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  • Martin Guy martinwguy
1 author
  1. Jan 15, 2022
  3. Oct 23, 2021
  5. Jul 29, 2021
  7. May 31, 2021
  9. May 26, 2021
  11. Dec 16, 2020
    • Timothy B. Terriberry's avatar
      Fix an incorrect assertion in op_pcm_seek_page(). · 729c88e7
      Timothy B. Terriberry authored 
      When we were checking the current file offset to see if we should
 use it as the starting bisection point, we assumed that offset was
 larger than the start of the data range for that link (and
 consequently, inside the bisection range).
If there is a random page earlier in the file that happens to use
 the same serial number as a link we identified later in the file
 at file open time, and we had stopped reading there before the
 seek, then this assumption might not be true.

Ironically, it was not the case that contained the assertion that
 had trouble with such an offset.
It would fail the check that we were cutting off more than half the
 range, since we were actually cutting off a negative amount, and
 fall back to the midpoint of the link as the first bisection
 point.
However, the case below that (where the target comes after the
 current timestamp), we might have erroneously cut off the entire
 range (setting end to offset, which was less than begin), causing
 the seek to immediately fail.

Instead, validate the curent offset against both ends of the link
 before attempting to use it as the initial bisection point.
Thanks to Felicia Lim for the report.

Fixes #2331
      729c88e7
    • Timothy B. Terriberry's avatar
      Fix intermediate overflow in op_pcm_total(). · 82adfb61
      Timothy B. Terriberry authored 
      Although link enumeration ensures the return value is in range, the
 order of operations allows the intermediate value pcm_total+diff
 to overflow the range of a 64-bit int.
Add parentheses to ensure this does not happen.
Thanks to Felcia Lim for the report.

Fixes #2330
      82adfb61
  13. Oct 13, 2020
    • Timothy B. Terriberry's avatar
      Fix short-circuit test when seeking in short files · 4174c26e
      Timothy B. Terriberry authored 
      When a file is very, very short (i.e., only one packet) and uses
 end-trimming, the apparent granule position preceding the first
 sample in the first packet can underflow.
We were computing this value by subtracting the packet duration
 from the computed per-packet granule position and expecting this
 computation to always succeed.
Because it could fail in the presence of end-trimming on the first
 packet (ironically, exactly the situation where the short-circuit
 is helpful), it would leave the value uninitialized, and then use
 it in a comparison, which is undefined behavior.
The correct solution is to check for failure and force the previous
 page's granule position to 0 in this case.
      4174c26e
  15. Sep 16, 2020
    • Timothy B. Terriberry's avatar
      Fix a possible divide-by-zero. · f94a1764
      Timothy B. Terriberry authored 
      We were attempting to ensure a minimum spacing between granule
 positions when guessing the start of a link location.
However, we took a strictly-positive granule position, added a
 fixed increment with op_granpos_add(), and checked if
 op_granpos_add() failed.
op_granpos_add() only fails if the sum would have overflowed past
 zero, which can never happen when adding two strictly positive
 granule positions.
Instead, we need to check if the result becomes negative (which is
 a legal granule position, but violates our assumptions in the
 search).

Thanks to Felicia Lim for the report.
      f94a1764
  17. Aug 01, 2020
  19. Jun 26, 2020