Re: [patch] netlink.7: srcfix Change buffer size in example code about reading netlink message.

Since there doesn't seem to be a define one could use in the user space 
linux/netlink.h (?), but there are comments in the example code in the 
manpage, how about also including a brief comment to the effect that 
using 8192 bytes will avoid message truncation problems on platforms 
with a large PAGE_SIZE?

/* avoid msg truncation on > 4096 byte PAGE_SIZE platforms */

or something like that.

rick jones
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On 11/14/2016 11:36 PM, Rick Jones wrote:

quoted

Lets change the example so others don't propagate the problem further.

Signed-off-by David Wilder [off-list ref]

--- man7/netlink.7.orig 2016-11-14 13:30:36.522101156 -0800
+++ man7/netlink.7      2016-11-14 13:30:51.002086354 -0800

@@ -511,7 +511,7 @@
 .in +4n
 .nf
 int len;
-char buf[4096];
+char buf[8192];

Since there doesn't seem to be a define one could use in the user space 
linux/netlink.h (?), but there are comments in the example code in the 
manpage, how about also including a brief comment to the effect that 
using 8192 bytes will avoid message truncation problems on platforms 
with a large PAGE_SIZE?

/* avoid msg truncation on > 4096 byte PAGE_SIZE platforms */

or something like that.

Thanks for the suggestion, Rick. Done!

Cheers,

Michael


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Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/