Allow apt to run if no dpkg/status file exists

Not having a dpkg/status file used to be a hard error which from a
boostrap perspective is suspect as in the beginning, there is no
status so you would need to touch it into existence.

We make a difference between factual non-existence and inaccessibility
to catch mistakes in which the file is not readable for some reason,
the testcase test-bug-254770-segfault-if-cache-not-buildable is an
example of this.

Note that apt has already figured out at this point that this is a
Debian-like system which should have a dpkg/status file. This change
does not effect the auto-detection and is not supposed to.

14 files changed, 34 insertions, 33 deletions

diff --git a/apt-pkg/deb/debsystem.cc b/apt-pkg/deb/debsystem.cc
index 65a27f72f..9c55e0a6e 100644
--- a/apt-pkg/deb/debsystem.cc
+++ b/apt-pkg/deb/debsystem.cc
@@ -338,6 +338,13 @@ bool debSystem::AddStatusFiles(std::vector<pkgIndexFile *> &List)
    if (d->StatusFile == nullptr)
    {
       auto dpkgstatus = _config->FindFile("Dir::State::status");
+      if (dpkgstatus.empty())
+	 return true;
+      // we ignore only if the file doesn't exist, not if it is inaccessible
+      // e.g. due to permissions on parent directories as FileExists would do
+      errno = 0;
+      if (access(dpkgstatus.c_str(), R_OK) != 0 && errno == ENOENT)
+	 return true;
       _error->PushToStack();
       d->StatusFile = new debStatusIndex(std::move(dpkgstatus));
       bool const errored = _error->PendingError();
diff --git a/apt-pkg/policy.cc b/apt-pkg/policy.cc
index 5fcc11b66..68b3f5e5f 100644
--- a/apt-pkg/policy.cc
+++ b/apt-pkg/policy.cc
@@ -70,17 +70,19 @@ pkgPolicy::pkgPolicy(pkgCache *Owner) : VerPins(nullptr),
    if (DefRel.empty() == false)
    {
       bool found = false;
-      // FIXME: make ExpressionMatches static to use it here easily
-      pkgVersionMatch vm("", pkgVersionMatch::None);
       for (pkgCache::PkgFileIterator F = Cache->FileBegin(); F != Cache->FileEnd(); ++F)
       {
-	 if (vm.ExpressionMatches(DefRel, F.Archive()) ||
-	     vm.ExpressionMatches(DefRel, F.Codename()) ||
-	     vm.ExpressionMatches(DefRel, F.Version()) ||
+	 if (pkgVersionMatch::ExpressionMatches(DefRel, F.Archive()) ||
+	     pkgVersionMatch::ExpressionMatches(DefRel, F.Codename()) ||
+	     pkgVersionMatch::ExpressionMatches(DefRel, F.Version()) ||
 	     (DefRel.length() > 2 && DefRel[1] == '='))
 	    found = true;
       }
-      if (found == false)
+      // "now" is our internal archive name for the status file,
+      // which we should accept even if we have no status file at the moment
+      if (not found && pkgVersionMatch::ExpressionMatches(DefRel, "now"))
+	 found = true;
+      if (not found)
 	 _error->Error(_("The value '%s' is invalid for APT::Default-Release as such a release is not available in the sources"), DefRel.c_str());
       else
 	 CreatePin(pkgVersionMatch::Release,"",DefRel,990);
diff --git a/test/integration/framework b/test/integration/framework
index 5e1e68a98..d50b63518 100644
--- a/test/integration/framework
+++ b/test/integration/framework
@@ -626,8 +626,6 @@ configdpkg() {
 			if tail -1 rootdir/var/lib/dpkg/status | grep -q .; then
 				echo >> rootdir/var/lib/dpkg/status
 			fi
-		else
-			echo -n > rootdir/var/lib/dpkg/status
 		fi
 	fi
 	rm -f rootdir/etc/apt/apt.conf.d/00foreigndpkg
diff --git a/test/integration/test-allow-scores-for-all-dependency-types b/test/integration/test-allow-scores-for-all-dependency-types
index b8a9ed3ea..999efc04e 100755
--- a/test/integration/test-allow-scores-for-all-dependency-types
+++ b/test/integration/test-allow-scores-for-all-dependency-types
@@ -37,7 +37,6 @@ insertpackage 'jessie' 'login' 'amd64' '2' 'Pre-Depends: libaudit1 (>= 0)'
 insertpackage 'jessie' 'libaudit1' 'amd64' '2' 'Depends: libaudit-common (>= 0)'
 insertpackage 'jessie' 'libaudit-common' 'amd64' '2' 'Breaks: libaudit0, libaudit1 (<< 2)'
 
-cp rootdir/var/lib/dpkg/status rootdir/var/lib/dpkg/status-backup
 setupaptarchive
 
 insertinstalledpackage 'libdb-dev' 'amd64' '5.1.7' 'Depends: libdb5.1-dev'
@@ -73,7 +72,7 @@ Inst libdb5.3-dev (5.3.28-3 versioned [amd64])
 Conf libdb-dev (5.3.0 versioned [amd64])
 Conf libdb5.3-dev (5.3.28-3 versioned [amd64])' aptget dist-upgrade -st versioned
 
-cp -f rootdir/var/lib/dpkg/status-backup rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 insertinstalledpackage 'foo' 'amd64' '1'
 insertinstalledpackage 'bar' 'amd64' '1'
 testsuccessequal 'Reading package lists...
@@ -131,7 +130,7 @@ Conf bar (2 versioned [amd64])
 Conf baz (2 versioned [amd64])' aptget install baz -st versioned
 
 # recreating the exact situation is hard, so we pull tricks to get the score
-cp -f rootdir/var/lib/dpkg/status-backup rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 insertinstalledpackage 'gdm3' 'amd64' '1' 'Depends: libaudit0, libaudit0'
 insertinstalledpackage 'login' 'amd64' '1' 'Essential: yes'
 insertinstalledpackage 'libaudit0' 'amd64' '1'
diff --git a/test/integration/test-apt-cache-remapping b/test/integration/test-apt-cache-remapping
index 31a406c57..19647a6a4 100755
--- a/test/integration/test-apt-cache-remapping
+++ b/test/integration/test-apt-cache-remapping
@@ -8,6 +8,7 @@ setupenvironment
 configarchitecture 'amd64'
 
 buildsimplenativepackage 'foo' 'amd64' '1'
+insertinstalledpackage 'bar' 'all' '1'
 
 # the default is 1MB – too much for our simple tests
 echo 'APT::Cache-Grow "1000";' > rootdir/etc/apt/apt.conf.d/limit-cachegrow.conf
diff --git a/test/integration/test-apt-cli-update b/test/integration/test-apt-cli-update
index cc8d051d2..810221510 100755
--- a/test/integration/test-apt-cli-update
+++ b/test/integration/test-apt-cli-update
@@ -8,7 +8,6 @@ setupenvironment
 configarchitecture "i386"
 
 insertpackage 'unstable' 'foo' 'all' '2.0'
-cp rootdir/var/lib/dpkg/status dpkg.status
 insertinstalledpackage 'foo' 'all' '1.0'
 
 setupaptarchive --no-update
@@ -18,6 +17,6 @@ testfailuremsg 'E: The update command takes no arguments' apt update arguments
 testempty apt update -qq -o pkgCacheFile::Generate=false
 testsuccessequal "1 package can be upgraded. Run 'apt list --upgradable' to see it." apt update -qq
 
-cp dpkg.status rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 insertinstalledpackage 'foo' 'all' '2.0'
 testsuccessequal 'All packages are up to date.' apt update -qq
diff --git a/test/integration/test-bug-604222-new-and-autoremove b/test/integration/test-bug-604222-new-and-autoremove
index 08756e03d..47da810c6 100755
--- a/test/integration/test-bug-604222-new-and-autoremove
+++ b/test/integration/test-bug-604222-new-and-autoremove
@@ -19,7 +19,6 @@ insertpackage 'stable' 'libkipi-data' 'i386' '4:15.08.0-1' '' 'important'
 
 setupaptarchive
 
-cp -a rootdir/var/lib/dpkg/status rootdir/var/lib/dpkg/status.backup
 insertinstalledpackage 'libvtk5.4' 'i386' '5.4.2-7'
 testsuccess aptmark markauto 'libvtk5.4'
 testmarkedauto 'libvtk5.4'
@@ -80,8 +79,7 @@ Need to get 0 B/126 B of archives.
 After this operation, 129 kB of additional disk space will be used.
 E: Trivial Only specified but this is not a trivial operation." aptget install dummy-archive --trivial-only -o APT::Get::HideAutoRemove=small
 
-cp rootdir/var/lib/dpkg/status.backup rootdir/var/lib/dpkg/status
-rm -f rootdir/var/lib/apt/extended_states
+rm -f rootdir/var/lib/dpkg/status rootdir/var/lib/apt/extended_states
 
 CONFLICTING='Reading package lists...
 Building dependency tree...
diff --git a/test/integration/test-bug-673536-pre-depends-breaks-loop b/test/integration/test-bug-673536-pre-depends-breaks-loop
index a4cf66973..650866ee5 100755
--- a/test/integration/test-bug-673536-pre-depends-breaks-loop
+++ b/test/integration/test-bug-673536-pre-depends-breaks-loop
@@ -18,11 +18,8 @@ setupaptarchive
 # we check with 'real' packages here as the simulation reports a 'Conf broken'
 # which is technical correct for the simulation, but testing errormsg is ugly
 
-cp -a rootdir/var/lib/dpkg/status dpkg.status.backup
-
 testloopbreak() {
-	cp -a dpkg.status.backup rootdir/var/lib/dpkg/status
-	rm -f rootdir/var/lib/apt/extended_states
+	rm -f rootdir/var/lib/dpkg/status rootdir/var/lib/apt/extended_states
 
 	testsuccess aptget install advanced=1 -y -t "$1"
 	testdpkginstalled advanced
diff --git a/test/integration/test-bug-782777-single-arch-weirdness b/test/integration/test-bug-782777-single-arch-weirdness
index 41be1e79c..695d053d3 100755
--- a/test/integration/test-bug-782777-single-arch-weirdness
+++ b/test/integration/test-bug-782777-single-arch-weirdness
@@ -50,7 +50,6 @@ is only available from another source
 E: Package 'abar:amd64' has no installation candidate
 E: Package 'zfoo:amd64' has no installation candidate" aptget install abar:amd64 zfoo:amd64 -s
 
-	cp -f rootdir/var/lib/dpkg/status status.backup
 	insertinstalledpackage 'abar' 'i386' '1'
 	insertinstalledpackage 'zfoo' 'i386' '1'
 
@@ -62,7 +61,7 @@ zfoo set to automatically installed.' aptmark auto abar zfoo
 	testequal 'abar
 zfoo' aptmark showauto abar zfoo
 
-	mv -f status.backup rootdir/var/lib/dpkg/status
+	rm -f rootdir/var/lib/dpkg/status
 }
 
 msgmsg 'Single-Arch testrun'
diff --git a/test/integration/test-failing-maintainer-scripts b/test/integration/test-failing-maintainer-scripts
index 8cf2380ee..c2d631634 100755
--- a/test/integration/test-failing-maintainer-scripts
+++ b/test/integration/test-failing-maintainer-scripts
@@ -70,22 +70,21 @@ testmyfailure() {
 	testmarkedauto 'dependee'
 }
 
-cp -a rootdir/var/lib/dpkg/status rootdir/var/lib/dpkg/status.backup
 testmyfailure aptget install failure-preinst -y
-cp -a rootdir/var/lib/dpkg/status.backup rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 testmyfailure aptget install failure-postinst -y
-cp -a rootdir/var/lib/dpkg/status.backup rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 testsuccess aptget install failure-prerm -y
 testdpkginstalled failure-prerm
 testmyfailure aptget purge failure-prerm -y
-cp -a rootdir/var/lib/dpkg/status.backup rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 testsuccess aptget install failure-postrm -y
 testdpkginstalled failure-postrm
 testmyfailure aptget purge failure-postrm -y
 
 # FIXME: test with output going to a PTY as it usually does
 if false; then
-	cp -a rootdir/var/lib/dpkg/status.backup rootdir/var/lib/dpkg/status
+	rm -f rootdir/var/lib/dpkg/status
 	apt install dependee -y || true
 	apt install failure-postinst -y || true
 fi
diff --git a/test/integration/test-policy-pinning b/test/integration/test-policy-pinning
index fccef6da3..dc3192fe9 100755
--- a/test/integration/test-policy-pinning
+++ b/test/integration/test-policy-pinning
@@ -7,6 +7,8 @@ TESTDIR="$(readlink -f "$(dirname "$0")")"
 setupenvironment
 configarchitecture "i386"
 
+insertinstalledpackage 'foobar' 'all' '1'
+
 buildaptarchive
 setupflataptarchive
 
diff --git a/test/integration/test-ubuntu-bug-1130419-prefer-installed-ma-same-siblings b/test/integration/test-ubuntu-bug-1130419-prefer-installed-ma-same-siblings
index 4ac5e9060..d76602631 100755
--- a/test/integration/test-ubuntu-bug-1130419-prefer-installed-ma-same-siblings
+++ b/test/integration/test-ubuntu-bug-1130419-prefer-installed-ma-same-siblings
@@ -43,7 +43,6 @@ Inst steam:i386 (2 unstable [i386])
 Conf libmesa:i386 (2 unstable [i386])
 Conf steam:i386 (2 unstable [i386])' aptget install steam -st unstable
 
-cp rootdir/var/lib/dpkg/status default-status.dpkg
 insertinstalledpackage 'libmesa' 'amd64' '1' 'Multi-Arch: same'
 testsuccessequal 'Reading package lists...
 Building dependency tree...
@@ -72,7 +71,7 @@ Conf libmesa (2 unstable [amd64])
 Conf libmesa:i386 (2 unstable [i386])
 Conf steam:i386 (2 unstable [i386])' aptget install steam -st unstable
 
-cp default-status.dpkg rootdir/var/lib/dpkg/status
+rm -f rootdir/var/lib/dpkg/status
 insertinstalledpackage 'libmesa-lts' 'amd64' '1' 'Provides: libmesa
 Conflicts: libmesa
 Multi-Arch: same'
diff --git a/test/integration/test-ubuntu-bug-784473-InRelease-one-message-only b/test/integration/test-ubuntu-bug-784473-InRelease-one-message-only
index fe42ba83d..80e41f2c2 100755
--- a/test/integration/test-ubuntu-bug-784473-InRelease-one-message-only
+++ b/test/integration/test-ubuntu-bug-784473-InRelease-one-message-only
@@ -28,6 +28,10 @@ done
 testfailure aptget update
 testsuccess grep '^E:.*Clearsigned file .*NOSPLIT.*' rootdir/tmp/testfailure.output
 
+testsuccessequal "Package files:
+Pinned packages:" aptcache policy
+
+insertinstalledpackage 'foo' 'all' '1'
 
 ROOTDIR="$(readlink -f .)"
 testsuccessequal "Package files:
diff --git a/test/integration/test-unpack-different-version-unpacked b/test/integration/test-unpack-different-version-unpacked
index bcb483639..e7da64ceb 100755
--- a/test/integration/test-unpack-different-version-unpacked
+++ b/test/integration/test-unpack-different-version-unpacked
@@ -9,11 +9,8 @@ configarchitecture 'amd64' 'i386'
 insertpackage 'unstable' 'libqtcore4' 'i386,amd64' '2' 'Multi-Arch: same'
 setupaptarchive
 
-DPKGSTATUS='rootdir/var/lib/dpkg/status'
-cp $DPKGSTATUS dpkg.status
-
 cleanstatus() {
-	cp dpkg.status $DPKGSTATUS
+	rm -f rootdir/var/lib/dpkg/status
 	rm rootdir/var/cache/apt/*.bin
 }