From 2ad4442acea9ccd996e25d09827aa9d556603a93 Mon Sep 17 00:00:00 2001
From: Renato Alves <alves.rjc@gmail.com>
Date: Sun, 7 Apr 2024 21:35:32 +0200
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20Env=20NSS=5FLIB=5FPATH=20can=20now?=
 =?UTF-8?q?=20be=20used=20to=20specify=20libnss=20location?=
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Closes #108
---
 CHANGELOG.md       |  1 +
 README.md          | 22 ++++++++++++++++++++++
 firefox_decrypt.py |  4 +++-
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index afee7ac..c3d5ee1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ##### 1.1.0+git
 - Fix unhandled exception with deleted passwords - see #99
+- Environment variable `NSS_LIB_PATH` can now be used to specify `libnss` location
 
 ##### 1.1.0
 - Include `pyproject.toml` to facilitate usage via `pipx`
diff --git a/README.md b/README.md
index f9bb8cc..ec50d94 100644
--- a/README.md
+++ b/README.md
@@ -85,6 +85,28 @@ You can also choose from one of the supported formats with `--format`:
 
 (*) `pass` can produce unintended consequences. Make sure to backup your password store before using this option.
 
+##### Specify NSS library location
+
+In order to decode your passwords, Firefox Decrypt uses a series of heuristics to try to locate a compatible [NSS library](https://developer.mozilla.org/docs/Mozilla/Projects/NSS) on your system.
+As this approach can sometimes fail, starting with version 1.1.1 of Firefox Decrypt you can now define the `NSS_LIB_PATH` environment variable to manually specify the location of the library.
+This location will be prioritized and if no compatible library is found, the script will continue with the built-in heuristics.
+
+```
+# On Linux it will look for libnss3.so in /opt/nss/lib/
+# On Mac it will look for libnss3.dylib
+NSS_LIB_PATH=/opt/nss/lib/ python firefox_decrypt.py
+
+# On Windows it will look for nss3.dll
+set NSS_LIB_PATH=D:\NSS\lib\ && python firefox_decrypt.py
+```
+
+You can confirm if this was successful by running the script in high-verbosity mode (`-vv`) and look for the `Loaded NSS` message after `Loading NSS`:
+
+```
+(...) DEBUG - Loading NSS library from /opt/nss/lib/libnss3.so
+(...) DEBUG - Loaded NSS library from /opt/nss/lib/libnss3.so
+```
+
 ##### Non-interactive mode
 
 A non-interactive mode which bypasses all prompts, including profile choice and master password, can be enabled with `-n/--no-interactive`.
diff --git a/firefox_decrypt.py b/firefox_decrypt.py
index 76792fb..2718dd8 100755
--- a/firefox_decrypt.py
+++ b/firefox_decrypt.py
@@ -279,7 +279,9 @@ def find_nss(locations: list[str], nssname: str) -> ct.CDLL:
 def load_libnss():
     """Load libnss into python using the CDLL interface"""
 
-    locations: list[str] = []
+    locations: list[str] = [
+        os.environ.get("NSS_LIB_PATH", ""),
+    ]
 
     if SYSTEM == "Windows":
         nssname = "nss3.dll"