File 6301-Fix-bit-syntax-creation-of-a-bignum-in-a-short-non-a.patch of Package erlang
From 0da697c17faded2f59009156053682a2961735ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Mon, 26 Jun 2023 13:15:21 +0200
Subject: [PATCH] Fix bit syntax creation of a bignum in a short non-aligned
segment
This bug was introduced in 9256aad02f77bc4ca8c2ed5a4b41d5cad834fad1.
---
erts/emulator/beam/erl_bits.c | 27 ++++++++++++++++++-----
erts/emulator/test/bs_construct_SUITE.erl | 8 ++++++-
2 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/erts/emulator/beam/erl_bits.c b/erts/emulator/beam/erl_bits.c
index 0dc1d84627..d1bf243620 100644
--- a/erts/emulator/beam/erl_bits.c
+++ b/erts/emulator/beam/erl_bits.c
@@ -775,7 +775,7 @@ erts_new_bs_put_integer(ERL_BITS_PROTO_3(Eterm arg, Uint num_bits, unsigned flag
*/
iptr = erts_current_bin+BYTE_OFFSET(bin_offset);
b = *iptr & (0xff << rbits);
- b |= (signed_val(arg) & ((1 << num_bits)-1)) << (8-bit_offset-num_bits);
+ b |= (signed_val(arg) & ((1 << num_bits)-1)) << (rbits-num_bits);
*iptr = b;
} else if (bit_offset == 0) {
/*
@@ -791,8 +791,8 @@ erts_new_bs_put_integer(ERL_BITS_PROTO_3(Eterm arg, Uint num_bits, unsigned flag
Sint val = signed_val(arg);
Uint rshift = bit_offset;
Uint lshift = rbits;
- Uint lmask = MAKE_MASK(8 - bit_offset);
- Uint count = (num_bits - (8 - bit_offset)) / 8;
+ Uint lmask = MAKE_MASK(rbits);
+ Uint count = (num_bits - rbits) / 8;
Uint bits, bits1;
iptr = erts_current_bin+BYTE_OFFSET(bin_offset);
@@ -881,6 +881,19 @@ erts_new_bs_put_integer(ERL_BITS_PROTO_3(Eterm arg, Uint num_bits, unsigned flag
*/
fmt_big(erts_current_bin+BYTE_OFFSET(bin_offset),
NBYTES(num_bits), arg, num_bits, flags);
+ } else if (is_big(arg) && bit_offset + num_bits <= 8) {
+ /*
+ * All bits are in the same byte.
+ */
+ Uint rbits = 8 - bit_offset;
+ Sint sign = big_sign(arg);
+ ErtsDigit* dp = big_v(arg);
+ Uint val = sign ? -*dp : *dp;
+
+ iptr = erts_current_bin+BYTE_OFFSET(bin_offset);
+ b = *iptr & (0xff << rbits);
+ b |= (val & ((1 << num_bits)-1)) << (rbits-num_bits);
+ *iptr = b;
} else if (is_big(arg)) {
/*
* Big number, not aligned on a byte boundary.
@@ -890,12 +903,14 @@ erts_new_bs_put_integer(ERL_BITS_PROTO_3(Eterm arg, Uint num_bits, unsigned flag
Uint deoffs = BIT_OFFSET(bit_offset + num_bits);
Uint lmask = MAKE_MASK(8 - bit_offset);
Uint rmask = (deoffs) ? (MAKE_MASK(deoffs)<<(8-deoffs)) : 0;
- Uint count = (num_bits - (8 - bit_offset)) / 8;
+ Uint count = (num_bits - lshift) / 8;
Uint bits, bits1;
+ ASSERT(num_bits - lshift >= 0);
+
/*
- * Format it byte-aligned using the binary itself as a
- * temporary buffer.
+ * Format the integer byte-aligned using the binary itself as
+ * a temporary buffer.
*/
iptr = erts_current_bin + BYTE_OFFSET(bin_offset);
b = *iptr;
diff --git a/erts/emulator/test/bs_construct_SUITE.erl b/erts/emulator/test/bs_construct_SUITE.erl
index 0e9a39b976..a346ec2ed6 100644
--- a/erts/emulator/test/bs_construct_SUITE.erl
+++ b/erts/emulator/test/bs_construct_SUITE.erl
@@ -779,10 +779,16 @@ dynamic_3(Bef, N, {Int0,Lpad,Rpad,Dynamic}=Data, Count) ->
Dynamic(Bef, N, Int1, Lpad, Rpad),
Dynamic(Bef, N, -Int1, Lpad, Rpad),
- %% OTP-7085: Test a small number in a wide field.
+ %% OTP-7085: Test a small number in a wide segment.
Int2 = Int0 band 16#FFFFFF,
Dynamic(Bef, N, Int2, Lpad, Rpad),
Dynamic(Bef, N, -Int2, Lpad, Rpad),
+
+ %% Test a bignum in a short segment.
+ Int4 = ((Lpad bxor Rpad) bsl N) bor Int0,
+ Dynamic(Bef, N, Int4, Lpad, Rpad),
+ Dynamic(Bef, N, -Int4, Lpad, Rpad),
+
dynamic_3(Bef, N-1, Data, Count+1).
dynamic_big(Bef, N, Int, Lpad, Rpad) ->
--
2.35.3
