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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2018-07-15 10:22:58 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2018-07-15 10:33:32 +0200 |
| commit | c0e56ed687f4bae9adc2af19119917fbd8f552d2 (patch) | |
| tree | 4b848d1c23f7242216ed568f4a0ea866578d1d93 /man7/unix.7 | |
| parent | 4564dd1feee2118e34849a4f8530b75ceb96a78a (diff) | |
| download | man-pages-c0e56ed687f4bae9adc2af19119917fbd8f552d2.tar.gz | |
unix.7: Clarify treatment of incoming ancillary data if 'msg_control' is NULL
If no buffer is supplied for incoming ancillary data, then
the data is lost.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Diffstat (limited to 'man7/unix.7')
| -rw-r--r-- | man7/unix.7 | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/man7/unix.7 b/man7/unix.7 index 17a10d3db0..07f9e9bf30 100644 --- a/man7/unix.7 +++ b/man7/unix.7 @@ -447,12 +447,20 @@ When sending ancillary data with .BR sendmsg (2), only one item of each of the above types may be included in the sent message. .PP -If the space allocated for receiving incoming ancillary data is too small, +If the space allocated for receiving incoming ancillary data is too small then the ancillary data is truncated to the number of headers that will fit in the supplied buffer (or, in the case of an .BR SCM_RIGHTS file descriptor list, the list of file descriptors may be truncated). -In the event of such truncation, the +If no buffer is provided for incoming ancillary data (i.e., the +.I msg_control +field of the +.I msghdr +structure supplied to +.BR recvmsg (2) +is NULL), +then the incoming ancillary data is discarded. +In both of these cases, the .BR MSG_CTRUNC flag will be set in the .I msg.msg_flags |