci: generalize "unused" rule to cover more than "strbuf" Ævar Arnfjörð Bjarmason
2022-07-06 19:30       ` [PATCH v4 0/6] add and apply a rule to find "unused" init+free Junio C Hamano
2022-07-11  9:41       ` Jeff King
2022-07-11 10:54         ` Ævar Arnfjörð Bjarmason

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=patch-v3-1.4-49e9ccb5819-20220701T102506Z-avarab@gmail.com \
    --to=avarab@gmail.com \
    --cc=derrickstolee@github.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=newren@gmail.com \
    --cc=peff@peff.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).