From efffb62b362553a1542fda2757283350678f9732 Mon Sep 17 00:00:00 2001
From: Jeff Epler <jepler@gmail.com>
Date: Tue, 2 Nov 2021 18:21:45 -0500
Subject: [PATCH] truncate boot_out.txt if it's long

Now this boot.py:
```py
for i in range(1000):
    print(i)
```
creates a 512-byte boot_out.txt that ends
```
88
89
...
```
---
 supervisor/shared/micropython.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/supervisor/shared/micropython.c b/supervisor/shared/micropython.c
index 24bc57ec12..6c850f9b00 100644
--- a/supervisor/shared/micropython.c
+++ b/supervisor/shared/micropython.c
@@ -60,7 +60,13 @@ void mp_hal_stdout_tx_strn(const char *str, size_t len) {
 
     #ifdef CIRCUITPY_BOOT_OUTPUT_FILE
     if (boot_output != NULL) {
-        vstr_add_strn(boot_output, str, len);
+        // Ensure boot_out.txt is capped at 1 filesystem block and ends with a newline
+        if (len + boot_output->len > 508) {
+            vstr_add_str(boot_output, "...\n");
+            boot_output = NULL;
+        } else {
+            vstr_add_strn(boot_output, str, len);
+        }
     }
     #endif