busybox/libbb/copyfd.c

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/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <errno.h>
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#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "libbb.h"
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#if BUFSIZ < 4096
#undef BUFSIZ
#define BUFSIZ 4096
#endif
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static ssize_t bb_full_fd_action(int src_fd, int dst_fd, size_t size)
{
int status = -1;
size_t total = 0;
RESERVE_CONFIG_BUFFER(buffer,BUFSIZ);
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if (src_fd < 0) goto out;
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while (!size || total < size) {
ssize_t wr, rd;
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rd = safe_read(src_fd, buffer,
(!size || size - total > BUFSIZ) ? BUFSIZ : size - total);
if (rd > 0) {
/* A -1 dst_fd means we need to fake it... */
wr = (dst_fd < 0) ? rd : full_write(dst_fd, buffer, rd);
if (wr < rd) {
bb_perror_msg(bb_msg_write_error);
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break;
}
total += wr;
if (total == size) status = 0;
} else if (rd < 0) {
bb_perror_msg(bb_msg_read_error);
break;
} else if (rd == 0) {
/* All done. */
status = 0;
break;
}
}
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out:
RELEASE_CONFIG_BUFFER(buffer);
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return status ? status : (ssize_t)total;
}
int bb_copyfd_size(int fd1, int fd2, const off_t size)
{
if (size) {
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return bb_full_fd_action(fd1, fd2, size);
}
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return 0;
}
int bb_copyfd_eof(int fd1, int fd2)
{
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return bb_full_fd_action(fd1, fd2, 0);
}