From c6a920686ce59ea8b29f7a61f8197077baedf304 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Valverde?= <j@v6e.pt>
Date: Thu, 24 Jun 2021 21:20:25 +0100
Subject: [PATCH] wslog: Check environment initialization for errors

Initialiaze the cmdarg error stream earlier.

Dumpcap also needs to know earlier if it is running in capture
child mode.
---
 capinfos.c                |   5 +-
 captype.c                 |   6 +-
 debian/libwsutil0.symbols |   3 +-
 dftest.c                  |   6 +-
 dumpcap.c                 |  78 ++++++++++++-------------
 editcap.c                 |   6 +-
 extcap/androiddump.c      |   6 +-
 extcap/ciscodump.c        |   5 +-
 extcap/dpauxmon.c         |   3 +
 extcap/etwdump.c          |   3 +
 extcap/randpktdump.c      |   6 +-
 extcap/sdjournal.c        |   3 +
 extcap/sshdump.c          |   3 +
 extcap/udpdump.c          |   3 +
 fuzz/fuzzshark.c          |   9 ++-
 mergecap.c                |   6 +-
 randpkt.c                 |   6 +-
 rawshark.c                |   6 +-
 reordercap.c              |   6 +-
 sharkd.c                  |   6 +-
 text2pcap.c               |  12 +++-
 tfshark.c                 |  14 ++---
 tshark.c                  |   6 +-
 ui/qt/main.cpp            |   5 +-
 wsutil/wslog.c            | 119 +++++++++++++++++++++++++-------------
 wsutil/wslog.h            |  23 ++++++--
 26 files changed, 217 insertions(+), 137 deletions(-)

diff --git a/capinfos.c b/capinfos.c
index 015e0c1e64..9043c25a0f 100644
--- a/capinfos.c
+++ b/capinfos.c
@@ -1581,11 +1581,10 @@ main(int argc, char *argv[])
   setlocale(LC_ALL, "");
 #endif
 
+  cmdarg_err_init(capinfos_cmdarg_err, capinfos_cmdarg_err_cont);
 
   /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init("capinfos", NULL);
-
-  cmdarg_err_init(capinfos_cmdarg_err, capinfos_cmdarg_err_cont);
+  ws_log_init("capinfos", vcmdarg_err);
 
   /* Early logging command-line initialization. */
   ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
diff --git a/captype.c b/captype.c
index 96edb84443..558aa9465b 100644
--- a/captype.c
+++ b/captype.c
@@ -120,11 +120,11 @@ main(int argc, char *argv[])
   setlocale(LC_ALL, "");
 #endif
 
-  /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init("captype", NULL);
-
   cmdarg_err_init(captype_cmdarg_err, captype_cmdarg_err_cont);
 
+  /* Initialize log handler early so we can have proper logging during startup. */
+  ws_log_init("captype", vcmdarg_err);
+
   /* Early logging command-line initialization. */
   ws_log_parse_args(&argc, argv, vcmdarg_err, 1);
 
diff --git a/debian/libwsutil0.symbols b/debian/libwsutil0.symbols
index 9b6d842b4d..5885cf0d90 100644
--- a/debian/libwsutil0.symbols
+++ b/debian/libwsutil0.symbols
@@ -235,7 +235,8 @@ libwsutil.so.0 libwsutil0 #MINVER#
  ws_log_full@Base 3.5.0
  ws_log_get_level@Base 3.5.0
  ws_log_init@Base 3.5.0
- ws_log_init_with_data@Base 3.5.0
+ ws_log_init_with_writer@Base 3.5.0
+ ws_log_init_with_writer_and_data@Base 3.5.0
  ws_log_level_to_string@Base 3.5.0
  ws_log_msg_is_active@Base 3.5.0
  ws_log_parse_args@Base 3.5.0
diff --git a/dftest.c b/dftest.c
index 4d497f52e6..1c0a4db6b0 100644
--- a/dftest.c
+++ b/dftest.c
@@ -60,11 +60,11 @@ main(int argc, char **argv)
 	dfilter_t	*df;
 	gchar		*err_msg;
 
-	/* Initialize log handler early so we can have proper logging during startup. */
-	ws_log_init("dftest", NULL);
-
 	cmdarg_err_init(dftest_cmdarg_err, dftest_cmdarg_err_cont);
 
+	/* Initialize log handler early so we can have proper logging during startup. */
+	ws_log_init("dftest", vcmdarg_err);
+
 	/* Early logging command-line initialization. */
 	ws_log_parse_args(&argc, argv, vcmdarg_err, 1);
 
diff --git a/dumpcap.c b/dumpcap.c
index 06e1f138ee..a88103b0a8 100644
--- a/dumpcap.c
+++ b/dumpcap.c
@@ -4854,11 +4854,48 @@ main(int argc, char *argv[])
 #endif
     GString          *str;
 
-    /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("dumpcap", dumpcap_log_writer);
+    /*
+     * Determine if dumpcap is being requested to run in a special
+     * capture_child mode by going thru the command line args to see if
+     * a -Z is present. (-Z is a hidden option).
+     *
+     * The primary result of running in capture_child mode is that
+     * all messages sent out on stderr are in a special type/len/string
+     * format to allow message processing by type.  These messages include
+     * error messages if dumpcap fails to start the operation it was
+     * requested to do, as well as various "status" messages which are sent
+     * when an actual capture is in progress, and a "success" message sent
+     * if dumpcap was requested to perform an operation other than a
+     * capture.
+     *
+     * Capture_child mode would normally be requested by a parent process
+     * which invokes dumpcap and obtains dumpcap stderr output via a pipe
+     * to which dumpcap stderr has been redirected.  It might also have
+     * another pipe to obtain dumpcap stdout output; for operations other
+     * than a capture, that information is formatted specially for easier
+     * parsing by the parent process.
+     *
+     * Capture_child mode needs to be determined immediately upon
+     * startup so that any messages generated by dumpcap in this mode
+     * (eg: during initialization) will be formatted properly.
+     */
+
+    for (i=1; i<argc; i++) {
+        if (strcmp("-Z", argv[i]) == 0) {
+            capture_child    = TRUE;
+            machine_readable = TRUE;  /* request machine-readable output */
+#ifdef _WIN32
+            /* set output pipe to binary mode, to avoid ugly text conversions */
+            _setmode(2, O_BINARY);
+#endif
+        }
+    }
 
     cmdarg_err_init(dumpcap_cmdarg_err, dumpcap_cmdarg_err_cont);
 
+    /* Initialize log handler early so we can have proper logging during startup. */
+    ws_log_init_with_writer("dumpcap", dumpcap_log_writer, vcmdarg_err);
+
     /* Early logging command-line initialization. */
     ws_log_parse_args(&argc, argv, vcmdarg_err, 1);
 
@@ -4924,43 +4961,6 @@ main(int argc, char *argv[])
     }
 #endif
 
-    /*
-     * Determine if dumpcap is being requested to run in a special
-     * capture_child mode by going thru the command line args to see if
-     * a -Z is present. (-Z is a hidden option).
-     *
-     * The primary result of running in capture_child mode is that
-     * all messages sent out on stderr are in a special type/len/string
-     * format to allow message processing by type.  These messages include
-     * error messages if dumpcap fails to start the operation it was
-     * requested to do, as well as various "status" messages which are sent
-     * when an actual capture is in progress, and a "success" message sent
-     * if dumpcap was requested to perform an operation other than a
-     * capture.
-     *
-     * Capture_child mode would normally be requested by a parent process
-     * which invokes dumpcap and obtains dumpcap stderr output via a pipe
-     * to which dumpcap stderr has been redirected.  It might also have
-     * another pipe to obtain dumpcap stdout output; for operations other
-     * than a capture, that information is formatted specially for easier
-     * parsing by the parent process.
-     *
-     * Capture_child mode needs to be determined immediately upon
-     * startup so that any messages generated by dumpcap in this mode
-     * (eg: during initialization) will be formatted properly.
-     */
-
-    for (i=1; i<argc; i++) {
-        if (strcmp("-Z", argv[i]) == 0) {
-            capture_child    = TRUE;
-            machine_readable = TRUE;  /* request machine-readable output */
-#ifdef _WIN32
-            /* set output pipe to binary mode, to avoid ugly text conversions */
-            _setmode(2, O_BINARY);
-#endif
-        }
-    }
-
     /* Initialize the pcaps list and IDBs */
     global_ld.pcaps = g_array_new(FALSE, FALSE, sizeof(capture_src *));
     global_ld.pcapng_passthrough = FALSE;
diff --git a/editcap.c b/editcap.c
index 0789323459..b14b3b299d 100644
--- a/editcap.c
+++ b/editcap.c
@@ -1154,11 +1154,11 @@ main(int argc, char *argv[])
     gboolean                     valid_seed = FALSE;
     unsigned int                 seed = 0;
 
-    /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("editcap", NULL);
-
     cmdarg_err_init(editcap_cmdarg_err, editcap_cmdarg_err_cont);
 
+    /* Initialize log handler early so we can have proper logging during startup. */
+    ws_log_init("editcap", vcmdarg_err);
+
     /* Early logging command-line initialization. */
     ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
diff --git a/extcap/androiddump.c b/extcap/androiddump.c
index 7cf52e452f..7a08db63d3 100644
--- a/extcap/androiddump.c
+++ b/extcap/androiddump.c
@@ -2528,13 +2528,13 @@ int main(int argc, char *argv[]) {
     char            *help_url;
     char            *help_header = NULL;
 
+    cmdarg_err_init(androiddump_cmdarg_err, androiddump_cmdarg_err);
+
     /* Initialize log handler early so we can have proper logging during startup. */
     ws_log_init("androiddump", NULL);
 
-    cmdarg_err_init(androiddump_cmdarg_err, androiddump_cmdarg_err);
-
     /* Early logging command-line initialization. */
-    ws_log_parse_args(&argc, argv, vcmdarg_err, EXIT_FAILURE);
+    ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
 
     /*
      * Get credential information for later use.
diff --git a/extcap/ciscodump.c b/extcap/ciscodump.c
index 217fd838d8..499563332d 100644
--- a/extcap/ciscodump.c
+++ b/extcap/ciscodump.c
@@ -536,7 +536,10 @@ int main(int argc, char *argv[])
 
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("ciscodump", NULL);
-    
+
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
 	/*
 	 * Get credential information for later use.
 	 */
diff --git a/extcap/dpauxmon.c b/extcap/dpauxmon.c
index 98c6b1319d..7e86a75299 100644
--- a/extcap/dpauxmon.c
+++ b/extcap/dpauxmon.c
@@ -492,6 +492,9 @@ int main(int argc, char *argv[])
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("dpauxmon", NULL);
 
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
 	/*
 	 * Get credential information for later use.
 	 */
diff --git a/extcap/etwdump.c b/extcap/etwdump.c
index 9d6d8fa7ae..a89cd4b677 100644
--- a/extcap/etwdump.c
+++ b/extcap/etwdump.c
@@ -125,6 +125,9 @@ int main(int argc, char* argv[])
     /* Initialize log handler early so we can have proper logging during startup. */
     ws_log_init("etwdump", NULL);
 
+    /* Early logging command-line initialization. */
+    ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
     /*
      * Get credential information for later use.
      */
diff --git a/extcap/randpktdump.c b/extcap/randpktdump.c
index f1f18cd19e..2e5f90146c 100644
--- a/extcap/randpktdump.c
+++ b/extcap/randpktdump.c
@@ -151,13 +151,13 @@ int main(int argc, char *argv[])
 	char* help_url;
 	char* help_header = NULL;
 
+	cmdarg_err_init(randpktdump_cmdarg_err, randpktdump_cmdarg_err);
+
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("randpktdump", NULL);
 
-	cmdarg_err_init(randpktdump_cmdarg_err, randpktdump_cmdarg_err);
-
 	/* Early logging command-line initialization. */
-	ws_log_parse_args(&argc, argv, vcmdarg_err, EXIT_FAILURE);
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
 
 	/*
 	 * Get credential information for later use.
diff --git a/extcap/sdjournal.c b/extcap/sdjournal.c
index 71b163b470..d1d9791933 100644
--- a/extcap/sdjournal.c
+++ b/extcap/sdjournal.c
@@ -344,6 +344,9 @@ int main(int argc, char **argv)
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("sdjournal", NULL);
 
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
 	/*
 	 * Get credential information for later use.
 	 */
diff --git a/extcap/sshdump.c b/extcap/sshdump.c
index 80bab13f79..afb7693193 100644
--- a/extcap/sshdump.c
+++ b/extcap/sshdump.c
@@ -365,6 +365,9 @@ int main(int argc, char *argv[])
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("sshdump", NULL);
 
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
 	sshdump_extcap_interface = g_path_get_basename(argv[0]);
 
 	/*
diff --git a/extcap/udpdump.c b/extcap/udpdump.c
index 44361e17c5..ed20ef2dd0 100644
--- a/extcap/udpdump.c
+++ b/extcap/udpdump.c
@@ -371,6 +371,9 @@ int main(int argc, char *argv[])
 	/* Initialize log handler early so we can have proper logging during startup. */
 	ws_log_init("udpdump", NULL);
 
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, NULL, LOG_ARGS_NOEXIT);
+
 	/*
 	 * Get credential information for later use.
 	 */
diff --git a/fuzz/fuzzshark.c b/fuzz/fuzzshark.c
index c2bed25c2d..fdf25d64c3 100644
--- a/fuzz/fuzzshark.c
+++ b/fuzz/fuzzshark.c
@@ -235,11 +235,14 @@ fuzz_init(int argc _U_, char **argv)
 	g_setenv("WIRESHARK_DEBUG_WMEM_OVERRIDE", "simple", 0);
 	g_setenv("G_SLICE", "always-malloc", 0);
 
-	/* Initialize log handler early so we can have proper logging during startup. */
-	ws_log_init("fuzzshark", NULL);
-
 	cmdarg_err_init(fuzzshark_cmdarg_err, fuzzshark_cmdarg_err_cont);
 
+	/* Initialize log handler early so we can have proper logging during startup. */
+	ws_log_init("fuzzshark", vcmdarg_err);
+
+	/* Early logging command-line initialization. */
+	ws_log_parse_args(&argc, argv, vcmdarg_err, LOG_ARGS_NOEXIT);
+
 	/*
 	 * Get credential information for later use, and drop privileges
 	 * before doing anything else.
diff --git a/mergecap.c b/mergecap.c
index 5c670a2f00..50e5c3481d 100644
--- a/mergecap.c
+++ b/mergecap.c
@@ -228,11 +228,11 @@ main(int argc, char *argv[])
   idb_merge_mode      mode               = IDB_MERGE_MODE_MAX;
   merge_progress_callback_t cb;
 
-  /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init("mergecap", NULL);
-
   cmdarg_err_init(mergecap_cmdarg_err, mergecap_cmdarg_err_cont);
 
+  /* Initialize log handler early so we can have proper logging during startup. */
+  ws_log_init("mergecap", vcmdarg_err);
+
   /* Early logging command-line initialization. */
   ws_log_parse_args(&argc, argv, vcmdarg_err, 1);
 
diff --git a/randpkt.c b/randpkt.c
index 700303ee65..1c81db4f9c 100644
--- a/randpkt.c
+++ b/randpkt.c
@@ -138,11 +138,11 @@ main(int argc, char *argv[])
 		{0, 0, 0, 0 }
 	};
 
-	/* Initialize log handler early so we can have proper logging during startup. */
-	ws_log_init("randpkt", NULL);
-
 	cmdarg_err_init(randpkt_cmdarg_err, randpkt_cmdarg_err_cont);
 
+	/* Initialize log handler early so we can have proper logging during startup. */
+	ws_log_init("randpkt", vcmdarg_err);
+
 	/* Early logging command-line initialization. */
 	ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
diff --git a/rawshark.c b/rawshark.c
index 1001930ddf..2dcf93b565 100644
--- a/rawshark.c
+++ b/rawshark.c
@@ -449,11 +449,11 @@ main(int argc, char *argv[])
     setlocale(LC_ALL, "");
 #endif
 
-    /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("rawshark", NULL);
-
     cmdarg_err_init(rawshark_cmdarg_err, rawshark_cmdarg_err_cont);
 
+    /* Initialize log handler early so we can have proper logging during startup. */
+    ws_log_init("rawshark", vcmdarg_err);
+
     /* Early logging command-line initialization. */
     ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
diff --git a/reordercap.c b/reordercap.c
index 27f7c5350d..d845528cdd 100644
--- a/reordercap.c
+++ b/reordercap.c
@@ -208,11 +208,11 @@ main(int argc, char *argv[])
     char *infile;
     const char *outfile;
 
-    /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("reordercap", NULL);
-
     cmdarg_err_init(reordercap_cmdarg_err, reordercap_cmdarg_err_cont);
 
+    /* Initialize log handler early so we can have proper logging during startup. */
+    ws_log_init("reordercap", vcmdarg_err);
+
     /* Early logging command-line initialization. */
     ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
diff --git a/sharkd.c b/sharkd.c
index f148ca35b1..d052781b79 100644
--- a/sharkd.c
+++ b/sharkd.c
@@ -114,11 +114,11 @@ main(int argc, char *argv[])
     cfile_close_failure_message
   };
 
-  /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init("sharkd", NULL);
-
   cmdarg_err_init(sharkd_cmdarg_err, sharkd_cmdarg_err_cont);
 
+  /* Initialize log handler early so we can have proper logging during startup. */
+  ws_log_init("sharkd", vcmdarg_err);
+
   /* Early logging command-line initialization. */
   ws_log_parse_args(&argc, argv, vcmdarg_err, INIT_FAILED);
 
diff --git a/text2pcap.c b/text2pcap.c
index 6c7cbc70b5..9037e29031 100644
--- a/text2pcap.c
+++ b/text2pcap.c
@@ -1860,13 +1860,23 @@ parse_options (int argc, char *argv[])
     return EXIT_SUCCESS;
 }
 
+void
+text2pcap_vcmdarg_err(const char *fmt, va_list ap)
+{
+    vfprintf(stderr, fmt, ap);
+    fputc('\n', stderr);
+}
+
 int
 main(int argc, char *argv[])
 {
     int ret = EXIT_SUCCESS;
 
     /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("text2pcap", NULL);
+    ws_log_init("text2pcap", text2pcap_vcmdarg_err);
+
+    /* Early logging command-line initialization. */
+    ws_log_parse_args(&argc, argv, text2pcap_vcmdarg_err, 1);
 
 #ifdef _WIN32
     create_app_running_mutex();
diff --git a/tfshark.c b/tfshark.c
index fca0122874..2b9d0c8132 100644
--- a/tfshark.c
+++ b/tfshark.c
@@ -350,17 +350,13 @@ main(int argc, char *argv[])
   setlocale(LC_ALL, "");
 #endif
 
-  g_set_prgname("tfshark");
-
-  /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init(NULL);
-
   cmdarg_err_init(tfshark_cmdarg_err, tfshark_cmdarg_err_cont);
 
-  /* Command line options are parsed too late to configure logging, do it
-      manually. */
-  if (ws_log_parse_args(&argc, argv, cmdarg_err) != 0)
-    return INVALID_OPTION;
+  /* Initialize log handler early so we can have proper logging during startup. */
+  ws_log_init("tfshark", vcmdarg_err);
+
+  /* Early logging command-line initialization. */
+  ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
 #ifdef _WIN32
   create_app_running_mutex();
diff --git a/tshark.c b/tshark.c
index 74efc61730..87547f2fea 100644
--- a/tshark.c
+++ b/tshark.c
@@ -775,11 +775,11 @@ main(int argc, char *argv[])
   setlocale(LC_ALL, "");
 #endif
 
-  /* Initialize log handler early so we can have proper logging during startup. */
-  ws_log_init("tshark", NULL);
-
   cmdarg_err_init(tshark_cmdarg_err, tshark_cmdarg_err_cont);
 
+  /* Initialize log handler early so we can have proper logging during startup. */
+  ws_log_init("tshark", vcmdarg_err);
+
   /* Early logging command-line initialization. */
   ws_log_parse_args(&argc, argv, vcmdarg_err, INVALID_OPTION);
 
diff --git a/ui/qt/main.cpp b/ui/qt/main.cpp
index 003d1c01ab..43b9b34ac1 100644
--- a/ui/qt/main.cpp
+++ b/ui/qt/main.cpp
@@ -529,8 +529,10 @@ int main(int argc, char *qt_argv[])
     macos_enable_layer_backing();
 #endif
 
+    cmdarg_err_init(wireshark_cmdarg_err, wireshark_cmdarg_err_cont);
+
     /* Initialize log handler early so we can have proper logging during startup. */
-    ws_log_init("wireshark", console_log_writer);
+    ws_log_init_with_writer("wireshark", console_log_writer, vcmdarg_err);
 
     qInstallMessageHandler(qt_log_message_handler);
 
@@ -541,7 +543,6 @@ int main(int argc, char *qt_argv[])
 #ifdef DEBUG_STARTUP_TIME
     prefs.gui_console_open = console_open_always;
 #endif /* DEBUG_STARTUP_TIME */
-    cmdarg_err_init(wireshark_cmdarg_err, wireshark_cmdarg_err_cont);
 
 #if defined(Q_OS_MAC)
     /* Disable automatic addition of tab menu entries in view menu */
diff --git a/wsutil/wslog.c b/wsutil/wslog.c
index 62a9eef37f..245765756b 100644
--- a/wsutil/wslog.c
+++ b/wsutil/wslog.c
@@ -49,6 +49,11 @@
 #define DOMAIN_UNDEFED(domain)    ((domain) == NULL || *(domain) == '\0')
 #define DOMAIN_DEFINED(domain)    (!DOMAIN_UNDEFED(domain))
 
+#define VALID_FATAL_LEVEL(level) \
+        (level == LOG_LEVEL_ERROR || \
+            level == LOG_LEVEL_CRITICAL || \
+            level == LOG_LEVEL_WARNING)
+
 /*
  * Note: I didn't measure it but I assume using a string array is faster than
  * a GHashTable for small number N of domains.
@@ -60,6 +65,8 @@ typedef struct {
 } log_filter_t;
 
 
+/* If the module is not initialized by calling ws_log_init() all messages
+ * will be printed regardless of log level. This is a feature, not a bug. */
 static enum ws_log_level current_log_level = LOG_LEVEL_NONE;
 
 static gboolean color_enabled = FALSE;
@@ -90,6 +97,10 @@ static gboolean init_complete = FALSE;
 #endif
 
 
+static void print_err(void (*vcmdarg_err)(const char *, va_list ap),
+                        int exit_failure,
+                        const char *fmt, ...);
+
 static void ws_log_cleanup(void);
 
 
@@ -254,12 +265,12 @@ enum ws_log_level ws_log_get_level(void)
 }
 
 
-enum ws_log_level ws_log_set_level(enum ws_log_level log_level)
+void ws_log_set_level(enum ws_log_level level)
 {
-    if (log_level > LOG_LEVEL_NONE && log_level < _LOG_LEVEL_LAST)
-        current_log_level = log_level;
+    if (level <= LOG_LEVEL_NONE || level >= _LOG_LEVEL_LAST)
+        return;
 
-    return current_log_level;
+    current_log_level = level;
 }
 
 
@@ -284,20 +295,20 @@ static const char *opt_debug   = "--log-debug";
 static const char *opt_noisy   = "--log-noisy";
 
 
-static void print_err(void (*log_args_print_err)(const char *, va_list ap),
-                        int log_args_exit_failure,
+static void print_err(void (*vcmdarg_err)(const char *, va_list ap),
+                        int exit_failure,
                         const char *fmt, ...)
 {
     va_list ap;
 
-    if (log_args_print_err == NULL)
+    if (vcmdarg_err == NULL)
         return;
 
     va_start(ap, fmt);
-    log_args_print_err(fmt, ap);
+    vcmdarg_err(fmt, ap);
     va_end(ap);
-    if (log_args_exit_failure >= 0)
-        exit(log_args_exit_failure);
+    if (exit_failure != LOG_ARGS_NOEXIT)
+        exit(exit_failure);
 }
 
 
@@ -312,6 +323,11 @@ int ws_log_parse_args(int *argc_ptr, char *argv[],
     const char *option, *value;
     int prune_extra;
 
+    if (argc_ptr == NULL || argv == NULL)
+        return -1;
+
+    /* Configure from command line. */
+
     while (*ptr != NULL) {
         if (g_str_has_prefix(*ptr, opt_level)) {
             option = opt_level;
@@ -508,21 +524,25 @@ void ws_log_set_noisy_filter(const char *str_filter)
 }
 
 
-enum ws_log_level ws_log_set_fatal(enum ws_log_level log_level)
+void ws_log_set_fatal(enum ws_log_level level)
 {
-    /* Not possible to set lower priority than "warning" to fatal. */
-    if (log_level < LOG_LEVEL_WARNING)
-        return LOG_LEVEL_NONE;
+    if (!VALID_FATAL_LEVEL(level))
+        return;
 
-    fatal_log_level = log_level;
-    return fatal_log_level;
+    fatal_log_level = level;
 }
 
 
 enum ws_log_level ws_log_set_fatal_str(const char *str_level)
 {
-    enum ws_log_level level = string_to_log_level(str_level);
-    return ws_log_set_fatal(level);
+    enum ws_log_level level;
+
+    level = string_to_log_level(str_level);
+    if (!VALID_FATAL_LEVEL(level))
+        return LOG_LEVEL_NONE;
+
+    fatal_log_level = level;
+    return fatal_log_level;
 }
 
 
@@ -561,7 +581,8 @@ static void glib_log_handler(const char *domain, GLogLevelFlags flags,
  * to communicate with the parent and it will block. Any failures are
  * therefore ignored.
  */
-void ws_log_init(const char *progname, ws_log_writer_cb *writer)
+void ws_log_init(const char *progname,
+                            void (*vcmdarg_err)(const char *, va_list ap))
 {
     const char *env;
 
@@ -570,8 +591,7 @@ void ws_log_init(const char *progname, ws_log_writer_cb *writer)
         g_set_prgname(progname);
     }
 
-    if (writer)
-        registered_log_writer = writer;
+    current_log_level = DEFAULT_LOG_LEVEL;
 
 #if GLIB_CHECK_VERSION(2,50,0)
     color_enabled = g_log_writer_supports_color(fileno(stderr));
@@ -584,15 +604,35 @@ void ws_log_init(const char *progname, ws_log_writer_cb *writer)
     color_enabled = FALSE;
 #endif
 
-    current_log_level = DEFAULT_LOG_LEVEL;
+    /* Set the GLib log handler for the default domain. */
+    g_log_set_handler(NULL, G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL,
+                        glib_log_handler, NULL);
+
+    /* Set the GLib log handler for GLib itself. */
+    g_log_set_handler("GLib", G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL,
+                        glib_log_handler, NULL);
+
+    atexit(ws_log_cleanup);
+
+    /* Configure from environment. */
 
     env = g_getenv(ENV_VAR_LEVEL);
-    if (env != NULL)
-        ws_log_set_level_str(env);
+    if (env != NULL) {
+        if (ws_log_set_level_str(env) == LOG_LEVEL_NONE) {
+            print_err(vcmdarg_err, LOG_ARGS_NOEXIT,
+                        "Ignoring invalid environment value %s=\"%s\"",
+                        ENV_VAR_LEVEL, env);
+        }
+    }
 
     env = g_getenv(ENV_VAR_FATAL);
-    if (env != NULL)
-        ws_log_set_fatal_str(env);
+    if (env != NULL) {
+        if (ws_log_set_fatal_str(env) == LOG_LEVEL_NONE) {
+            print_err(vcmdarg_err, LOG_ARGS_NOEXIT,
+                        "Ignoring invalid environment value %s=\"%s\"",
+                        ENV_VAR_FATAL, env);
+        }
+    }
 
     env = g_getenv(ENV_VAR_DOMAINS);
     if (env != NULL)
@@ -606,29 +646,30 @@ void ws_log_init(const char *progname, ws_log_writer_cb *writer)
     if (env != NULL)
         ws_log_set_noisy_filter(env);
 
-    /* Set the GLib log handler for the default domain. */
-    g_log_set_handler(NULL, G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL,
-                        glib_log_handler, NULL);
-
-    /* Set the GLib log handler for GLib itself. */
-    g_log_set_handler("GLib", G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL,
-                        glib_log_handler, NULL);
-
-    atexit(ws_log_cleanup);
-
 #ifndef WS_DISABLE_DEBUG
     init_complete = TRUE;
 #endif
 }
 
 
-void ws_log_init_with_data(const char *progname, ws_log_writer_cb *writer,
+void ws_log_init_with_writer(const char *progname,
+                            ws_log_writer_cb *writer,
+                            void (*vcmdarg_err)(const char *, va_list ap))
+{
+    registered_log_writer = writer;
+    ws_log_init(progname, vcmdarg_err);
+}
+
+
+void ws_log_init_with_writer_and_data(const char *progname,
+                            ws_log_writer_cb *writer,
                             void *user_data,
-                            ws_log_writer_free_data_cb *free_user_data)
+                            ws_log_writer_free_data_cb *free_user_data,
+                            void (*vcmdarg_err)(const char *, va_list ap))
 {
     registered_log_writer_data = user_data;
     registered_log_writer_data_free = free_user_data;
-    ws_log_init(progname, writer);
+    ws_log_init_with_writer(progname, writer, vcmdarg_err);
 }
 
 
diff --git a/wsutil/wslog.h b/wsutil/wslog.h
index 50687932d6..b72bd39c1c 100644
--- a/wsutil/wslog.h
+++ b/wsutil/wslog.h
@@ -67,7 +67,7 @@ enum ws_log_level ws_log_get_level(void);
 
 /** Set the actice log level. Returns the same value (the active level). */
 WS_DLL_PUBLIC
-enum ws_log_level ws_log_set_level(enum ws_log_level log_level);
+void ws_log_set_level(enum ws_log_level log_level);
 
 
 /** Set the actice log level from a string.
@@ -117,7 +117,7 @@ void ws_log_set_noisy_filter(const char *str_filter);
  * LOG_LEVEL_ERROR is always fatal.
  */
 WS_DLL_PUBLIC
-enum ws_log_level ws_log_set_fatal(enum ws_log_level log_level);
+void ws_log_set_fatal(enum ws_log_level log_level);
 
 
 /** Set the fatal log level from a string.
@@ -129,6 +129,8 @@ WS_DLL_PUBLIC
 enum ws_log_level  ws_log_set_fatal_str(const char *str_level);
 
 
+#define LOG_ARGS_NOEXIT -1
+
 /** Parses the command line arguments for log options.
  *
  * Returns zero for no error, non-zero for a bad option value.
@@ -146,7 +148,8 @@ int ws_log_parse_args(int *argc_ptr, char *argv[],
  * is NULL the default log writer is used.
  */
 WS_DLL_PUBLIC
-void ws_log_init(const char *progname, ws_log_writer_cb *writer);
+void ws_log_init(const char *progname,
+                        void (*vcmdarg_err)(const char *, va_list ap));
 
 
 /** Initializes the logging code.
@@ -156,9 +159,17 @@ void ws_log_init(const char *progname, ws_log_writer_cb *writer);
  * is passed it will be called with user_data when the program terminates.
  */
 WS_DLL_PUBLIC
-void ws_log_init_with_data(const char *progname, ws_log_writer_cb *writer,
-                              void *user_data,
-                              ws_log_writer_free_data_cb *free_user_data);
+void ws_log_init_with_writer(const char *progname,
+                        ws_log_writer_cb *writer,
+                        void (*vcmdarg_err)(const char *, va_list ap));
+
+
+WS_DLL_PUBLIC
+void ws_log_init_with_writer_and_data(const char *progname,
+                        ws_log_writer_cb *writer,
+                        void *user_data,
+                        ws_log_writer_free_data_cb *free_user_data,
+                        void (*vcmdarg_err)(const char *, va_list ap));
 
 
 /** This function is called to output a message to the log.