feat: improve error messaging for shell config permission issues (#3788)

install.sh

@@ -56,6 +56,24 @@ nvm_profile_is_bash_or_zsh() {
 # * The method used ("script" or "git" in the script, defaults to "git")
 # NVM_SOURCE always takes precedence unless the method is "script-nvm-exec"
 #
+nvm_check_file_writable(){
+  if [ -f "$1" ]; then 
+    if ! [ -w "$1" ]; then
+      local OWNER_NAME
+      OWNER_NAME=$(command id -un "$(command stat -c '%u' "$1"  2>/dev/null|| command stat -f '%u' "$1" 2>/dev/null)")
+      nvm_echo >&2 "=> Error: $1 is not writable!"
+      nvm_echo >&2 "=> This file is currently owned by $OWNER_NAME."
+      nvm_echo >&2 "=> Please ensure you have write access to this file."
+      nvm_echo >&2 "=> If this is a personal machine, you might run: sudo chown $(id -un) \"$1\""
+      nvm_echo >&2 "=> On managed systems, please contact your administrator."
+      return 1
+    elif [ -w "$1" ]; then
+      return 0
+    fi
+  else
+    return 2
+  fi  
+}
 nvm_source() {
   local NVM_GITHUB_REPO
   NVM_GITHUB_REPO="${NVM_INSTALL_GITHUB_REPO:-nvm-sh/nvm}"
@@ -456,13 +474,19 @@ nvm_do_install() {
       BASH_OR_ZSH=true
     fi
     if ! command grep -qc '/nvm.sh' "$NVM_PROFILE"; then
+      if ! nvm_check_file_writable "${NVM_PROFILE}"; then
+        exit 1
+      fi
       nvm_echo "=> Appending nvm source string to $NVM_PROFILE"
       command printf '%b' "${SOURCE_STR}" >> "$NVM_PROFILE"
     else
       nvm_echo "=> nvm source string already in ${NVM_PROFILE}"
     fi
     # shellcheck disable=SC2016
     if ${BASH_OR_ZSH} && ! command grep -qc '$NVM_DIR/bash_completion' "$NVM_PROFILE"; then
+      if ! nvm_check_file_writable "${NVM_PROFILE}"; then
+        exit 1
+      fi
       nvm_echo "=> Appending bash_completion source string to $NVM_PROFILE"
       command printf '%b' "$COMPLETION_STR" >> "$NVM_PROFILE"
     else

test/install_script/nvm_check_file_writable

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+setup () {
+  HOME="."
+  if [ -z "$BASH_VERSION" ]; then
+    export BASH_VERSION=$(command -v bash >/dev/null && bash -c 'echo $BASH_VERSION' || echo "5.0.0")
+  fi
+  NVM_ENV=testing \. ../../install.sh
+  touch "writable_test_file"
+  touch "readonly_test_file"
+  chmod -w "readonly_test_file"   
+}
+
+cleanup () {
+  unset HOME
+  unset NVM_ENV
+  unset -f setup cleanup die  
+  rm -f "writable_test_file" "readonly_test_file" > "/dev/null" 2>&1
+}
+
+die () { echo "$@"; cleanup; exit 1; }
+
+setup
+nvm_check_file_writable "file_not_exists"
+if [ $? -ne 2 ] ; then 
+  die "nvm_check_file_writable did not reject nonexisting file with code 2"
+fi
+
+nvm_check_file_writable "readonly_test_file"
+if [ $? -ne 1 ]; then
+  die "nvm_check_file_writable did not reject nonwritable file with code 1"
+fi 
+
+nvm_check_file_writable "writable_test_file"
+if [ $? -ne  0 ]; then 
+  die "nvm_check_file_writable failed on writable file for unknown reason"
+fi 
+
+cleanup