1 /* sendfile -- copy data directly from one file descriptor to another
2 Copyright (C) 2002-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <sys/sendfile.h>
20 #include <hurd.h>
21 #include <hurd/fd.h>
22 #include <sys/mman.h>
23
24 /* Send COUNT bytes from file associated with IN_FD starting at OFFSET to
25 descriptor OUT_FD. */
26 ssize_t
__sendfile64(int out_fd,int in_fd,off64_t * offset,size_t count)27 __sendfile64 (int out_fd, int in_fd, off64_t *offset, size_t count)
28 {
29 /* We just do a vanilla io_read followed by a vanilla io_write here.
30 In theory the IN_FD filesystem can return us out-of-line data that
31 we then send out-of-line to the OUT_FD filesystem and no copying
32 takes place until those pages need to be flushed or packaged by
33 that filesystem (e.g. packetized by a network socket). However,
34 we momentarily consume COUNT bytes of our local address space,
35 which might blow if it's huge or address space is real tight. */
36
37 char *data = 0;
38 size_t datalen = 0;
39 error_t err = HURD_DPORT_USE (in_fd,
40 __io_read (port, &data, &datalen,
41 offset ? *offset : (off_t) -1,
42 count));
43 if (err == 0)
44 {
45 size_t nwrote;
46 if (datalen == 0)
47 return 0;
48 err = HURD_DPORT_USE (out_fd, __io_write (port, data, datalen,
49 (off_t) -1, &nwrote));
50 __munmap (data, datalen);
51 if (err == 0)
52 {
53 if (offset)
54 *offset += datalen;
55 return nwrote;
56 }
57 }
58 return __hurd_fail (err);
59 }
60 strong_alias (__sendfile64, sendfile64)
61