Initial commit.

src/debug.h

@@ -0,0 +1,50 @@
+/*
+ * Debug functions.
+ *
+ * Copyright (C) 2013  Simon Ruderich
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef DEBUG_H
+#define DEBUG_H 1
+
+static void debug(const char *format, ...) {
+    char buffer[1024];
+
+    /* If the file doesn't exist, do nothing. Prevents writing log files in
+     * unexpected places. The user must create the file manually. */
+    int fd = open(DEBUG_FILE, O_WRONLY | O_APPEND);
+    if (fd == -1)
+        return;
+
+    va_list ap;
+    va_start(ap, format);
+    int written = vsnprintf(buffer, sizeof(buffer), format, ap);
+    va_end(ap);
+
+    /* Make sure these functions are loaded. */
+    DLSYM_FUNCTION(real_write, "write");
+    DLSYM_FUNCTION(real_close, "close");
+
+    static int first_call = 0;
+    if (!first_call++) {
+        char nl = '\n';
+        real_write(fd, &nl, 1);
+    }
+    real_write(fd, buffer, (size_t)written);
+    real_close(fd);
+}
+
+#endif