I think I just implemented patty_kiss_write(); tons o' system calls, but fuggit man!

src/kiss.c

@@ -75,3 +75,44 @@ ssize_t patty_kiss_read(int fd, void *buf, size_t len, int *port) {
 error_io:
     return -1;
 }
+
+ssize_t patty_kiss_write(int fd, const void *buf, size_t len, int port) {
+    size_t i;
+
+    unsigned char escape_fend[2] = { PATTY_KISS_FESC, PATTY_KISS_TFEND };
+    unsigned char escape_fesc[2] = { PATTY_KISS_FESC, PATTY_KISS_TFESC };
+
+    unsigned char command = (port & 0x0f) << 4;
+
+    if (write(fd, &command, 1) < 0) {
+        goto error_io;
+    }
+
+    for (i=0; i<len; i++) {
+        unsigned char c = ((unsigned char *)buf)[i];
+        ssize_t res = 0;
+
+        switch (c) {
+            case PATTY_KISS_FEND: {
+                res = write(fd, escape_fend, sizeof(escape_fend)); break;
+            }
+
+            case PATTY_KISS_FESC: {
+                res = write(fd, escape_fesc, sizeof(escape_fesc)); break;
+            }
+
+            default: {
+                res = write(fd, &c, 1); break;
+            }
+        }
+
+        if (res < 0) {
+            goto error_io;
+        }
+    }
+
+    return 0;
+
+error_io:
+    return -1;
+}