Add stdenv_prefix

[perso/Immae/Config/Nixies.git] / stdenv_prefix / prehook.sh

diff --git a/stdenv_prefix/prehook.sh b/stdenv_prefix/prehook.sh
new file mode 100644 (file)
index 0000000..db9a4d2
--- /dev/null
+++ b/stdenv_prefix/prehook.sh
@@ -0,0 +1,98 @@
+count_chunks() {
+  elements="${1//[^\/]}"
+  echo $(( "${#elements}" ))
+}
+
+oldout=$out
+prefix_chunks=$(count_chunks $NIX_STORE)
+
+: ${storepath_length=${#NIX_STORE}}
+: ${storepath_chunks=$prefix_chunks}
+
+if [ "$storepath_chunks" -lt $prefix_chunks ]; then
+  echo "Need to have at least as much path elements as the initial prefix"
+  exit 1
+fi
+
+min_length=$(( ${#NIX_STORE} + 2 * $storepath_chunks - 2 * $prefix_chunks ))
+if [ "$storepath_length" -lt "$min_length" ]; then
+  echo "The storepath length needs to be at least the length of the prefix"
+  exit 1
+fi
+
+if [ "$storepath_chunks" -eq "$prefix_chunks" -a "$storepath_length" -gt "$min_length" ]; then
+  echo "You need at least one more chunk for a non-standard path length"
+  exit 1
+fi
+
+appendOut() {
+  chunk_prefix=$(for (( c=$prefix_chunks ; c < $storepath_chunks ; c++ )); do echo -n "/x"; done)
+  length_prefix=$(for (( c=$(( ${#NIX_STORE} + ${#chunk_prefix} )) ; c < $storepath_length ; c++ )); do echo -n "x"; done)
+  out="$out$chunk_prefix$length_prefix"
+  if [ -n $chunk_prefix -o -n $length_prefix ]; then
+    mkdir -p $(dirname $out)
+  fi
+
+  : ${libc_path=}
+  : ${configureFlags=}
+  configureFlags="${configureFlags//$oldout/$out}"
+  if [ -n "$libc_path" ]; then
+    libc_oldpath=$libc_path/lib
+    libc_newpath=$(cat $libc_path/nix-support/new-out)/lib
+    configureFlags="${configureFlags//$libc_oldpath/$libc_newpath}"
+  fi
+}
+
+addNixSupport() {
+  if [ ! -d $out ]; then
+    return
+  fi
+  mkdir -p $out/nix-support
+  echo $out > $out/nix-support/new-out
+}
+
+overridePlaceholder() {
+function _callImplicitHook {
+  local def="$1"
+  local hookName="$2"
+  if declare -F "$hookName" > /dev/null; then
+      "$hookName"
+  elif type -p "$hookName" > /dev/null; then
+      source "$hookName"
+  elif [ -n "${!hookName:-}" ]; then
+      content="${!hookName}"
+      eval "${content//$oldout/$out}"
+  else
+      return "$def"
+  fi
+}
+}
+
+preHooks+=(appendOut overridePlaceholder)
+
+restoreSingleFile() {
+  if [ "$out" != "$oldout" -a -f $out ]; then
+    cp -a $out ./file
+    rm -rf $oldout
+    cp -a ./file $oldout
+  fi
+}
+
+addSymlinks() {
+  if [ "$out" != "$oldout" -a -d $out ]; then
+    ln -s $out/* $oldout/
+  fi
+}
+
+rename_generic_build() {
+eval "$(echo "orig_genericBuild()"; declare -f genericBuild | tail -n +2)"
+function genericBuild {
+  orig_genericBuild "$@"
+  restoreSingleFile
+  addSymlinks
+  addNixSupport
+}
+}
+
+exitHooks+=(restoreSingleFile addSymlinks addNixSupport)
+postHooks+=(rename_generic_build)