aboutsummaryrefslogtreecommitdiff
path: root/libbb/copyfd.c
blob: 82622c06f2309cd693e93ec119a89ba97ee68425 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/* 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 "libbb.h"

/* 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;
#if CONFIG_FEATURE_COPYBUF_KB <= 4
	char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];
	enum { buffer_size = sizeof(buffer) };
#else
	char *buffer;
	int buffer_size;
#endif

	if (size < 0) {
		size = -size;
		continue_on_write_error = 1;
	}

#if CONFIG_FEATURE_COPYBUF_KB > 4
	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

	if (src_fd < 0)
		goto out;

	if (!size) {
		size = buffer_size;
		status = 1; /* copy until eof */
	}

	while (1) {
		ssize_t rd;

		rd = safe_read(src_fd, buffer, size > buffer_size ? buffer_size : size);

		if (!rd) { /* eof - all done */
			status = 0;
			break;
		}
		if (rd < 0) {
			bb_perror_msg(bb_msg_read_error);
			break;
		}
		/* dst_fd == -1 is a fake, else... */
		if (dst_fd >= 0) {
			ssize_t wr = full_write(dst_fd, buffer, rd);
			if (wr < rd) {
				if (!continue_on_write_error) {
					bb_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:

#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_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);
}