[GitHub] [spark] kiszk commented on a change in pull request #28937: [SPARK-32115][SQL] Incorrect results for SUBSTRING when overflow

[GitBox <gi...@apache.org>]

kiszk commented on a change in pull request #28937:
URL: https://github.com/apache/spark/pull/28937#discussion_r446607693



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File path: common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
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@@ -341,8 +341,17 @@ public UTF8String substringSQL(int pos, int length) {
     // to the -ith element before the end of the sequence. If a start index i is 0, it
     // refers to the first element.
     int len = numChars();
+    // `len + pos` does not overflow as `len >= 0`.
     int start = (pos > 0) ? pos -1 : ((pos < 0) ? len + pos : 0);
-    int end = (length == Integer.MAX_VALUE) ? len : start + length;
+
+    int end;
+    if((long) start + length > Integer.MAX_VALUE) {

Review comment:
       nit: `if ((long) start ...`




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