fix(linux): make installed printer forwarding reliable

downloads/install.sh

@@ -52,9 +52,15 @@ else
 fi
 
 if command -v apt-get >/dev/null 2>&1; then
+  say "Installing CUPS printer tools..."
+  $sudo_cmd apt-get update
+  $sudo_cmd apt-get install -y cups-client policykit-1 || $sudo_cmd apt-get install -y cups-client
   say "Installing FieldLens Print..."
   $sudo_cmd apt-get install -y "$package_path"
 elif command -v apt >/dev/null 2>&1; then
+  say "Installing CUPS printer tools..."
+  $sudo_cmd apt update
+  $sudo_cmd apt install -y cups-client policykit-1 || $sudo_cmd apt install -y cups-client
   say "Installing FieldLens Print..."
   $sudo_cmd apt install -y "$package_path"
 elif command -v dpkg >/dev/null 2>&1; then

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fieldlens/print",
-  "version": "0.1.2",
+  "version": "0.1.3",
   "private": true,
   "type": "module",
   "scripts": {

src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fieldlens-print"
-version = "0.1.2"
+version = "0.1.3"
 description = "FieldLens print-stream barcode capture companion"
 authors = ["Arrowstack"]
 edition = "2021"

src-tauri/src/capture.rs

@@ -11,6 +11,9 @@ use std::{
     time::Duration,
 };
 
+#[cfg(target_os = "linux")]
+use std::process::{Command, Stdio};
+
 use anyhow::{anyhow, Context, Result};
 use tauri::AppHandle;
 use uuid::Uuid;
@@ -170,14 +173,25 @@ fn handle_raw_connection(
         return;
     }
 
+    let tcp_requested = !config.forward_addr.trim().is_empty();
+    let (forwarded, final_error) = if forward_error.is_some() {
+        (false, forward_error)
+    } else if tcp_requested {
+        (true, None)
+    } else if !config.forward_printer.trim().is_empty() {
+        forward_to_system_printer(&config.forward_printer, &bytes)
+    } else {
+        (false, None)
+    };
+
     process_payload(
         state,
         app,
         "raw-proxy",
         label,
         bytes,
-        !config.forward_addr.trim().is_empty() && forward_error.is_none(),
-        forward_error,
+        forwarded,
+        final_error,
     );
 }
 
@@ -237,7 +251,7 @@ fn spool_folder_loop(
 
             match fs::read(&path) {
                 Ok(bytes) => {
-                    let (forwarded, error) = forward_all(&config.forward_addr, &bytes);
+                    let (forwarded, error) = forward_payload(&config, &bytes);
                     process_payload(
                         &state,
                         &app,
@@ -287,6 +301,16 @@ fn unique_processed_path(dir: &std::path::Path, filename: &str) -> PathBuf {
     ))
 }
 
+fn forward_payload(config: &AppConfig, bytes: &[u8]) -> (bool, Option<String>) {
+    if !config.forward_addr.trim().is_empty() {
+        return forward_all(&config.forward_addr, bytes);
+    }
+    if !config.forward_printer.trim().is_empty() {
+        return forward_to_system_printer(&config.forward_printer, bytes);
+    }
+    (false, None)
+}
+
 fn forward_all(address: &str, bytes: &[u8]) -> (bool, Option<String>) {
     if address.trim().is_empty() {
         return (false, None);
@@ -306,6 +330,57 @@ fn forward_all(address: &str, bytes: &[u8]) -> (bool, Option<String>) {
     }
 }
 
+#[cfg(target_os = "linux")]
+fn forward_to_system_printer(printer: &str, bytes: &[u8]) -> (bool, Option<String>) {
+    let mut child = match Command::new("lp")
+        .args(["-d", printer, "-o", "raw", "-t", "FieldLens Print"])
+        .stdin(Stdio::piped())
+        .stdout(Stdio::null())
+        .stderr(Stdio::piped())
+        .spawn()
+    {
+        Ok(child) => child,
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
+            return (
+                false,
+                Some("CUPS client tools are missing; install cups-client".into()),
+            )
+        }
+        Err(error) => {
+            return (false, Some(format!("forward to CUPS printer failed: {error}")))
+        }
+    };
+
+    if let Some(mut stdin) = child.stdin.take() {
+        if let Err(error) = stdin.write_all(bytes) {
+            let _ = child.kill();
+            return (false, Some(format!("forward to CUPS printer failed: {error}")));
+        }
+    }
+
+    match child.wait_with_output() {
+        Ok(output) if output.status.success() => (true, None),
+        Ok(output) => (
+            false,
+            Some(format!(
+                "CUPS forward failed: {}",
+                String::from_utf8_lossy(&output.stderr).trim()
+            )),
+        ),
+        Err(error) => (false, Some(format!("CUPS forward failed: {error}"))),
+    }
+}
+
+#[cfg(not(target_os = "linux"))]
+fn forward_to_system_printer(printer: &str, _bytes: &[u8]) -> (bool, Option<String>) {
+    (
+        false,
+        Some(format!(
+            "installed-printer RAW forwarding is not available for '{printer}' without a network RAW/TCP address"
+        )),
+    )
+}
+
 fn process_payload(
     state: &SharedState,
     app: &AppHandle,

src-tauri/src/printers.rs

@@ -1,10 +1,13 @@
-use std::{
-    fs,
-    process::Command,
-};
+use std::process::Command;
+
+#[cfg(target_os = "windows")]
+use std::fs;
+#[cfg(target_os = "linux")]
+use std::path::PathBuf;
 
 use anyhow::{anyhow, Context, Result};
 use serde::{Deserialize, Serialize};
+#[cfg(target_os = "windows")]
 use serde_json::Value;
 
 pub const VIRTUAL_PRINTER_NAME: &str = "FieldLens Print";
@@ -77,7 +80,7 @@ pub fn install_virtual_printer(target_printer: &str) -> Result<VirtualPrinterSta
     install_windows_virtual_printer(target_printer)?;
 
     #[cfg(target_os = "linux")]
-    install_linux_virtual_printer()?;
+    install_linux_virtual_printer(target_printer)?;
 
     virtual_printer_status()
 }
@@ -242,10 +245,15 @@ fn ps_quote(value: &str) -> String {
 
 #[cfg(target_os = "linux")]
 fn list_linux_printers() -> Result<Vec<SystemPrinter>> {
-    let output = Command::new("lpstat")
-        .arg("-v")
-        .output()
-        .context("query CUPS printers with lpstat")?;
+    let output = match Command::new("lpstat").arg("-v").output() {
+        Ok(output) => output,
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
+            return Err(anyhow!(
+                "CUPS client tools are missing. Install the cups-client package, then reopen FieldLens Print."
+            ))
+        }
+        Err(error) => return Err(error).context("query CUPS printers with lpstat"),
+    };
 
     if !output.status.success() {
         return Err(anyhow!(
@@ -289,27 +297,42 @@ fn socket_uri_to_address(uri: &str) -> Option<String> {
 }
 
 #[cfg(target_os = "linux")]
-fn install_linux_virtual_printer() -> Result<()> {
-    let args = [
-        "-p",
-        "FieldLens-Print",
-        "-E",
-        "-v",
-        "socket://127.0.0.1:9100",
-        "-m",
-        "raw",
-        "-D",
-        VIRTUAL_PRINTER_NAME,
+fn install_linux_virtual_printer(target_printer: &str) -> Result<()> {
+    let printers = list_linux_printers()?;
+    if !printers.iter().any(|printer| printer.name == target_printer && !printer.is_virtual) {
+        return Err(anyhow!(
+            "selected printer '{target_printer}' is not installed or available in CUPS"
+        ));
+    }
+
+    let ppd_path = PathBuf::from("/etc/cups/ppd").join(format!("{target_printer}.ppd"));
+    let mut args = vec![
+        "-p".to_string(),
+        "FieldLens-Print".to_string(),
+        "-E".to_string(),
+        "-v".to_string(),
+        "socket://127.0.0.1:9100".to_string(),
     ];
 
-    let direct = Command::new("lpadmin").args(args).status();
+    if ppd_path.exists() {
+        args.push("-P".to_string());
+        args.push(ppd_path.to_string_lossy().into_owned());
+    } else {
+        args.push("-m".to_string());
+        args.push("raw".to_string());
+    }
+
+    args.push("-D".to_string());
+    args.push(VIRTUAL_PRINTER_NAME.to_string());
+
+    let direct = Command::new("lpadmin").args(&args).status();
     if matches!(direct, Ok(status) if status.success()) {
         return Ok(());
     }
 
     let status = Command::new("pkexec")
         .arg("lpadmin")
-        .args(args)
+        .args(&args)
         .status()
         .context("run elevated CUPS printer setup")?;
 

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "FieldLens Print",
-  "version": "0.1.2",
+  "version": "0.1.3",
   "identifier": "dev.arrowstack.fieldlens.print",
   "build": {
     "beforeDevCommand": "npm run dev",
@@ -34,7 +34,17 @@
         "installMode": "currentUser"
       }
     },
-    "createUpdaterArtifacts": true
+    "createUpdaterArtifacts": true,
+    "linux": {
+      "deb": {
+        "depends": [
+          "cups-client"
+        ],
+        "recommends": [
+          "policykit-1"
+        ]
+      }
+    }
   },
   "plugins": {
     "updater": {

src/main.ts

@@ -69,7 +69,7 @@ let config: AppConfig
 let jobs: Job[] = []
 let status: Status
 let loginTimer: number | undefined
-let currentVersion = '0.1.2'
+let currentVersion = '0.1.3'
 let bundleType: BundleType | null = null
 let availableUpdate: Update | null = null
 let updateBusy = false
@@ -221,7 +221,8 @@ function renderPrinters() {
   const current = select.value || config?.forwardPrinter || ''
   const options = systemPrinters.filter((printer) => !printer.isVirtual)
 
-  select.innerHTML = '<option value="">Choose a printer…</option>' + options.map((printer) => {
+  const emptyLabel = options.length ? 'Choose a printer…' : 'No installed printers found'
+  select.innerHTML = `<option value="">${emptyLabel}</option>` + options.map((printer) => {
     const suffix = printer.address ? ` · ${printer.address}` : printer.port ? ` · ${printer.port}` : ''
     return `<option value="${escapeHtml(printer.name)}">${escapeHtml(printer.name + suffix)}</option>`
   }).join('')
@@ -234,10 +235,16 @@ function renderPrinters() {
     help.textContent = `Detected RAW network endpoint: ${selected.address}`
   } else if (selected) {
     help.textContent = 'No RAW/TCP address was exposed for this queue. Enter the printer IP:9100 manually.'
+  } else if (config?.forwardPrinter && !options.some((printer) => printer.name === config.forwardPrinter)) {
+    help.textContent = `Previously selected printer "${config.forwardPrinter}" is not installed or available. Add it in system printer settings, then Refresh printers.`
+  } else if (!options.length) {
+    help.textContent = 'No installed CUPS printers were found. Add the physical printer in system settings, then Refresh printers.'
   } else {
     help.textContent = 'Select the physical printer that should receive the original print bytes.'
   }
 
+  el<HTMLButtonElement>('install-printer').disabled = !options.length
+
   const virtualState = el('virtual-printer-state')
   virtualState.textContent = virtualPrinterStatus?.detail ?? 'Printer status unavailable.'
   virtualState.classList.toggle('ready', Boolean(virtualPrinterStatus?.installed))