PR/59054 CVS commit: [netbsd-10] src/share/man/man3

["Martin Husemann" <martin%netbsd.org@localhost>]

The following reply was made to PR lib/59054; it has been noted by GNATS.

From: "Martin Husemann" <martin%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/59054 CVS commit: [netbsd-10] src/share/man/man3
Date: Wed, 21 Oct 2026 18:39:05 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Wed Oct 21 18:39:05 UTC 2026
 
 Modified Files:
 	src/share/man/man3 [netbsd-10]: CMSG_DATA.3
 
 Log Message:
 Pull up following revision(s) (requested by riastradh in ticket #1368):
 
 	share/man/man3/CMSG_DATA.3: revision 1.4
 	share/man/man3/CMSG_DATA.3: revision 1.5
 	share/man/man3/CMSG_DATA.3: revision 1.6
 
 cmsg(3): Don't use malloc in example.
 
 Since CMSG_SPACE (and CMSG_LEN) is required to expand to an integer
 constant expression by POSIX, and it does in NetBSD as of 2012, there
 is no reason to use malloc here -- we can just allocate the buffer on
 the stack without tripping over variable-length arrays.
 
 PR lib/59054: cmsg(3) uses malloc(3) unnecessarily
 
 cmsg(3): Handle as many descriptors as the sender sends in example.
 
 Due to a quirk of alignment, sizing the control buffer for
 CMSG_SPACE(sizeof(int)) does not guarantee at most one file
 descriptor fits in the buffer -- so if there is a chance the sender
 may send more than one descriptor, the receiver has to loop over all
 of them to avoid leaks.
 
 Prompted by:
 PR lib/59054: cmsg(3) uses malloc(3) unnecessarily
 
 cmsg(3): Clarify guarantees about CMSG_SPACE/LEN constancy.
 
 Add some line breaks while here to break up walls of text so it's
 easier to compare the two paragraphs and see how CMSG_SPACE is meant
 for struct msghdr::msg_controllen and CMSG_LEN is meant for struct
 cmsghdr::cmsg_len.
 
 PR lib/59054: cmsg(3) uses malloc(3) unnecessarily
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.3 -r1.3.26.1 src/share/man/man3/CMSG_DATA.3
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.