From: Eric Botcazou <ebotca...@adacore.com>
Even though the issue is not user-visible, it's a (minor) departure from the
specification of the procedure.
gcc/ada/ChangeLog:
* libgnat/s-valued.adb (Integer_to_Decimal): Add Extra parameter and
use its value to call Bad_Value on boundary values.
(Scan_Decimal): Adjust call to Integer_to_Decimal.
(Value_Decimal): Likewise.
Tested on x86_64-pc-linux-gnu, committed on master.
---
gcc/ada/libgnat/s-valued.adb | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/gcc/ada/libgnat/s-valued.adb b/gcc/ada/libgnat/s-valued.adb
index dfef9a885e5..cc2cffc72a6 100644
--- a/gcc/ada/libgnat/s-valued.adb
+++ b/gcc/ada/libgnat/s-valued.adb
@@ -39,13 +39,15 @@ package body System.Value_D is
-- We need an unsigned type large enough to represent the mantissa
package Impl is new Value_R (Uns, 1, 2**(Int'Size - 1), Round => False);
- -- We do not use the Extra digit for decimal fixed-point types
+ -- We do not use the Extra digit for decimal fixed-point types, except to
+ -- effectively ensure that overflow is detected near the boundaries.
function Integer_to_Decimal
(Str : String;
Val : Uns;
Base : Unsigned;
ScaleB : Integer;
+ Extra : Unsigned;
Minus : Boolean;
Scale : Integer) return Int;
-- Convert the real value from integer to decimal representation
@@ -59,6 +61,7 @@ package body System.Value_D is
Val : Uns;
Base : Unsigned;
ScaleB : Integer;
+ Extra : Unsigned;
Minus : Boolean;
Scale : Integer) return Int
is
@@ -126,6 +129,10 @@ package body System.Value_D is
end if;
end Unsigned_To_Signed;
+ -- Local variables
+
+ E : Uns := Uns (Extra);
+
begin
-- If the base of the value is 10 or its scaling factor is zero, then
-- add the scales (they are defined in the opposite sense) and apply
@@ -143,9 +150,10 @@ package body System.Value_D is
end loop;
while S > 0 loop
- if V <= Uns'Last / 10 then
- V := V * 10;
+ if V <= (Uns'Last - E) / 10 then
+ V := V * 10 + E;
S := S - 1;
+ E := 0;
else
Bad_Value (Str);
end if;
@@ -193,8 +201,9 @@ package body System.Value_D is
Z := 10 ** Integer'Max (0, -Scale);
for J in 1 .. LS loop
- if V <= Uns'Last / Uns (B) then
- V := V * Uns (B);
+ if V <= (Uns'Last - E) / Uns (B) then
+ V := V * Uns (B) + E;
+ E := 0;
else
Bad_Value (Str);
end if;
@@ -207,7 +216,7 @@ package body System.Value_D is
raise Program_Error;
end if;
- -- Perform a scale divide operation with rounding to match 'Image
+ -- Perform a scaled divide operation with rounding to match 'Image
Scaled_Divide (Unsigned_To_Signed (V), Y, Z, Q, R, Round => True);
@@ -238,7 +247,8 @@ package body System.Value_D is
begin
Val := Impl.Scan_Raw_Real (Str, Ptr, Max, Base, Scl, Extra, Minus);
- return Integer_to_Decimal (Str, Val (1), Base, Scl (1), Minus, Scale);
+ return
+ Integer_to_Decimal (Str, Val (1), Base, Scl (1), Extra, Minus, Scale);
end Scan_Decimal;
-------------------
@@ -255,7 +265,8 @@ package body System.Value_D is
begin
Val := Impl.Value_Raw_Real (Str, Base, Scl, Extra, Minus);
- return Integer_to_Decimal (Str, Val (1), Base, Scl (1), Minus, Scale);
+ return
+ Integer_to_Decimal (Str, Val (1), Base, Scl (1), Extra, Minus, Scale);
end Value_Decimal;
end System.Value_D;
--
2.43.0
