fix: buffer command fifo input until a full line arrives

dvtm.c

@@ -1657,19 +1657,10 @@ get_cmd_by_name(const char *name) {
 }
 
 static void
-handle_cmdfifo(void) {
-	int r;
-	char *p, *s, cmdbuf[512], c;
+process_cmdbuf(char *p) {
+	char *s, c;
 	Cmd *cmd;
 
-	r = read(cmdfifo.fd, cmdbuf, sizeof cmdbuf - 1);
-	if (r <= 0) {
-		cmdfifo.fd = -1;
-		return;
-	}
-
-	cmdbuf[r] = '\0';
-	p = cmdbuf;
 	while (*p) {
 		/* find the command name */
 		for (; *p == ' ' || *p == '\n'; p++);
@@ -1751,6 +1742,51 @@ handle_cmdfifo(void) {
 	}
 }
 
+static void
+handle_cmdfifo(void) {
+	static char buf[4096];
+	static size_t len;
+	static bool skipping;
+	ssize_t r;
+	size_t end;
+
+	r = read(cmdfifo.fd, buf + len, sizeof buf - 1 - len);
+	if (r < 0 && (errno == EINTR || errno == EAGAIN))
+		return;
+	if (r <= 0) {
+		cmdfifo.fd = -1;
+		return;
+	}
+	len += r;
+
+	if (skipping) {
+		char *nl = memchr(buf, '\n', len);
+		if (!nl) {
+			len = 0;
+			return;
+		}
+		len -= nl + 1 - buf;
+		memmove(buf, nl + 1, len);
+		skipping = false;
+	}
+
+	for (end = len; end > 0 && buf[end - 1] != '\n'; end--);
+	if (!end) {
+		if (len == sizeof buf - 1) {
+			len = 0;
+			skipping = true;
+		}
+		return;
+	}
+
+	char next = buf[end];
+	buf[end] = '\0';
+	process_cmdbuf(buf);
+	buf[end] = next;
+	memmove(buf, buf + end, len - end);
+	len -= end;
+}
+
 static void
 handle_mouse(void) {
 #ifdef CONFIG_MOUSE

test/test_dvtm.py

@@ -117,6 +117,20 @@ def test_cmd_fifo(self):
         self.p.expect_exact('title-x')
         self.p.expect_exact('from-42')
 
+    def test_cmd_fifo_split_writes(self):
+        fd = os.open(self.cmdfifo, os.O_WRONLY)
+        os.write(fd, b"create 'echo split-$((6*7)); sleep 60' ti")
+        time.sleep(0.5)
+        os.write(fd, b"tle-y\n")
+        os.close(fd)
+        self.p.expect_exact('title-y')
+        self.p.expect_exact('split-42')
+
+    def test_cmd_fifo_long_input(self):
+        with open(self.cmdfifo, 'w') as f:
+            f.write("create 'echo ok-$((6*7)); sleep 60' " + 'x' * 600 + '\n')
+        self.p.expect_exact('ok-42')
+
     def test_status_fifo(self):
         with open(self.status, 'w') as f:
             f.write('hello-status\n')