Fix integer-overflow problem in intarray's g_int_decompress().

An array element equal to INT_MAX gave this code indigestion,
causing an infinite loop that surely ended in SIGSEGV.  We fixed
some nearby problems awhile ago (cf 757c5182f) but missed this.

Report and diagnosis by Alexander Lakhin (bug #18273); patch by me

Discussion: https://postgr.es/m/18273-9a832d1da122600c@postgresql.org

contrib/intarray/_int_gist.c

@@ -297,8 +297,7 @@ g_int_decompress(PG_FUNCTION_ARGS)
 	ArrayType  *in;
 	int			lenin;
 	int		   *din;
-	int			i,
-				j;
+	int			i;
 
 	in = DatumGetArrayTypeP(entry->key);
 
@@ -342,9 +341,12 @@ g_int_decompress(PG_FUNCTION_ARGS)
 	dr = ARRPTR(r);
 
 	for (i = 0; i < lenin; i += 2)
-		for (j = din[i]; j <= din[i + 1]; j++)
+	{
+		/* use int64 for j in case din[i + 1] is INT_MAX */
+		for (int64 j = din[i]; j <= din[i + 1]; j++)
 			if ((!i) || *(dr - 1) != j)
-				*dr++ = j;
+				*dr++ = (int) j;
+	}
 
 	if (in != (ArrayType *) DatumGetPointer(entry->key))
 		pfree(in);

contrib/intarray/data/test__int.data

@@ -6998,3 +6998,4 @@
 {173,208,229}
 {6,22,142,267,299}
 {22,122,173,245,293}
+{1,2,101,102,201,202,2147483647}

contrib/intarray/expected/_int.out

@@ -483,13 +483,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 SET enable_seqscan = off;  -- not all of these would use index by default
@@ -557,13 +557,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 INSERT INTO test__int SELECT array(SELECT x FROM generate_series(1, 1001) x); -- should fail
@@ -639,13 +639,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -719,13 +719,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -793,13 +793,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -867,13 +867,13 @@ SELECT count(*) from test__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from test__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from test__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 DROP INDEX text_idx;
@@ -889,9 +889,10 @@ DROP INDEX text_idx;
 -- core that would reach the same codepaths.
 CREATE TABLE more__int AS SELECT
    -- Leave alone NULLs, empty arrays and the one row that we use to test
-   -- equality
+   -- equality; also skip INT_MAX
    CASE WHEN a IS NULL OR a = '{}' OR a = '{73,23,20}' THEN a ELSE
-     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000) from (select unnest(a) u) x)
+     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000)
+      from unnest(a) u where u < 2000000000)
    END AS a, a as b
    FROM test__int;
 CREATE INDEX ON more__int using gist (a gist__int_ops(numranges = 252));
@@ -958,13 +959,13 @@ SELECT count(*) from more__int WHERE a @@ '(20&23)|(50&68)';
 SELECT count(*) from more__int WHERE a @@ '20 | !21';
  count 
 -------
-  6566
+  6567
 (1 row)
 
 SELECT count(*) from more__int WHERE a @@ '!20 & !21';
  count 
 -------
-  6343
+  6344
 (1 row)
 
 RESET enable_seqscan;

contrib/intarray/sql/_int.sql

@@ -209,9 +209,10 @@ DROP INDEX text_idx;
 -- core that would reach the same codepaths.
 CREATE TABLE more__int AS SELECT
    -- Leave alone NULLs, empty arrays and the one row that we use to test
-   -- equality
+   -- equality; also skip INT_MAX
    CASE WHEN a IS NULL OR a = '{}' OR a = '{73,23,20}' THEN a ELSE
-     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000) from (select unnest(a) u) x)
+     (select array_agg(u) || array_agg(u + 1000) || array_agg(u + 2000)
+      from unnest(a) u where u < 2000000000)
    END AS a, a as b
    FROM test__int;
 CREATE INDEX ON more__int using gist (a gist__int_ops(numranges = 252));