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