error: refactor the whole thing

a.k.a. make it more complicated.

include/neo/_error.h

@@ -6,6 +6,9 @@
 
 /**
  * Throw an error.  If `err` is `nil`, the program halts.
+ * Functions accepting an `err` object must call either `yeet` or `neat`
+ * on the object exactly once, or the behavior is undefined.
+ * If a function yeets an error, its return value is undefined.
  *
  * @param err: The error pointer passed to the callee
  * @param number: An error number appropriate for the condition,
@@ -14,24 +17,47 @@
  *	the values to insert which will become the error message.
  */
 __attribute__(( __format__(printf, 3, 4) ))
-void yeet(error *err, int number, const char *restrict fmt, ...);
+void yeet(error *err, u32 number, const char *restrict fmt, ...);
 
 /**
- * Functions accepting an error pointer must call this to indicate success.
+ * Indicate an operation has completed successfully.
+ * Functions accepting an `error` pointer must call either `yeet` or `neat`,
+ * or the begavior is undefined.
+ *
+ * @param err: Error object
  */
-#define neat(errptr) ({			\
-	if (errptr)			\
-		*(errptr) = nil;	\
-})
+void neat(error *err);
 
 /**
- * Functions passing an error pointer must call this to acknowledge an error.
+ * Release any resources allocated for an error.
+ * This must always be called within the catch block of the outermost calling
+ * function, i.e. the one that declared the error variable (not the ones just
+ * accepting an error * argument and passing it through to further calls).
+ *
+ * Put another way, you probably need to call this if you had to put an `&`
+ * before the error variable for passing it into `catch`.
+ *
+ * @param err: Error object to destroy
  */
-void catch(error *err);
+void errput(error *err);
 
-/** Get the error number */
+/**
+ * Execute the expression after this macro call if the error pointed to
+ * by `err` is an actual error, i.e. it has been `yeet`ed to.
+ * Resources for the error must be released using `nput`.
+ */
+#define catch(err) if ((err) != nil && (err)->_number != 0)
+
+/**
+ * Get the error number.
+ * Must only be used within a catch block and before `errput` is called.
+ */
 #define errnum(err) ((err)->_number)
-/** Get an optional error message, this may be `nil` */
+
+/**
+ * Get an optional error message, this may be `nil`
+ * Must only be used within a catch block and before `errput` is called.
+ */
 #define errmsg(err) ((err)->_message)
 
 /*

include/neo/_types.h

@@ -53,7 +53,7 @@ struct _neo_error {
 	u32 _number;
 	u32 _flags; /* see src/error.c */
 };
-typedef struct _neo_error *error;
+typedef struct _neo_error error;
 
 /*
  * This file is part of libneo.

src/error.c

@@ -11,37 +11,26 @@
 #include "neo/_nref.h"
 #include "neo/_stddef.h"
 #include "neo/_string.h"
-#include "neo/_toolchain.h"
 #include "neo/_types.h"
 
-/* flags for the error structure */
-#define NEO_ERR_CAUGHT		(1 << 0)
-
-/* TODO: we need one of these for every thread */
-static struct _neo_error _neo_error_instance = {
-	._number = 0,
-	._message = nil,
-	._flags = NEO_ERR_CAUGHT,
-};
-
-void yeet(error *err, int number, const char *restrict fmt, ...)
+void yeet(error *err, u32 number, const char *restrict fmt, ...)
 {
 	va_list vargs;
 	usize msg_capacity = 64;
 	char *msg = nil;
-	int printf_ret;
+	int vsnprintf_ret;
 
 	if (fmt != nil) {
 		do {
 			msg = nalloc(msg_capacity, nil);
 			va_start(vargs, fmt);
-			printf_ret = vsnprintf(msg, msg_capacity, fmt, vargs);
+			vsnprintf_ret = vsnprintf(msg, msg_capacity, fmt, vargs);
 			va_end(vargs);
-			if (printf_ret > 0) {
-				msg_capacity += printf_ret;
+			if (vsnprintf_ret > 0) {
+				msg_capacity += vsnprintf_ret;
 				nfree(msg);
 				msg = nil;
-			} else if (printf_ret < 0) {
+			} else if (vsnprintf_ret < 0) {
 				write(1, "Runtime error\n", 14);
 				exit(1);
 			}
@@ -55,18 +44,25 @@ void yeet(error *err, int number, const char *restrict fmt, ...)
 		exit(number);
 	}
 
-	*err = &_neo_error_instance;
-	(*err)->_number = number;
-	(*err)->_message = nstr(msg, nil);
-	(*err)->_flags &= ~NEO_ERR_CAUGHT;
+	err->_number = number;
+	err->_message = nstr(msg, nil);
 }
 
-void catch(error *err)
+void neat(error *err)
 {
-	if ((*err)->_message)
-		nput((*err)->_message);
-	(*err)->_flags |= NEO_ERR_CAUGHT;
-	*err = nil;
+	if (err) {
+		err->_number = 0;
+		err->_message = nil;
+	}
+}
+
+void errput(error *err)
+{
+	if (err != nil) {
+		if (err->_message != nil)
+			nput(err->_message);
+		err->_number = 0xffffffff;
+	}
 }
 
 /*