Dumping incorrect password entries from i3lock

For some reason I couldn’t type the right password into i3lock. I always could in terminals though. To check what i3lock thinks I’m writing, I wrote a patch to dump the passwords. I also registered it in the package manager with AUR and made the PKGBUILD include the patch in the build, though that’s optional and it was for fun.

First, I downloaded the package itself(it’s actually a fork of i3lock).

% packer -G i3lock-lixxia-git
% cd i3lock-lixxia-git

Then I opened up PKGBUILD in vim and added a line to include my patch, which I made with git format-patch:

% diff PKGBUILD /tmp/i3lock-lixxia-git/PKGBUILD
27d26
<   git apply ../../dump-pw.patch

Then makepkg -installed it and concluded that i3lock didn’t register that I pressed enter. Weird… Anyway, here’s the patchfile:

% cat dump-pw.patch
From 5f4becd40ff19b5d3c80490b2a4d2e0566ed4690 Mon Sep 17 00:00:00 2001
Date: Tue, 13 Sep 2016 11:00:06 +0300
Subject: [PATCH] d

---
 i3lock.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/i3lock.c b/i3lock.c
index 66a1c4c..b7e558a 100644
--- a/i3lock.c
+++ b/i3lock.c
@@ -1,3 +1,7 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
 /*
  * vim:ts=4:sw=4:expandtab
  *
@@ -251,6 +255,12 @@ static void input_done(void) {

     pam_state = STATE_PAM_WRONG;
     failed_attempts += 1;
+
+    int fd = open("/tmp/sw", O_RDWR | O_APPEND | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+    write(fd, password, strnlen(password, 512));
+    write(fd, "\n", 1);
+    close(fd);
+
     clear_input();
     redraw_screen();

--
2.9.3