vvellanki commented on a change in pull request #11287:
URL: https://github.com/apache/arrow/pull/11287#discussion_r747696180
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File path: cpp/src/gandiva/precompiled/string_ops.cc
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@@ -2195,4 +2195,22 @@ const char* byte_substr_binary_int32_int32(gdv_int64
context, const char* text,
memcpy(ret, text + startPos, *out_len);
return ret;
}
+
+FORCE_INLINE
+int32_t instr_utf8(const char* string, int32_t string_len, const char*
substring,
+ int32_t substring_len) {
+ if (substring_len == 0) {
+ return 1;
+ }
+
+ int32_t end_idx =
+ (string_len - substring_len) <= 0 ? string_len : string_len -
substring_len;
+
+ for (int i = 0; i < end_idx; i++) {
Review comment:
Let the input be: "Hello" with string_len = 5
substring = "lower" with substring_len = 5
end_idx = 5 in this case
For i = 2, string[i] = 'l' = substring[0]. The memcmp() is going to access
string + i + substring_len, which is string + 2 + 5 = string + 7. string + 7 is
out of range of the input. We cannot do this, it will cause issues
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