Download JCEF at docker build step (#132)

* Add `LD_PRELOAD` to startup script

Closes #131

* Script to download and extract a JCEF release

Closely mirrors what KCEF does, but written in glorious AWK

* Call kcef_download and link downloaded JCEF where Suwayomi expects it

The script downloads JCEF into /opt. Link this folder at runtime into
the data folder where Suwayomi expects it. This allows us to easily
bundle the predownloaded release without modifying Suwayomi startup.
Move `LD_PRELOAD` down a bit to avoid warnings about preloading
libcef.so before the symlink exists.

* Add KCEF url to workflow to embed JCEF into container

scripts/kcef_download.sh

@@ -0,0 +1,83 @@
+#!/bin/sh
+
+set -e
+
+url="$1"
+arch="$2"
+installdir="${3:-/opt/kcef/jcef}"
+
+echo "Will try to download matching KCEF to $installdir, arch=$arch, api url=$url"
+
+if [ -d "$installdir" ] && [ -f "$installdir/install.lock" ]; then
+  echo "JCEF already downloaded to $installdir, nothing to do"
+  exit 0
+fi
+
+if [ -z "$url" ]; then
+  echo "Not downloading KCEF since no URL specified"
+  exit 0
+fi
+
+arpath=/tmp/kcef/jcef.tar.gz
+expath=/tmp/kcef/jcef
+mkdir -p "$expath"
+
+if [ ! -f "$arpath" ]; then
+  body="`curl -# -H 'accept: application/vnd.github+json' "$url" | jq -r '.body'`"
+  archive="`echo "$body" | gawk -F'|' '
+    function compare_sdk(i1, v1, i2, v2) {
+      # sort sdks last (https://github.com/DatL4g/KCEF/blob/0665269b7d6a91b0ee187f4432bb5be5ca41a112/kcef/src/main/kotlin/dev/datlag/kcef/KCEFBuilder.kt#L743-L755)
+      if (v1 ~ /sdk/ && v2 ~ /sdk/) return 0;
+      if (v1 ~ /sdk/) return 1;
+      if (v2 ~ /sdk/) return -1;
+      return 0;
+    }
+    BEGIN {
+      # ensure urls is an array
+      delete urls[0];
+      # parse os/arch tuple
+      match("'"$arch"'", /(.*)\/(.*)/, a);
+      os=a[1];
+      arch=a[2];
+      if (arch == "amd64") arch="x64";
+      if (arch == "arm64") arch="aarch64";
+    }
+    # for each line, check that the third table column contains a url and if so, extract it
+    # also need to check that it contains JCEF and matches the os/arch tuple
+    match($4, /(https?:\/\/|www.)[-a-zA-Z0-9+&@#\/%?=~_|!:.;]*[-a-zA-Z0-9+&@#/%=~_|]/, m) {
+      # if so, push to the urls array; there is no push function, so do this cursed construction
+      # arrays by convention start at 1, so do that
+      if (m[0] ~ /jcef/ && m[0] ~ os && m[0] ~ arch && m[0] ~ /\.tar\.gz$/) urls[length(urls)+1] = m[0];
+    }
+    END {
+      # now make sure sdk is sorted last, since we dont actually need the full sdk
+      asort(urls, sorted, "compare_sdk");
+      for (x in sorted) print sorted[x];
+    }
+  ' | head -n1`"
+
+  if [ -z "$archive" ]; then
+    echo "No suitable archive found on release page, so not downloading"
+    exit 0
+  fi
+
+  echo "Found suitable JCEF release: $archive"
+  curl -# -L -H 'accept: application/x-tar' -o "$arpath" "$archive"
+fi
+
+set -xe
+tar -C "$expath" -xf "$arpath"
+libfolder="`find "$expath" -type d -name lib`"
+
+if [ -z "$libfolder" ]; then
+  echo "lib folder not found in extracted archive, aborting"
+  rm -rf /tmp/kcef
+  exit 0
+fi
+
+mkdir -p "$installdir"
+rmdir "$installdir" # we abuse -p to make sure all parent directories are created, then delete the actual target, since mv would move the libfolder inside otherwise
+mv "$libfolder" "$installdir"
+chmod -R a+x "$installdir"
+touch "$installdir/install.lock"
+rm -rf /tmp/kcef

scripts/startup_script.sh

@@ -92,6 +92,14 @@ sed -i -r "s/server.opdsChapterSortOrder = \"(.*?)\"( #)?/server.opdsChapterSort
 if command -v Xvfb >/dev/null; then
   Xvfb :0 -screen 0 800x680x24 -nolisten tcp >/dev/null 2>&1 &
   export DISPLAY=:0
+
+  if [ ! -d /home/suwayomi/.local/share/Tachidesk/bin ]; then
+    mkdir -p /home/suwayomi/.local/share/Tachidesk/bin
+  fi
+  if [ ! -d /home/suwayomi/.local/share/Tachidesk/bin/kcef ] && [ ! -L /home/suwayomi/.local/share/Tachidesk/bin/kcef ]; then
+    ln -s /opt/kcef/jcef /home/suwayomi/.local/share/Tachidesk/bin/kcef
+  fi
+  export LD_PRELOAD=/home/suwayomi/.local/share/Tachidesk/bin/kcef/libcef.so
 else
   echo "Suwayomi built without KCEF support, not starting Xvfb"
 fi