Added `--help` option

Fortune for naka's current commit: Small curse − 小凶

include/map.h

@@ -38,6 +38,7 @@ typedef union memory_map {
 } map_t;
 
 map_result_t map_fd(int fd, bool write, usize size, off_t offset, map_t *pOUT map);
+/// Specify size as 0 to use the file's full size for the map.
 map_result_t map_file(const char* file, bool write, usize size, off_t offset, map_t *pOUT map);
 map_result_t map_anon(void* ptr, usize len, map_t *pOUT map);
 map_result_t map_free(map_t map);

include/project.h

@@ -24,4 +24,18 @@
 /// Compiled time (UTC unix timestamp)
 #define PROG_COMPILED_TIMESTAMP AS(_PROJECT_COMPILED, u64)
 
+
+// Returns from the program
+
+// Invalid arguments to program (print usage to stderr)
+#define PROG_RET_ARGS 1
+// Mapping of argv[1] failed
+#define PROG_RET_MAP_NEEDLE_FAILED 2
+// `h` is the number in argv[] of the haystack file
+#define PROG_RET_MAP_HAYSTACK_N_FAILED(h) ((h) << 2)
+// `h` is the number in argv[] of the haystack file
+#define PROG_RET_UNMAP_HAYSTACK_N_FAILED(h) (((h) << 2) | 1)
+// Unmapping of argv[1] failed
+#define PROG_RET_UNMAP_NEEDLE_FAILED 3
+
 #endif /* _PROJECT_H */

src/main.c

@@ -33,6 +33,7 @@ void usage(FILE* out, int argc, char** argv)
 
 	prog_info(out);
 	fprintf(out, "\nUsage: %s <needle> <haystack(s)...>\n", argv[0] ?: PROG_NAME);
+	fprintf(out, "\nUsage: %s --help\n", argv[0] ?: PROG_NAME);
 }
 
 // err: 0 for normal exit and print to stdout.
@@ -43,20 +44,27 @@ noreturn void usage_then_exit(int err, int argc, char** argv)
 	exit(err);
 }
 
+
 int main(int argc, char** argv)
 {
 	TRACE("main start with %d (pn: %s, a1: %s)", argc, argv[0], argv[1] ?: "<null>");
 
-	if(!argv[1] || !argv[2]) usage_then_exit(1, argc, argv);
+	if(!argv[1]) 
+inv_args:
+		usage_then_exit(PROG_RET_ARGS, argc, argv);
+	else if(strcmp(argv[1], "--help")==0)
+		usage_then_exit(0, argc, argv);
+	else if(!argv[2])
+		goto inv_args;
 
 	map_t needle;
 	INFO("Mapping needle file `%s'", argv[1]);
-	if(!map_handle_err(map_file(argv[1], false, 0, 0, &needle))) return 2;
+	if(!map_handle_err(map_file(argv[1], false, 0, 0, &needle))) return PROG_RET_MAP_NEEDLE_FAILED;
 
-	if(!map_handle_err(map_free(needle))) return 3;
+	
 
+	if(!map_handle_err(map_free(needle))) return PROG_RET_UNMAP_NEEDLE_FAILED;
 	TRACE("main end");
-
 	return 0;
 }