ICEpdf
  1. ICEpdf
  2. PDF-336

Improve read support for handling files with incorrect xref offsets

          Details

          • Type: Bug Bug
          • Status: Closed
          • Priority: Major Major
          • Resolution: Fixed
          • Affects Version/s: 4.2.2
          • Fix Version/s: 5.0.0 alpha1, 5.0
          • Component/s: Core/Parsing
          • Labels:
            None
          • Environment:
            any

            Description

            The PDF in question has several Errors in the byte offsets defined in the xref table. Generally speaking ICEpdf should detect the error and start a full document parse, locating all the objects in the file. For some reason the fall back code isn't getting executed and page loading fails. It should be noted that acrobat displays a few errors when loading the document.

            Tasks for this bug.
            - figure out why the fallback code isn't executing
            - consider an parser enhancement, instead of parsing the whole file into memory on failure, we should consider updating the xref table with new byte offset found by parsing file, but not keeping the objects in memory.
            1. PDF File
              graph.pdf
              638 kB
              Patrick Corless
            2. PDF File
              linearized.pdf
              3.07 MB
              Patrick Corless

              Activity

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              Patrick Corless created issue -
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              Patrick Corless added a comment -

              Xref problems.

              Show
              Patrick Corless added a comment - Xref problems.
              Patrick Corless made changes -
              Field Original Value New Value
              Attachment linearized.pdf [ 13597 ]
              Patrick Corless made changes -
              Attachment graph.pdf [ 13599 ]
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              Patrick Corless added a comment -

              This represent quite a big block of work and would be really nice feature. Moving to 5.0.

              Show
              Patrick Corless added a comment - This represent quite a big block of work and would be really nice feature. Moving to 5.0.
              Patrick Corless made changes -
              Salesforce Case []
              Fix Version/s 5.0 [ 10314 ]
              Fix Version/s 4.3 [ 10266 ]
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              Patrick Corless added a comment -

              Changes made for PDF-410, have correct the load issues with graph.pdf. The document Linerized.pdf is still a problem.

              Show
              Patrick Corless added a comment - Changes made for PDF-410 , have correct the load issues with graph.pdf. The document Linerized.pdf is still a problem.
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              Patrick Corless added a comment -

              Quite a bit of work has already been done to improve how we handle file that have incorrect xrefs. Under the new model if the catalog can not be found we fall back to linear read that also keeps track of the actual object offsets and rebuilds the xref table. Once the xref table is rebuild it's possible to re-fetch the objects lazily as the Page references are garbage collected.

              Of the attached documents the graph.pdf no loads correctly but there are some logged exceptions that need to be cleaned up. The second pdf still does not load so I'll used it to review our fall back logic.

              Show
              Patrick Corless added a comment - Quite a bit of work has already been done to improve how we handle file that have incorrect xrefs. Under the new model if the catalog can not be found we fall back to linear read that also keeps track of the actual object offsets and rebuilds the xref table. Once the xref table is rebuild it's possible to re-fetch the objects lazily as the Page references are garbage collected. Of the attached documents the graph.pdf no loads correctly but there are some logged exceptions that need to be cleaned up. The second pdf still does not load so I'll used it to review our fall back logic.
              Repository Revision Date User Message
              ICEsoft Public SVN Repository #32602 Tue Dec 04 09:56:34 MST 2012 patrick.corless PDF-336 updated catalog initialization to try and force ny potential xref errors upfront so that the the linear traversal code can properly execute.
              Files Changed
              Commit graph MODIFY /icepdf/trunk/icepdf/core/src/org/icepdf/core/util/Parser.java
              Commit graph MODIFY /icepdf/trunk/icepdf/core/src/org/icepdf/core/util/ContentParser.java
              Commit graph MODIFY /icepdf/trunk/icepdf/core/src/org/icepdf/core/pobjects/Catalog.java
              Commit graph MODIFY /icepdf/trunk/icepdf/core/src/org/icepdf/core/pobjects/graphics/ImageReference.java
              Commit graph MODIFY /icepdf/trunk/icepdf/core/src/org/icepdf/core/pobjects/Document.java
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              Patrick Corless added a comment -

              Updated catalog initialization to try an force any objects offset errors to show up while we still have a change to fall back to a linear traversal and subsequent reindex of the cross reference table.

              Show
              Patrick Corless added a comment - Updated catalog initialization to try an force any objects offset errors to show up while we still have a change to fall back to a linear traversal and subsequent reindex of the cross reference table.
              Patrick Corless made changes -
              Status Open [ 1 ] Resolved [ 5 ]
              Resolution Fixed [ 1 ]
              Patrick Corless made changes -
              Fix Version/s 5.0.0 alpha1 [ 10676 ]
              Patrick Corless made changes -
              Status Resolved [ 5 ] Closed [ 6 ]

                People

                • Assignee:
                  Patrick Corless
                  Reporter:
                  Patrick Corless
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                  Dates

                  • Created:
                    Updated:
                    Resolved: