1 /* vi: set sw=4 ts=4: */
2 /*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
6 *
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
8 */
9
10 #include "libbb.h"
11 #if ENABLE_FEATURE_USE_SENDFILE
12 # include <sys/sendfile.h>
13 #else
14 # define sendfile(a,b,c,d) (-1)
15 #endif
16
17 /*
18 * We were using 0x7fff0000 as sendfile chunk size, but it
19 * was seen to cause largish delays when user tries to ^C a file copy.
20 * Let's use a saner size.
21 * Note: needs to be >= max(CONFIG_FEATURE_COPYBUF_KB),
22 * or else "copy to eof" code will use neddlesly short reads.
23 */
24 #define SENDFILE_BIGBUF (16*1024*1024)
25
26 /* Used by NOFORK applets (e.g. cat) - must not use xmalloc.
27 * size < 0 means "ignore write errors", used by tar --to-command
28 * size = 0 means "copy till EOF"
29 */
bb_full_fd_action(int src_fd,int dst_fd,off_t size)30 static off_t bb_full_fd_action(int src_fd, int dst_fd, off_t size)
31 {
32 int status = -1;
33 off_t total = 0;
34 bool continue_on_write_error = 0;
35 ssize_t sendfile_sz;
36 #if CONFIG_FEATURE_COPYBUF_KB > 4
37 char *buffer = buffer; /* for compiler */
38 int buffer_size = 0;
39 #else
40 char buffer[CONFIG_FEATURE_COPYBUF_KB * 1024];
41 enum { buffer_size = sizeof(buffer) };
42 #endif
43
44 if (size < 0) {
45 size = -size;
46 continue_on_write_error = 1;
47 }
48
49 if (src_fd < 0)
50 goto out;
51
52 sendfile_sz = !ENABLE_FEATURE_USE_SENDFILE
53 ? 0
54 : SENDFILE_BIGBUF;
55 if (!size) {
56 size = SENDFILE_BIGBUF;
57 status = 1; /* copy until eof */
58 }
59
60 while (1) {
61 ssize_t rd;
62
63 if (sendfile_sz) {
64 rd = sendfile(dst_fd, src_fd, NULL,
65 size > sendfile_sz ? sendfile_sz : size);
66 if (rd >= 0)
67 goto read_ok;
68 sendfile_sz = 0; /* do not try sendfile anymore */
69 }
70 #if CONFIG_FEATURE_COPYBUF_KB > 4
71 if (buffer_size == 0) {
72 if (size > 0 && size <= 4 * 1024)
73 goto use_small_buf;
74 /* We want page-aligned buffer, just in case kernel is clever
75 * and can do page-aligned io more efficiently */
76 buffer = mmap(NULL, CONFIG_FEATURE_COPYBUF_KB * 1024,
77 PROT_READ | PROT_WRITE,
78 MAP_PRIVATE | MAP_ANON,
79 /* ignored: */ -1, 0);
80 buffer_size = CONFIG_FEATURE_COPYBUF_KB * 1024;
81 if (buffer == MAP_FAILED) {
82 use_small_buf:
83 buffer = alloca(4 * 1024);
84 buffer_size = 4 * 1024;
85 }
86 }
87 #endif
88 rd = safe_read(src_fd, buffer,
89 size > buffer_size ? buffer_size : size);
90 if (rd < 0) {
91 bb_perror_msg(bb_msg_read_error);
92 break;
93 }
94 read_ok:
95 if (!rd) { /* eof - all done */
96 status = 0;
97 break;
98 }
99 /* dst_fd == -1 is a fake, else... */
100 if (dst_fd >= 0 && !sendfile_sz) {
101 ssize_t wr = full_write(dst_fd, buffer, rd);
102 if (wr < rd) {
103 if (!continue_on_write_error) {
104 bb_perror_msg(bb_msg_write_error);
105 break;
106 }
107 dst_fd = -1;
108 }
109 }
110 total += rd;
111 if (status < 0) { /* if we aren't copying till EOF... */
112 size -= rd;
113 if (!size) {
114 /* 'size' bytes copied - all done */
115 status = 0;
116 break;
117 }
118 }
119 }
120 out:
121
122 if (buffer_size > 4 * 1024)
123 munmap(buffer, buffer_size);
124 return status ? -1 : total;
125 }
126
127
128 #if 0
129 void FAST_FUNC complain_copyfd_and_die(off_t sz)
130 {
131 if (sz != -1)
132 bb_error_msg_and_die("short read");
133 /* if sz == -1, bb_copyfd_XX already complained */
134 xfunc_die();
135 }
136 #endif
137
bb_copyfd_size(int fd1,int fd2,off_t size)138 off_t FAST_FUNC bb_copyfd_size(int fd1, int fd2, off_t size)
139 {
140 if (size) {
141 return bb_full_fd_action(fd1, fd2, size);
142 }
143 return 0;
144 }
145
bb_copyfd_exact_size(int fd1,int fd2,off_t size)146 void FAST_FUNC bb_copyfd_exact_size(int fd1, int fd2, off_t size)
147 {
148 off_t sz = bb_copyfd_size(fd1, fd2, size);
149 if (sz == (size >= 0 ? size : -size))
150 return;
151 if (sz != -1)
152 bb_error_msg_and_die("short read");
153 /* if sz == -1, bb_copyfd_XX already complained */
154 xfunc_die();
155 }
156
bb_copyfd_eof(int fd1,int fd2)157 off_t FAST_FUNC bb_copyfd_eof(int fd1, int fd2)
158 {
159 return bb_full_fd_action(fd1, fd2, 0);
160 }
161