man/io_uring_prep_ftruncate: Add the new ftruncate command

Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com>

man/io_uring_prep_ftruncate.3

@@ -0,0 +1,48 @@
+.\" Copyright (C) 2024 Tony Solomonik <tony.solomonik@gmail.com>
+.\"
+.\" SPDX-License-Identifier: LGPL-2.0-or-later
+.\"
+.TH io_uring_prep_ftruncate 3 "January 23, 2024" "liburing-2.6" "liburing Manual"
+.SH NAME
+io_uring_prep_ftruncate \- prepare an ftruncate request
+.SH SYNOPSIS
+.nf
+.B #include <liburing.h>
+.PP
+.BI "void io_uring_prep_ftruncate(struct io_uring_sqe *" sqe ","
+.BI "                             int " fd ","
+.BI "                             loff_t " len ");"
+.fi
+.SH DESCRIPTION
+.PP
+The
+.BR io_uring_prep_ftruncate (3)
+function prepares an ftruncate request. The submission queue entry
+.I sqe
+is setup to use the file descriptor
+.I fd
+that should get truncated to the length indicated by the
+.I len
+argument.
+
+.SH RETURN VALUE
+None
+.SH ERRORS
+The CQE
+.I res
+field will contain the result of the operation. See the related man page for
+details on possible values. Note that where synchronous system calls will return
+.B -1
+on failure and set
+.I errno
+to the actual error value, io_uring never uses
+.IR errno .
+Instead it returns the negated
+.I errno
+directly in the CQE
+.I res
+field.
+.SH SEE ALSO
+.BR io_uring_get_sqe (3),
+.BR io_uring_submit (3),
+.BR ftruncate (2),