[PATCH 5/8] port-serial: new internal method to run tcsetattr()

[Aleksander Morgado]

The method takes care of looping if EAGAIN errors happen, as well as
checking whether all attributes were set or not.
---
 src/mm-port-serial.c | 119 ++++++++++++++++++++++++---------------------------
 1 file changed, 57 insertions(+), 62 deletions(-)

diff --git a/src/mm-port-serial.c b/src/mm-port-serial.c
index 2b6b92d3..f2b97a02 100644
--- a/src/mm-port-serial.c
+++ b/src/mm-port-serial.c
@@ -347,9 +347,62 @@ parse_stopbits (guint i)
 }
 
 static gboolean
+internal_tcsetattr (MMPortSerial          *self,
+                    gint                   fd,
+                    const struct termios  *options,
+                    GError               **error)
+{
+    guint          count;
+    struct termios other;
+
+#define MAX_TCSETATTR_RETRIES 4
+
+    for (count = 0; count < MAX_TCSETATTR_RETRIES; count++) {
+        /* try to set the new port attributes */
+        errno = 0;
+        if (tcsetattr (fd, TCSANOW, options) == 0)
+            break;
+
+        /* hard error if not EAGAIN */
+        if (errno != EAGAIN) {
+            g_set_error (error, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
+                         "couldn't set serial port attributes: %s", g_strerror (errno));
+            return FALSE;
+        }
+
+        /* try a few times if EAGAIN */
+        g_usleep (100000);
+    }
+
+    /* too many retries? */
+    if (count == MAX_TCSETATTR_RETRIES) {
+        g_set_error (error, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
+                     "couldn't set serial port attributes: too many retries (%u)", count);
+        return FALSE;
+    }
+
+    /* tcsetattr() returns 0 if any of the requested attributes could be set,
+     * so we should double-check that all were set and log if not. Just with
+     * debug level, as we're ignoring this issue all together anyway.
+     */
+    memset (&other, 0, sizeof (struct termios));
+    errno = 0;
+    if (tcgetattr (fd, &other) != 0)
+        mm_dbg ("(%s): couldn't get serial port attributes after setting them: %s",
+                mm_port_get_device (MM_PORT (self)), g_strerror (errno));
+    else if (memcmp (options, &other, sizeof (struct termios)) != 0)
+        mm_dbg ("(%s): port attributes not fully set",
+                mm_port_get_device (MM_PORT (self)));
+
+#undef MAX_TCSETATTR_RETRIES
+
+    return TRUE;
+}
+
+static gboolean
 real_config_fd (MMPortSerial *self, int fd, GError **error)
 {
-    struct termios stbuf, other;
+    struct termios stbuf;
     guint speed;
     gint bits;
     gint parity;
@@ -416,32 +469,7 @@ real_config_fd (MMPortSerial *self, int fd, GError **error)
         return FALSE;
     }
 
-    if (tcsetattr (fd, TCSANOW, &stbuf) < 0) {
-        g_set_error (error,
-                     MM_CORE_ERROR,
-                     MM_CORE_ERROR_FAILED,
-                     "%s: failed to set serial port attributes; errno %d",
-                     __func__, errno);
-        return FALSE;
-    }
-
-    /* tcsetattr() returns 0 if any of the requested attributes could be set,
-     * so we should double-check that all were set and log a warning if not.
-     */
-    memset (&other, 0, sizeof (struct termios));
-    errno = 0;
-    if (tcgetattr (fd, &other) != 0) {
-        mm_warn ("(%s): tcgetattr() error: %d",
-                 mm_port_get_device (MM_PORT (self)),
-                 errno);
-    }
-
-    if (memcmp (&stbuf, &other, sizeof (other)) != 0) {
-        mm_warn ("(%s): port attributes not fully set",
-                 mm_port_get_device (MM_PORT (self)));
-    }
-
-    return TRUE;
+    return internal_tcsetattr (self, fd, &stbuf, error);
 }
 
 static void
@@ -1576,15 +1604,11 @@ static gboolean
 set_speed (MMPortSerial *self, speed_t speed, GError **error)
 {
     struct termios options;
-    int fd, count = 4;
-    gboolean success = FALSE;
 
     g_assert (self->priv->fd >= 0);
 
-    fd = self->priv->fd;
-
     memset (&options, 0, sizeof (struct termios));
-    if (tcgetattr (fd, &options) != 0) {
+    if (tcgetattr (self->priv->fd, &options) != 0) {
         g_set_error (error,
                      MM_CORE_ERROR,
                      MM_CORE_ERROR_FAILED,
@@ -1601,36 +1625,7 @@ set_speed (MMPortSerial *self, speed_t speed, GError **error)
     if (self->priv->rts_cts)
         options.c_cflag |= (CRTSCTS);
 
-    while (count-- > 0) {
-        if (tcsetattr (fd, TCSANOW, &options) == 0) {
-            success = TRUE;
-            break;  /* Operation successful */
-        }
-
-        /* Try a few times if EAGAIN */
-        if (errno == EAGAIN)
-            g_usleep (100000);
-        else {
-            /* If not EAGAIN, hard error */
-            g_set_error (error,
-                            MM_CORE_ERROR,
-                            MM_CORE_ERROR_FAILED,
-                            "%s: tcsetattr() error %d",
-                            __func__, errno);
-            return FALSE;
-        }
-    }
-
-    if (!success) {
-        g_set_error (error,
-                        MM_CORE_ERROR,
-                        MM_CORE_ERROR_FAILED,
-                        "%s: tcsetattr() retry timeout",
-                        __func__);
-        return FALSE;
-    }
-
-    return TRUE;
+    return internal_tcsetattr (self, self->priv->fd, &options, error);
 }
 
 /*****************************************************************************/
-- 
2.12.0