[COMPRESS-244] 7z reading of UINT64 data type is wrong for big values

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.6
• Fix Version/s: 1.7
• Component/s: Archivers
• Labels: 7z easyfix patch
• Assignee: Unassigned
• Reporter: Nico Kruber
• Created: 25/Nov/13 12:36
• Updated: 10/Aug/21 13:16
• Resolved: 27/Nov/13 05:36

Description

Brief description

large values with a first byte indicating at least 4 additional bytes shift an integer by at least 32bits thus leading to an overflow and an incorrect value - the value needs to be casted to long before the bitshift!
(see the attached patch)

Details from the 7z documentation

UINT64 means real UINT64 encoded with the following scheme:
  Size of encoding sequence depends from first byte:
  First_Byte  Extra_Bytes        Value
  (binary)   
  0xxxxxxx               : ( xxxxxxx           )
  10xxxxxx    BYTE y[1]  : (  xxxxxx << (8 * 1)) + y
  110xxxxx    BYTE y[2]  : (   xxxxx << (8 * 2)) + y
  ...
  1111110x    BYTE y[6]  : (       x << (8 * 6)) + y
  11111110    BYTE y[7]  :                         y
  11111111    BYTE y[8]  :                         y