Subject: new positional i/o system calls
To: None <current-users@NetBSD.ORG>
From: Jason Thorpe <>
List: current-users
Date: 06/30/1998 12:37:50
Hi folks...

I have just added new positional I/O system calls, per XPG4.2, pread(2)
and pwrite(2).  These are like read(2) and write(2) except they also
take an absolute offset at which to begin the I/O.  They do not modify
the file pointer.

I also added preadv(2) and pwritev(2), like readv(2) and writev(2), but
also taking a positional argument.

SVR4 has had these for a while, and database applications like to use
them because they eliminate 50% of the system calls for completely
random access to a file.

I'm going to change some of NetBSD's code to use the new system calls
later today so that people will have some example usage, in addition
to the manual page.


Jason R. Thorpe                             
NASA Ames Research Center                            Home: +1 408 866 1912
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