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nixpkgs/pkgs/build-support/fetchcvs/nix-prefetch-cvs
Erik Arvstedt 3f54dfa475
treewide: fix bash exit handlers
Transform exit handlers of the form
trap cleanup EXIT [INT] [TERM] [QUIT] [HUP] [ERR]
  (where cleanup is idempotent)
to
trap cleanup EXIT

This fixes a common bash antipattern.

Each of the above signals causes the script to exit. For each signal,
bash first handles the signal by running `cleanup` and then runs
`cleanup` again when handling EXIT.
(Exception:  `vscode/*` prevents the second run of `cleanup` by removing
the trap in cleanup`).

Simplify the cleanup logic by just trapping exit, which is always run
when the script exits due to any of the above signals.

Note: In case of borgbackup, the exit handler is not idempotent, but just
trapping EXIT guarantees that it's only run once.
2022-07-02 16:13:12 +02:00

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#! /bin/sh -e
cvsRoot=$1
module=$2
tag=$3
expHash=$4
hashType=$NIX_HASH_ALGO
if test -z "$hashType"; then
hashType=sha256
fi
if test -z "$cvsRoot"; then
echo "syntax: nix-prefetch-cvs CVSROOT MODULE [TAG [HASH]]" >&2
exit 1
elif test -z "$module"; then
echo "syntax: nix-prefetch-cvs CVSROOT MODULE [TAG [HASH]]" >&2
exit 1
fi
mkTempDir() {
tmpPath="$(mktemp -d "${TMPDIR:-/tmp}/nix-prefetch-cvs-XXXXXXXX")"
trap removeTempDir EXIT
}
removeTempDir() {
rm -rf "$tmpPath"
}
# If the hash was given, a file with that hash may already be in the
# store.
if test -n "$expHash"; then
finalPath=$(nix-store --print-fixed-path --recursive "$hashType" "$expHash" cvs-export)
if ! nix-store --check-validity "$finalPath" 2> /dev/null; then
finalPath=
fi
hash=$expHash
fi
# If we don't know the hash or a path with that hash doesn't exist,
# download the file and add it to the store.
if test -z "$finalPath"; then
mkTempDir
tmpFile=$tmpPath/cvs-export
#mkdir $tmpPath
# Perform the checkout.
if test -z "$tag"; then
args=(-D "now")
elif test "$USE_DATE" = "1"; then
args=(-D "$tag")
else
args=(-r "$tag")
fi
(cd "$tmpPath" && cvs -f -z0 -d $cvsRoot export "${args[*]}" -d cvs-export $module >&2)
# Compute the hash.
hash=$(nix-hash --type $hashType $hashFormat $tmpFile)
if ! test -n "$QUIET"; then echo "hash is $hash" >&2; fi
# Add the downloaded file to the Nix store.
finalPath=$(nix-store --add-fixed --recursive "$hashType" $tmpFile)
if test -n "$expHash" -a "$expHash" != "$hash"; then
echo "hash mismatch for CVS root \`$cvsRoot'"
exit 1
fi
fi
if ! test -n "$QUIET"; then echo "path is $finalPath" >&2; fi
echo $hash
if test -n "$PRINT_PATH"; then
echo $finalPath
fi