Fix up the serial code

src/raw-serial.c

@@ -23,15 +23,31 @@ struct RawSerial {
   int fd_out;
 };
 
+static int max(int a, int b) {
+  return a > b ? a : b;
+}
+
 static uint32_t read_status(const struct RISC_Serial *serial) {
   struct RawSerial *s = (struct RawSerial *)serial;
   struct timeval tv = { 0, 0 };
-  fd_set rfds;
-  FD_ZERO(&rfds);
-  FD_SET(s->fd_in, &rfds);
-  int nfds = s->fd_in + 1;
-  int r = select(nfds, &rfds, NULL, NULL, &tv);
-  return r == 1;
+  fd_set read_fds;
+  fd_set write_fds;
+  FD_ZERO(&read_fds);
+  FD_SET(s->fd_in, &read_fds);
+  FD_ZERO(&write_fds);
+  FD_SET(s->fd_out, &write_fds);
+  int nfds = max(s->fd_in, s->fd_out) + 1;
+  int r = select(nfds, &read_fds, &write_fds, NULL, &tv);
+  int status = 0;
+  if (r > 0) {
+    if (FD_ISSET(s->fd_in, &read_fds)) {
+      status |= 1;
+    }
+    if (FD_ISSET(s->fd_out, &write_fds)) {
+      status |= 2;
+    }
+  }
+  return status;
 }
 
 static uint32_t read_data(const struct RISC_Serial *serial) {
@@ -47,30 +63,24 @@ static void write_data(const struct RISC_Serial *serial, uint32_t data) {
   write(s->fd_out, &byte, 1);
 }
 
-static bool set_non_blocking(int fd) {
-  int r = fcntl(fd, F_GETFL);
-  if (r != -1) {
-    int flags = r | O_NONBLOCK;
-    r = fcntl(fd, F_SETFL, flags);
-  }
-  return r != -1;
-}
+struct RISC_Serial *raw_serial_new(const char *filename_in, const char *filename_out) {
+  int fd_in, fd_out;
 
-struct RISC_Serial *raw_serial_new(int fd_in, int fd_out) {
-  if (!set_non_blocking(fd_in)) {
-    fprintf(stderr, "serial fd %d (input): ", fd_in);
-    perror(NULL);
-    return NULL;
+  fd_in = open(filename_in, O_RDONLY | O_NONBLOCK);
+  if (fd_in < 0) {
+    perror("Failed to open serial input file");
+    goto fail1;
   }
-  if (!set_non_blocking(fd_out)) {
-    fprintf(stderr, "serial fd %d (output): ", fd_out);
-    perror(NULL);
-    return NULL;
+
+  fd_out = open(filename_out, O_RDWR | O_NONBLOCK);
+  if (fd_out < 0) {
+    perror("Failed to open serial output file");
+    goto fail2;
   }
 
   struct RawSerial *s = malloc(sizeof(*s));
   if (!s) {
-    return NULL;
+    goto fail3;
   }
 
   *s = (struct RawSerial){
@@ -83,6 +93,13 @@ struct RISC_Serial *raw_serial_new(int fd_in, int fd_out) {
     .fd_out = fd_out
   };
   return &s->serial;
+
+ fail3:
+  close(fd_out);
+ fail2:
+  close(fd_in);
+ fail1:
+  return NULL;
 }
 
 #endif  // _WIN32

src/raw-serial.h

@@ -3,6 +3,6 @@
 
 #include "risc-io.h"
 
-struct RISC_Serial *raw_serial_new(int fd_in, int fd_out);
+struct RISC_Serial *raw_serial_new(const char *filename_in, const char *filename_out);
 
 #endif  // SERIAL_H

src/sdl-main.c

@@ -66,7 +66,8 @@ static struct option long_options[] = {
   { "fullscreen", no_argument,       NULL, 'f' },
   { "leds",       no_argument,       NULL, 'L' },
   { "size",       required_argument, NULL, 's' },
-  { "serial-fd",  required_argument, NULL, 'F' },
+  { "serial-in",  required_argument, NULL, 'I' },
+  { "serial-out", required_argument, NULL, 'O' },
   { NULL,         no_argument,       NULL, 0   }
 };
 
@@ -98,6 +99,8 @@ int main (int argc, char *argv[]) {
     .w = RISC_FRAMEBUFFER_WIDTH,
     .h = RISC_FRAMEBUFFER_HEIGHT
   };
+  const char *serial_in = NULL;
+  const char *serial_out = NULL;
 
   int opt;
   while ((opt = getopt_long(argc, argv, "z:fLS:F:", long_options, NULL)) != -1) {
@@ -127,8 +130,12 @@ int main (int argc, char *argv[]) {
         risc_screen_size_hack(risc, risc_rect.w, risc_rect.h);
         break;
       }
-      case 'F': {
-        risc_set_serial(risc, raw_serial_new(atoi(optarg), atoi(optarg) + 1));
+      case 'I': {
+        serial_in = optarg;
+        break;
+      }
+      case 'O': {
+        serial_out = optarg;
         break;
       }
       default: {
@@ -136,11 +143,22 @@ int main (int argc, char *argv[]) {
       }
     }
   }
+
   if (optind != argc - 1) {
     usage();
   }
   risc_set_spi(risc, 1, disk_new(argv[optind]));
 
+  if (serial_in || serial_out) {
+    if (!serial_in) {
+      serial_in = "/dev/null";
+    }
+    if (!serial_out) {
+      serial_out = "/dev/null";
+    }
+    risc_set_serial(risc, raw_serial_new(serial_in, serial_out));
+  }
+
   if (SDL_Init(SDL_INIT_VIDEO) != 0) {
     fail(1, "Unable to initialize SDL: %s", SDL_GetError());
   }