From 8e28398f3bc9cc9e8c5a038ef26823fc41dc5910 Mon Sep 17 00:00:00 2001
From: David Kalnischkies <david@kalnischkies.de>
Date: Wed, 15 Aug 2018 00:23:37 +0200
Subject: Support records larger than 32kb in 'apt show'
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The default buffer size for pkgTagFile is 32kb which should be big
enough for everything… expect for enormous lists of provides,
resulting in:

$ apt show librust-winapi-dev
E: Unable to parse package file /var/lib/apt/lists/ftp.br.debian.org_debian_dists_unstable_main_binary-amd64_Packages (2)
E: Internal Error, Unable to parse a package record

The "apt-cache show" codepath uses instead a max size for all files,
which seems a bit excessive, but works – using the max size for the file
in question seems most appropriate.

The patch is written for the 1.6.y series as a rewrite of the related
code in the 1.7.y series (commit bf53f39c9a0221b670ffff74053ed36fc502d5a0)
removed this problem before it was reported.

Closes: #905527
LP: #1787120
(cherry picked from commit 409ceec9ed30cbebd8ece1ef7ce667ab5a32f9df)
---
 apt-private/private-show.cc        |  4 ++--
 test/integration/test-apt-cli-show | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/apt-private/private-show.cc b/apt-private/private-show.cc
index cd7a2a064..d96335977 100644
--- a/apt-private/private-show.cc
+++ b/apt-private/private-show.cc
@@ -177,9 +177,9 @@ static bool DisplayRecordV2(pkgCacheFile &CacheFile, pkgCache::VerIterator const
 
    // Read the record
    pkgTagSection Tags;
-   pkgTagFile TagF(&PkgF);
+   pkgTagFile TagF(&PkgF, Vf->Size);
 
-   if (TagF.Jump(Tags, V.FileList()->Offset) == false)
+   if (TagF.Jump(Tags, Vf->Offset) == false)
       return _error->Error("Internal Error, Unable to parse a package record");
 
    // make size nice
diff --git a/test/integration/test-apt-cli-show b/test/integration/test-apt-cli-show
index 754b3aa5f..54aaee4b8 100755
--- a/test/integration/test-apt-cli-show
+++ b/test/integration/test-apt-cli-show
@@ -7,10 +7,18 @@ TESTDIR="$(readlink -f "$(dirname "$0")")"
 setupenvironment
 configarchitecture 'i386' 'amd64'
 
+generatelotsofnames() {
+	for i in $(seq 0 10000); do
+		printf ', this-is-a-long-pkg-name-%s (= 0.a.long.version)' "$i"
+	done
+}
+
 DESCR='Some description
  That has multiple lines'
 insertpackage 'unstable' 'foo' 'all' '1.0' '' '' "$DESCR"
 insertpackage 'unstable' 'bar' 'i386,amd64' '1' '' '' "$DESCR"
+insertpackage 'unstable' 'large' 'all' '1' "Provides: pkga$(generatelotsofnames)" '' "$DESCR"
+insertpackage 'unstable' 'large2' 'all' '1' "Provides: foobar, pkga$(generatelotsofnames)" '' "$DESCR"
 insertinstalledpackage 'foo' 'all' '1.0'
 
 setupaptarchive
@@ -54,6 +62,31 @@ Description: Some description
  That has multiple lines
 " apt show bar:amd64
 
+testsuccessequal "Package: large
+Version: 1
+Priority: optional
+Section: other
+Maintainer: Joe Sixpack <joe@example.org>
+Installed-Size: 43.0 kB
+Provides: pkga$(generatelotsofnames)
+Download-Size: unknown
+APT-Sources: file:$APTARCHIVE unstable/main all Packages
+Description: Some description
+ That has multiple lines
+" apt show large
+testsuccessequal "Package: large2
+Version: 1
+Priority: optional
+Section: other
+Maintainer: Joe Sixpack <joe@example.org>
+Installed-Size: 43.0 kB
+Provides: foobar, pkga$(generatelotsofnames)
+Download-Size: unknown
+APT-Sources: file:$APTARCHIVE unstable/main all Packages
+Description: Some description
+ That has multiple lines
+" apt show large2
+
 # this is the default, but disabled by the testcases
 testsuccess apt show foo -o Apt::Cmd::Disable-Script-Warning=0
 cp rootdir/tmp/testsuccess.output aptshow.output
-- 
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