Attempt to find xref streams during recovery (fixes #1103)

10 files changed, 31 insertions, 2 deletions

diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index cbb4ac1d..df2555d6 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -689,3 +689,4 @@ QPDFPageObjectHelper used fallback without copying 0
 QPDF skipping cache for known unchecked object 0
 QPDF fix dangling triggered xref reconstruction 0
 QPDFPageDocumentHelper flatten resources missing or invalid 0
+QPDF recover xref stream 0
diff --git a/qpdf/qtest/object-stream.test b/qpdf/qtest/object-stream.test
index 04d1bb0d..22b35af4 100644
--- a/qpdf/qtest/object-stream.test
+++ b/qpdf/qtest/object-stream.test
@@ -16,7 +16,7 @@ cleanup();
 
 my $td = new TestDriver('object-stream');
 
-my $n_tests = 3 + (36 * 4) + (12 * 2);
+my $n_tests = 5 + (36 * 4) + (12 * 2);
 my $n_compare_pdfs = 36;
 
 for (my $n = 16; $n <= 19; ++$n)
@@ -87,5 +87,15 @@ $td->runtest("check file",
              {$td->FILE => "gen1.qdf"});
 
 
+# Recover a file with xref streams
+$td->runtest("recover file with xref stream",
+             {$td->COMMAND => "qpdf --static-id --compress-streams=n" .
+                  " recover-xref-stream.pdf a.pdf"},
+             {$td->FILE => "recover-xref-stream.out", $td->EXIT_STATUS => 3},
+             $td->NORMALIZE_NEWLINES);
+$td->runtest("check file",
+             {$td->FILE => "a.pdf"},
+             {$td->FILE => "recover-xref-stream-recovered.pdf"});
+
 cleanup();
 $td->report(calc_ntests($n_tests, $n_compare_pdfs));
diff --git a/qpdf/qtest/qpdf/bad7-recover.out b/qpdf/qtest/qpdf/bad7-recover.out
index 1b39acd9..0e5d4a6c 100644
--- a/qpdf/qtest/qpdf/bad7-recover.out
+++ b/qpdf/qtest/qpdf/bad7-recover.out
@@ -1,4 +1,6 @@
 WARNING: bad7.pdf: file is damaged
 WARNING: bad7.pdf (offset 698): expected trailer dictionary
 WARNING: bad7.pdf: Attempting to reconstruct cross-reference table
+WARNING: bad7.pdf (object 2 0, offset 128): expected endobj
+WARNING: bad7.pdf (object 4 0, offset 389): expected endobj
 bad7.pdf: unable to find trailer dictionary while recovering damaged file
diff --git a/qpdf/qtest/qpdf/issue-146.out b/qpdf/qtest/qpdf/issue-146.out
index 0aa23ed8..3e3b50da 100644
--- a/qpdf/qtest/qpdf/issue-146.out
+++ b/qpdf/qtest/qpdf/issue-146.out
@@ -2,4 +2,7 @@ WARNING: issue-146.pdf: file is damaged
 WARNING: issue-146.pdf: can't find startxref
 WARNING: issue-146.pdf: Attempting to reconstruct cross-reference table
 WARNING: issue-146.pdf (trailer, offset 695): ignoring excessively deeply nested data structure
+WARNING: issue-146.pdf (object 1 0, offset 92): expected endobj
+WARNING: issue-146.pdf (object 7 0, offset 146): unknown token while reading object; treating as string
+WARNING: issue-146.pdf (object 7 0, offset 168): expected endobj
 qpdf: issue-146.pdf: unable to find trailer dictionary while recovering damaged file
diff --git a/qpdf/qtest/qpdf/issue-148.out b/qpdf/qtest/qpdf/issue-148.out
index a59c1343..dbc424f2 100644
--- a/qpdf/qtest/qpdf/issue-148.out
+++ b/qpdf/qtest/qpdf/issue-148.out
@@ -7,4 +7,9 @@ WARNING: issue-148.pdf (offset 73): error decoding stream data for object 8 0: s
 WARNING: issue-148.pdf: file is damaged
 WARNING: issue-148.pdf (offset 73): getStreamData called on unfilterable stream
 WARNING: issue-148.pdf: Attempting to reconstruct cross-reference table
-qpdf: issue-148.pdf: unable to find trailer dictionary while recovering damaged file
+WARNING: issue-148.pdf (xref stream: object 8 0, offset 26): stream dictionary lacks /Length key
+WARNING: issue-148.pdf (xref stream: object 8 0, offset 73): attempting to recover stream length
+WARNING: issue-148.pdf (xref stream: object 8 0, offset 73): recovered stream length: 2
+WARNING: issue-148.pdf (xref stream: object 8 0, offset 85): expected endobj
+WARNING: issue-148.pdf (offset 73): error decoding stream data for object 8 0: stream inflate: inflate: data: incorrect header check
+qpdf: issue-148.pdf: error decoding candidate xref stream while recovering damaged file
diff --git a/qpdf/qtest/qpdf/issue-150.out b/qpdf/qtest/qpdf/issue-150.out
index 3291f96f..9fe8b5ac 100644
--- a/qpdf/qtest/qpdf/issue-150.out
+++ b/qpdf/qtest/qpdf/issue-150.out
@@ -2,4 +2,5 @@ WARNING: issue-150.pdf: can't find PDF header
 WARNING: issue-150.pdf: file is damaged
 WARNING: issue-150.pdf: error reading xref: overflow/underflow converting 9900000000000000000 to 64-bit integer
 WARNING: issue-150.pdf: Attempting to reconstruct cross-reference table
+WARNING: issue-150.pdf (object 8 0): object has offset 0
 qpdf: issue-150.pdf: unable to find trailer dictionary while recovering damaged file
diff --git a/qpdf/qtest/qpdf/issue-202.out b/qpdf/qtest/qpdf/issue-202.out
index 8310c103..441b7087 100644
--- a/qpdf/qtest/qpdf/issue-202.out
+++ b/qpdf/qtest/qpdf/issue-202.out
@@ -3,4 +3,6 @@ WARNING: issue-202.pdf: file is damaged
 WARNING: issue-202.pdf (offset 54769): expected trailer dictionary
 WARNING: issue-202.pdf: Attempting to reconstruct cross-reference table
 WARNING: issue-202.pdf (trailer, offset 55770): ignoring excessively deeply nested data structure
+WARNING: issue-202.pdf (object 222 0, offset 50101): dictionary has duplicated key /Creator; last occurrence overrides earlier ones
+WARNING: issue-202.pdf (object 222 0, offset 50101): dictionary has duplicated key /Producer; last occurrence overrides earlier ones
 qpdf: issue-202.pdf: unable to find trailer dictionary while recovering damaged file
diff --git a/qpdf/qtest/qpdf/recover-xref-stream-recovered.pdf b/qpdf/qtest/qpdf/recover-xref-stream-recovered.pdf
new file mode 100644
index 00000000..dfbfceed
--- /dev/null
+++ b/qpdf/qtest/qpdf/recover-xref-stream-recovered.pdf
diff --git a/qpdf/qtest/qpdf/recover-xref-stream.out b/qpdf/qtest/qpdf/recover-xref-stream.out
new file mode 100644
index 00000000..ba0e1aa6
--- /dev/null
+++ b/qpdf/qtest/qpdf/recover-xref-stream.out
@@ -0,0 +1,5 @@
+WARNING: recover-xref-stream.pdf: file is damaged
+WARNING: recover-xref-stream.pdf: can't find startxref
+WARNING: recover-xref-stream.pdf: Attempting to reconstruct cross-reference table
+WARNING: recover-xref-stream.pdf: reported number of objects (14) is not one plus the highest object number (15)
+qpdf: operation succeeded with warnings; resulting file may have some problems
diff --git a/qpdf/qtest/qpdf/recover-xref-stream.pdf b/qpdf/qtest/qpdf/recover-xref-stream.pdf
new file mode 100644
index 00000000..f8da3f1b
--- /dev/null
+++ b/qpdf/qtest/qpdf/recover-xref-stream.pdf