Hi Klaus,
I have noticed a PMT parsing issue with VDR version 1.7.x. The bug is still
present in version 1.7.3 but the behaviour is worst because it segfaults.
First I found out that 2 lines where added in the ParsePmt method.
Data += Data[0] + 1; // this is the first packet
Length -= Data[0] + 1;
At the moment I don't know exactly what is the meaning of this 2 operations.
The second line can result in a negative Length which is the reason of the
segfault.
Could you kindly explain the offset drift? In a single section PMT (99.9% of
the time) Data[0] is always equal to 0 and we skip the first byte. Length is
reduced by 1. I a multiple section stream Data[0] can be above 188. Trying to
skip more than a section is not possible in the actual context.
I have done a quick and dirty hack to prevent the segfault:
--- remux.c_ori 2009-01-16 21:05:46.000000000 +0100
+++ remux.c 2009-01-17 13:34:17.000000000 +0100
@@ -361,6 +361,7 @@
if (pmtSize == 0) {
Data += Data[0] + 1; // this is the first packet
Length -= Data[0] + 1;
+ if ( Length < 0 ) Length = 0;
if (SectionLength(Data, Length) > Length) {
if (Length <= int(sizeof(pmt))) {
memcpy(pmt, Data, Length);
the second step will be to have the parsing of multiple section allowed. At
the moment when the data size exceed the section size (max 4096), PMT cannot
be parsed.
[2222] ERROR: can't parse PMT
[2222] ERROR: can't parse PMT
[2222] ERROR: can't parse PMT
[2222] ERROR: can't parse PMT
[2222] ERROR: can't parse PMT
[2222] ERROR: PMT section length too big (4176 byte)!
[2222] ERROR: can't parse PMT
Regards,
Alex
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