nixpkgs-suyu/pkgs/build-support/fetchsvn/nix-prefetch-svn
Eelco Dolstra 5c847a370a * fetchsvn' now requires the MD5 hash (as computed by nix-hash') of
the tree being fetched from a Subversion repository.  The revision
  number is now optional (and defaults to HEAD).

  This makes `fetchsvn' more pure.  First, a URL/revision tuple does
  not uniquely identify a file resource, since the repository itself
  might change.  Second, `svn:external' attributes can cause arbitrary
  resources to be exported.

  A script `nix-prefetch-svn' has been provided to determine the hash
  of a URL.

svn path=/nixpkgs/trunk/; revision=938
2004-04-14 10:55:33 +00:00

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#! /bin/sh -e
url=$1
rev=$2
if test -z "$url"; then
echo "syntax: nix-prefetch-svn URL [REVISION]" >&2
exit 1
fi
test -n "$rev" || rev="HEAD"
# !!! hacky; we should have a way to query the location of the store.
if storeDir=$(which nix-store); then
storeDir=$(dirname $(dirname "$storeDir"))/store
else
storeDir=/nix/store
fi
# !!! race? should be relatively safe, `svn export' barfs if $tmpPath exists.
tmpPath1=$storeDir/svn-checkout-tmp-$$
# Perform the checkout.
svn export -r "$rev" "$url" $tmpPath1 >&2
# Compute the hash.
hash=$(nix-hash $tmpPath1)
echo "hash is $hash" >&2
# Rename it so that the fetchsvn builder can find it.
tmpPath2=$storeDir/svn-checkout-tmp-$hash
test -e $tmpPath2 || mv $tmpPath1 $tmpPath2 # !!! race
# Create a Nix expression that does a fetchsvn.
nixExpr=$(dirname $(readlink -f $0))/../../system/i686-linux.nix
storeExpr=$( \
echo "(import $nixExpr).fetchsvn {url=\"$url\"; rev=\"$rev\"; md5=\"$hash\";}" \
| nix-instantiate -)
# Realise it.
finalPath=$(nix-store -qnB --force-realise $storeExpr)
echo "path is $finalPath" >&2
rm -rf $tmpPath2 || true
echo $hash