From d3adf7d773b8a9c498c73c7defc337d9a62dcc52 Mon Sep 17 00:00:00 2001
From: Dylan Araps <dylan.araps@gmail.com>
Date: Mon, 12 Jul 2021 01:05:24 +0300
Subject: [PATCH] kiss: fix installation of files causing processes to die.

This modifies pkg_install_files() to do atomic mv on each of the
files. This prevents processes from crashing when the underlying
shared library changes (but the inode stays the same).

Closes #226
---
 kiss | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/kiss b/kiss
index 2a72a4b..3487834 100755
--- a/kiss
+++ b/kiss
@@ -1085,7 +1085,23 @@ pkg_install_files() {
                 # Skip directories as they're likely symlinks in this case.
                 # Pure directories in manifests have a suffix of '/'.
                 [ -d "$_file" ] || test "$1" "$_file" || {
-                    cp -fP "$2/${file#/}" "$_file"
+                    _file_tmp=$2/${file#/}
+
+                    # Copy the file to a temporary location so that later
+                    # verification (after pkg_remove_files()) is possible.
+                    #
+                    # This duplication only occurs during the first
+                    # invocation of pkg_install_files() - the second call
+                    # will simply do the 'mv' call.
+                    case $1 in -z)
+                        cp -fP "$2/${file#/}" "$2/__f-$pid"
+                        _file_tmp=$2/__f-$pid
+                    esac
+
+                    # Atomically move the temporary file to the root
+                    # filesystem. The running processes will either get
+                    # the old file or the new one.
+                    mv -f "$_file_tmp" "$_file"
 
                     # Skip changing permissions of symlinks. This prevents
                     # errors when the symlink exists prior to the target.