gitAndTools.transcrypt: query dependencies in helper scripts

adds a tool to get the paths of the dependencies needed by the helper scripts
(which are written only once and are never updated) to the output and patches
them to use it expand their path

pkgs/applications/version-management/git-and-tools/transcrypt/default.nix

@@ -13,6 +13,8 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ makeWrapper git openssl coreutils utillinux gnugrep gnused gawk ];
 
+  patches = [ ./helper-scripts_depspathprefix.patch ];
+
   installPhase = ''
     install -m 755 -D transcrypt $out/bin/transcrypt
     install -m 644 -D man/transcrypt.1 $out/share/man/man1/transcrypt.1
@@ -21,6 +23,12 @@ stdenv.mkDerivation rec {
 
     wrapProgram $out/bin/transcrypt \
       --prefix PATH : "${stdenv.lib.makeBinPath [ git openssl coreutils utillinux gnugrep gnused gawk ]}"
+
+    cat > $out/bin/transcrypt-depspathprefix << EOF
+    #!${stdenv.shell}
+    echo "${stdenv.lib.makeBinPath [ git openssl coreutils gawk ]}:"
+    EOF
+    chmod +x $out/bin/transcrypt-depspathprefix
   '';
 
   meta = with stdenv.lib; {

pkgs/applications/version-management/git-and-tools/transcrypt/helper-scripts_depspathprefix.patch

@@ -0,0 +1,37 @@
+diff --git a/transcrypt b/transcrypt
+index a0b562d..7888f5d 100755
+--- a/transcrypt
++++ b/transcrypt
+@@ -278,6 +278,7 @@ save_helper_scripts() {
+ 
+ 	cat <<-'EOF' > "${GIT_DIR}/crypt/clean"
+ 		#!/usr/bin/env bash
++		PATH="$(transcrypt-depspathprefix 2>/dev/null)$PATH"
+ 		filename=$1
+ 		# ignore empty files
+ 		if [[ -s $filename ]]; then
+@@ -300,6 +301,7 @@ save_helper_scripts() {
+ 
+ 	cat <<-'EOF' > "${GIT_DIR}/crypt/smudge"
+ 		#!/usr/bin/env bash
++		PATH="$(transcrypt-depspathprefix 2>/dev/null)$PATH"
+ 		tempfile=$(mktemp 2> /dev/null || mktemp -t tmp)
+ 		trap 'rm -f "$tempfile"' EXIT
+ 		cipher=$(git config --get --local transcrypt.cipher)
+@@ -309,6 +311,7 @@ save_helper_scripts() {
+ 
+ 	cat <<-'EOF' > "${GIT_DIR}/crypt/textconv"
+ 		#!/usr/bin/env bash
++		PATH="$(transcrypt-depspathprefix 2>/dev/null)$PATH"
+ 		filename=$1
+ 		# ignore empty files
+ 		if [[ -s $filename ]]; then
+@@ -351,7 +354,7 @@ save_configuration() {
+ 	git config merge.renormalize 'true'
+ 
+ 	# add a git alias for listing encrypted files
+-	git config alias.ls-crypt "!git ls-files | git check-attr --stdin filter | awk 'BEGIN { FS = \":\" }; /crypt$/{ print \$1 }'"
++	git config alias.ls-crypt "!PATH=\"\$(transcrypt-depspathprefix 2>/dev/null)\$PATH\"; git ls-files | git check-attr --stdin filter | awk 'BEGIN { FS = \":\" }; /crypt$/{ print \$1 }'"
+ }
+ 
+ # display the current configuration settings