From 75b831aa879234db6d8821a32f4c411ef6cfc6ff Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Mon, 20 Feb 2012 19:52:13 +0100 Subject: erts: Fix bignum-bug in ETS with compressed option A large 64-bit immediate number will be stored as SMALL_BIG_EXT by ETS compressed format. When uncompressing, the SMALL_BIG_EXT was first decoded as as bignum (by bytes_to_big) and then turned into a small (by big_norm). This works for normal "binary_to_term" as decoded_size() over-estimates the needed heap size. But for ETS no over-estimation is done as the real term size is known and stored in DbTerm. Fixed by preventing bytes_to_big() from writing bignum digit when the number is seen to fit in an immediate. --- erts/emulator/beam/big.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) (limited to 'erts/emulator/beam') diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c index 976f05c990..25ac790d81 100644 --- a/erts/emulator/beam/big.c +++ b/erts/emulator/beam/big.c @@ -1844,6 +1844,7 @@ dsize_t big_bytes(Eterm x) /* ** Load a bignum from bytes ** xsz is the number of bytes in xp +** *r is untouched if number fits in small */ Eterm bytes_to_big(byte *xp, dsize_t xsz, int xsgn, Eterm *r) { @@ -1852,7 +1853,7 @@ Eterm bytes_to_big(byte *xp, dsize_t xsz, int xsgn, Eterm *r) ErtsDigit d; int i; - while(xsz >= sizeof(ErtsDigit)) { + while(xsz > sizeof(ErtsDigit)) { d = 0; for(i = sizeof(ErtsDigit); --i >= 0;) d = (d << 8) | xp[i]; @@ -1867,11 +1868,20 @@ Eterm bytes_to_big(byte *xp, dsize_t xsz, int xsgn, Eterm *r) d = 0; for(i = xsz; --i >= 0;) d = (d << 8) | xp[i]; + if (++rsz == 1 && IS_USMALL(xsgn,d)) { + if (xsgn) d = -d; + return make_small(d); + } *rwp = d; rwp++; - rsz++; } - return big_norm(r, rsz, (short) xsgn); + if (xsgn) { + *r = make_neg_bignum_header(rsz); + } + else { + *r = make_pos_bignum_header(rsz); + } + return make_big(r); } /* -- cgit v1.2.3