]> sigrok.org Git - libsigrok.git/commitdiff
hameg-hmo: Avoid getting stuck upon SCPI timeouts.
authorGuido Trentalancia <redacted>
Fri, 16 Nov 2018 17:42:16 +0000 (18:42 +0100)
committerUwe Hermann <redacted>
Thu, 25 Jul 2019 22:11:07 +0000 (00:11 +0200)
Correctly set the length of the buffer used to hold the SCPI response
from the device containing the binary acquisition data.

If a timeout occurs, truncate the buffer and send the partial response
from the device instead of getting stuck on timeouts!

Thanks to Stefan BrĂ¼ns for reviewing the first version of this patch
and spotting out a serious problem with it.

This fixes bug #1323.

src/scpi/scpi.c

index 31f82a3f912351c2bc653bb66dfed90f6e61a6db..2477cf2323971c314880c3bc235732fd076c0af3 100644 (file)
@@ -961,6 +961,7 @@ SR_PRIV int sr_scpi_get_block(struct sr_scpi_dev_inst *scpi,
 {
        int ret;
        GString* response;
+       gsize oldlen;
        char buf[10];
        long llen;
        long datalen;
@@ -990,14 +991,14 @@ SR_PRIV int sr_scpi_get_block(struct sr_scpi_dev_inst *scpi,
        *scpi_response = NULL;
 
        /* Get (the first chunk of) the response. */
-       while (response->len < 2) {
+       do {
                ret = scpi_read_response(scpi, response, timeout);
                if (ret < 0) {
                        g_mutex_unlock(&scpi->scpi_mutex);
                        g_string_free(response, TRUE);
                        return ret;
                }
-       }
+       } while (response->len < 2);
 
        /*
         * SCPI protocol data blocks are preceeded with a length spec.
@@ -1044,25 +1045,33 @@ SR_PRIV int sr_scpi_get_block(struct sr_scpi_dev_inst *scpi,
        g_string_erase(response, 0, 2 + llen);
 
        /*
-        * If the initially assumed length does not cover the data block
-        * length, then re-allocate the buffer size to the now known
-        * length, and keep reading more chunks of response data.
+        * Re-allocate the buffer size to the now known length
+        * and keep reading more chunks of response data.
         */
-       if (response->len < (unsigned long)(datalen)) {
-               int oldlen = response->len;
-               g_string_set_size(response, datalen);
-               g_string_set_size(response, oldlen);
-       }
-
-       while (response->len < (unsigned long)(datalen)) {
-               ret = scpi_read_response(scpi, response, timeout);
-               if (ret < 0) {
-                       g_mutex_unlock(&scpi->scpi_mutex);
-                       g_string_free(response, TRUE);
-                       return ret;
-               }
-               if (ret > 0)
-                       timeout = g_get_monotonic_time() + scpi->read_timeout_us;
+       oldlen = response->len;
+       g_string_set_size(response, datalen);
+       g_string_set_size(response, oldlen);
+
+       if (oldlen < (unsigned long)(datalen)) {
+               do {
+                       oldlen = response->len;
+                       ret = scpi_read_response(scpi, response, timeout);
+
+                       /* On timeout truncate the buffer and send the partial response
+                        * instead of getting stuck on timeouts...
+                        */
+                       if (ret == SR_ERR_TIMEOUT) {
+                               datalen = oldlen;
+                               break;
+                       }
+                       if (ret < 0) {
+                               g_mutex_unlock(&scpi->scpi_mutex);
+                               g_string_free(response, TRUE);
+                               return ret;
+                       }
+                       if (ret > 0)
+                               timeout = g_get_monotonic_time() + scpi->read_timeout_us;
+               } while (response->len < (unsigned long)(datalen));
        }
 
        g_mutex_unlock(&scpi->scpi_mutex);