--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/error.h	Sun Feb 22 06:44:16 2009 +0200
@@ -0,0 +1,76 @@
+#ifndef ERROR_H
+#define ERROR_H
+
+/*
+ * Error-handling functions
+ */
+#include <errno.h>
+
+/*
+ * Type used for error codes is an explicitly *unsigned* int, meaning that error codes themselves are positive.
+ * Negative error codes also exist in some places, and they are just a negative err_t.
+ */
+typedef unsigned int err_t;
+
+/*
+ * List of defined error codes, organized mostly by function name
+ */
+enum error_code {
+    ERR_CALLOC                  = 0x000100,
+    
+    // network resolver errors
+    ERR_GETADDRINFO             = 0x000200,
+    ERR_GETADDRINFO_EMPTY       = 0x000201,     /* No valid results */
+
+    // low-level network errors
+    ERR_SOCKET                  = 0x000301,
+    ERR_CONNECT                 = 0x000302,
+
+    // low-level IO errors
+    ERR_READ                    = 0x000401,
+    ERR_WRITE                   = 0x000402,
+};
+
+/*
+ * An error code and associated extra infos
+ */
+struct error_info {
+    /* The base error code */
+    err_t code;
+
+    /* Additional detail info, usually some third-part error code */
+    unsigned int extra;
+};
+
+/** No error, evaulates as logical false */
+#define SUCCESS (0)
+
+/* Evaulates to error_info.code as lvalue */
+#define ERROR_CODE(err_info) ((err_info).code)
+
+/* Evaulates to error_info.extra as lvalue */
+#define ERROR_EXTRA(err_info) ((err_info).extra)
+
+/* Set error_info.code to SUCCESS, evaulates as zero */
+#define RESET_ERROR(err_info) ((err_info).code = SUCCESS)
+
+/* Compare error_info.code != 0 */
+#define IS_ERROR(err_info) (!!(err_info).code)
+
+/* Set error_info.code, but leave err_extra as-is. Evaluates to err_code */
+#define SET_ERROR(err_info, err_code) ((err_info).code = (err_code))
+
+/* Set error_info.code/extra. XXX: should evaluate to err_code */
+#define _SET_ERROR_EXTRA(err_info, err_code, err_extra) (err_info).code = (err_code); err_info.extra = (err_extra)
+#define SET_ERROR_EXTRA(err_info, err_code, err_extra) do { _SET_ERROR_EXTRA(err_info, err_code, err_extra); } while (0)
+
+/* Set error.info.code to err_code, and .extra to errno. XXX: should evaulate to err_code */
+#define _SET_ERROR_ERRNO(err_info, err_code) _SET_ERROR_EXTRA(err_info, err_code, errno);
+#define SET_ERROR_ERRNO(err_info, err_code) SET_ERROR_EXTRA(err_info, err_code, errno);
+
+/* Ss above, but also return err_code from func. XXX: use 'return SET_ERROR...' instead */
+#define RETURN_SET_ERROR(err_info, err_code) do { _SET_ERROR(err_info, err_code); return (err_code); } while (0)
+#define RETURN_SET_ERROR_EXTRA(err_info, err_code, err_extra) do { _SET_ERROR_EXTRA(err_info, err_code, err_extra); return (err_code); } while (0)
+#define RETURN_SET_ERROR_ERRNO(err_info, err_code) do { _SET_ERROR_ERRNO(err_info, err_code); return (err_code); } while (0)
+
+#endif