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Fix %d/%o/%x overflow for large doubles #605

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Fix %d/%o/%x overflow for large doubles #605

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0586c2b
test: add failing tests for %d/%o/%x overflow with large doubles
JoshRosen Feb 18, 2026
4450eb9
fix: use BigInt truncation in format integer/octal/hex for large doubles
JoshRosen Feb 18, 2026
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43 changes: 24 additions & 19 deletions sjsonnet/src/sjsonnet/Format.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -236,21 +236,28 @@ object Format {
output.toString()
}

private def formatInteger(formatted: FormatSpec, s: Double): String = {
// Truncate a double toward zero, returning the integer part as a BigInt.
// Uses Long as a fast path (mirrors RenderUtils.renderDouble); falls back to
// BigDecimal for values that exceed Long range (~9.2e18).
private def truncateToInteger(s: Double): BigInt = {
val sl = s.toLong
val (lhs, rhs) = if (sl < 0) {
("-", sl.toString.substring(1))
} else {
("", sl.toString)
}
if (sl.toDouble == s) BigInt(sl)
else BigDecimal(s).toBigInt
}

private def formatInteger(formatted: FormatSpec, s: Double): String = {
val i = truncateToInteger(s)
val negative = i.signum < 0
val lhs = if (negative) "-" else ""
val rhs = i.abs.toString(10)
val rhs2 = precisionPad(lhs, rhs, formatted.precision)
widen(
formatted,
lhs,
"",
rhs2,
numeric = true,
signedConversion = sl >= 0
signedConversion = !negative
)
}

Expand All @@ -275,36 +282,34 @@ object Format {
}

private def formatOctal(formatted: FormatSpec, s: Double): String = {
val (lhs, rhs) = if (s < 0) {
("-", s.toLong.abs.toOctalString)
} else {
("", s.toLong.toOctalString)
}
val i = truncateToInteger(s)
val negative = i.signum < 0
val lhs = if (negative) "-" else ""
val rhs = i.abs.toString(8)
val rhs2 = precisionPad(lhs, rhs, formatted.precision)
widen(
formatted,
lhs,
if (!formatted.alternate || rhs2(0) == '0') "" else "0",
rhs2,
numeric = true,
signedConversion = s > 0
signedConversion = !negative
)
}

private def formatHexadecimal(formatted: FormatSpec, s: Double): String = {
val (lhs, rhs) = if (s < 0) {
("-", s.toLong.abs.toHexString)
} else {
("", s.toLong.toHexString)
}
val i = truncateToInteger(s)
val negative = i.signum < 0
val lhs = if (negative) "-" else ""
val rhs = i.abs.toString(16)
val rhs2 = precisionPad(lhs, rhs, formatted.precision)
widen(
formatted,
lhs,
if (!formatted.alternate) "" else "0x",
rhs2,
numeric = true,
signedConversion = s > 0
signedConversion = !negative
)
}

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18 changes: 18 additions & 0 deletions sjsonnet/test/src/sjsonnet/EvaluatorTests.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -572,6 +572,24 @@ object EvaluatorTests extends TestSuite {
"-123.45600"
)
}
test("formatIntegerOverflow") {
// %d, %o, %x should not overflow to Long.MAX_VALUE for large doubles
eval("'%d' % 1e19", useNewEvaluator = useNewEvaluator) ==> ujson.Str("10000000000000000000")
eval("'%d' % 1e20", useNewEvaluator = useNewEvaluator) ==> ujson.Str(
"100000000000000000000"
)
eval("'%d' % -1e19", useNewEvaluator = useNewEvaluator) ==> ujson.Str(
"-10000000000000000000"
)
eval("'%o' % 1e19", useNewEvaluator = useNewEvaluator) ==> ujson.Str(
"1053071060221172000000"
)
eval("'%x' % 1e19", useNewEvaluator = useNewEvaluator) ==> ujson.Str("8ac7230489e80000")
// Sign should be determined from the truncated integer, not the original double:
// -0.3 truncates to 0, so no minus sign should appear.
eval("'%5.3d' % -0.3", useNewEvaluator = useNewEvaluator) ==> ujson.Str(" 000")
eval("'%d' % -0.9", useNewEvaluator = useNewEvaluator) ==> ujson.Str("0")
}
test("strict") {
eval("({ a: 1 } { b: 2 }).a", strict = false, useNewEvaluator = useNewEvaluator) ==> ujson
.Num(1)
Expand Down
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