From 5341f4055b25f1bbc1629018ed83fca3e0253b48 Mon Sep 17 00:00:00 2001
From: Matt Mundell <matt@mundell.me>
Date: Thu, 9 May 2024 16:22:22 +0200
Subject: [PATCH] Add: set_log_tz

---
 base/logging.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 base/logging.h |  3 +++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/base/logging.c b/base/logging.c
index 290d4a26..36223c05 100644
--- a/base/logging.c
+++ b/base/logging.c
@@ -34,6 +34,13 @@
  */
 #define G_LOG_DOMAIN "libgvm base"
 
+/**
+ * @brief Timezone to use for logs.
+ *
+ * NULL means to use the current timezone.
+ */
+static gchar *log_tz = NULL;
+
 /**
  * @struct gvm_logging_t
  * @brief Logging stores the parameters loaded from a log configuration
@@ -69,7 +76,14 @@ get_time (gchar *time_fmt)
 {
   time_t now;
   struct tm ts;
-  gchar buf[80];
+  gchar buf[80], *original_tz;
+
+  if (log_tz)
+    {
+      original_tz = getenv ("TZ") ? g_strdup (getenv ("TZ")) : NULL;
+      setenv ("TZ", log_tz, 1);
+      tzset ();
+    }
 
   /* Get the current time. */
   now = time (NULL);
@@ -78,6 +92,19 @@ get_time (gchar *time_fmt)
   localtime_r (&now, &ts);
   strftime (buf, sizeof (buf), time_fmt, &ts);
 
+  if (log_tz)
+    {
+      /* Revert to stored TZ. */
+      if (original_tz)
+        {
+          setenv ("TZ", original_tz, 1);
+          g_free (original_tz);
+          tzset ();
+        }
+      else
+        unsetenv ("TZ");
+    }
+
   return g_strdup_printf ("%s", buf);
 }
 
@@ -873,6 +900,21 @@ check_log_file (gvm_logging_t *log_domain_entry)
   return 0;
 }
 
+/**
+ * @brief Set the log timezone.
+ *
+ * This is the timezone used for dates in log messages. If NULL then
+ * the current timezone is used.
+ *
+ * @param tz Timezone.
+ */
+void
+set_log_tz (const gchar *tz)
+{
+  g_free (log_tz);
+  log_tz = tz ? g_strdup (tz) : NULL;
+}
+
 /**
  * @brief Sets up routing of logdomains to log handlers.
  *
diff --git a/base/logging.h b/base/logging.h
index 5919e798..729a30ed 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -54,4 +54,7 @@ get_log_reference (void);
 void
 free_log_reference (void);
 
+void
+set_log_tz (const gchar *);
+
 #endif /* not _GVM_LOGGING_H */