io: don't leave errno as a random value when we hit EOF.

[ccan] / ccan / io / io.c

diff --git a/ccan/io/io.c b/ccan/io/io.c
index f298af70781d3fe90e606934614f5d06874e770f..bdcbf9e26b8f9f580fea08c2c0913d31efe9dcc7 100644 (file)
--- a/ccan/io/io.c
+++ b/ccan/io/io.c
@@ -72,16 +72,19 @@ static bool next_plan(struct io_conn *conn, struct io_plan *plan)
        return true;
 }
 
-static void set_blocking(int fd, bool block)
+bool io_fd_block(int fd, bool block)
 {
        int flags = fcntl(fd, F_GETFL);
 
+       if (flags == -1)
+               return false;
+
        if (block)
                flags &= ~O_NONBLOCK;
        else
                flags |= O_NONBLOCK;
 
-       fcntl(fd, F_SETFL, flags);
+       return fcntl(fd, F_SETFL, flags) != -1;
 }
 
 struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
@@ -103,7 +106,7 @@ struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
                return tal_free(conn);
 
        /* Keep our I/O async. */
-       set_blocking(fd, false);
+       io_fd_block(fd, false);
 
        /* We start with out doing nothing, and in doing our init. */
        conn->plan[IO_OUT].status = IO_UNSET;
@@ -128,7 +131,7 @@ struct io_plan_arg *io_plan_arg(struct io_conn *conn, enum io_direction dir)
 {
        assert(conn->plan[dir].status == IO_UNSET);
 
-       conn->plan[dir].status = IO_POLLING;
+       conn->plan[dir].status = IO_POLLING_NOTSTARTED;
        return &conn->plan[dir].arg;
 }
 
@@ -199,8 +202,12 @@ struct io_plan *io_write_(struct io_conn *conn, const void *data, size_t len,
 static int do_read(int fd, struct io_plan_arg *arg)
 {
        ssize_t ret = read(fd, arg->u1.cp, arg->u2.s);
-       if (ret <= 0)
+       if (ret <= 0) {
+               /* Errno isn't set if we hit EOF, so set it to distinct value */
+               if (ret == 0)
+                       errno = 0;
                return -1;
+       }
 
        arg->u1.cp += ret;
        arg->u2.s -= ret;
@@ -227,8 +234,12 @@ struct io_plan *io_read_(struct io_conn *conn,
 static int do_read_partial(int fd, struct io_plan_arg *arg)
 {
        ssize_t ret = read(fd, arg->u1.cp, *(size_t *)arg->u2.vp);
-       if (ret <= 0)
+       if (ret <= 0) {
+               /* Errno isn't set if we hit EOF, so set it to distinct value */
+               if (ret == 0)
+                       errno = 0;
                return -1;
+       }
 
        *(size_t *)arg->u2.vp = ret;
        return 1;
@@ -360,17 +371,25 @@ void io_wake(const void *wait)
        backend_wake(wait);
 }
 
-/* Returns false if this has been freed. */
-static bool do_plan(struct io_conn *conn, struct io_plan *plan)
+/* Returns false if this should not be touched (eg. freed). */
+static bool do_plan(struct io_conn *conn, struct io_plan *plan,
+                   bool idle_on_epipe)
 {
        /* We shouldn't have polled for this event if this wasn't true! */
-       assert(plan->status == IO_POLLING);
+       assert(plan->status == IO_POLLING_NOTSTARTED
+              || plan->status == IO_POLLING_STARTED);
 
        switch (plan->io(conn->fd.fd, &plan->arg)) {
        case -1:
+               if (errno == EPIPE && idle_on_epipe) {
+                       plan->status = IO_UNSET;
+                       backend_new_plan(conn);
+                       return false;
+               }
                io_close(conn);
                return false;
        case 0:
+               plan->status = IO_POLLING_STARTED;
                return true;
        case 1:
                return next_plan(conn, plan);
@@ -383,21 +402,38 @@ static bool do_plan(struct io_conn *conn, struct io_plan *plan)
 void io_ready(struct io_conn *conn, int pollflags)
 {
        if (pollflags & POLLIN)
-               if (!do_plan(conn, &conn->plan[IO_IN]))
+               if (!do_plan(conn, &conn->plan[IO_IN], false))
                        return;
 
        if (pollflags & POLLOUT)
-               do_plan(conn, &conn->plan[IO_OUT]);
+               /* If we're writing to a closed pipe, we need to wait for
+                * read to fail if we're duplex: we want to drain it! */
+               do_plan(conn, &conn->plan[IO_OUT],
+                       conn->plan[IO_IN].status == IO_POLLING_NOTSTARTED
+                       || conn->plan[IO_IN].status == IO_POLLING_STARTED);
 }
 
 void io_do_always(struct io_conn *conn)
 {
+       /* There's a corner case where the in next_plan wakes up the
+        * out, placing it in IO_ALWAYS and we end up processing it immediately,
+        * only to leave it in the always list.
+        *
+        * Yet we can't just process one, in case they are both supposed
+        * to be done, so grab state beforehand.
+        */
+       bool always_out = (conn->plan[IO_OUT].status == IO_ALWAYS);
+
        if (conn->plan[IO_IN].status == IO_ALWAYS)
                if (!next_plan(conn, &conn->plan[IO_IN]))
                        return;
 
-       if (conn->plan[IO_OUT].status == IO_ALWAYS)
+       if (always_out) {
+               /* You can't *unalways* a conn (except by freeing, in which
+                * case next_plan() returned false */
+               assert(conn->plan[IO_OUT].status == IO_ALWAYS);
                next_plan(conn, &conn->plan[IO_OUT]);
+       }
 }
 
 void io_do_wakeup(struct io_conn *conn, enum io_direction dir)
@@ -423,7 +459,7 @@ struct io_plan *io_close_cb(struct io_conn *conn, void *next_arg)
 
 struct io_plan *io_close_taken_fd(struct io_conn *conn)
 {
-       set_blocking(conn->fd.fd, true);
+       io_fd_block(conn->fd.fd, true);
 
        cleanup_conn_without_close(conn);
        return io_close(conn);
@@ -484,17 +520,28 @@ struct io_plan *io_set_plan(struct io_conn *conn, enum io_direction dir,
        return plan;
 }
 
+bool io_plan_in_started(const struct io_conn *conn)
+{
+       return conn->plan[IO_IN].status == IO_POLLING_STARTED;
+}
+
+bool io_plan_out_started(const struct io_conn *conn)
+{
+       return conn->plan[IO_OUT].status == IO_POLLING_STARTED;
+}
+
 bool io_flush_sync(struct io_conn *conn)
 {
        struct io_plan *plan = &conn->plan[IO_OUT];
        bool ok;
 
        /* Not writing?  Nothing to do. */
-       if (plan->status != IO_POLLING)
+       if (plan->status != IO_POLLING_STARTED
+           && plan->status != IO_POLLING_NOTSTARTED)
                return true;
 
        /* Synchronous please. */
-       set_blocking(io_conn_fd(conn), true);
+       io_fd_block(io_conn_fd(conn), true);
 
 again:
        switch (plan->io(conn->fd.fd, &plan->arg)) {
@@ -503,6 +550,7 @@ again:
                break;
        /* Incomplete, try again. */
        case 0:
+               plan->status = IO_POLLING_STARTED;
                goto again;
        case 1:
                ok = true;
@@ -514,6 +562,6 @@ again:
                abort();
        }
 
-       set_blocking(io_conn_fd(conn), false);
+       io_fd_block(io_conn_fd(conn), false);
        return ok;
 }