apply -0 to stdin/-i as well

while i was initially against this since it can be done via `xargs -0`.
the problem with this approach is that there's a limit to how many args
a command can recieve, leading to problem like this [0] when opening
large (1k~) amount of images.

there's no limit on how big stdin can be, so being able to read a
null-separated list from stdin doesn't have this problem.

[0]: https://github.com/ranger/ranger/pull/2307#issuecomment-818683515

main.c

@@ -105,6 +105,14 @@ void cleanup(void)
 	win_close(&win);
 }
 
+static bool xgetline(char **lineptr, size_t *n)
+{
+	ssize_t len = getdelim(lineptr, n, options->using_null ? '\0' : '\n', stdin);
+	if (!options->using_null && len > 0 && (*lineptr)[len-1] == '\n')
+		(*lineptr)[len-1] = '\0';
+	return len > 0;
+}
+
 void check_add_file(char *filename, bool given)
 {
 	char *path;
@@ -853,7 +861,6 @@ int main(int argc, char *argv[])
 {
 	int i, start;
 	size_t n;
-	ssize_t len;
 	char *filename;
 	const char *homedir, *dsuffix = "";
 	struct stat fstats;
@@ -889,11 +896,8 @@ int main(int argc, char *argv[])
 	if (options->from_stdin) {
 		n = 0;
 		filename = NULL;
-		while ((len = getline(&filename, &n, stdin)) > 0) {
+		while (xgetline(&filename, &n))
-			if (filename[len-1] == '\n')
-				filename[len-1] = '\0';
 			check_add_file(filename, true);
-		}
 		free(filename);
 	}
 

nsxiv.1

@@ -128,7 +128,7 @@ Set zoom level to ZOOM percent.
 .TP
 .B \-0
 Use NULL-separator. With this option output of \-o and file-list sent to the
-key-handler will be seperated by a NULL character.
+key-handler and the input of \-i will be seperated by a NULL character.
 .SH KEYBOARD COMMANDS
 .SS General
 The following keyboard commands are available in both image and thumbnail mode: