arg parsing: rework error handling to return optional extra information with error code.

arg parsing: added freeing and cloning of internally allocated parts of `struct args_parsed` and `struct args_parse_error`.

Fortune for sink's current commit: Half blessing − 半吉

args.c

@@ -1,26 +1,162 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
 
 #include "args.h"
 
+#define _PASTE_(x, y) x ## y
+#define _PASTE(x, y) _PASTE_(x, y)
+
+#define _box_name(nm) _PASTE(_box_, _PASTE(nm, __LINE__))
+#define $box(expr) ({  __typeof((expr))* _box_name(p) = aligned_alloc(_Alignof(__typeof((expr))), sizeof(__typeof((expr)))); \
+			if(__builtin_expect(_box_name(p) != NULL, true)) *_box_name(p) = (expr); \
+			_box_name(p); })
+
+#define $box_t(T, expr) ({ T* _box_name(pT) = aligned_alloc(_Alignof(T), sizeof(T)); \
+				if(__builtin_expect(_box_name(pT) != NULL, true)) *_box_name(pT) = (expr); \
+			_box_name(pT); })
+
+typedef __typeof( *((pargs_t*)0)->fd_pass ) fd_pass_t;
+
 const pargs_t* parsed_args = NULL;
 static const pargs_t default_args[1] = { A_DEFAULT_ARGS }; //A_DEFAULT_ARGS_P;
 
+static fd_pass_t* _a_alloc_fd_pass(size_t n)
+{
+	fd_pass_t* pass = aligned_alloc(_Alignof(fd_pass_t), sizeof(fd_pass_t) + (sizeof(int)*n));
+	if(__builtin_expect(pass!=NULL,true)) {
+		pass->n = n;
+		//memset(pass->fds, 0, sizeof(int) * n);
+	}
+	return pass;
+}
+
+void* a_pass_fds(size_t n, ...)
+{
+	va_list va;
+	va_start(va, n);
+	fd_pass_t* pass;
+	if(!n) {
+		pass = A_FD_PASS_NONE;
+		goto _end;
+	}
+	pass = _a_alloc_fd_pass(n);
+	if(__builtin_expect(pass!=NULL, true)) {
+		int* fds = pass->fds;
+		while ( n --> 0 ) {
+			int fd = va_arg(va, int);
+			*fds++ = fd;
+		}
+	}
+_end:
+	va_end(va);
+	return pass;
+}
+
+inline void* a_pass_fds_a(size_t n, int ar[const restrict n])
+{
+	if(!n) return A_FD_PASS_NONE;
+	fd_pass_t* pass = _a_alloc_fd_pass(n);
+	if(__builtin_expect(pass!=NULL, true))
+		memcpy(pass->fds, ar, n * sizeof(int));
+	return pass;
+}
+
 const pargs_t* a_get_program_args() {
 	return parsed_args ?: default_args; 
 }
 
 bool a_is_parsed() { return parsed_args != NULL; }
 
-enum arg_parse_result a_parse_into(pargs_t *restrict parsed, int *restrict argc, char** *restrict p_argv, char** *restrict p_envp)
+bool a_parse_into(union arg_parse_result *restrict parsed, int *restrict argc, char** *restrict p_argv, char** *restrict p_envp)
 {
 	//TODO
-	return A_PF_UNKNOWN;
+	parsed->err = (struct arg_parse_error) { .kind = A_PF_UNKNOWN, ._data = { .none = {} } };
+	return false;
+}
+
+const struct arg_parse_error* a_parse(int *restrict argc, char** *restrict p_argv, char** *restrict p_envp)
+{
+	/*XXX: Probably not needed... _Thread_local*/ 
+	static union arg_parse_result glob_parsed_args_r;
+
+	if(a_parse_into(&glob_parsed_args_r, argc, p_argv, p_envp))
+		parsed_args = &glob_parsed_args_r.ok; // A_P_OK
+	else
+		return &glob_parsed_args_r.err;
+	return NULL;
+}
+
+pargs_t* a_clone_args(const pargs_t* args)
+{
+	if(__builtin_expect(args!=NULL, true)) {
+		pargs_t clone;
+
+		/* replace */ clone.replace = args->replace;
+
+		/* target */ {
+			const char* target_p = args->target;
+			clone.target = target_p ? strdup(target_p) : NULL;
+		};
+
+		/* fd_pass */ {
+			__auto_type fd_pass_p = args->fd_pass;
+			switch((uintptr_t)fd_pass_p) {
+				case ((uintptr_t)A_FD_PASS_ALL): 
+				case ((uintptr_t)A_FD_PASS_NONE):
+					clone.fd_pass = fd_pass_p;
+					break;
+				default: {
+					// Clone fd_pass_p.
+					clone.fd_pass = a_pass_fds_a(fd_pass_p->n, fd_pass_p->fds);
+				} break;
+			}
+		};
+
+		return $box(clone);
+	} else return NULL;
+}
+
+inline void a_free_args(const pargs_t* args)
+{
+	if(__builtin_expect(args==NULL, false)) return;
+
+	/* fd_pass */ {
+		__auto_type fd_pass_p = args->fd_pass;
+		if(fd_pass_p != A_FD_PASS_NONE
+			&& fd_pass_p != A_FD_PASS_ALL) free(fd_pass_p);
+	};
+
+	/* target */ {
+		char* target_p = args->target;
+		if(target_p) free(target_p);
+	};
 }
 
-enum arg_parse_result a_parse(int *restrict argc, char** *restrict p_argv, char** *restrict p_envp)
+void a_free(pargs_t* restrict args)
 {
-	_Thread_local static pargs_t glob_parsed_args;
-	enum arg_parse_result r = a_parse_into(&glob_parsed_args, argc, p_argv, p_envp);
+	if(__builtin_expect(args!=NULL, true)) {
+		a_free_args(args);
+		free(args);
+	}
+}
 
-	if(!r) parsed_args = &glob_parsed_args; // A_P_OK
-	return r;
+struct arg_parse_error* a_clone_error(const struct arg_parse_error* error)
+{
+	/* no-op, for now */
+	if(__builtin_expect(error != NULL, true)) {
+		return $box_t(struct arg_parse_error, *error);
+	}
+	else return NULL;
+}
+
+void a_free_error(const struct arg_parse_error* error)
+{
+	(void)error; // no-op, for now;
+}
+
+__attribute__((destructor))
+static void _a__free_globals()
+{
+	a_free_args(parsed_args);
 }

args.h

@@ -6,19 +6,19 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-enum arg_parse_result {
+enum arg_parse_error_kind {
 	A_PF_UNKNOWN = -1,
 	A_P_OK = 0,
 
 	// TODO: specific errors... 
 };
 
-typedef struct {
+typedef struct arg_parsed {
 	struct {
 		bool in,out,err;
 	} replace; // { 1, 1, 0 }
 
-	const char* target; // NULL -> default "/dev/null"
+	char* target; // NULL -> default "/dev/null"
 
 	struct {
 		/*struct _Alignas(uint64_t) {
@@ -32,6 +32,19 @@ typedef struct {
 
 } pargs_t;
 
+struct arg_parse_error {
+	enum arg_parse_error_kind kind;
+	union {
+		struct{} none;
+	} _data;
+};
+_Static_assert(sizeof(  ((struct arg_parse_error*)(0))->_data ) == 0, "Bad union ZST");
+
+union arg_parse_result {
+	struct arg_parsed ok;
+	struct arg_parse_error err;
+};
+
 #define A_FD_PASS_ALL  ((void*)(~((uintptr_t)0ul)))
 #define A_FD_PASS_NONE NULL
 
@@ -53,16 +66,28 @@ _a_inline_proto const pargs_t* a_get_program_args()
 _a_inline_proto bool a_is_parsed() 
 { return parsed_args != NULL; }
 
-enum arg_parse_result a_parse_into(pargs_t *restrict parsed, int *restrict argc, char** *restrict p_argv, char** *restrict p_envp);
+/// Create an `pargs_t.fd_pass` value for `n` fds.
+void* a_pass_fds(size_t n, ...);
+/// Create an `pargs_t.fd_pass` value for `n` fds from the array `ar`.
+void* a_pass_fds_a(size_t n, int ar[const restrict n]);
 
-_a_inline_proto // TODO: XXX: Is this worth it?
-enum arg_parse_result a_parse(int *restrict argc, char** *restrict p_argv, char** *restrict p_envp)
-{
-	static pargs_t glob_parsed_args; //XXX: Wth is this an error?
-	enum arg_parse_result r = a_parse_into(&glob_parsed_args, argc, p_argv, p_envp);
+bool a_parse_into(union arg_parse_result *restrict parsed, int *restrict argc, char** *restrict p_argv, char** *restrict p_envp);
+const struct arg_parse_error* a_parse(int *restrict argc, char** *restrict p_argv, char** *restrict p_envp);
+
+/// Clone a `pargs_t` struct. The returned struct pointer must be freed with `a_free()`.
+pargs_t* a_clone_args(const pargs_t* args);
+
+/// Clone a `struct arg_parse_error`. The returned struct pointer must be freed with `a_free_args()`, then with stdlib `free()` itself.
+struct arg_parse_error* a_clone_error(const struct arg_parse_error* error);
+
+/// Free the internals of a `pargs_t` struct.
+void a_free_args(const pargs_t* args);
+
+/// Free the internals of an `arg_parse_error` struct.
+void a_free_error(const struct arg_parse_error* error);
+
+/// Free a `malloc()` or `a_clone_args()`'d `pargs_t` struct (NOTE: do *not* pass the result of `a_get_program_args()` or `parsed_args` to this, use `a_free_args()` for those instead.
+void a_free(pargs_t* restrict args);
 
-	if(!r) parsed_args = &glob_parsed_args; // A_P_OK
-	return r;
-}
 #undef _a_inline_proto
 #endif /* _ARGS_H */

sink.c

@@ -210,7 +210,7 @@ static void print_debug_info(int argc, char* const* argv, char* const* envp)
 
 static bool parse_args(int *restrict argc, char** *restrict argv, char** *restrict envp)
 {
-	return a_parse(argc, argv, envp) == A_P_OK   || true; //TODO: Print proper error messages on failures.
+	return a_parse(argc, argv, envp) /* == NULL */ || true; //TODO: Print proper error messages on failures.
 }
 
 int main(int argc, char** argv, char** envp)