ADDED   newtab.c
Index: newtab.c
==================================================================
--- newtab.c
+++ newtab.c
@@ -0,0 +1,151 @@
+/* [ʞ] newtab.c
+ *  ~ lexi hale <lexi@hale.su>
+ *  $ cc -Ofast newtab.c -onewtab \
+ *      [-D_default_qutebrowser_location=/...]
+ *  $ ./newtab [example.net]
+ *  © AGPLv3
+ *  ? may god have mercy on my soul.
+ *    i wrote this because qutebrowser, being a python
+ *    abomination, takes an absurdly fucking long time
+ *    to load, even when there's already an instance
+ *    running and i just want a new goddamn tab. it
+ *    turns out, qutebrowser publishes an inane IPC
+ *    mechanism, in which JSON (i know!!) written to a
+ *    unix domain socket (I KNOW) can send signals to
+ *    a running qutebrowser process. newtab checks if
+ *    there's a running qutebrowser process and sends
+ *    the appropriate IPC signal if so. otherwise, it
+ *    execs a new qutebrowser instance.
+ *
+ *    it takes a single argument, the URI of a page to
+ *    navigate to. if launched without an argument,
+ *    newtab simply opens a blank new tab. simple
+ *    enough, right? but why write it in C? to talk to
+ *    a goddammned python application, of all things?
+ *    well, i was originally going to do this in a
+ *    bash script with socat, but then i pulled up the
+ *    socat manpage and immediately decided it would
+ *    be faster to implement the damn thing in C, and
+ *    performance would be better anyway. i think it
+ *    is fair to say that i was correct.
+ *
+ *    so, that's half the story. the code quality is
+ *    the other half. i'm going to be straight with
+ *    you: i wrote this sleep-deprived at 7am because
+ *    i'd stayed up all night with my boyfriend who's
+ *    still remote-working on German time because his
+ *    employers are kind of assholes. i'm aware that's
+ *    not an excuse and i apologize sincerely. if
+ *    anyone wants to submit a MR to tidy up this
+ *    abomination without sacrificing performance, i
+ *    would welcome it gratefully. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <dirent.h>
+#include <unistd.h>
+#define _POSIX_C_SOURCE 200809L
+#include <string.h>
+
+#define ssz(str) (str), (sizeof str)
+#define dupl(x) x,x
+
+#ifndef _default_qutebrowser_location
+#	define _default_qutebrowser_location "/usr/bin/qutebrowser"
+#endif
+
+#define jstr(val) "\"" val "\""
+#define j(key, val) jstr(#key) ": " val
+#define json_msg_start "{" \
+			j(protocol_version, "1") "," \
+			j(target_arg, jstr("")) "," \
+			jstr("args")": [\""
+#define json_msg_end "\"]}\n"
+
+enum status {
+	ok,
+	start_instance,
+	fail_xdg_null,
+	fail_find,
+};
+
+const char* errors [] = {
+	[ok] = NULL,
+	[start_instance] = NULL,
+	[fail_xdg_null] = "$XDG_RUNTIME_DIR is not set - cannot locate IPC socket",
+	[fail_find] = "cannot find qutebrowser - is your $PATH set correctly?",
+};
+
+enum status
+transmit(const char* uri) {
+	const char* const run = getenv("XDG_RUNTIME_DIR");
+	if (run == NULL) return fail_xdg_null;
+
+	struct sockaddr_un srv = {
+		.sun_family = AF_UNIX,
+	} ; {
+		/* fuck this fuck this fuck this fuck this */
+		char* end = stpncpy(srv.sun_path, run, sizeof srv.sun_path);
+		end = stpncpy(end, ssz("/qutebrowser/"));
+		DIR* qb = opendir(srv.sun_path);
+		if (!qb) return start_instance;
+		struct dirent* ent;
+		while (ent = readdir(qb)) {
+			if (ent == NULL) return start_instance;
+			if (ent -> d_name[0] != '.') break;
+		}
+		if (ent == NULL) return start_instance;
+		end = stpncpy(end, ent->d_name,
+				(sizeof srv.sun_path) - (end - srv.sun_path));
+		closedir(qb);
+	}
+
+	int sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (connect(sock, (struct sockaddr*)&srv, sizeof srv) != 0)
+		return start_instance;
+
+	const char msg_blank [] = json_msg_start json_msg_end;
+	const size_t extra = uri != NULL ? strlen(uri) : 0;
+	char msg_start [(sizeof json_msg_start) + extra];
+
+	const size_t msgsz = sizeof msg_blank + extra - 1;
+	const char*  msg;
+	if (uri == NULL) msg = msg_blank; else {
+		strcpy(msg_start, json_msg_start);
+		strcpy(msg_start + (sizeof json_msg_start) - 1, uri);
+		strcpy(msg_start + (sizeof json_msg_start) - 1 + extra, json_msg_end);
+		msg = msg_start;
+	}
+
+	const char* cur = msg;
+	while(cur < msg + msgsz)
+		cur += write(sock, cur, msgsz - (cur - msg));
+
+	close(sock);
+
+	return ok;
+}
+
+int main(int argc, char** argv) {
+	if (argc > 2) {
+		printf("\x1b[1musage:\x1b[m %s [uri]\n", argv[0]);
+	} else {
+		const char* uri = argc < 2 ? NULL : argv[1];
+		enum status st = transmit(uri);
+		if (st == start_instance) {
+			if (!fork()) {
+				execl(dupl(_default_qutebrowser_location), uri, NULL);
+				execl(dupl("/usr/local/bin/qutebrowser"), uri, NULL);
+				execlp(dupl("qutebrowser"), uri, NULL);
+				st = fail_find;
+			} else {
+				return start_instance;
+			}
+		}
+		if (errors[st] != NULL) printf("\x1b[1;31m(error)\x1b[m %s\n", errors[st]);
+		return st;
+	}
+}