fix: Use update-alternatives instead of symlinks for #7500

.changeset/use-update-alternatives-93f81a.md

@@ -0,0 +1,23 @@
+---
+"app-builder-lib": patch
+---
+
+Use `update-alternatives` when available.
+
+## What is changing?
+Test for `update-alternatives` in DEB based installations and use this whenever possible.
+In this way, middleware and downstream projects and users can specify binaries of their
+own priority that would override this programs' configured executable.
+
+## Why is this changing?
+Personally, I don't want apps running as myself or a privileged user in my system.
+For this. I have a shell that is executed to drop permissions first, then execute the
+selected software.
+Electron apps don't conform to this since they link directly rather than using a linking
+system.
+
+This change is to ensure that system is used before resorting to direct links.
+
+## How should this be consumed?
+Simply update as normal and this package will switch to using update-alternatives.
+This will allow middleware and end-users to better control the active executable.

packages/app-builder-lib/templates/linux/after-install.tpl

@@ -1,7 +1,14 @@
 #!/bin/bash
 
-# Link to the binary
-ln -sf '/opt/${sanitizedProductName}/${executable}' '/usr/bin/${executable}'
+if type update-alternatives 2>/dev/null >&1; then
+    # Remove previous link if it doesn't use update-alternatives
+    if [ -L '/usr/bin/${executable}' -a -e '/usr/bin/${executable}' -a "`readlink '/usr/bin/${executable}'`" != '/etc/alternatives/${executable}' ]; then
+      rm -f '/usr/bin/${executable}'
+    fi
+    update-alternatives --install '/usr/bin/${executable}' '${executable}' '/opt/${sanitizedProductName}/${executable}' 100
+else
+    ln -sf '/opt/${sanitizedProductName}/${executable}' '/usr/bin/${executable}'
+fi
 
 # SUID chrome-sandbox for Electron 5+
 chmod 4755 '/opt/${sanitizedProductName}/chrome-sandbox' || true

packages/app-builder-lib/templates/linux/after-remove.tpl

@@ -1,4 +1,8 @@
 #!/bin/bash
 
 # Delete the link to the binary
-rm -f '/usr/bin/${executable}'
+if type update-alternatives >/dev/null 2>&1; then
+    update-alternatives --remove '${executable}' '/usr/bin/${executable}'
+else
+    rm -f '/usr/bin/${executable}'
+fi

test/snapshots/linux/debTest.js.snap

@@ -532,8 +532,15 @@ exports[`executable path in postinst script 4`] = `"Test Application (test quite
 exports[`executable path in postinst script 5`] = `
 "#!/bin/bash
 
-# Link to the binary
-ln -sf '/opt/foo/Boo' '/usr/bin/Boo'
+if type update-alternatives 2>/dev/null >&1; then
+    # Remove previous link if it doesn't use update-alternatives
+    if [ -L '/usr/bin/Boo' -a -e '/usr/bin/Boo' -a \\"\`readlink '/usr/bin/Boo'\`\\" != '/etc/alternatives/Boo' ]; then
+      rm -f '/usr/bin/Boo'
+    fi
+    update-alternatives --install '/usr/bin/Boo' 'Boo' '/opt/foo/Boo' 100
+else
+    ln -sf '/opt/foo/Boo' '/usr/bin/Boo'
+fi
 
 # SUID chrome-sandbox for Electron 5+
 chmod 4755 '/opt/foo/chrome-sandbox' || true