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71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/* safe-read.c -- an interface to read that retries after interrupts
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Copyright (C) 1993, 1994, 1998, 2002 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <sys/types.h>
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#include <stdlib.h>
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#include <errno.h>
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#ifndef errno
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extern int errno;
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#endif
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#include "safe-read.h"
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/* Read LEN bytes at PTR from descriptor DESC, retrying if interrupted.
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Return the actual number of bytes read, zero upon EOF,
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or SAFE_READ_ERROR upon error.
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Abort if LEN is SAFE_READ_ERROR (aka `(size_t) -1').
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WARNING: although both LEN and the return value are of type size_t,
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the range of the return value is restricted -- by virtue of being
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returned from read(2) -- and will never be larger than SSIZE_MAX,
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with the exception of SAFE_READ_ERROR, of course.
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So don't test `safe_read (..., N) == N' unless you're sure that
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N <= SSIZE_MAX. */
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size_t
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safe_read (int desc, void *ptr, size_t len)
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{
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ssize_t n_chars;
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if (len == SAFE_READ_ERROR)
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abort ();
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if (len == 0)
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return len;
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#ifdef EINTR
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do
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{
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n_chars = read (desc, ptr, len);
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}
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while (n_chars < 0 && errno == EINTR);
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#else
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n_chars = read (desc, ptr, len);
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#endif
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return n_chars;
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}
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