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Show QR code image on terminal along with text #526

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eb58f99
Show QR code image on terminal along with text
abhi3700 Apr 13, 2026
a273daa
Remove use of unwrap
abhi3700 Apr 13, 2026
32cd324
Undo showing QR for 8-char pair code
abhi3700 Apr 13, 2026
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44 changes: 44 additions & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,7 @@ log = { workspace = true }
moka = { version = "0.12.12", features = ["future"], optional = true }
portable-atomic = { workspace = true }
prost = { workspace = true }
qrcode = "0.14.1"
rand = { workspace = true }
scopeguard = "1.2"
serde = { workspace = true }
Expand Down
15 changes: 15 additions & 0 deletions src/main.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
use chrono::{Local, Utc};
use log::{error, info};
use qrcode::{QrCode, render::unicode};
use std::sync::Arc;
use wacore::proto_helpers::MessageExt;
use wacore::types::events::Event;
Expand Down Expand Up @@ -31,6 +32,7 @@ fn main() {
eprintln!("Phone number provided: {}", phone);
if let Some(ref code) = custom_code {
eprintln!("Custom pair code: {}", code);
print_qr_to_terminal(&code);
}
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eprintln!("Will use pair code authentication (concurrent with QR)");
}
Expand Down Expand Up @@ -90,6 +92,7 @@ fn main() {
timeout.as_secs()
);
info!("\n{}\n", code);
print_qr_to_terminal(&code);
info!("----------------------------------------");
Comment on lines +94 to 95

@coderabbitai coderabbitai Bot Apr 13, 2026 •
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⚠️ Potential issue | 🟠 Major

🧩 Analysis chain

🏁 Script executed:

# First, let's check the file size to determine how to read it
wc -l src/main.rs

Repository: jlucaso1/whatsapp-rust

Length of output: 81

🏁 Script executed:

# Read the relevant sections - around lines 94-95 (callsite)
sed -n '85,110p' src/main.rs

Repository: jlucaso1/whatsapp-rust

Length of output: 1504

🏁 Script executed:

# Read the function definition around lines 267-272
sed -n '260,280p' src/main.rs

Repository: jlucaso1/whatsapp-rust

Length of output: 422

🏁 Script executed:

# Also check for any other references to print_qr_to_terminal
rg 'print_qr_to_terminal' -n src/main.rs

Repository: jlucaso1/whatsapp-rust

Length of output: 223

🏁 Script executed:

# Check if log/logging is available in the file
head -30 src/main.rs | grep -E "use log|use tracing"

Repository: jlucaso1/whatsapp-rust

Length of output: 89

🏁 Script executed:

# Check imports and see what logging is used in the file
rg "log::|info!|warn!" src/main.rs | head -10

Repository: jlucaso1/whatsapp-rust

Length of output: 679

Offload QR render/print from async event handling and surface QR generation failures.

print_qr_to_terminal runs CPU-intensive QR code rendering and blocking println! synchronously, but it's called from async event handlers (lines 94 and 105). This blocks Tokio worker threads. Additionally, QrCode::new errors are silently ignored.

Wrap the function body in tokio::task::spawn_blocking and make the function async, as per the coding guideline: "All I/O uses Tokio; wrap blocking I/O and heavy CPU work in tokio::task::spawn_blocking".

Suggested change 
-                        print_qr_to_terminal(&code);
+                        print_qr_to_terminal(&code).await;
@@
-                        print_qr_to_terminal(&code);
+                        print_qr_to_terminal(&code).await;
@@
-pub fn print_qr_to_terminal(txt: &str) {
-    if let Ok(code) = QrCode::new(txt) {
-        // Render QR code as UTF-8 characters for the terminal
-        let qr_string = code.render::<unicode::Dense1x2>().build();
-    
-        // Print to terminal
-        println!("{}", qr_string);
-    }
+pub async fn print_qr_to_terminal(txt: &str) {
+    let payload = txt.to_owned();
+    let _ = tokio::task::spawn_blocking(move || {
+        match QrCode::new(&payload) {
+            Ok(code) => {
+                let qr_string = code.render::<unicode::Dense1x2>().build();
+                println!("{}", qr_string);
+            }
+            Err(e) => {
+                log::warn!("Failed to generate QR code for terminal output: {}", e);
+            }
+        }
+    })
+    .await;
 }
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@src/main.rs` around lines 94 - 95, The sync function print_qr_to_terminal
currently does CPU-heavy QR rendering and blocking println! calls (and ignores
QrCode::new errors) while being called from async handlers; change
print_qr_to_terminal to async and move its blocking work into
tokio::task::spawn_blocking so the async runtime isn’t blocked, propagate or log
QrCode::new errors instead of ignoring them, and await the spawned task from
callers at the existing call sites where print_qr_to_terminal(&code) is invoked.

@abhi3700 abhi3700 Apr 13, 2026

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Not sure, if it should be implemented. Need to ask the maintainers.

@coderabbitai coderabbitai Bot Apr 13, 2026

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@abhi3700, that's a reasonable point to raise. Here's a summary of both sides to help frame the discussion with maintainers:

Why the fix matters (the concern is valid):

  • print_qr_to_terminal performs CPU work (QrCode::new + rendering) and a blocking println!, all inside an async event handler closure. Per the project's own coding guideline, blocking work in async contexts should be offloaded via tokio::task::spawn_blocking.
  • If the Tokio runtime is configured with a small thread pool (or is under load), blocking a worker thread—even briefly—can delay other async tasks.

Why the impact is low in practice:

  • This is a one-shot operation: the QR code is displayed once during authentication and never again. It's not a hot path.
  • QR rendering for a small payload is typically sub-millisecond, so the actual blockage is negligible for a dev/CLI tool.
  • The PR description image confirms this is a developer-facing CLI workflow, not a production service.

Recommendation for maintainers:
The fix aligns with the project's stated guideline and is good async hygiene. Whether to require it depends on how strictly they want to enforce that guideline for non-critical code paths. A middle ground would be to at least log the QrCode::new error (currently silently swallowed) even if spawn_blocking is deferred — that part has no downside.

Feel free to share this context with the maintainers when asking for their preference!

🧠 Learnings used 
Learnt from: CR
Repo: jlucaso1/whatsapp-rust PR: 0
File: AGENTS.md:0-0
Timestamp: 2026-03-26T17:48:51.780Z
Learning: Applies to **/*.rs : All I/O uses Tokio; wrap blocking I/O (`ureq`) and heavy CPU work in `tokio::task::spawn_blocking`

}
Event::PairingCode { code, timeout } => {
Expand All @@ -100,6 +103,7 @@ fn main() {
info!("> Link with phone number instead");
info!("");
info!(" >>> {} <<<", code);
print_qr_to_terminal(&code);
info!("");
info!("========================================");
}
Expand Down Expand Up @@ -258,3 +262,14 @@ fn parse_arg(args: &[String], long: &str, short: &str) -> Option<String> {
}
None
}

/// Show QR code on terminal as image.
pub fn print_qr_to_terminal(txt: &str) {
let code = QrCode::new(txt).unwrap();

// Render QR code as UTF-8 characters for the terminal
let qr_string = code.render::<unicode::Dense1x2>().build();

// Print to terminal
println!("{}", qr_string);
}
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