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Fix a segfault reported by Etienne Renault using dve2check.

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* src/misc/intvcmp2.cc (stream_compression_base::run): Fix a case
where the "id" of the compression to use would be miscalculated,
causing wrong values to be encoded.
* src/tgbatest/intvcmp2.cc: Add this particular test case.
This commit is contained in:
Alexandre Duret-Lutz 2012-01-24 19:09:07 +01:00
parent 4b5734d8ec
commit 547715463a
3 changed files with 26 additions and 12 deletions
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9
ChangeLog
View file

@ -1,3 +1,12 @@
2012-01-24 Alexandre Duret-Lutz <adl@lrde.epita.fr>
Fix a segfault reported by Etienne Renault using dve2check.
* src/misc/intvcmp2.cc (stream_compression_base::run): Fix a case
where the "id" of the compression to use would be miscalculated,
causing wrong values to be encoded.
* src/tgbatest/intvcmp2.cc: Add this particular test case.
2012-01-20 Alexandre Duret-Lutz <adl@lrde.epita.fr> 2012-01-20 Alexandre Duret-Lutz <adl@lrde.epita.fr>
* NEWS: Add missing dates. * NEWS: Add missing dates.

26
src/misc/intvcmp2.cc
View file

@ -37,13 +37,13 @@ namespace spot
// This implements integer compression inspired from "Simple-9". // This implements integer compression inspired from "Simple-9".
// //
// The first bits of an integer tell how the rest of the integer is coded: // The first bits of an integer tell how the rest of the integer is coded:
// 00: 30 1-bit values // 00: 30 1-bit values id=0
// 01: 10 3-bit values // 01: 10 3-bit values id=1
// 10: 6 5-bit values // 10: 6 5-bit values id=2
// 1100: 4 7-bit values // 1100: 4 7-bit values id=3
// 1101: 3 9-bit values (1 bit lost) // 1101: 3 9-bit values (1 bit lost) id=4
// 1110: 2 14-bit values // 1110: 2 14-bit values id=5
// 1111: 1 28-bit value // 1111: 1 28-bit value id=6
template <class Self> template <class Self>
class stream_compression_base class stream_compression_base
@ -94,7 +94,7 @@ namespace spot
{ {
unsigned id = 0; // Current level in the above two tables. unsigned id = 0; // Current level in the above two tables.
unsigned curmax_allowed = max_allowed[id]; unsigned curmax_allowed = max_allowed[id];
unsigned compressable = 0; // Number of integer ready to pack. unsigned compressable = 0; // Number of integers ready to pack.
do do
{ {
unsigned int val = self().data_at(compressable); unsigned int val = self().data_at(compressable);
@ -103,17 +103,19 @@ namespace spot
{ {
curmax_allowed = max_allowed[++id]; curmax_allowed = max_allowed[++id];
if (compressable >= max_count[id]) if (compressable > max_count[id])
goto fast_encode; goto fast_encode;
} }
if (compressable >= max_count[id])
goto fast_encode;
} }
while (likely(compressable < max_count[id] while (likely(compressable < size_));
&& compressable < size_));
assert(compressable <= max_count[id]); assert(compressable < max_count[id]);
// Since we have less data than the current "id" allows, // Since we have less data than the current "id" allows,
// try to use more bits so we can encode faster. // try to use more bits so we can encode faster.
id = count_to_level[compressable - 1]; id = count_to_level[compressable - 1];
if (compressable == max_count[id]) if (compressable == max_count[id])

3
src/tgbatest/intvcmp2.cc
View file

@ -127,5 +127,8 @@ int main()
0, 0, 0, 0, 0, 0, 0, 0, 9 }; 0, 0, 0, 0, 0, 0, 0, 0, 9 };
errors += check(comp10, sizeof(comp10) / sizeof(*comp10)); errors += check(comp10, sizeof(comp10) / sizeof(*comp10));
int comp11[] = { 2, 254, 254, 0, 1, 4, 0, 0, 0, 1, 0, 1, 253, 0 };
errors += check(comp11, sizeof(comp11) / sizeof(*comp11));
return errors; return errors;
} }