logd: implement oneshot mode for stream log read

This will terminate the connection after all log messages have been
sent. Useful for logread without follow

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/log/logd.c b/log/logd.c
index 58abfade94d38940db9f0f323b1c5162043aa50a..ee30984e69721769fe2d1bd11d9b3c032e058efd 100644 (file)
--- a/log/logd.c
+++ b/log/logd.c
@@ -34,12 +34,14 @@ static LIST_HEAD(clients);
 enum {
        READ_LINES,
        READ_STREAM,
+       READ_ONESHOT,
        __READ_MAX
 };
 
 static const struct blobmsg_policy read_policy[__READ_MAX] = {
        [READ_LINES] = { .name = "lines", .type = BLOBMSG_TYPE_INT32 },
        [READ_STREAM] = { .name = "stream", .type = BLOBMSG_TYPE_BOOL },
+       [READ_ONESHOT] = { .name = "oneshot", .type = BLOBMSG_TYPE_BOOL },
 };
 
 static const struct blobmsg_policy write_policy =
@@ -68,6 +70,14 @@ static void client_notify_state(struct ustream *s)
        client_close(s);
 }
 
+static void client_notify_write(struct ustream *s, int bytes)
+{
+       if (ustream_pending_data(s, true))
+               return;
+
+       client_close(s);
+}
+
 static void
 log_fill_msg(struct blob_buf *b, struct log_head *l)
 {
@@ -90,6 +100,7 @@ read_log(struct ubus_context *ctx, struct ubus_object *obj,
        int fds[2];
        int ret;
        bool stream = true;
+       bool oneshot = false;
        void *c, *e;
 
        if (!stream)
@@ -101,6 +112,8 @@ read_log(struct ubus_context *ctx, struct ubus_object *obj,
                        count = blobmsg_get_u32(tb[READ_LINES]);
                if (tb[READ_STREAM])
                        stream = blobmsg_get_bool(tb[READ_STREAM]);
+               if (tb[READ_ONESHOT])
+                       oneshot = blobmsg_get_bool(tb[READ_ONESHOT]);
        }
 
        l = log_list(count, NULL);
@@ -124,6 +137,11 @@ read_log(struct ubus_context *ctx, struct ubus_object *obj,
                        if (ret < 0)
                                break;
                }
+
+               if (oneshot) {
+                       cl->s.stream.notify_write = client_notify_write;
+                       client_notify_write(&cl->s.stream, 0);
+               }
        } else {
                blob_buf_init(&b, 0);
                c = blobmsg_open_array(&b, "log");