Handle -EAGAIN in non-blocking reads on Unix, and return 0 from sp_read().

diff --git a/serialport.c b/serialport.c
index fbeb76ee52c88c01f4ab08af5f73b09d2d0abf48..fd42034f9b44700221f24d29d373b21a1425ecc3 100644 (file)
--- a/serialport.c
+++ b/serialport.c
@@ -60,6 +60,7 @@
 
 struct sp_port {
        char *name;
+       int nonblocking;
 #ifdef _WIN32
        HANDLE hdl;
 #else
@@ -578,6 +579,8 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
        DEBUG("Opening port %s", port->name);
 
+       port->nonblocking = (flags & SP_MODE_NONBLOCK) ? 1 : 0;
+
 #ifdef _WIN32
        DWORD desired_access = 0, flags_and_attributes = 0;
        char *escaped_port_name;
@@ -786,8 +789,14 @@ enum sp_return sp_read(struct sp_port *port, void *buf, size_t count)
        ssize_t bytes_read;
 
        /* Returns the number of bytes read, or -1 upon failure. */
-       if ((bytes_read = read(port->fd, buf, count)) < 0)
-               RETURN_FAIL("read() failed");
+       if ((bytes_read = read(port->fd, buf, count)) < 0) {
+               if (port->nonblocking && errno == EAGAIN)
+                       /* Port is opened in nonblocking mode and there are no bytes available. */
+                       bytes_read = 0;
+               else
+                       /* This is an actual failure. */
+                       RETURN_FAIL("read() failed");
+       }
        RETURN_VALUE("%d", bytes_read);
 #endif
 }