Separate socket EOF from socket error conditions

harness.c

@@ -165,9 +165,14 @@ static void output_isr(struct bufferevent *bufev, IOHandle *h) {
 }
 
 static void error_isr(struct bufferevent *bufev, short what, IOHandle *h) {
-  info("error_isr 0x%04X\n", what);
+  unsigned short kind = what & ~(EVBUFFER_READ | EVBUFFER_WRITE);
+  info("error_isr 0x%04X fd %d\n", what, h->fd);
   h->error_direction = what & (EVBUFFER_READ | EVBUFFER_WRITE);
-  h->error_kind = what & ~(EVBUFFER_READ | EVBUFFER_WRITE);
+  if (kind == EVBUFFER_EOF) {
+    h->eof = 1;
+  } else {
+    h->error_kind = kind;
+  }
   awaken_waiters(h, EV_READ | EV_WRITE);
 }
 
@@ -181,6 +186,7 @@ IOHandle *new_iohandle(int fd) {
 			  (everrorcb) error_isr,
 			  h);
   PCHECK(h->io, "bufferevent_new");
+  h->eof = 0;
   iohandle_clear_error(h);
   return h;
 }
@@ -212,7 +218,7 @@ static void block_on_io(IOHandle *h, short event) {
 
 cmsg_bytes_t iohandle_readwait(IOHandle *h, size_t at_least) {
   while (EVBUFFER_LENGTH(h->io->input) < at_least) {
-    if (h->error_kind) {
+    if (h->eof || h->error_kind) {
       return EMPTY_BYTES;
     }
     ICHECK(bufferevent_enable(h->io, EV_READ), "bufferevent_enable");

harness.h

@@ -21,6 +21,7 @@ typedef struct IOHandle {
   Process *waiters;
   int fd;
   struct bufferevent *io;
+  int eof;
   unsigned short error_direction;
   unsigned short error_kind;
 } IOHandle;

main.c

@@ -84,7 +84,7 @@ static void console_listener(void *arg) {
   IOHandle *in_handle = new_iohandle(0);
   while (1) {
     cmsg_bytes_t buf = iohandle_readwait(in_handle, 1);
-    if (in_handle->error_kind) break;
+    if (buf.len == 0) break;
     iohandle_drain(in_handle, buf.len);
   }
   delete_iohandle(in_handle);

relay.c

@@ -109,9 +109,8 @@ static void relay_main(node_t *n) {
   while (1) {
     DECREF(message, sexp_destructor);
     message = NULL;
-    message = INCREF(sexp_read(inh));
-
-    if (inh->error_kind != 0) goto network_error;
+    if (!sexp_read(inh, &message)) goto network_error;
+    INCREF(message);
 
     /*
     info("fd %d --> ", r->fd);
@@ -119,6 +118,7 @@ static void relay_main(node_t *n) {
     */
 
     if (!(sexp_pairp(message) && sexp_stringp(sexp_head(message)))) {
+      info("Ill-formed message\n");
       send_error(r->outh, "ill-formed message", NULL);
       goto protocol_error;
     }
@@ -169,22 +169,22 @@ static void relay_main(node_t *n) {
   }
 
  network_error:
-  switch (inh->error_kind) {
-    case EVBUFFER_EOF:
-      info("Disconnecting fd %d normally.\n", r->fd);
-      break;
+  if (inh->eof) {
+    info("Disconnecting fd %d normally.\n", r->fd);
+  } else {
+    switch (inh->error_kind) {
+      case SEXP_ERROR_OVERFLOW:
+	send_sexp_syntax_error(r->outh, "sexp too big");
+	break;
 
-    case SEXP_ERROR_OVERFLOW:
-      send_sexp_syntax_error(r->outh, "sexp too big");
-      break;
+      case SEXP_ERROR_SYNTAX:
+	send_sexp_syntax_error(r->outh, "sexp syntax error");
+	break;
 
-    case SEXP_ERROR_SYNTAX:
-      send_sexp_syntax_error(r->outh, "sexp syntax error");
-      break;
-
-    default:
-      warn("Relay handle error on fd %d: 0x%04X\n", r->fd, inh->error_kind);
-      break;
+      default:
+	warn("Relay handle error on fd %d: 0x%04X\n", r->fd, inh->error_kind);
+	break;
+    }
   }
 
  protocol_error:

sexpio.c

@@ -22,7 +22,7 @@ static sexp_t *read_simple_string(IOHandle *h, cmsg_bytes_t buf) {
 
   while (1) {
     buf = iohandle_readwait(h, buf.len + 1);
-    if (h->error_kind) return NULL;
+    if (buf.len == 0) return NULL;
     /* Don't reset i to zero: avoids scanning the beginning of the
        number repeatedly */
 
@@ -39,6 +39,10 @@ static sexp_t *read_simple_string(IOHandle *h, cmsg_bytes_t buf) {
 	count = atoi((char *) buf.bytes);
 	iohandle_drain(h, i + 1);
 	buf = iohandle_readwait(h, count);
+	if (buf.len < count) {
+	  /* Error or EOF. */
+	  return NULL;
+	}
 	buf.len = count;
 	result = sexp_bytes(buf);
 	iohandle_drain(h, count);
@@ -59,14 +63,11 @@ sexp_t *sexp_read_atom(IOHandle *h) {
   return read_simple_string(h, EMPTY_BYTES);
 }
 
-#define CHECKH \
-  if (h->error_kind) goto error;
-
 #define READ1					\
   buf = iohandle_readwait(h, 1);		\
-  CHECKH;
+  if (buf.len == 0) goto error;
 
-sexp_t *sexp_read(IOHandle *h) {
+int sexp_read(IOHandle *h, sexp_t **result_ptr) {
   cmsg_bytes_t buf;
   sexp_t *stack = NULL; /* held */
   sexp_t *hint = NULL; /* held */
@@ -79,7 +80,7 @@ sexp_t *sexp_read(IOHandle *h) {
       case '[': {
 	iohandle_drain(h, 1);
 	hint = INCREF(read_simple_string(h, EMPTY_BYTES));
-	CHECKH;
+	if (hint == NULL) goto error;
 	READ1;
 	if (buf.bytes[0] != ']') {
 	  h->error_kind = SEXP_ERROR_SYNTAX;
@@ -93,7 +94,7 @@ sexp_t *sexp_read(IOHandle *h) {
 	  goto skip_whitespace_in_display_hint;
 	}
 	body = INCREF(read_simple_string(h, EMPTY_BYTES));
-	CHECKH;
+	if (body == NULL) goto error;
 	accumulator = sexp_display_hint(hint, body);
 	DECREF(hint, sexp_destructor); /* these could be UNGRABs */
 	DECREF(body, sexp_destructor);
@@ -132,7 +133,8 @@ sexp_t *sexp_read(IOHandle *h) {
     }
 
     if (stack == NULL) {
-      return accumulator;
+      *result_ptr = accumulator;
+      return 1;
     } else {
       sexp_t *current = sexp_head(stack); /* not held */
       sexp_t *cell = sexp_cons(accumulator, NULL);
@@ -149,7 +151,7 @@ sexp_t *sexp_read(IOHandle *h) {
   DECREF(stack, sexp_destructor);
   DECREF(hint, sexp_destructor);
   DECREF(body, sexp_destructor);
-  return NULL;
+  return 0;
 }
 
 void write_simple_string(IOHandle *h, sexp_t *x) {

sexpio.h

@@ -5,7 +5,7 @@
 #define SEXP_ERROR_SYNTAX	0x8001
 
 extern sexp_t *sexp_read_atom(IOHandle *h);
-extern sexp_t *sexp_read(IOHandle *h);
+extern int sexp_read(IOHandle *h, sexp_t **result_ptr);
 extern unsigned short sexp_write(IOHandle *h, sexp_t *x);
 extern unsigned short sexp_writeln(IOHandle *h, sexp_t *x);