busybox/libbb/full_read.c

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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <stdio.h>
#include <unistd.h>
#include "libbb.h"
/*
* Read all of the supplied buffer from a file.
* This does multiple reads as necessary.
* Returns the amount read, or -1 on an error.
* A short read is returned on an end of file.
*/
ssize_t full_read(int fd, void *buf, size_t len)
{
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ssize_t cc;
ssize_t total;
total = 0;
while (len > 0) {
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cc = safe_read(fd, buf, len);
if (cc < 0)
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return cc; /* read() returns -1 on failure. */
if (cc == 0)
break;
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buf = ((char *)buf) + cc;
total += cc;
len -= cc;
}
return total;
}