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 Brüns for reviewing the first version of this patch
and spotting out a serious problem with it.
Signed-off-by: Guido Trentalancia <gu...@trentalancia.com>
---
src/scpi/scpi.c | 49 +++++++++++++++++++++++++++++--------------------
1 file changed, 29 insertions(+), 20 deletions(-)
diff -pru libsigrok-git-20102018-orig/src/scpi/scpi.c
libsigrok-git-20102018-fix-scpi-response-buffer-length/src/scpi/scpi.c
--- libsigrok-git-20102018-orig/src/scpi/scpi.c 2018-10-20 13:12:30.983966965
+0200
+++ libsigrok-git-20102018-fix-scpi-response-buffer-length/src/scpi/scpi.c
2018-10-29 22:53:10.419718436 +0100
@@ -945,6 +945,7 @@ SR_PRIV int sr_scpi_get_block(struct sr_
{
int ret;
GString* response;
+ gsize oldlen;
char buf[10];
long llen;
long datalen;
@@ -974,14 +975,14 @@ SR_PRIV int sr_scpi_get_block(struct sr_
*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.
@@ -1028,25 +1029,33 @@ SR_PRIV int sr_scpi_get_block(struct sr_
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);
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