120 lines
3.7 KiB
C++
120 lines
3.7 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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ioleast.cpp
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Versions of {,p}{read,write} that don't return until it has returned as much
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data as requested, end of file, or an error occurs. This is sometimes needed
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as read(2) and write(2) is not always guaranteed to fill up the entire
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buffer or write it all.
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*******************************************************************************/
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#include <sys/types.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <errno.h>
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#ifndef EEOF
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#define EEOF EIO
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#endif
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extern "C" size_t readleast(int fd, void* buf, size_t least, size_t max)
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{
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ssize_t amount = read(fd, buf, max);
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if ( amount < 0 ) { return 0; }
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if ( least && !amount ) { errno = EEOF; return 0; }
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if ( (size_t) amount < least )
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{
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void* nextbuf = (uint8_t*) buf + amount;
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size_t nextleast = least - amount;
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size_t nextmax = max - amount;
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amount += readleast(fd, nextbuf, nextleast, nextmax);
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}
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return amount;
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}
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extern "C" size_t readall(int fd, void* buf, size_t count)
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{
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return readleast(fd, buf, count, count);
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}
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extern "C" size_t preadleast(int fd, void* buf, size_t least, size_t max,
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off_t off)
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{
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ssize_t amount = pread(fd, buf, max, off);
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if ( amount < 0 ) { return 0; }
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if ( least && !amount ) { errno = EEOF; return 0; }
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if ( (size_t) amount < least )
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{
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void* nextbuf = (uint8_t*) buf + amount;
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size_t nextleast = least - amount;
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size_t nextmax = max - amount;
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off_t nextoff = off + amount;
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amount += preadleast(fd, nextbuf, nextleast, nextmax, nextoff);
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}
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return amount;
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}
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extern "C" size_t preadall(int fd, void* buf, size_t count, off_t off)
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{
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return preadleast(fd, buf, count, count, off);
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}
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extern "C" size_t writeleast(int fd, const void* buf, size_t least, size_t max)
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{
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ssize_t amount = write(fd, buf, max);
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if ( amount < 0 ) { return 0; }
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if ( least && !amount ) { errno = EEOF; return 0; }
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if ( (size_t) amount < least )
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{
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const void* nextbuf = (const uint8_t*) buf + amount;
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size_t nextleast = least - amount;
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size_t nextmax = max - amount;
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amount += writeleast(fd, nextbuf, nextleast, nextmax);
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}
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return amount;
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}
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extern "C" size_t writeall(int fd, const void* buf, size_t count)
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{
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return writeleast(fd, buf, count, count);
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}
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extern "C" size_t pwriteleast(int fd, const void* buf, size_t least, size_t max,
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off_t off)
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{
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ssize_t amount = pwrite(fd, buf, max, off);
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if ( amount < 0 ) { return 0; }
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if ( least && !amount ) { errno = EEOF; return 0; }
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if ( (size_t) amount < least )
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{
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const void* nextbuf = (const uint8_t*) buf + amount;
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size_t nextleast = least - amount;
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size_t nextmax = max - amount;
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off_t nextoff = off + amount;
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amount += pwriteleast(fd, nextbuf, nextleast, nextmax, nextoff);
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}
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return amount;
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}
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extern "C" size_t pwriteall(int fd, const void* buf, size_t count, off_t off)
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{
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return pwriteleast(fd, buf, count, count, off);
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}
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