GH-49753: [C++][Gandiva]: Incorporated review comments.

- Added extra context error checks in test code.
- Removed dead code.

Author: abtom87

cpp/src/gandiva/gdv_string_function_stubs.cc

@@ -485,10 +485,6 @@ const char* gdv_fn_substring_index(int64_t context, const char* txt, int32_t txt
     return out;
 
   } else {
-    if (txt_len < 0) {
-      *out_len = 0;
-      return "";
-    }
     memcpy(out, txt, static_cast<size_t>(txt_len));
     *out_len = txt_len;
     return out;

cpp/src/gandiva/precompiled/string_ops.cc

@@ -1929,7 +1929,7 @@ const char* quote_utf8(gdv_int64 context, const char* in, gdv_int32 in_len,
   // Test multiply overflow for in_len
   if (ARROW_PREDICT_FALSE(
           arrow::internal::MultiplyWithOverflow(2, in_len, &double_len))) {
-    gdv_fn_context_set_error_msg(context, "Memory allocation size too large");
+    gdv_fn_context_set_error_msg(context, "Memory allocation size too large.");
     *out_len = 0;
     return "";
   }
@@ -2557,9 +2557,6 @@ static inline const char* concat_ws_impl(int64_t context, const char* separator,
       *out_valid = false;
       return "";
     }
-    if (state.overflow) {
-      return handle_overflow_failure(out_valid, out_len);
-    }
   }
 
   // Add separator lengths
@@ -2780,7 +2777,8 @@ const char* elt_int32_utf8_utf8_utf8_utf8_utf8(
 FORCE_INLINE
 const char* to_hex_binary(int64_t context, const char* text, int32_t text_len,
                           int32_t* out_len) {
-  if (ARROW_PREDICT_FALSE(text_len <= 0)) {
+  if (ARROW_PREDICT_FALSE(text_len < 0)) {
+    gdv_fn_context_set_error_msg(context, "Text length invalid(negative).");
     *out_len = 0;
     return "";
   }
@@ -2789,7 +2787,7 @@ const char* to_hex_binary(int64_t context, const char* text, int32_t text_len,
   // Check multiply overflow for text_len
   if (ARROW_PREDICT_FALSE(
           arrow::internal::MultiplyWithOverflow(2, text_len, &double_len))) {
-    gdv_fn_context_set_error_msg(context, "Memory allocation size too large");
+    gdv_fn_context_set_error_msg(context, "Memory allocation size too large.");
     *out_len = 0;
     return "";
   }

cpp/src/gandiva/precompiled/string_ops_test.cc

@@ -1168,11 +1168,13 @@ TEST(TestStringOps, TestQuote) {
 
   int32_t bad_in_len = std::numeric_limits<int32_t>::max() / 2 + 1;
   out_str = quote_utf8(ctx_ptr, "YYZ", bad_in_len, &out_len);
+  EXPECT_EQ(ctx.get_error(), "Memory allocation size too large.");
   EXPECT_EQ(out_len, 0);
   EXPECT_STREQ(out_str, "");
 
   bad_in_len = std::numeric_limits<int32_t>::max() / 2 + 20;
   out_str = quote_utf8(ctx_ptr, "ABCDE", bad_in_len, &out_len);
+  EXPECT_EQ(ctx.get_error(), "Memory allocation size too large.");
   EXPECT_EQ(out_len, 0);
   EXPECT_STREQ(out_str, "");
 }
@@ -2573,12 +2575,14 @@ TEST(TestStringOps, TestToHex) {
   out_str = to_hex_binary(ctx_ptr, binary_string, bad_text_len, &out_len);
   EXPECT_EQ(out_len, 0);
   EXPECT_STREQ(out_str, "");
+  EXPECT_EQ(ctx.get_error(), "Memory allocation size too large.");
   ctx.Reset();
 
   int32_t neg_in_len = -20;
   out_str = to_hex_binary(ctx_ptr, binary_string, neg_in_len, &out_len);
   EXPECT_EQ(out_len, 0);
   EXPECT_STREQ(out_str, "");
+  EXPECT_EQ(ctx.get_error(), "Text length invalid(negative).");
   ctx.Reset();
 }