busybox/libbb/copyfd.c

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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 1999,2000,2001 by Erik Andersen <andersee@debian.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <unistd.h>
#include <string.h>
#include <errno.h>
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#include "busybox.h"
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#if BUFSIZ < 4096
#undef BUFSIZ
#define BUFSIZ 4096
#endif
/* If chunksize is 0 copy until EOF */
extern int bb_copyfd(int fd1, int fd2, const off_t chunksize)
{
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ssize_t nread;
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size_t size;
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off_t remaining;
RESERVE_CONFIG_BUFFER(buffer,BUFSIZ);
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remaining = size = BUFSIZ;
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if (chunksize) {
remaining = chunksize;
}
do {
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if (size > remaining) {
size = remaining;
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}
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if ((nread = safe_read(fd1, buffer, size)) > 0) {
if (bb_full_write(fd2, buffer, nread) < 0) {
bb_perror_msg(bb_msg_write_error); /* match Read error below */
break;
}
if (chunksize && ((remaining -= nread) == 0)) {
return 0;
}
} else if (!nread) {
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if (chunksize) {
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bb_error_msg("Unable to read all data");
break;
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}
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return 0;
} else { /* nread < 0 */
bb_perror_msg("Read error"); /* match bb_msg_write_error above */
break;
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}
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} while (1);
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return -1;
}