busybox

/* 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 source tree.

 */

​

#include "libbb.h"

#if ENABLE_FEATURE_USE_SENDFILE

# include <sys/sendfile.h>

#else

# define sendfile(a,b,c,d) (-1)

#endif

​

/*

 * We were using 0x7fff0000 as sendfile chunk size, but it

 * was seen to cause largish delays when user tries to ^C a file copy.

 * Let's use a saner size.

 * Note: needs to be >= max(CONFIG_FEATURE_COPYBUF_KB),

 * or else "copy to eof" code will use neddlesly short reads.

 */

#define SENDFILE_BIGBUF (16*1024*1024)

​

/* Used by NOFORK applets (e.g. cat) - must not use xmalloc.

 * size < 0 means "ignore write errors", used by tar --to-command

 * size = 0 means "copy till EOF"

 */

static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)

{

    int status = -1;

    off_t total = 0;

    bool continue_on_write_error = 0;

    ssize_t sendfile_sz;

#if CONFIG_FEATURE_COPYBUF_KB > 4

    char *buffer = buffer; /* for compiler */

    int buffer_size = 0;

#else

    char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];

    enum { buffer_size = sizeof(buffer) };

#endif

​

    if (size < 0) {

        size = -size;

        continue_on_write_error = 1;

    }

​

    if (src_fd < 0)

        goto out;

​

    sendfile_sz = !ENABLE_FEATURE_USE_SENDFILE

        ? 0

        : SENDFILE_BIGBUF;

    if (!size) {

        size = SENDFILE_BIGBUF;

        status = 1; /* copy until eof */

    }

​

    while (1) {

        ssize_t rd;

​

        if (sendfile_sz) {