uobject: First stab at a generic logging mechanism.

[upkg.git] / src / uobject / uobject.c

diff --git a/src/uobject/uobject.c b/src/uobject/uobject.c
index 91740054514799f0f2c477f4622e99814eea4169..1a3d740f9e4ab7a786e049bd0111d1978d4e1c0f 100644 (file)
--- a/src/uobject/uobject.c
+++ b/src/uobject/uobject.c
@@ -19,7 +19,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdarg.h>
 #include <stdbool.h>
+#include <inttypes.h>
 #include <assert.h>
 #include <glib-object.h>
 
@@ -375,3 +377,74 @@ static void u_object_class_init(UObjectClass *class)
        class->deserialize = deserialize;
        go->finalize       = u_object_finalize;
 }
+
+/*
+ * Prepend a prefix to a printf-style format string.  Unfortunately, there's
+ * no way to construct va_list values on the fly in C, so we cannot simply
+ * prepend %s and pass the prefix as an argument.  Any % characters in the
+ * prefix will be escaped.
+ *
+ * Returns a pointer to a newly allocated string, which should be freed by the
+ * caller, or NULL otherwise.
+ */
+static char *prepend_fmt(const char *prefix, const char *fmt)
+{
+       size_t prefix_len = strlen(prefix), fmt_len = strlen(fmt);
+       char *new_fmt;
+
+       if (prefix_len > SIZE_MAX/2 - sizeof ": ")
+               return NULL;
+       if (2*prefix_len > SIZE_MAX - fmt_len)
+               return NULL;
+
+       new_fmt = malloc(2*prefix_len + fmt_len + 1);
+       if (new_fmt) {
+               size_t offset = 0;
+
+               for (size_t i = 0; i < prefix_len; i++) {
+                       if (prefix[i] == '%')
+                               new_fmt[offset++] = '%';
+                       new_fmt[offset++] = prefix[i];
+               }
+
+               new_fmt[offset++] = ':';
+               new_fmt[offset++] = ' ';
+               strcpy(new_fmt+offset, fmt);
+       }
+
+       return new_fmt;
+}
+
+/* Logging helpers that automatically prepend the UObject class information. */
+void u_vlog_full(GObject *o, GLogLevelFlags level, const char *fmt, va_list ap)
+{
+       g_return_if_fail(IS_U_OBJECT(o));
+       UObject *uo = U_OBJECT(o);
+       char *new_fmt = NULL;
+
+       if (uo->pkg_file) {
+               /* XXX: Currently, there's no way to get the full object name
+                * here because the object path information is discarded
+                * after opening it.  In principle, there's no reason why
+                * we couldn't keep it around to improve log messages. */
+               new_fmt = prepend_fmt(uo->pkg_file->name, fmt);
+               if (!new_fmt) {
+                       g_log(G_OBJECT_TYPE_NAME(o), level, "%s",
+                             uo->pkg_file->name);
+               } else {
+                       fmt = new_fmt;
+               }
+       }
+
+       g_logv(G_OBJECT_TYPE_NAME(o), level, fmt, ap);
+       free(new_fmt);
+}
+
+void u_log_full(GObject *o, GLogLevelFlags level, const char *fmt, ...)
+{
+       va_list ap;
+
+       va_start(ap, fmt);
+       u_vlog_full(o, level, fmt, ap);
+       va_end(ap);
+}