Replace UUID file mechanism with per-directory 'map' attribute [v2]

The UUID files would be placed in each font directory to provide the
unique cache name, independent of path, for that directory. The UUID
files are undesireable for a couple of reasons:

 1) They must be placed in the font directories to be useful. This
    requires modifying the font directories themselves, introducing
    potential visible timestamp changes when running multiple
    applications, and makes the cache processing inconsistent between
    applications with permission to write to the font directories and
    applications without such permission.

 2) The UUID contents were generated randomly, which makes the font
    cache not reproducible across multiple runs.

One proposed fix for 2) is to make the UUID dependent on the font
directory path, but once we do that, we can simply use the font
directory path itself as the key as the original MD5-based font cache
naming mechanism did.

The goal of the UUID file mechanism was to fix startup time of
flatpaks; as the font path names inside the flatpak did not match the
font path names in the base system, the font cache would need to be
reconstructed the first time the flatpak was launched.

The new mechanism for doing this is to allow each '<dir>' element in
the configuration include a 'map' attribute. When looking for a cache
file for a particular directory, if the directory name starts with the
contents of the <dir> element, that portion of the name will be
replaced with the value of the 'map' attribute.

Outside of the flatpak, nothing need change -- fontconfig will build
cache files using real directory names.

Inside the flatpak, the custom fonts.conf file will now include
mappings such as this:

	<dir map="/usr/share/fonts">/run/host/fonts</dir>

When scanning the directory /run/host/fonts/ttf, fontconfig will
use the name /usr/share/fonts/ttf as the source for building the cache
file name.

The existing FC_FILE replacement code used for the UUID-based
implementation continues to correctly adapt font path names seen by
applications.

v2:
	Leave FcDirCacheCreateUUID stub around to avoid removing
	public API function.

	Document 'map' attribute of <dir> element in
	fontconfig-user.sgml

	Suggested-by: Akira TAGOH <akira@tagoh.org>

Signed-off-by: Keith Packard <keithp@keithp.com>

4 files changed, 111 insertions, 2 deletions

diff --git a/test/Makefile.am b/test/Makefile.am
index ff693e4..81aace0 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,4 +1,4 @@
-check_SCRIPTS=run-test.sh
+check_SCRIPTS=run-test.sh run-test-map.sh
 TEST_EXTENSIONS = \
 	.sh \
 	$(NULL)
diff --git a/test/fonts.conf.in b/test/fonts.conf.in
index 95def72..24bd58b 100644
--- a/test/fonts.conf.in
+++ b/test/fonts.conf.in
@@ -1,4 +1,4 @@
 <fontconfig>
-<dir>@FONTDIR@</dir>
+<dir @MAP@>@FONTDIR@</dir>
 <cachedir>@CACHEDIR@</cachedir>
 </fontconfig>
diff --git a/test/run-test-map.sh b/test/run-test-map.sh
new file mode 100755
index 0000000..869d7b2
--- /dev/null
+++ b/test/run-test-map.sh
@@ -0,0 +1,107 @@
+#!/bin/bash
+# fontconfig/test/run-test-cache-map.sh
+#
+# Copyright © 2018 Keith Packard
+#
+# Permission to use, copy, modify, distribute, and sell this software and its
+# documentation for any purpose is hereby granted without fee, provided that
+# the above copyright notice appear in all copies and that both that copyright
+# notice and this permission notice appear in supporting documentation, and
+# that the name of the copyright holders not be used in advertising or
+# publicity pertaining to distribution of the software without specific,
+# written prior permission.  The copyright holders make no representations
+# about the suitability of this software for any purpose.  It is provided "as
+# is" without express or implied warranty.
+#
+# THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+# EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+# DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+# TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+case "$OSTYPE" in
+    msys ) MyPWD=`pwd -W` ;;  # On Msys/MinGW, returns a MS Windows style path.
+    *    ) MyPWD=`pwd`    ;;  # On any other platforms, returns a Unix style path.
+esac
+
+TESTDIR=${srcdir-"$MyPWD"}
+BUILDTESTDIR=${builddir-"$MyPWD"}
+
+FONTDIRA="$MyPWD"/fontsa
+FONTDIRB="$MyPWD"/fontsb
+CACHEDIR="$MyPWD"/cache.dir
+EXPECTEDIN=${EXPECTEDIN-"out-map.expected.in"}
+EXPECTEDA="out-map-a.expected"
+EXPECTEDB="out-map-b.expected"
+EXPECTED="out-map.expected"
+
+FCLIST=../fc-list/fc-list$EXEEXT
+FCCACHE=../fc-cache/fc-cache$EXEEXT
+
+which bwrap > /dev/null 2>&1
+if [ $? -eq 0 ]; then
+    BWRAP=`which bwrap`
+fi
+
+FONT1=$TESTDIR/4x6.pcf
+FONT2=$TESTDIR/8x16.pcf
+
+check () {
+  $FCLIST - file family pixelsize | sort > out
+  echo "=" >> out
+  $FCLIST - file family pixelsize | sort >> out
+  echo "=" >> out
+  $FCLIST - file family pixelsize | sort >> out
+  tr -d '\015' <out >out.tmp; mv out.tmp out
+  if cmp out $BUILDTESTDIR/$EXPECTED > /dev/null ; then : ; else
+    echo "*** Test failed: $TEST"
+    echo "*** output is in 'out', expected output in '$EXPECTED'"
+    exit 1
+  fi
+  rm -f out
+}
+
+prep() {
+  rm -rf $CACHEDIR
+  rm -rf $FONTDIRA $FONTDIRB
+  mkdir $FONTDIRA
+  mkdir $CACHEDIR
+}
+
+dotest () {
+  TEST=$1
+  test x$VERBOSE = x || echo Running: $TEST
+}
+
+sed "s!@FONTDIR@!$FONTDIRA!
+s!@MAP@!!
+s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts-a.conf
+
+sed "s!@FONTDIR@!$FONTDIRB!
+s!@MAP@!map="'"'"$FONTDIRA"'"'"!
+s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts-b.conf
+
+sed "s!@FONTDIR@!$FONTDIRA!" < $EXPECTEDIN > $EXPECTEDA
+sed "s!@FONTDIR@!$FONTDIRB!" < $EXPECTEDIN > $EXPECTEDB
+
+FONTCONFIG_FILE="$MyPWD"/fonts-a.conf
+export FONTCONFIG_FILE
+
+dotest "Basic check"
+prep
+cp $FONT1 $FONT2 $FONTDIRA
+cp $EXPECTEDA $EXPECTED
+$FCCACHE $FONTDIRA
+check
+
+dotest "mapped check"
+prep
+cp $FONT1 $FONT2 $FONTDIRA
+cp $EXPECTEDB $EXPECTED
+$FCCACHE $FONTDIRA
+mv $FONTDIRA $FONTDIRB
+export FONTCONFIG_FILE="$MyPWD"/fonts-b.conf
+check
diff --git a/test/run-test.sh b/test/run-test.sh
index a05dadb..b9a07b8 100644
--- a/test/run-test.sh
+++ b/test/run-test.sh
@@ -73,6 +73,7 @@ dotest () {
 }
 
 sed "s!@FONTDIR@!$FONTDIR!
+s!@MAP@!!
 s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts.conf
 
 FONTCONFIG_FILE="$MyPWD"/fonts.conf
@@ -145,6 +146,7 @@ sleep 1
 ls -l $CACHEDIR > out1
 TESTTMPDIR=`mktemp -d /tmp/fontconfig.XXXXXXXX`
 sed "s!@FONTDIR@!$TESTTMPDIR/fonts!
+s!@MAP@!map="'"'"$FONTDIR"'"'"!
 s!@CACHEDIR@!$TESTTMPDIR/cache.dir!" < $TESTDIR/fonts.conf.in > bind-fonts.conf
 $BWRAP --bind / / --bind $CACHEDIR $TESTTMPDIR/cache.dir --bind $FONTDIR $TESTTMPDIR/fonts --bind .. $TESTTMPDIR/build --dev-bind /dev /dev --setenv FONTCONFIG_FILE $TESTTMPDIR/build/test/bind-fonts.conf $TESTTMPDIR/build/fc-match/fc-match$EXEEXT -f "%{file}\n" ":foundry=Misc" > xxx
 $BWRAP --bind / / --bind $CACHEDIR $TESTTMPDIR/cache.dir --bind $FONTDIR $TESTTMPDIR/fonts --bind .. $TESTTMPDIR/build --dev-bind /dev /dev --setenv FONTCONFIG_FILE $TESTTMPDIR/build/test/bind-fonts.conf $TESTTMPDIR/build/test/test-bz106618$EXEEXT | sort > flist1