tvl-depot/scripts/nix-build.in
Eelco Dolstra dcc37c236c * nix-store, nix-instantiate: added an option `--add-root' to
immediately add the result as a permanent GC root.  This is the only
  way to prevent a race with the garbage collector.  For instance, the
  old style

    ln -s $(nix-store -r $(nix-instantiate foo.nix)) \
      /nix/var/nix/gcroots/result

  has two time windows in which the garbage collector can interfere
  (by GC'ing the derivation and the output, respectively).  On the
  other hand,

    nix-store --add-root /nix/var/nix/gcroots/result -r \
      $(nix-instantiate --add-root /nix/var/nix/gcroots/drv \
        foo.nix)

  is safe.

* nix-build: use `--add-root' to prevent GC races.
2005-02-01 12:36:25 +00:00

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#! @shell@ -e
nixExpr=$1
if test -z "$nixExpr"; then
echo "syntax: $0 NIX-EXPR..." >&2
exit 1
fi
extraArgs=
noLink=
userName=$USER
if test -z "$username"; then userName="unknown"; fi
for i in "$@"; do
case "$i" in
--no-link)
noLink=1
;;
-*)
extraArgs="$extraArgs $i"
;;
*)
storeExprs=$(@bindir@/nix-instantiate \
--add-root "@localstatedir@/nix/gcroots/nix-build/$userName-drv" \
"$i")
for j in $storeExprs; do
echo "store expression is $j" >&2
done
outPaths=$(@bindir@/nix-store \
--add-root "@localstatedir@/nix/gcroots/nix-build/$userName-out" \
-rv $extraArgs $storeExprs)
for j in $outPaths; do
echo "$j"
if test -z "$noLink"; then
if test -L result; then
rm result
elif test -e result; then
echo "cannot remove \`result' (not a symlink)"
exit 1
fi
ln -s "$j" result
fi
done
;;
esac
done