date API: add and use a date_mode_release()

avar · gitster · commit 974c919d36d9 · 2022-02-16T09:40:00.000-08:00
Fix a memory leak in the parse_date_format() function by providing a
new date_mode_release() companion function.

By using this in "t/helper/test-date.c" we can mark the
"t0006-date.sh" test as passing when git is compiled with
SANITIZE=leak, and whitelist it to run under
"GIT_TEST_PASSING_SANITIZE_LEAK=true" by adding
"TEST_PASSES_SANITIZE_LEAK=true" to the test itself.

The other tests that expose this memory leak (i.e. take the
"mode-&gt;type == DATE_STRFTIME" branch in parse_date_format()) are
"t6300-for-each-ref.sh" and "t7004-tag.sh". The former is due to an
easily fixed leak in "ref-filter.c", and brings the failures in
"t6300-for-each-ref.sh" down from 51 to 48.

Fixing the remaining leaks will have to wait until there's a
release_revisions() in "revision.c", as they have to do with leaks via
"struct rev_info".

There is also a leak in "builtin/blame.c" due to its call to
parse_date_format() to parse the "blame.date" configuration. However
as it declares a file-level "static struct date_mode blame_date_mode"
to track the data, LSAN will not report it as a leak. It's possible to
get valgrind(1) to complain about it with e.g.:

    valgrind --leak-check=full --show-leak-kinds=all ./git -P -c blame.date=format:%Y blame README.md

But let's focus on things LSAN complains about, and are thus
observable with "TEST_PASSES_SANITIZE_LEAK=true". We should get to
fixing memory leaks in "builtin/blame.c", but as doing so would
require some re-arrangement of cmd_blame() let's leave it for some
other time.

Signed-off-by: Ævar Arnfjörð Bjarmason &lt;avarab@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/date.c b/date.c
@@ -993,6 +993,11 @@ void parse_date_format(const char *format, struct date_mode *mode)
 		die("unknown date format %s", format);
 }
 
+void date_mode_release(struct date_mode *mode)
+{
+	free((char *)mode->strftime_fmt);
+}
+
 void datestamp(struct strbuf *out)
 {
 	time_t now;
diff --git a/date.h b/date.h
@@ -50,10 +50,17 @@ const char *show_date(timestamp_t time, int timezone, const struct date_mode *mo
  *
  * When the "date_mode_type" is DATE_STRFTIME the "strftime_fmt"
  * member of "struct date_mode" will be a malloc()'d format string to
- * be used with strbuf_addftime().
+ * be used with strbuf_addftime(), in which case you'll need to call
+ * date_mode_release() later.
  */
 void parse_date_format(const char *format, struct date_mode *mode);
 
+/**
+ * Release a "struct date_mode", currently only required if
+ * parse_date_format() has parsed a "DATE_STRFTIME" format.
+ */
+void date_mode_release(struct date_mode *mode);
+
 void show_date_relative(timestamp_t time, struct strbuf *timebuf);
 int parse_date(const char *date, struct strbuf *out);
 int parse_date_basic(const char *date, timestamp_t *timestamp, int *offset);
diff --git a/ref-filter.c b/ref-filter.c
@@ -1276,6 +1276,7 @@ static void grab_date(const char *buf, struct atom_value *v, const char *atomnam
 		goto bad;
 	v->s = xstrdup(show_date(timestamp, tz, &date_mode));
 	v->value = timestamp;
+	date_mode_release(&date_mode);
 	return;
  bad:
 	v->s = xstrdup("");
diff --git a/t/helper/test-date.c b/t/helper/test-date.c
@@ -54,6 +54,8 @@ static void show_dates(const char **argv, const char *format)
 
 		printf("%s -> %s\n", *argv, show_date(t, tz, &mode));
 	}
+
+	date_mode_release(&mode);
 }
 
 static void parse_dates(const char **argv)
diff --git a/t/t0006-date.sh b/t/t0006-date.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
 test_description='test date parsing and printing'
+
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # arbitrary reference time: 2009-08-30 19:20:00

Original file line number	Diff line number	Diff line change
`@@ -993,6 +993,11 @@ void parse_date_format(const char format, struct date_mode mode)`
`993`	`993`	`die("unknown date format %s", format);`
`994`	`994`	`}`
`995`	`995`
	`996`	`+void date_mode_release(struct date_mode *mode)`
	`997`	`+{`
	`998`	`+ free((char *)mode->strftime_fmt);`
	`999`	`+}`
	`1000`	`+`
`996`	`1001`	`void datestamp(struct strbuf *out)`
`997`	`1002`	`{`
`998`	`1003`	`time_t now;`
Original file line number	Diff line number	Diff line change
`@@ -54,6 +54,8 @@ static void show_dates(const char *argv, const char format)`
`54`	`54`
`55`	`55`	`printf("%s -> %s\n", *argv, show_date(t, tz, &mode));`
`56`	`56`	`}`
	`57`	`+`
	`58`	`+ date_mode_release(&mode);`
`57`	`59`	`}`
`58`	`60`
`59`	`61`	`static void parse_dates(const char **argv)`