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From 0f8dfa23744150b2aa91f6bd169b871308ecb43f Mon Sep 17 00:00:00 2001
Message-Id: <0f8dfa23744150b2aa91f6bd169b871308ecb43f.1589805773.git.maciej.zenon.borzecki@canonical.com>
In-Reply-To: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
References: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
From: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
Date: Wed, 6 May 2020 10:45:38 +0200
Subject: [PATCH 1/3] interfaces/builtin/desktop: do not mount fonts cache on
distros with quirks
There is a problem with compatibility of fontconfig cache files generated across
different versions of the fontconfig library. The cache files appear to be using
the same format, but when loaded by an older version of the library, they cause
instability, bad font rendering or plain segfaults.
The following versions of packages present on specific distros are known to
generate incompatible cache files:
- Arch: fontconfig 2:2.13.91+24+g75eadca-2
- Fedora 32: fontconfig-2.13.92-9.fc32.x86_64
More information is provided in the following post:
https://forum.snapcraft.io/t/snapped-app-not-loading-fonts-on-fedora-and-arch/12484/32
A bisect identified this commit where the problem first occurred:
https://gitlab.freedesktop.org/fontconfig/fontconfig/commit/0f9bbbcf8f6f8264efb0a2ded4d8d05f3b10f7a4
Until we work out a better solution, disable the fonts cache on distros that are
known to cause issues. This comes at the potential cost of slightly longer
application startup times, but a working app is better than a segfaulting one.
Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
---
interfaces/builtin/desktop.go | 13 ++++++++
interfaces/builtin/desktop_test.go | 52 +++++++++++++++++-------------
2 files changed, 42 insertions(+), 23 deletions(-)
diff --git a/interfaces/builtin/desktop.go b/interfaces/builtin/desktop.go
index 05a97251f7fcad66a356ea7d77690dcb02f724d1..8e18a4fc4409e957b51f0763dc791c8e54eec09e 100644
--- a/interfaces/builtin/desktop.go
+++ b/interfaces/builtin/desktop.go
@@ -26,6 +26,7 @@ import (
"github.com/snapcore/snapd/interfaces/mount"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/release"
+ "github.com/snapcore/snapd/strutil"
)
const desktopSummary = `allows access to basic graphical desktop resources`
@@ -288,6 +289,18 @@ func (iface *desktopInterface) MountConnectedPlug(spec *mount.Specification, plu
if !osutil.IsDirectory(dir) {
continue
}
+ if release.DistroLike("arch", "fedora") {
+ // XXX: on Arch and Fedora 32+ there is a known
+ // incompatibility between the binary fonts cache files
+ // and ones expected by desktop snaps; even though the
+ // cache format level is same for both, the host
+ // generated cache files cause instability, segfaults or
+ // incorrect rendering of fonts, for this reason do not
+ // mount the cache directories on those distributions
+ if strutil.ListContains(dirs.SystemFontconfigCacheDirs, dir) {
+ continue
+ }
+ }
// Since /etc/fonts/fonts.conf in the snap mount ns is the same
// as on the host, we need to preserve the original directory
// paths for the fontconfig runtime to poke the correct
diff --git a/interfaces/builtin/desktop_test.go b/interfaces/builtin/desktop_test.go
index d30af78ddea39f874eb2f4d8b765c82adab6872b..e0f995fd7633b06f81d4439c700fab34a59264d5 100644
--- a/interfaces/builtin/desktop_test.go
+++ b/interfaces/builtin/desktop_test.go
@@ -154,6 +154,8 @@ func (s *DesktopInterfaceSuite) TestMountSpec(c *C) {
// are bind mounted from the host system if they exist.
restore = release.MockOnClassic(true)
defer restore()
+ restore = release.MockReleaseInfo(&release.OS{ID: "ubuntu"})
+ defer restore()
spec = &mount.Specification{}
c.Assert(spec.AddConnectedPlug(s.iface, s.plug, s.coreSlot), IsNil)
@@ -177,29 +179,33 @@ func (s *DesktopInterfaceSuite) TestMountSpec(c *C) {
c.Assert(entries, HasLen, 1)
c.Check(entries[0].Dir, Equals, "$XDG_RUNTIME_DIR/doc")
- // Fedora is a little special with their fontconfig cache location(s)
- restore = release.MockReleaseInfo(&release.OS{ID: "fedora"})
- defer restore()
-
- tmpdir = c.MkDir()
- dirs.SetRootDir(tmpdir)
- c.Assert(dirs.SystemFontconfigCacheDirs, DeepEquals, []string{filepath.Join(tmpdir, "/var/cache/fontconfig"), filepath.Join(tmpdir, "/usr/lib/fontconfig/cache")})
- c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/share/fonts"), 0777), IsNil)
- c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/local/share/fonts"), 0777), IsNil)
- c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/lib/fontconfig/cache"), 0777), IsNil)
- c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/var/cache/fontconfig"), 0777), IsNil)
- spec = &mount.Specification{}
- c.Assert(spec.AddConnectedPlug(s.iface, s.plug, s.coreSlot), IsNil)
- entries = spec.MountEntries()
- c.Assert(entries, HasLen, 4)
-
- c.Check(entries[2].Name, Equals, hostfs+dirs.SystemFontconfigCacheDirs[0])
- c.Check(entries[2].Dir, Equals, "/var/cache/fontconfig")
- c.Check(entries[2].Options, DeepEquals, []string{"bind", "ro"})
-
- c.Check(entries[3].Name, Equals, hostfs+dirs.SystemFontconfigCacheDirs[1])
- c.Check(entries[3].Dir, Equals, "/usr/lib/fontconfig/cache")
- c.Check(entries[3].Options, DeepEquals, []string{"bind", "ro"})
+ for _, distroWithQuirks := range []string{"fedora", "arch"} {
+ restore = release.MockReleaseInfo(&release.OS{ID: distroWithQuirks})
+ defer restore()
+
+ tmpdir = c.MkDir()
+ dirs.SetRootDir(tmpdir)
+ if distroWithQuirks == "fedora" {
+ // Fedora is a little special with their fontconfig cache location(s) and how we handle them
+ c.Assert(dirs.SystemFontconfigCacheDirs, DeepEquals, []string{filepath.Join(tmpdir, "/var/cache/fontconfig"), filepath.Join(tmpdir, "/usr/lib/fontconfig/cache")})
+ } else {
+ c.Assert(dirs.SystemFontconfigCacheDirs, DeepEquals, []string{filepath.Join(tmpdir, "/var/cache/fontconfig")})
+ }
+ c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/share/fonts"), 0777), IsNil)
+ c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/local/share/fonts"), 0777), IsNil)
+ c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/usr/lib/fontconfig/cache"), 0777), IsNil)
+ c.Assert(os.MkdirAll(filepath.Join(tmpdir, "/var/cache/fontconfig"), 0777), IsNil)
+ spec = &mount.Specification{}
+ c.Assert(spec.AddConnectedPlug(s.iface, s.plug, s.coreSlot), IsNil)
+ entries = spec.MountEntries()
+ c.Assert(entries, HasLen, 2)
+
+ for _, en := range entries {
+ if en.Dir == "/var/cache/fontconfig" || en.Dir == "/usr/lib/fontconfig/cache" {
+ c.Fatalf("unpexected cache mount entry: %q", en.Dir)
+ }
+ }
+ }
}
func (s *DesktopInterfaceSuite) TestStaticInfo(c *C) {
--
2.26.2
From b1183c5ed448e61f7da7ec518682a00ca4cb9161 Mon Sep 17 00:00:00 2001
Message-Id: <b1183c5ed448e61f7da7ec518682a00ca4cb9161.1589805773.git.maciej.zenon.borzecki@canonical.com>
In-Reply-To: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
References: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
From: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
Date: Wed, 6 May 2020 15:39:48 +0200
Subject: [PATCH 2/3] interfaces/builtin/desktop: mention the fonts bug report
in comments
Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
---
interfaces/builtin/desktop.go | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/interfaces/builtin/desktop.go b/interfaces/builtin/desktop.go
index 8e18a4fc4409e957b51f0763dc791c8e54eec09e..950c02c2463879bd997ddd5ff95f35051912b26a 100644
--- a/interfaces/builtin/desktop.go
+++ b/interfaces/builtin/desktop.go
@@ -296,7 +296,8 @@ func (iface *desktopInterface) MountConnectedPlug(spec *mount.Specification, plu
// cache format level is same for both, the host
// generated cache files cause instability, segfaults or
// incorrect rendering of fonts, for this reason do not
- // mount the cache directories on those distributions
+ // mount the cache directories on those distributions,
+ // see https://bugs.launchpad.net/snapd/+bug/1877109
if strutil.ListContains(dirs.SystemFontconfigCacheDirs, dir) {
continue
}
--
2.26.2
From c73b5879d78f10b16f7b3168948299dacd6da40c Mon Sep 17 00:00:00 2001
Message-Id: <c73b5879d78f10b16f7b3168948299dacd6da40c.1589805773.git.maciej.zenon.borzecki@canonical.com>
In-Reply-To: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
References: <cover.1589805773.git.maciej.zenon.borzecki@canonical.com>
From: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
Date: Wed, 6 May 2020 15:40:58 +0200
Subject: [PATCH 3/3] tests/main/interfaces-desktop-host-fonts: update fonts
cache test
Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
---
tests/main/interfaces-desktop-host-fonts/task.yaml | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/tests/main/interfaces-desktop-host-fonts/task.yaml b/tests/main/interfaces-desktop-host-fonts/task.yaml
index c61dbf83b37331537a8d2c36cff2c844330540f0..02f2aa120b80c71c80ed20c4ceb772e8df63cb9a 100644
--- a/tests/main/interfaces-desktop-host-fonts/task.yaml
+++ b/tests/main/interfaces-desktop-host-fonts/task.yaml
@@ -49,7 +49,16 @@ execute: |
test-snapd-desktop.check-files /usr/local/share/fonts/local-font.txt | MATCH "Local font"
echo "Checking access to host $cache_dir"
- test-snapd-desktop.check-files "$cache_dir"/cache.txt | MATCH "Cache file"
+ case "$SPREAD_SYSTEM" in
+ fedora-*|centos-*|amazon-linux-*|arch-linux-*)
+ # system fonts cache is inaccessible due to
+ # https://bugs.launchpad.net/snapd/+bug/1877109
+ test-snapd-desktop.sh -c "test ! -e $cache_dir/cache.txt"
+ ;;
+ *)
+ test-snapd-desktop.check-files "$cache_dir"/cache.txt | MATCH "Cache file"
+ ;;
+ esac
echo "Checking access to host ~/.fonts"
test-snapd-desktop.check-files "$HOME"/.fonts/user-font1.txt | MATCH "User font 1"
--
2.26.2
|