From 780976bf91de549599fc1165d391ddc7d5dc895d Mon Sep 17 00:00:00 2001
From: Arne Welzel <arne.welzel@corelight.com>
Date: Thu, 26 Sep 2024 10:49:50 +0200
Subject: [PATCH] zeek-setup: Support enabling debug streams through env
 variable

For debugging btests, it can be convenient to enable debug streams
by setting an environment variable rather than editing zeek invocations
and adding -B selectively.

Sample use case:

    $ export ZEEK_DEBUG_LOG_STREAMS=all
    $ btest -d core/failing-test.zeek
    $ less .tmp/core/failing-test/debug.log

This change makes Zeek's -B option and ZEEK_DEBUG_LOG_STREAMS are additive.
---
 src/DebugLogger.h | 3 +++
 src/Options.cc    | 5 ++++-
 src/zeek-setup.cc | 6 +++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/DebugLogger.h b/src/DebugLogger.h
index d22373b3ae..a8df9cd977 100644
--- a/src/DebugLogger.h
+++ b/src/DebugLogger.h
@@ -85,6 +85,9 @@ public:
 
     bool IsEnabled(DebugStream stream) const { return streams[int(stream)].enabled; }
 
+    // Are any streams enabled?
+    bool HasEnabledStreams() const { return ! enabled_streams.empty(); }
+
     void SetVerbose(bool arg_verbose) { verbose = arg_verbose; }
     bool IsVerbose() const { return verbose; }
 
diff --git a/src/Options.cc b/src/Options.cc
index c0c6ff3d4e..2d0bb632c0 100644
--- a/src/Options.cc
+++ b/src/Options.cc
@@ -170,7 +170,10 @@ void usage(const char* prog, int code) {
                                           "not set, will use first IPv4 address from /etc/resolv.conf");
     fprintf(stderr,
             "    $ZEEK_DEBUG_LOG_STDERR          | Use stderr for debug logs generated via "
-            "the -B flag");
+            "the -B flag\n");
+    fprintf(stderr,
+            "    $ZEEK_DEBUG_LOG_STREAMS         | Enable debugging output for selected "
+            "streams (see the -B flag)");
 
     fprintf(stderr, "\n");
 
diff --git a/src/zeek-setup.cc b/src/zeek-setup.cc
index 8e39653b6d..3cf44a5b7f 100644
--- a/src/zeek-setup.cc
+++ b/src/zeek-setup.cc
@@ -556,9 +556,13 @@ SetupResult setup(int argc, char** argv, Options* zopts) {
         reporter->FatalError("-u incompatible with --no-unused-warnings");
 
 #ifdef DEBUG
-    if ( options.debug_log_streams ) {
+    if ( options.debug_log_streams )
         debug_logger.EnableStreams(options.debug_log_streams->data());
 
+    if ( const auto* streams = getenv("ZEEK_DEBUG_LOG_STREAMS") )
+        debug_logger.EnableStreams(streams);
+
+    if ( debug_logger.HasEnabledStreams() ) {
         if ( getenv("ZEEK_DEBUG_LOG_STDERR") )
             debug_logger.OpenDebugLog(nullptr);
         else