From: Nick Bowler <nbowler@draconx.ca>
Date: Wed, 9 May 2012 04:06:19 +0000 (-0400)
Subject: uobject: First stab at a generic logging mechanism.
X-Git-Url: https://git.draconx.ca/gitweb/upkg.git/commitdiff_plain/e3726c0480d74840dd9104850cba0f3e5f93beed?ds=sidebyside

uobject: First stab at a generic logging mechanism.

Let's build something on top of Glib's logging facilities which probably
work well enough for what we want to do.  Add a couple calls to the
texture class for starters.
---

diff --git a/src/engine/texture.gob b/src/engine/texture.gob
index 3db176e..8059c3a 100644
--- a/src/engine/texture.gob
+++ b/src/engine/texture.gob
@@ -84,8 +84,10 @@ struct engine_texture_data *decode_mipmap(UObject *uo)
 
 	/* At this point, the current file offset should match the one recorded
 	 * above. */
-	if (uo->pkg->version >= 63 && end_offset != (f->base + f->offset))
+	if (uo->pkg->version >= 63 && end_offset != (f->base + f->offset)) {
+		u_err(uo, "mipmap end offset does not match data size");
 		goto err_free;
+	}
 
 	/* Read in the remaining fields */
 	buflen = upkg_export_read(f, buf, 10);
@@ -136,6 +138,8 @@ class Engine:Texture from U:Object (dynamic)
 		for (int i = 0; i < self->_priv->mipmap_count; i++) {
 			data[i] = decode_mipmap(uo);
 			if (!data[i]) {
+				u_err(uo, "error decoding mipmap level %d", i);
+
 				/* Unwind the allocations. */
 				for (; i >= 0; i--)
 					free(data[i]);
diff --git a/src/uobject/uobject.c b/src/uobject/uobject.c
index 9174005..1a3d740 100644
--- 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);
+}
diff --git a/src/uobject/uobject.h b/src/uobject/uobject.h
index 2f70940..e91bf5b 100644
--- a/src/uobject/uobject.h
+++ b/src/uobject/uobject.h
@@ -20,6 +20,7 @@
 #define U_OBJECT_H_
 
 #include <glib-object.h>
+#include <stdarg.h>
 #include "upkg.h"
 
 #define U_TYPE_OBJECT u_object_get_type()
@@ -56,4 +57,12 @@ int u_object_deserialize(GObject *obj, struct upkg *pkg, unsigned long idx);
 
 GObject *u_object_new_from_package(struct upkg *pkg, unsigned long idx);
 
+/* Logging helpers for UObject class implementations. */
+void u_vlog_full(GObject *o, GLogLevelFlags level, const char *fmt, va_list ap);
+void u_log_full(GObject *o, GLogLevelFlags level, const char *fmt, ...);
+
+#define u_log(uo, ...)  u_log_full(G_OBJECT(uo), G_LOG_LEVEL_MESSAGE, __VA_ARGS__)
+#define u_warn(uo, ...) u_log_full(G_OBJECT(uo), G_LOG_LEVEL_WARNING, __VA_ARGS__)
+#define u_err(uo, ...)  u_log_full(G_OBJECT(uo), G_LOG_LEVEL_CRITICAL, __VA_ARGS__)
+
 #endif