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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 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 needlesly 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) {
/* dst_fd == -1 is a fake, else... */
if (dst_fd >= 0) {
rd = sendfile(dst_fd, src_fd, NULL,
size > sendfile_sz ? sendfile_sz : size);
if (rd >= 0)
goto read_ok;
}
sendfile_sz = 0; /* do not try sendfile anymore */
}
#if CONFIG_FEATURE_COPYBUF_KB > 4
if (buffer_size == 0) {
if (size > 0 && size <= 4 * 1024)
goto use_small_buf;
/* We want page-aligned buffer, just in case kernel is clever
* and can do page-aligned io more efficiently */
buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON,
/* ignored: */ -1, 0);
buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024;
if (buffer == MAP_FAILED) {
use_small_buf:
buffer = alloca(4 * 1024);
buffer_size = 4 * 1024;
}
}
#endif
rd = safe_read(src_fd, buffer,
size > buffer_size ? buffer_size : size);
if (rd < 0) {
bb_simple_perror_msg(bb_msg_read_error);
break;
}
read_ok:
if (!rd) { /* eof - all done */
status = 0;
break;
}
/* dst_fd == -1 is a fake, else... */
if (dst_fd >= 0 && !sendfile_sz) {
ssize_t wr = full_write(dst_fd, buffer, rd);
if (wr < rd) {
if (!continue_on_write_error) {
bb_simple_perror_msg(bb_msg_write_error);
break;
}
dst_fd = -1;
}
}
total += rd;
if (status < 0) { /* if we aren't copying till EOF... */
size -= rd;
if (!size) {
/* 'size' bytes copied - all done */
status = 0;
break;
}
}
}
out:
/* some environments don't have munmap(), hide it in #if */
#if CONFIG_FEATURE_COPYBUF_KB > 4
if (buffer_size > 4 * 1024)
munmap(buffer, buffer_size);
#endif
return status ? -1 : total;
}
#if 0
void FAST_FUNC complain_copyfd_and_die(off_t sz)
{
if (sz != -1)
bb_error_msg_and_die("short read");
/* if sz == -1, bb_copyfd_XX already complained */
xfunc_die();
}
#endif
off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size)
{
if (size) {
return bb_full_fd_action(fd1, fd2, size);
}
return 0;
}
void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size)
{
off_t sz = bb_copyfd_size(fd1, fd2, size);
if (sz == (size >= 0 ? size : -size))
return;
if (sz != -1)
bb_simple_error_msg_and_die("short read");
/* if sz == -1, bb_copyfd_XX already complained */
xfunc_die();
}
off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2)
{
return bb_full_fd_action(fd1, fd2, 0);
}
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