From 7d9337ed77b08ee691568172e7c074d2b5d8e15e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Thu, 23 Jun 2022 12:56:34 +0200 Subject: [PATCH] sd-netlink: allow sd_netlink_message_read() to be used for union types Before, sd_netlink_message_read() expected to fill a buffer completely, and would return -EIO if the attribute being read was shorter than the buffer. This means that the function can be used to "peek" into attributes (by specifying a short buffer to just read part of the attribute), but cannot be used to read something into a union without knowing beforehand which specific field in the union is being filled. That latter operation seems more useful (messages are short, so we don't really need to do partial reads), so let's allow reads that don't fill the output buffer completely. --- src/libsystemd/sd-netlink/netlink-message.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/libsystemd/sd-netlink/netlink-message.c b/src/libsystemd/sd-netlink/netlink-message.c index dafc16f258..34b4c23bd5 100644 --- a/src/libsystemd/sd-netlink/netlink-message.c +++ b/src/libsystemd/sd-netlink/netlink-message.c @@ -741,11 +741,11 @@ _public_ int sd_netlink_message_read(sd_netlink_message *m, unsigned short type, if (r < 0) return r; - if ((size_t) r < size) - return -EIO; + if ((size_t) r > size) + return -ENOBUFS; if (data) - memcpy(data, attr_data, size); + memcpy(data, attr_data, r); return r; }