From 15eba7b7e6f7e684812eb7a569b7e0fa9478f7c6 Mon Sep 17 00:00:00 2001
From: Oliver Henshaw <oliver.henshaw@gmail.com>
Date: Wed, 21 Jun 2023 15:47:52 +0100
Subject: [PATCH] [Fix] `nvm_strip_path`: Preserve leading/trailing colons

Path lists in environmental variables often give special meaning to
empty entries (e.g. in PATH or MANPATH). These are represented by
leading or trailing colons, or by doubled colons in the middle of the
list.

Adjust the awk invocation to correctly deal with trailing colons by
printing the separator before every field except the first, and then
printing the final separator that is read from the input - this will
either be a colon or the null string. This preserves leading and
trailing colons in all cases while not adding extra colons in the wrong
place.

Add test to confirm the correct behaviour.

Fixes #3144
---
 nvm.sh                              | 3 ++-
 test/fast/Unit tests/nvm_strip_path | 6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/nvm.sh b/nvm.sh
index c789b02..c37df6b 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -823,7 +823,8 @@ nvm_strip_path() {
     path = substr($0, length(NVM_DIR) + 1)
     if (path ~ "^(/versions/[^/]*)?/[^/]*'"${2-}"'.*$") { next }
   }
-  { print }' | command paste -s -d: -
+  # The final RT will contain a colon if the input has a trailing colon, or a null string otherwise
+  { printf "%s%s", sep, $0; sep=RS } END { printf "%s", RT }'
 }
 
 nvm_change_path() {
diff --git a/test/fast/Unit tests/nvm_strip_path b/test/fast/Unit tests/nvm_strip_path
index adce734..6f00da0 100755
--- a/test/fast/Unit tests/nvm_strip_path	
+++ b/test/fast/Unit tests/nvm_strip_path	
@@ -16,3 +16,9 @@ TEST_PATH="$NVM_DIR/v0.10.5/bin:/usr/bin:$NVM_DIR/v0.11.5/bin:$NVM_DIR/v0.9.5/bi
 STRIPPED_PATH=`nvm_strip_path "$TEST_PATH" "/bin"`
 
 [ "$STRIPPED_PATH" = "/usr/bin:/usr/local/bin" ] || die "Not correctly stripped: $STRIPPED_PATH "
+
+TEST_PATH=":/a/b/bin::/c/d/bin:"
+
+STRIPPED_PATH=`nvm_strip_path "$TEST_PATH" "/bin"`
+
+[ "$STRIPPED_PATH" = "$TEST_PATH" ] || die "Stripping does not preserve colons: $STRIPPED_PATH "