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60 lines
2.1 KiB
C
60 lines
2.1 KiB
C
/* sendfile -- copy data directly from one file descriptor to another
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Copyright (C) 2002 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sys/sendfile.h>
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#include <hurd.h>
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#include <hurd/fd.h>
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#include <sys/mman.h>
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/* Send COUNT bytes from file associated with IN_FD starting at OFFSET to
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descriptor OUT_FD. */
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ssize_t
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sendfile64 (int out_fd, int in_fd, off64_t *offset, size_t count)
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{
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/* We just do a vanilla io_read followed by a vanilla io_write here.
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In theory the IN_FD filesystem can return us out-of-line data that
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we then send out-of-line to the OUT_FD filesystem and no copying
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takes place until those pages need to be flushed or packaged by
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that filesystem (e.g. packetized by a network socket). However,
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we momentarily consume COUNT bytes of our local address space,
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which might blow if it's huge or address space is real tight. */
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char *data = 0;
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size_t datalen = 0;
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error_t err = HURD_DPORT_USE (in_fd,
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__io_read (port, &data, &datalen,
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offset ? *offset : (off_t) -1,
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count));
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if (err == 0)
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{
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size_t nwrote;
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if (datalen == 0)
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return 0;
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err = HURD_DPORT_USE (out_fd, __io_write (port, data, datalen,
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(off_t) -1, &nwrote));
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munmap (data, datalen);
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if (err == 0)
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{
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if (offset)
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*offset += datalen;
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return nwrote;
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}
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}
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return __hurd_fail (err);
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}
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