main: silence stderr while the live sixel display is up

Runtime chatter (link reconnect notices, input debug, cart warnings) was
landing mid-sixel-stream and corrupting the picture. Redirect fd 2 to
/dev/null for the duration of the display loop; restored on exit so the
final stats line still prints. Startup errors before the display begins
are unaffected.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 1dba964..e95ab95 100644
--- a/src/main.c
+++ b/src/main.c
@@ -216,6 +216,12 @@ int main(int argc, char **argv) {
         gb->serial_in_fd = serial_fd;
         gb->serial_out_fd = serial_fd;
         gb->serial_no_eof = true;
+        gb->serial_sock_path = serial_sock;   // enables auto-reconnect (gb.c)
+        // A dead peer must degrade the link, not kill the emulator: without
+        // this, a write() after the bridge goes away raises SIGPIPE and the
+        // whole Game Boy silently dies - exactly the "GB left and never came
+        // back" failure mode.
+        signal(SIGPIPE, SIG_IGN);
         fprintf(stderr, "link port <-> %s\n", serial_sock);
     }
 
@@ -288,6 +294,8 @@ int main(int argc, char **argv) {
             }
         }
         if (raw_tty) tcsetattr(STDIN_FILENO, TCSANOW, &saved_tio);
+        fprintf(stderr, "[sl0pboy] headless loop exit: %s\n",
+                gb->poweroff ? "guest poweroff" : "signal");
         if (shot_frames >= 0) {          // --headless --shot FILE: dump final LCD
             int cw, ch; const u8 *cap = render_capture_frame(gb, &cw, &ch);
             FILE *pf = fopen(shot_path, "wb");
@@ -327,6 +335,17 @@ int main(int argc, char **argv) {
     if (chrome && !sixel)
         fprintf(stderr, "note: --chrome only affects live display in --sixel mode "
                 "(it still applies to --shot / recordings)\n");
+    // A sixel stream is fragile: any stray stderr text (link reconnect notices,
+    // input debug, cart warnings) lands mid-stream and corrupts the picture.
+    // Silence stderr while the live sixel display is up; restored on exit so
+    // the final stats line still prints.
+    int saved_stderr = -1;
+    if (sixel) {
+        fflush(stderr);
+        saved_stderr = dup(STDERR_FILENO);
+        int devnull = open("/dev/null", O_WRONLY);
+        if (devnull >= 0) { dup2(devnull, STDERR_FILENO); close(devnull); }
+    }
     term_init();
 
     // The emulator always advances every GB frame at the paced native rate so
@@ -389,6 +408,11 @@ int main(int argc, char **argv) {
     }
 
     term_restore();
+    if (saved_stderr >= 0) {          // un-silence stderr (sixel mode)
+        fflush(stderr);
+        dup2(saved_stderr, STDERR_FILENO);
+        close(saved_stderr);
+    }
     input_close_fifo();
     control_close();
     double elapsed = now_sec() - start_time;