44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
/*
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* Copyright (c) 2012, 2013, 2015 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* ioleast/pwriteleast.c
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* Writes at least as much data as requested or more at the given offset.
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*/
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#include <assert.h>
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#include <errno.h>
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#include <ioleast.h>
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#include <stdint.h>
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#include <unistd.h>
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size_t pwriteleast(int fd, const void* buf_ptr, size_t least, size_t max, off_t off)
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{
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assert(least <= max);
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const unsigned char* buf = (const unsigned char*) buf_ptr;
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size_t done = 0;
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do
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{
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ssize_t amount = pwrite(fd, buf + done, max - done, off + done);
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if ( amount < 0 )
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return done;
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if ( !amount && done < least )
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return errno = EEOF, done;
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if ( !amount )
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break;
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done += amount;
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} while ( done < least );
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return done;
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}
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