Guard against null t->tm_zone in strftime.c.

tglsfdc · tglsfdc · commit fab2d0d7f45a · 2017-05-07T12:33:18.000-04:00
The upstream IANA code does not guard against null TM_ZONE pointers in this
function, but in our code there is such a check in the other pre-existing
use of t-&gt;tm_zone.  We do have some places that set pg_tm.tm_zone to NULL.
I'm not entirely sure it's possible to reach strftime with such a value,
but I'm not sure it isn't either, so be safe.

Per Coverity complaint.
diff --git a/src/timezone/strftime.c b/src/timezone/strftime.c
@@ -459,7 +459,8 @@ _fmt(const char *format, const struct pg_tm * t, char *pt, const char *ptlim,
 						negative = diff < 0;
 						if (diff == 0)
 						{
-							negative = t->tm_zone[0] == '-';
+							if (t->tm_zone != NULL)
+								negative = t->tm_zone[0] == '-';
 						}
 						if (negative)
 						{

Original file line number	Diff line number	Diff line change
`@@ -459,7 +459,8 @@ _fmt(const char format, const struct pg_tm t, char pt, const char ptlim,`
`459`	`459`	`negative = diff < 0;`
`460`	`460`	`if (diff == 0)`
`461`	`461`	`{`
`462`		`- negative = t->tm_zone[0] == '-';`
	`462`	`+ if (t->tm_zone != NULL)`
	`463`	`+ negative = t->tm_zone[0] == '-';`
`463`	`464`	`}`
`464`	`465`	`if (negative)`
`465`	`466`	`{`