X-Git-Url: https://sigrok.org/gitweb/?p=libsigrok.git;a=blobdiff_plain;f=src%2Fhardware%2Fhp-3457a%2Fapi.c;h=4cfc2d758b54e79625609d408ef0f506d028a5b7;hp=5325224e5e8207e7593b5a0c55765e20866be7e2;hb=69498046f64006a11234b0d281a481338f6f329c;hpb=758906aa711c2936e7e9adcb449f70905087a5d9

diff --git a/src/hardware/hp-3457a/api.c b/src/hardware/hp-3457a/api.c
index 5325224e..4cfc2d75 100644
--- a/src/hardware/hp-3457a/api.c
+++ b/src/hardware/hp-3457a/api.c
@@ -127,6 +127,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
 
+	/*
+	 * The device cannot get identified by means of SCPI queries.
+	 * Neither shall non-SCPI requests get emitted before reliable
+	 * identification of the device. Assume that we only get here
+	 * when user specs led us to believe it's safe to communicate
+	 * to the expected kind of device.
+	 */
+
 	/*
 	 * This command ensures we receive an EOI after every response, so that
 	 * we don't wait the entire timeout after the response is received.
@@ -138,13 +146,15 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 	if ((ret != SR_OK) || !response)
 		return NULL;
 
-	if (strcmp(response, "HP3457A"))
+	if (strcmp(response, "HP3457A") != 0) {
+		g_free(response);
 		return NULL;
+	}
 
 	g_free(response);
 
-	devc = g_malloc0(sizeof(struct dev_context));
-	sdi = g_malloc0(sizeof(struct sr_dev_inst));
+	devc = g_malloc0(sizeof(*devc));
+	sdi = g_malloc0(sizeof(*sdi));
 	sdi->vendor = g_strdup("Hewlett-Packard");
 	sdi->model = g_strdup("3457A");
 	sdi->version = get_revision(scpi);
@@ -168,6 +178,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 
 static GSList *scan(struct sr_dev_driver *di, GSList *options)
 {
+	const char *conn;
+
+	/* Only scan for a device when conn= was specified. */
+	conn = NULL;
+	(void)sr_serial_extract_options(options, &conn, NULL);
+	if (!conn)
+		return NULL;
+
 	return sr_scpi_scan(di->context, options, probe_device);
 }
 
@@ -359,8 +377,13 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 		return SR_ERR_ARG;
 	}
 
-	devc->current_channel = devc->active_channels->data;
 	devc->num_active_channels = g_slist_length(devc->active_channels);
+	if (!devc->num_active_channels) {
+		sr_err("Need at least one active channel!");
+		g_slist_free(devc->active_channels);
+		return SR_ERR_ARG;
+	}
+	devc->current_channel = devc->active_channels->data;
 
 	hp_3457a_select_input(sdi, front_selected ? CONN_FRONT : CONN_REAR);