create a new Logger interface

diff --git a/src/Makefile.am b/src/Makefile.am
index 1be9a5d7177df5db2e54ef0a7b636005a4b04f00..457d70630b08b1e959fb5320205fb356083f93c9 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -18,6 +18,8 @@ lightdm_SOURCES = \
        guest-account.c \
        guest-account.h \
        lightdm.c \
+       logger.c \
+       logger.h \
        login1.c \
        login1.h \
        mir-server.c \

diff --git a/src/logger.c b/src/logger.c
new file mode 100644 (file)
index 0000000..23bce20
--- /dev/null
+++ b/src/logger.c
@@ -0,0 +1,81 @@
+#include "logger.h"
+
+G_DEFINE_INTERFACE (Logger, logger, G_TYPE_INVALID);
+
+static void
+logger_logv_default (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap);
+
+static void
+logger_default_init (LoggerInterface *iface)
+{
+    iface->logv = &logger_logv_default;
+}
+
+gint
+logger_logprefix (Logger *self, gchar *buf, gulong buflen)
+{
+    g_return_val_if_fail (IS_LOGGER (self), -1);
+    return LOGGER_GET_INTERFACE (self)->logprefix (self, buf, buflen);
+}
+
+void
+logger_logv (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap)
+{
+    g_return_if_fail (IS_LOGGER (self));
+    LOGGER_GET_INTERFACE (self)->logv (self, log_level, format, ap);
+}
+
+void
+logger_logv_default (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap)
+{
+    va_list ap_copy;
+    gint tmp;
+
+    /* figure out how long the prefix is */
+    tmp = logger_logprefix (self, NULL, 0);
+    if (tmp < 0)
+    {
+        g_error ("failed to get log prefix");
+        return;
+    }
+
+    /* print the prefix to a variable length array (to avoid malloc) */
+    gchar pfx[tmp + 1];
+    tmp = logger_logprefix (self, pfx, sizeof(pfx));
+    if (tmp < 0)
+    {
+        g_error ("failed to get log prefix");
+        return;
+    }
+
+    /* figure out how long the formatted message is */
+    va_copy (ap_copy, ap);
+    tmp = g_vsnprintf (NULL, 0, format, ap_copy);
+    va_end (ap_copy);
+    if (tmp < 0)
+    {
+        g_error ("failed to format log message");
+        return;
+    }
+
+    /* print the message to a variable length array (to avoid malloc) */
+    gchar msg[tmp+1];
+    tmp = g_vsnprintf (msg, sizeof(msg), format, ap);
+    if (tmp < 0)
+    {
+        g_error ("failed to format log message");
+        return;
+    }
+
+    /* log the message with the prefix */
+    g_log (G_LOG_DOMAIN, log_level, "%s%s", pfx, msg);
+}
+
+void
+logger_log (Logger *self, GLogLevelFlags log_level, const gchar *format, ...)
+{
+    va_list ap;
+    va_start (ap, format);
+    logger_logv (self, log_level, format, ap);
+    va_end (ap);
+}

diff --git a/src/logger.h b/src/logger.h
new file mode 100644 (file)
index 0000000..f139e78
--- /dev/null
+++ b/src/logger.h
@@ -0,0 +1,60 @@
+#ifndef LOGGER_H_
+#define LOGGER_H_
+
+#include <glib-object.h>
+
+#ifdef __cplusplus
+#include <cstdarg>  /* for va_list */
+#else
+#include <stdarg.h>  /* for va_list */
+#endif
+
+G_BEGIN_DECLS
+
+#define LOGGER_TYPE (logger_get_type ())
+#define LOGGER(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), LOGGER_TYPE, Logger))
+#define IS_LOGGER(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), LOGGER_TYPE))
+#define LOGGER_GET_INTERFACE(obj) (G_TYPE_INSTANCE_GET_INTERFACE ((obj), LOGGER_TYPE, LoggerInterface))
+
+typedef struct Logger Logger;
+
+typedef struct {
+    GTypeInterface parent;
+
+    gint (*logprefix) (Logger *self, gchar *buf, gulong buflen);
+    void (*logv) (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap);
+} LoggerInterface;
+
+GType logger_get_type (void);
+
+/*!
+ * \brief instruct \c self to generate a log message prefix
+ *
+ * the semantics of the \c buf and \c buflen arguments and the return
+ * value are the same as g_snprintf()
+ *
+ * there is no default implementation
+ */
+gint logger_logprefix (Logger *self, gchar *buf, gulong buflen);
+
+/*!
+ * \brief instruct \c self to log the given message
+ *
+ * the default implementation prefixes the log message with the
+ * output of logger_logprefix() and then passes the result to
+ * g_log()
+ */
+void logger_logv (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap);
+
+/*! \brief convenience wrapper around \c logger_logv() */
+void logger_log (Logger *self, GLogLevelFlags log_level, const gchar *format, ...);
+
+/* convenience wrappers around logger_log() */
+#define l_debug(self, ...) \
+    logger_log (LOGGER (self), G_LOG_LEVEL_DEBUG, __VA_ARGS__)
+#define l_warning(self, ...) \
+    logger_log (LOGGER (self), G_LOG_LEVEL_WARNING, __VA_ARGS__)
+
+G_END_DECLS
+
+#endif /* !LOGGER_H_ */