[CALCITE-7750] Bound plain-notation expansion of DECIMAL literals in Primitive.checkOverflow

[shoemoney]

Sibling of CALCITE-7731.

Bug: Primitive.checkOverflow calls BigDecimal.toPlainString on a value with scale < 0 without bounding the plain-notation expansion. A large negative scale can force toPlainString to materialize gigabytes and OOM, same pattern bounded elsewhere in CALCITE-7731.

Fix: Gate the toPlainString call with isBoundedDecimal. This mirrors SqlUtil.isBoundedDecimal in core but is inlined in linq4j to avoid a circular linq4j -> core dependency. The bound reads calcite.parser.maxDecimalLiteralPlainDigits (default 10000) and checks precision + abs(scale) <= limit. If exceeded, throw IllegalArgumentException before allocation.

Evidence: RED->GREEN verified. Both :linq4j:compileJava configurations succeed. Formatter blast radius is one file.

[mihaibudiu]

The linter won't like your commit message. Have you tried to validate this locally?
Maybe you should just use 7731 again in the commit message

[shoemoney]

Fixed, commit message now uses [CALCITE-7731] in c9ed2c6.

[mihaibudiu]

I have changed your PR title to match

[rubenada]

Is this really needed? Can we get into a "risky" scenario here, considering the checks introduced in CALCITE-7731 ?

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
62.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[rubenada]

@shoemoney , thanks for the patch.

Honestly, I don't know if we can realistically fall into a risky scenario for this class (looks like a "pattern-matching" fix). But the check won't hurt.
I have created a specific ticket for this: "[CALCITE-7750] Bound plain-notation expansion of DECIMAL literals in Primitive.checkOverflow". I have updated the PR title to reflect it.
Please use it on the commit message.

Also, please add some unit tests for this in PrimitiveTest.java, e.g. one for regression coverage, one reproducing the actual issue:

  @Test void testCharToDecimalCastWithinBounds() {
    assertThat(Primitive.charToDecimalCast("1.5", 5, 2),
        is(new BigDecimal("1.50")));
    assertThat(Primitive.charToDecimalCast("0", 38, 0),
        is(new BigDecimal("0")));
    // scale < 0 branch, well below the bound.
    assertThat(Primitive.charToDecimalCast("1000", 4, -3),
        is(new BigDecimal("1000")));
  }

  /** Test case for
   * <a href="https://issues.apache.org/jira/browse/CALCITE-7750">[CALCITE-7750]
   * Bound plain-notation expansion of DECIMAL literals in Primitive.checkOverflow</a>. */
  @Test void testCharToDecimalCastRejectsPathologicalScale() {
    IllegalArgumentException e =
        assertThrows(IllegalArgumentException.class, () ->
            Primitive.charToDecimalCast("1E10000", 1, -10_000));
    assertThat(e.getMessage(),
        containsString("plain-notation bound"));
  }