device: don't accept empty names for sigrok channels

It's unexpected when sigrok channels "have no name". Previous versions
would not strictly enforce non-empty names and could let empty names
slip in, but application code was reported to be confused when it
happened. The benefit of having channels "with no names" is questioned.

Adjust the public API routines. Accept missing name specs in the
sr_channel_new() routine for maximum backwards compatibility. Reject
missing names in sr_dev_channel_name_set() so that empty or non-empty
names can only be replaced by non-empty names. Check the return code of
sr_channel_new() in sr_dev_inst_channel_add() so that failed channel
creation gets propagated to callers. The current implementation will
never fail sr_channel_new(), but future versions might.

None of libsigrok code (device drivers, input modules) assign empty
names to channels. Applications still need to get checked. A future
commit might make names in sr_channel_new() mandatory.

diff --git a/src/device.c b/src/device.c
index 7973d1e53629e0ccba5d4bf76b1e5f1fa8e37034..5c681378fab01a99a33befa74dc0df3754e0a1ae 100644 (file)
--- a/src/device.c
+++ b/src/device.c
@@ -67,7 +67,7 @@ SR_PRIV struct sr_channel *sr_channel_new(struct sr_dev_inst *sdi,
        ch->index = index;
        ch->type = type;
        ch->enabled = enabled;
-       if (name)
+       if (name && *name)
                ch->name = g_strdup(name);
 
        sdi->channels = g_slist_append(sdi->channels, ch);
@@ -120,6 +120,8 @@ SR_API int sr_dev_channel_name_set(struct sr_channel *channel,
 {
        if (!channel)
                return SR_ERR_ARG;
+       if (!name || !*name)
+               return SR_ERR_ARG;
 
        g_free(channel->name);
        channel->name = g_strdup(name);
@@ -489,7 +491,8 @@ SR_API int sr_dev_inst_channel_add(struct sr_dev_inst *sdi, int index, int type,
        if (!sdi || sdi->inst_type != SR_INST_USER || index < 0)
                return SR_ERR_ARG;
 
-       sr_channel_new(sdi, index, type, TRUE, name);
+       if (!sr_channel_new(sdi, index, type, TRUE, name))
+               return SR_ERR_DATA;
 
        return SR_OK;
 }