svn commit: r283916 - in stable: 10/lib/libc/sys 8/lib/libc/sys 9/lib/libc/sys
jhb at FreeBSD.org
Tue Jun 2 15:12:35 UTC 2015
Date: Tue Jun 2 15:12:33 2015
New Revision: 283916
Various updates to the ftruncate(2) documentation:
- Note that ftruncate(2) can operate on shared memory objects and cross
- Note that ftruncate(2) does not change the file position pointer (aka
seek pointer) of the file descriptor.
- ftruncate(2) will fail with EINVAL for all sorts of other fd types than
just sockets, so instead note that it fails for all but regular files and
shared memory objects.
- Note that ftruncate(2) also appeared in 4.2BSD along with truncate(2).
(Or at least the manpage for both appeared in 4.2, I did not check the
kernel code itself to see if either predated 4.2.)
stable/8/lib/libc/ (props changed)
stable/8/lib/libc/sys/ (props changed)
Changes in other areas also in this revision:
stable/10/ (props changed)
stable/9/lib/libc/ (props changed)
stable/9/lib/libc/sys/ (props changed)
--- stable/8/lib/libc/sys/truncate.2 Tue Jun 2 15:09:33 2015 (r283915)
+++ stable/8/lib/libc/sys/truncate.2 Tue Jun 2 15:12:33 2015 (r283916)
@@ -28,7 +28,7 @@
.\" @(#)truncate.2 8.1 (Berkeley) 6/4/93
-.Dd December 13, 2006
+.Dd May 4, 2015
.Dt TRUNCATE 2
@@ -60,9 +60,18 @@ is lost.
If the file was smaller than this size,
it will be extended as if by writing bytes
with the value zero.
-.Fn ftruncate ,
-the file must be open for writing.
+system call causes the file or shared memory object backing the file descriptor
+to be truncated or extended to
+bytes in size.
+The file descriptor must be a valid file descriptor open for writing.
+The file position pointer associated with the file descriptor
+will not be modified.
.Sh RETURN VALUES
If the file to be modified is not a directory or
@@ -129,7 +138,7 @@ is not a valid descriptor.
-references a socket, not a file.
+references a file descriptor that is not a regular file or shared memory object.
.It Bq Er EINVAL
@@ -138,11 +147,14 @@ is not open for writing.
.Sh SEE ALSO
.Xr chflags 2 ,
-.Xr open 2
+.Xr open 2 ,
+.Xr shm_open 2
-system call appeared in
+system calls appeared in
.Bx 4.2 .
These calls should be generalized to allow ranges
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