From daa47b20614c4f5587365fdc2124c403c1b5948d Mon Sep 17 00:00:00 2001
From: Jiri Jakes <jiri@jirijakes.com>
Date: Tue, 12 Dec 2023 18:33:44 +0800
Subject: [PATCH] Allow `SignedAmount` parse values equal to i64::MIN

Previously, parsing such textual value returned 'too big' error. This
change fixes it and adds relevant tests.
---
 units/src/amount.rs | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/units/src/amount.rs b/units/src/amount.rs
index e61cfaa6..3f3e323e 100644
--- a/units/src/amount.rs
+++ b/units/src/amount.rs
@@ -938,14 +938,14 @@ impl SignedAmount {
     /// Note: This only parses the value string.  If you want to parse a value
     /// with denomination, use [FromStr].
     pub fn from_str_in(s: &str, denom: Denomination) -> Result<SignedAmount, ParseAmountError> {
-        let (negative, satoshi) = parse_signed_to_satoshi(s, denom)?;
-        if satoshi > i64::MAX as u64 {
-            return Err(ParseAmountError::TooBig);
+        match parse_signed_to_satoshi(s, denom)? {
+            // (negative, amount)
+            (false, sat) if sat > i64::MAX as u64     => Err(ParseAmountError::TooBig),
+            (false, sat)                              => Ok(SignedAmount(sat as i64)),
+            (true, sat) if sat == i64::MAX as u64 + 1 => Ok(SignedAmount(i64::MIN)),
+            (true, sat) if sat > i64::MAX as u64 + 1  => Err(ParseAmountError::TooBig),
+            (true, sat)                               => Ok(SignedAmount(-(sat as i64))),
         }
-        Ok(match negative {
-            true => SignedAmount(-(satoshi as i64)),
-            false => SignedAmount(satoshi as i64),
-        })
     }
 
     /// Parses amounts with denomination suffix like they are produced with
@@ -1762,6 +1762,7 @@ mod tests {
 
         assert_eq!(p("1", btc), Ok(Amount::from_sat(1_000_000_00)));
         assert_eq!(sp("-.5", btc), Ok(SignedAmount::from_sat(-500_000_00)));
+        assert_eq!(sp(&i64::MIN.to_string(), sat), Ok(SignedAmount::from_sat(i64::MIN)));
         assert_eq!(p("1.1", btc), Ok(Amount::from_sat(1_100_000_00)));
         assert_eq!(p("100", sat), Ok(Amount::from_sat(100)));
         assert_eq!(p("55", sat), Ok(Amount::from_sat(55)));
@@ -2067,6 +2068,7 @@ mod tests {
         scase("-5 satoshi", Ok(SignedAmount::from_sat(-5)));
         case("0.10000000 BTC", Ok(Amount::from_sat(100_000_00)));
         scase("-100 bits", Ok(SignedAmount::from_sat(-10_000)));
+        scase(&format!("{} SAT", i64::MIN), Ok(SignedAmount::from_sat(i64::MIN)));
     }
 
     #[test]